Remediation of antibiotics-contaminated wastewater through photocatalytic techniques: Implications for SDGs that support a more sustainable future and a healthy planet

Pharmaceuticals are compounds used to restore, rectify, or modify organic activities as well as for the diagnosis, treatment, or prevention of disease (Younas et al. 2020). Medicinal plant and mineral records go back to the ancient Mediterranean, Hindu, and Chinese civilizations. In their line of work, ancient Greek physicians like Galen employed a wide range of medications. Pharmaceutical practice started to grow quickly in the 16th century AD, when Western medicine was emerging from the long slumber of the Dark and Middle Ages (Ndubuisi 2022). The first pharmacopoeia, or book of medications and how they were prepared, was published in Germany in 1546. The Society of Apothecaries, which was founded in London in 1617, is credited with starting the pharmacy profession. Pharmaceuticals are often categorized by chemical group, therapeutic purpose, and how they function in the body (pharmacological impact), according to Saxena et al. (2022). Quinine, nicotine, cocaine, atropine, morphine, and other natural compounds (plants) were the first pure medications known as alkaloids. Hormone-containing glandular extracts, such as insulin used to treat diabetes, are examples of drugs derived from animals. Among the other significant medications made from natural materials are steroid hormones, vaccinations, human blood–plasma fractions, and antibiotics. Nowadays, vitamins are frequently produced in a laboratory, as opposed to their previous natural source (Mackenzie & Jeggo 2019).

The pharmaceutical industry is made up of both public and private businesses that are engaged in the research, development, and production of pharmaceuticals (Mackenzie & Jeggo 2019; Osterhaus et al. 2020). The 19th century saw the development of large-scale manufacturing methods and the ability to isolate and purify medicinal substances, which laid the groundwork for the current era of drug research and development. The 20th century saw a significant decline in the prevalence and severity of diseases including syphilis, poliomyelitis, and typhoid fever as knowledge of biology and chemistry increased. While many medications, such as morphine and quinine, are derived from plants, other medications are found and made using methods such as combinatorial chemistry and recombinant DNA technology (González et al. 2022). Medical advancement has benefited immensely from the pharmaceutical business, since numerous novel medications have been identified and manufactured in industrial laboratories. Achieving regulatory approval, finding novel medication targets, and improving drug discovery procedures are some of the obstacles the pharmaceutical business must overcome to promote disease control and elimination. While the development of pharmaceuticals dates back centuries, the recent rise of pharmaceutical pollutants, particularly antibiotics, in water systems has become an urgent environmental issue. Thus, the pharmaceutical industry has been paying more and more attention lately to worries about the presence and fate of raw materials, solvents, intermediates, and active pharmaceutical ingredients (APIs) in water and wastewater (Martin et al. 2019). Particularly in the proximity of pharmaceutical industrial zones, pharmaceutical effluents have a direct or indirect impact on the environment and human health. Water samples ranging from mg/L to μg/L have been shown to include several pharmaceutical chemicals, such as steroids, hormones, antidepressants, antihypertensives, antibiotics, and contraceptives (Zaied et al. 2020). Despite being extremely small, the amounts found are extremely harmful to aquatic, animal, and human life.

The accumulation of these pharmaceuticals in wastewater poses significant ecological and human health risks. It has been reported that humans and aquatic life may be at risk due to the numerous pharmaceutical contaminants (PCs) that are released into wastewater (Barakat et al. 2020). Even though their existence in drinking water has raised serious concerns, not much is known about their fate or how they affect the environment. Because of this, even at low concentrations, harmful pollutants are pushed inexorably up the food chain. The environment and human health are impacted by pharmaceutical effluents in both direct and indirect ways, particularly when these areas are close to pharmaceutical industries. Changes in raw materials, process technology, and industry operating methods can all lead to a reduction in waste at the point of generation (Alafif et al. 2019). While pharmaceutical substances are highly significant, they also discharge harmful pollutants into the environment. Groundwater storage, streams, and aquifers can receive pharmaceutical compounds, medications, and active pharmaceutical ingredients (APIs) from a variety of sources.

To protect the environment and living things from health risks, the content of pharmaceutical chemicals in pharmaceutical effluents emitted must be regularly monitored (Anjum et al. 2019). As a result, the active pharmaceutical compounds and other wastewater constituents cannot be completely removed from these waters using conventional wastewater treatment techniques such as activated sludge (Anjum et al. 2023). Therefore, before wastewater is finally released into the environment, it is crucial to eliminate PCs. Among many different forms of treatment, photocatalysis has received a lot of attention lately and is seen to be a promising technique for eliminating a range of environmental pollutants, including pharmaceutical wastes (Barakat et al. 2020). One of the cardinal goals of the Sustainable Development Goal (SDG) programs introduced by the United Nations is devotion to safe, clean water, and the environment, which are associated with wastewater management. To achieve the SDGs, the following must be taken into consideration: reduction in the level of contaminants, the treatment and recycling of treated water, and by-products recovery (Weststrate et al. 2019). Wastewater and contamination of groundwater results in lack of clean and safe water for human use, and it has attracted attention at different levels of both academia and governance, resulting in the objectives in line with the SDGs of the United Nations. This review focuses on the efficiency of photocatalytic techniques in degrading these pollutants from pharmaceutical wastewater, presenting it as a promising solution for environmental sustainability. Moreover, the implications of the study to the SDGs were detailed. This review is organized as follows: Sections 1 through 5 thoroughly introduce the topic, covering the Mechanism of Action (MoA) of pharmaceuticals, their environmental impact, and toxicity. The management of pharmaceuticals, including antibiotics and their metabolites, is discussed in Sections 6 and 7. Section 8 explores the treatment technologies for antibiotics, with a focus on photocatalysis. Sections 9 and 10 examine the current trends in the photocatalytic degradation of antibiotics and future considerations in this area. Finally, Section 11 highlights the relevance of the study to the SDGs.

Over 300 published articles were considered in this review with major contributions obtained from Publishers such as Elsevier (>60%) and SpringerNature (≈30%), while the remaining spread across Taylor and Francis, Multidisciplinary Digital Publishing Institute (MDPI), Wiley, Nature Portfolio, and chapters in open access books. The literature used was retrieved from Scopus, Web of Science, Google Scholar, and PubMed databases in December, 2023. The objective of the review was to evaluate the progress made towards achieving a safe environment, in line with the SDGs, by utilizing photocatalysis for the degradation of antibiotics in wastewater. The review encompassed both research studies and review articles. Articles published before 2016 were excluded in this study. Search terms such as antibiotics-contaminated water, photocatalysis, or photocalytic mechanisms or techniques, nanomaterials/nanoparticles, advanced oxidation processes (AOPs), and SDGs were employed in searching for articles from search engines.

The efficacy of pharmaceuticals is intricately linked with the mechanism by which therapeutic effects are related to the various biochemical processes in the human body system (Chauhan et al. 2021; Mezzelani & Regoli 2022). The MOA of pharmaceuticals involves the precise biochemical interactions that allow a medication to bring about its pharmacological effect (Levêque et al. 2010; Cui et al. 2017; Atanasov et al. 2021). Drugs operate in different ways to achieve their therapeutic effects. Comprehending these mechanisms is critical in the context of both the development of novel pharmaceuticals and the enhancement of already established therapeutic substances (Cui et al. 2017). These mechanisms encompass a broad range of interactions, spanning from the molecular to the cellular levels, exerting their influence on crucial elements such as receptors, enzymes, ion channels, and nucleic acids (Tirona 2011; Atanasov et al. 2021). However, there are still numerous drugs for which the MOA remains completely unknown, but there are now novel technologies to uncover our ignorance. Knowledge regarding drug MOA not only drives progress in the field of medical science but also empowers healthcare practitioners to make well-informed decisions when prescribing and dispensing drugs, thereby ultimately enhancing patient outcomes. It is imperative to know that 7% of approved drugs are purported to have no known primary target, and up to 18% lack a well-defined MOA.

Although there are a few exceptions, it is generally recognized that the efficacy of drugs depends on their ability to form a bond with a receptor. A receptor is an indispensable cellular constituent that facilitates the interaction between drugs, ultimately resulting in cellular reactions. These receptors can be identified as extracellular entities that play a role in transmitting signals, regulating ion flow, controlling intracellular enzymes, or targeting intra nuclear components (Li et al. 2014). Drug molecules require affinity to bind to a receptor and possess intrinsic activity to activate the receptor and induce downstream signalling. The classifications of drugs that demonstrate affinity towards receptors include agonists, partial agonists, antagonists, and inverse agonists (Rosenbaum et al. 2020). Multiple drugs exhibit their effects by binding to specific receptors located either on the cell surface or within the cytoplasm (Salahudeen & Nishtala 2017). These receptors usually include proteins that have an essential function in cell signalling.

Most drugs function by acting as agonists or antagonists at receptors that respond to chemical messengers, such as neurotransmitters. An agonist forms a connection with the receptor and triggers a cellular effect. By contrast, an antagonist is capable of binding to the same receptor, but it does not produce a response; instead, it inhibits the ability of a natural agonist to bind to that receptor (Pleuvry 2004). Agonists bind to receptors and activate them, mimicking the action of endogenous signalling molecules. Beta-2 Receptor Agonists are designed to imitate the inherent effects of epinephrine and norepinephrine hormones on the human body, thus categorized as sympathomimetics, with the aim of minimizing the activation of B2 receptors as much as possible to mitigate undesirable consequences (Abosamak & Shahin 2023). Their primary usage is centred around the management of respiratory disorders, particularly chronic obstructive pulmonary disease (COPD) and asthma (Abosamak & Shahin 2023). Antagonists demonstrate the capability to bind to receptors without activating them, thereby obstructing the interaction between endogenous signalling molecules and impeding the subsequent biological response (Raj & Raveendran 2019).

Many pharmaceutical substances function as inhibitors of enzymes that play a crucial role in facilitating the progression of disease processes (Davis 2020). Through the inhibition of certain enzymes, medications are capable of altering metabolic pathways and cellular processes. Enzyme inhibitors can either exhibit competitive behaviour, wherein they engage in competition with substrates to occupy the active site of the enzyme, or they can display non-competitive characteristics, binding to an alternate site on the enzyme (Craciunescu et al. 2021). Three categories of inhibitions, namely, competitive, non-competitive, and uncompetitive, are commonly utilized to elucidate the interaction between an inhibitor and a specific enzyme.

However, a comprehensive analysis of the modus operandi requires the scientist to also evaluate other possible inhibition occurrences, such as allosteric, partial, tight-binding, and time-dependent inhibition. For instance, neostigmine, a reversible cholinesterase inhibitor, is used to treat myasthenia gravis by raising acetylcholine concentrations at the muscle motor end-plate, which helps to relieve the neuromuscular transmission block that is associated with this illness. Allopurinol inhibits the enzyme xanthine oxidase, which converts xanthine and hypoxanthine to uric acid. Thus, allopurinol inhibits the production of uric acid. Its active metabolite, alloxanthine (also known as oxypurinol), a non-competitive inhibitor of xanthine oxidase, is primarily responsible for this action (Sekine et al. 2023).

Additionally, the decrease in uric acid production lowers the incidence of chronic gouty arthritis, lowers the risk of acute gouty arthritis episodes, and avoids the development of uric acid stones (gouty nephropathy). Moreover, the metabolism of the monoamines 5-hydroxytryptamine, noradrenaline, and dopamine in the brain is hindered by monoamine oxidase (MAO) inhibitors, which in turn is presumed to be the cause of their antidepressant effects (Tirona 2011; Cui et al. 2017; Paul 2019). MAO irreversibly binds to isocarboxazid and phenelzine, necessitating the synthesis of new enzyme molecules to restore normal monoamine metabolism, a process that typically takes approximately 2 weeks (Strelow et al. 2004; Cui et al. 2017).

Drugs possess the capability to alter ion channels, which are protein in nature and are responsible for the movement of ions through cellular membranes. Therefore, this phenomenon directly influences the excitability and functioning of cells (Ramírez et al. 2023). By obstructing ion channels, it becomes feasible to impede the entry or exit of specific ions, thereby impacting the potential of the cellular membrane as well as signalling processes (Wu 2023). The transport and arrangement of positively charged ions, namely, sodium, potassium, and calcium, as well as various other substances such as organic acids in the kidneys and neurotransmitters in the nervous system, assume a multitude of crucial functions in the preservation of regular cellular operations.

Consequently, hindering the transportation of these entities represents a significant modality of drug action (Ramírez et al. 2023). Furosemide and bumetanide, two loop diuretics, for instance, function at the luminal surface of the ascending limb of the loop of Henle by blocking the Na/K/Cl cotransport system, an active transport mechanism that involves the simultaneous movement of sodium, potassium, and chloride across cell membranes. Similarly, calcium channel blockers, including diltiazem, verapamil, and the dihydropyridines (such as nifedipine and amlodipine), function by preventing calcium from transmembranely entering cells through potential-operated L-type calcium channels (Levêque et al. 2010). Some anticancer drugs, such as imatinib, inhibit tyrosine kinase, and other kinases, and also the anticancer drug cytarabine, inhibit DNA polymerase activity (Crisci et al. 2019). Certain anti-infectious agents also function by blocking bacterial or viral enzymes. For instance, trimethoprim inhibits bacterial dihydrofolate reductase, quinolones inhibit bacterial DNA gyrase, zidovudine and didanosine inhibit HIV reverse transcriptase, and oseltamivir and zanamivir inhibit influenza virus neuraminidase (Pham et al. 2019).

In the same way that certain medications operate by blocking enzymes, there are also drugs that promote enzymes or act as enzymes themselves. The best example is the oral utilization of pancreatic enzymes in the management of malabsorption in individuals exhibiting chronic pancreatic insufficiency, which involves the application of specially coated formulations in combination with antacids to diminish the inactivation caused by gastric acid (Ketwaroo & Graham 2019). The enzymes that play a role in the process of clot formation and breakdown of fibrin are commonly referred to as clotting and fibrinolytic factors. Clotting and fibrinolytic factors are the enzymes involved in the process of clot formation and breakdown of fibrin. Certain medications can augment the activity of these enzymes to influence clotting and fibrinolysis. Heparin is a medication that functions as an anticoagulant by stimulating antithrombin III (Rezaie & Giri 2020). Other substances such as streptokinase, urokinase, alteplase, and anistreplase have the capability to activate plasminogen, resulting in the degradation of blood clots (Adivitiya 2016).

Immunomodulatory compounds elicit an influence on the operational dynamics of the immune system. They possess the capacity to augment or diminish immune responses contingent upon the therapeutic objective (Saito 2019). Immunomodulatory agents possess the ability to operate through one of two distinct mechanisms. Specifically, they possess the capacity to either enhance or impede the functioning of the immune system (Zebeaman et al. 2023). In the event that an immunomodulator induces an enhancement effect, it provides a crucial boost to the immune system in order to facilitate its response towards a given ailment or pathological condition. Immunomodulatory agents have been found to possess a commendable safety profile and demonstrate remarkable efficacy in the management of diverse immune-mediated inflammatory diseases (IMIDs), albeit marginally elevating the susceptibility to infections (Opdam et al. 2023). Owing to their potent anti-inflammatory and immunosuppressive properties, synthetic corticosteroids such as dexamethasone, prednisolone, and budesonide are utilized in the management of respiratory illnesses, including asthma, COPD, and acute respiratory disease (ARD), as well as allergies and certain autoimmune disorders, specifically arthritis and lupus (Kapri et al. 2023).

Certain medications affect various pharmacological systems in multiple ways. Harmful consequences are occasionally explained by behaviours that differ from those that are thought to produce favourable outcomes. For instance, several tricyclic antidepressants include anticholinergic properties that can result in negative side effects such as dry mouth, glaucoma, and urine retention in males with prostatic hyperplasia in addition to inhibiting the absorption of monoamines at nerve terminals (Strelow et al. 2004; Paul 2019). In addition to acting as agonists at opioid receptors, opiates like morphine also release histamine, which causes itchiness. Many pharmacological actions of tramadol have been reported; these include agonistic effects on the μ opioid receptor, inhibition and release of 5HT, noradrenaline reuptake inhibitor, antagonistic effects on the NMDA receptor, antagonistic effects on the 5HT2C receptor, and antagonistic effects on the nicotinic acetylcholine receptor. Some of these actions mediate the drug's beneficial and harmful effects (Saito 2019). Inhibiting the enzymes responsible for metabolizing medicines is a common side effect of many medications, which can lead to interactions between different treatments. Some medications work on many subtypes of the same receptor, which is more subtle. The so-called ‘typical’ antipsychotic medications, such as haloperidol and chlorpromazine, function at many subtypes of dopamine receptors, and non-selective beta-adrenoceptor antagonists work at both β1 and β2 adrenoceptors (Kubota et al. 2023).

Pharmaceuticals are necessary for human health and well-being. Their rapid use resulting from population growth and ageing has become a new environmental concern due to potential negative effects on humans and ecosystems. In recent decades, the production and consumption of pharmaceutical products have increased with the development of medicine. Over hundreds of tons are produced annually, with about 3,000 chemicals being employed as medications. The most widely used medications worldwide are analgesics, antibiotics, and anti-inflammatory treatments (Ortuzar et al. 2022).

Over time, man has produced a number of artificial substances that have the potential to harm the environment. Pharmaceuticals are eliminated as active ingredients, or metabolites, in the urine and faeces after consumption. In addition to effluent and influent wastewater, these medications are also prevalent in groundwater, freshwater ecosystems, and marine environments, among other surface water bodies (Patel et al. 2019). As a result, they are constantly entering the environment and are present in a variety of aquatic environments throughout the world (Mezzelani et al. 2019). Concerns have been raised about the fact that some of these emerging contaminants (ECs) cannot be completely removed by traditional treatment plants, necessitating the development of novel methods based on mycoremediation (Fekadu et al. 2019; Letsinger et al. 2019; Zainab et al. 2020).

Emissions of pharmaceutical residues may occur during drug manufacturing, via urine and faeces following use in humans or domestic animals, in some cases via use on plants, and through inappropriate disposal of unused drugs (Malmqvist et al. 2023). The improper disposal of pharmaceuticals in the garbage, toilets, sinks, and industrial effluents are additional possible sources of pharmaceutical pollution. Even at low quantities, pharmaceuticals in the environment have the potential to be harmful to living things (Xin et al. 2020; Chaturvedi et al. 2021; Souza et al. 2021). Some APIs in medications are non-biodegradable or only degrade slowly in the environment because they are intended to be stable (Miettinen & Khan 2021). Due to increased attention being paid to global threats such as antimicrobial resistance (AMR), pharmaceutical pollution in the environment has gained international attention. Pharmaceuticals enter the environment through three main routes: wastewater released from manufacturing plants, regular consumer or animal use, and inappropriate consumer disposal of unused or expired medication.

Water is essential to life, for both people and wildlife, and clean water is necessary for the planet to function. Since ground and surface water are the main sources of water for residential and commercial usage, quality monitoring of these resources is essential (Patel et al. 2019). One of the most concerning categories of newly discovered pollutants is pharmaceutical. These come from the pharmaceutical industry, whose biologically active substances are utilized to treat, prevent, or cure illnesses (Mahapatra et al. 2022). Pharmaceuticals and Personal Care Products (PPCPs), which include shampoos, toothpaste, conditioners, hair dyes, lipsticks, cosmetics, creams, bath soaps, dental care products, lotions, detergents, sunscreens, fragrances, and other household items, are thought to be the sources of PCs in the environment. The release of PPCP effluent into streams and rivers may result in ecotoxicological and mutagenesis impacts on humans, animals, and plants. Aquatic plants and animals may have long-term (chronic) effects if PCs are continuously released into water bodies and exposed to them. In addition, older individuals, neonates, and those with renal or hepatic impairment may be adversely affected by PCs in drinking water. Due to the numerous negative effects that pharmaceutical pollutants in water bodies can have on both humans and animals, it is crucial to develop effective and efficient treatment procedures for removing PCs from wastewater. A number of mechanisms and techniques are investigated for the removal of PCs and the treatment of pharmaceutical wastewater; however, in recent times, the most successful removal mechanism has been the use of biological approaches by wastewater treatment plants (WWTPs) in their treatment programmes. A few examples of biological treatment schemes are the algal photobioreactor, membrane bioreactor, constructed wetland, activated sludge treatment plant, rotating biological contactor, waste stabilization pond, and so on (Samal et al. 2022).

Microorganisms are essential to our ecosystem's ability to operate. For an ecosystem to respond quickly and effectively to the different natural and man-made disruptions that might occur, a small and large microbial community must exist. Since microorganisms may break down pollutants through metabolic and co-metabolic pathways, they play a role in the ecosystem's self-purification processes. The removal of medicines by biodegradation is a crucial process, and contamination can only be recovered from if the molecules' toxicity does not prevent microbiological activity. Because pharmaceuticals usually enter the environment as complicated effluents, a variety of active chemicals are exposed to natural microbial populations. According to experiments, diclofenac is a polar medicinal molecule that is primarily used to treat inflammation and pain in both human and veterinary medicine as the sodium salt diclofenac-Na. Subsequently, when exposed to diclofenac, lotic biofilms made up of bacterial and algal populations lost almost 70% of their whole starting biomass (depending on the thickness of the biofilm) (Samal et al. 2022).

The several factors that impact human health include drug concentration, type, and distribution; each drug's pharmacokinetics; altered structural, metabolic, or breakdown processes; and potential overdosing from medications. Research on the aquatic toxicity of four distinct pharmaceutical groups – antibiotics, antineoplastics, cardiovascular drugs, and sex hormones (estrogens and androgens) – showed that while daphnia fish and algae were susceptible to these compounds, antibiotics and sex hormones posed an equal threat to aquatic and human life. It is challenging to ascertain the precise chemical values of these substances in water, which can range from parts per billion to trillions of parts. Antibiotic resistance genes have a direct and indirect negative influence on human health. They enter the environment through manuring and wastewater treatment facilities (Sammut et al. 2021).

Man's actions have caused the atmospheric concentration of carbon dioxide to rise dramatically and quickly. According to a 2019 study by Belkhir & Elmeligi (2019), the carbon footprint of the pharmaceutical business was almost 55% more than that of the automobile industry in terms of emission intensity. Approximately 52 million metric tons of carbon dioxide equivalent (MMTCO₂Eq) were produced globally by the pharmaceutical business in 2015, compared to 46 million MMTCO₂Eq produced by the automobile sector. Carbon dioxide, methane, nitrous oxide, hydro fluorocarbons, per fluorocarbons, sulfur hexafluoride, and anaesthetic gases are among the greenhouse gases released by the healthcare industry. These gasses are produced as a result of both direct and indirect activities including travel, services, purchasing, and the energy needs of buildings and equipment, among other things. About 4.4% of the world's net emissions are attributed to the global healthcare industry. As a fraction of the overall impact on the country, emissions from the healthcare industry in the United States have been determined to contribute to acidification (12%), global warming (10%), and ozone depletion (2%). According to a 2009 research, the hospital (39%) and prescription medication (14%) sectors accounted for the majority of the healthcare sector's estimated 546 MMTCO₂Eq generated in the United States (Chung & Meltzer 2009). In terms of the global healthcare footprint, the United States leads the world in absolute healthcare emissions (27%), followed by China (17%), Europe (12%), and Japan (5%) (Sammut et al. 2021).

Human health and climate change are negatively impacted by the greenhouse gases generated by the healthcare industry. According to estimates, the consequences of climate change are anticipated to cause an additional 250,000 fatalities per year between 2030 and 2050 (WHO 2020). Harsh weather conditions and increasing sea levels can be caused by climate change. In addition to other illnesses and deaths, these occurrences may cause malnutrition, respiratory allergies, asthma, cardiovascular ailments, and heat-related illnesses. A rise in temperature can put susceptible people – such as the elderly and infants – at danger for heat-related illnesses including heat stress, which can be fatal. This was shown during the 2003 heat wave that struck Europe, which contributed to an additional 70,000 deaths. Because the number of animals that serve as disease-transmission vectors changes as a result of climate change, the frequency of vector-borne illnesses can also fluctuate. The rise in infectious illnesses brought on by germs that would normally be latent is another consequence of climate change (Rees 2019).

Sustainable chemistry and clean chemistry are other names for green chemistry. The usage of a set of guidelines known as ‘green chemistry’ is the process of designing, producing, and using chemicals in a way that uses fewer or no hazardous materials. Reducing the environmental effect of API synthesis and final dosage from manufacture can be achieved by implementing green business practices. When creating a synthetic pathway, the most effective pathway should be chosen as it produces a product in a high yield with the least number of contaminants created, while also taking other criteria like toxicity into consideration. This is because an efficient process is seen to be more environmentally friendly. It has been observed that between 80 and 90% of the whole mass is used as the solvent during a procedure. In the pharmaceutical sector, solvents are regarded as significant pollutants. When solvents are released into the environment, these substances may accumulate in aquatic life. Additional steps that may be taken to lessen the environmental effect of pharmaceutical manufacture include producing the right size packaging and treating sewage and wastewater. The amount of API contamination of marine and aquatic habitats is reduced by the treatment of sewage and wastewater, while the number of unwanted medications – which, if improperly disposed of, might wind up in the sewage or table water – would reduce with the introduction of pharmaceutical packaging of the proper size.

Medicine distributors can take steps to lessen the pharmaceutical industry's environmental effect, such as rotating and properly storing their inventory to prevent drug waste. It is recommended that medicine distributors distribute orders filed by community pharmacies in an orderly fashion, clustering delivery in adjacent regions to reduce the carbon footprint that comes with drug transportation. Community pharmacists have a responsibility to protect the environment by implementing stock rotation and applying the first-in, first-out policy to reduce the quantity of outdated goods that are thrown away. Keeping track of inventory is crucial to the operation of a community pharmacy because it prevents needless orders for prescription drugs, which can lead to resource waste if they expire. Community pharmacy owners and pharmacists can also inform their clientele on environmentally friendly behaviours (Sammut et al. 2021).

A key component of maintaining a respectable environment and reducing actions that contribute to climate change is educating the public and the pharmaceutical staff. Many institutions have already incorporated the adoption of green techniques in the pharmaceutical industry into their curricula. The educational component aids in establishing the significance of these practices from the outset of the career development process. Given their significant influence in reducing the quantity of medicine in the environment, consumer education is especially vital. To prevent squandering pharmaceuticals that go unused, consumers should be discouraged from hoarding drugs. They should also be taught the correct methods for handling and discarding outdated and unused medications, as they might wind up in the water table or sewage system.

Toxins in pharmaceutical studies are classified as a distinctive vocabulary in toxicology, and which in pharmacology is reserved for harmful substances produced from living organisms such as microbial (toxigenic) pathogens, venomous spiders, and some marine organisms that are poisonous. Toxin is a terminology used in pharmaceutical toxicology when considering the adverse effects of drugs on any living organism. The sole aim of pharmaceutical toxicology is geared towards understanding the benefits and risks of drug medication as well as the development of strategies for an effective minimization of drug toxicity. Although the intention of drug medication is to prevent diseases so as to improve a patient's quality of life through the treatment of infections with eventual cure, the toxicity of these useful mediations (pharmaceuticals) should not be treated flippantly. The contribution of pharmaceutical toxicity (drugs) to high cost of drug development occurs if recognized at a later stage during clinical trial and after marketing.

Drugs are pharmaceutical products, so also are cosmetics. However, the toxicity of pharmaceuticals in toxicology as studied in the area of pharmaceutical toxicology simply means the adverse effects of drugs on human health (Nikhil 2023). Drug toxicity in pharmacology occurs when there is too much accumulation of a prescribed drug in the bloodstream with resultant negative effects (Schimelpfening 2023). However, drug toxicity can be defined formally as an adverse effect of diverse array that results from therapeutic or non-therapeutic drug doses (Silakari & Singh 2021). The increased use of pharmaceuticals in the treatment of diseases has also resulted in lots of adverse drug reactions (ADRs), which are the major cause of hospital admissions, diseases, and deaths globally. Thus, the need to understand pharmaceutical safety profile and the ADRs risks mitigation measures should be overemphasized since over 2 million hospital admissions and 100,000 deaths annually are associated with ADRs (Nikhil 2023).

Drug toxicity and drug overdose have been used interchangeably over time. According to Dasgupta (2018), drug toxicity results from over-ingestion of medication (drug overdose), which causes too much drug to be found in someone's system at a time. While toxicity of drugs occurs accidentally and over time, drug overdose results from too much of a substance being taken at once. Drug toxicity occurs when the dose taken is higher than the prescribed or a higher dosage is prescribed. It has been reported that drug toxicity of some medications occurs in the form of ADRs with the normal dose of such medications causing harmful side effects that are not intended and unwanted (Dasgupta 2018). Usually, ADRs associated with the use of pharmaceuticals are identified and managed by healthcare professionals who are the first contact of such patients. Since there is only a thin threshold between an effective dose and a toxic dose, one person's dose of therapy might be a toxic dose for another (Schulz et al. 2012). For drugs having longer half-life, toxicity results from their build up and subsequent increase in the bloodstream over time. Several factors such as kidney function, age, and hydration determine how quickly drugs are cleared from the system (Schulz et al. 2012). However, the toxicity of pharmaceuticals (prescription drugs) is determined by three major factors as follows:

• (a) Chemical structure of the pharmaceutical;

• (b) The quantity that the blood can absorb;

• (c) The ability of the body to detoxify the pharmaceutical with subsequent elimination.

Based on the axiom of Paracelsus, pharmaceutical products like drugs are toxic when administered at high doses but very safe when taken at lower doses (Borzelleca 2000). Considering the context of toxicity in pharmaceuticals will facilitate approaches that will circumvent toxicity or aid in discovery of alternative products not having such problems. Usually, the most common toxicity problems of drugs as pharmaceuticals are hepatic and cardiovascular toxicity (Guengerinch 2011).

This is a mechanism-based toxicity that occurs when a drug interacts with the target that is to elicit the desired pharmacological response. In this type of toxicity, the binding of the drug at target site elicits a biological response similar to the drug efficacy response and toxic effects. This is always difficult to handle since all developed drugs for the treatment of diseases elicit on-target toxicity. Hence, the need to change the disease target (Guengerinch 2011). In the case of statin, for example, hypercholesterolemic property is produced through the inhibition of 3-hydroxy-3methylglutaryl CoA (HMG CoA) reductase enzyme in the target (liver), which produces adverse effects (Johnson et al. 2004).

The concept of this drug toxicity context is based on Landsteiner's pioneering work where drugs or drug metabolites cause inductions that produce antibodies and other immune responses by binding to hapten proteins in the body (Landsteiner 1935). This can be observed in the documented allergic reactions to penicillins, which have the capability of binding to proteins covalently and initiating the production of antibodies.

Off-target toxicity occurs by the binding of a drug on an alternate target due to non-specificity in the drug interactions as drugs are not totally specific in their binding. This has been reported with terfenadine, which produces its antihistaminic response by binding to the H₁ receptor but as well causes arrhythmias by binding to the hERG channel. However, this can be addressed through an intensive screening to develop a drug with lower values of IC₅₀ and K_d so as to avert the specificity issue (Guengerinch 2011).

Some drugs become toxic once they are converted to reactive metabolites, which cause modification of the proteins they react with through an evasive mechanism. Such modified proteins lose their functions or cause an immune response induction that leads to a second toxicity context. In Bristol Myers Squibb Drug Company, a drug analysis showed that 28% of toxicity cases were linked to metabolism issues that stopped the development of such drugs (Guengerinch 2011).

Idiosyncratic reactions are rare and not well understood, occurring in 1/10³ to 1/10⁴ individuals. This context of toxicity is highly problematic as only few of the animal models can be predicted. Thus, even in a very large clinical trial, the low incidence of idiosyncracy makes it difficult to detect the ADRs.

The toxicity of pharmaceuticals can differ based on the drugs taken. For instance, the use of lithium, which is primarily used as a mood stabilizer mostly in people that have bipolar disorder, has resulted in lithium toxicity in certain individuals resulting from the presence of too much lithium in the system. Lithium is usually prescribed to control depression, hypomania, mania, and psychosis in people having bipolar disorder to stabilize their mood. This drug toxicity occurs at least once in the majority of the people that take lithium regularly (Altschul et al. 2016). Lithium toxicity can be associated with mild, more severe, and chronic symptoms. While some of the mild symptoms include diarrhea, dizziness, nausea, stomach pains, and vomiting weakness; the severe symptoms of acute lithium toxicity are as follows:

• (a) Ataxia – which is poor control of the muscles that leads to clumsy movement

• (b) Coma

• (c) Tremors of the hand

• (d) Rare cases of heart problems

• (e) Muscle twitches

• (f) An involuntary jerking of the eyeball known as nystagmus

• (g) Seizures

• (h) Slurred speech

However, chronic lithium toxicity that is caused by the accumulation of lithium over time in the body system is associated with increased reflexes, tremors, and slurred speech. Although the toxic concentration of lithium (≥ 1.5 mEq/L) is close to the therapeutic dose range of 0.8 to 1.2 mEq/L, abnormal sensitivity to lithium in some patients results in the exhibition of toxic signs at serum concentrations that are considered to be within the therapeutic range (National Library of Medicine 2022).

Among the different types of pharmaceutical toxicity, acute drug toxicity can be diagnosed easily because the symptoms occur immediately after a one-time medication. The level of the drug in the bloodstream can be ascertained by screening the blood sample to determine if the level is too high. Cases of chronic toxicity of pharmaceuticals, which results from long-term build-up, are more difficult to diagnose. Thus, such toxicity can be diagnosed by stopping the medication for a while and starting it again much later. However, in cases where the drug has no substitute, disrupting the treatment can be problematic (Schimelpfening 2023).

Drug toxicity is largely associated with metabolic processes. The covalent binding of drugs to proteins has been a recognized phenomenon since at least 1973, highlighted by the landmark studies of Gillette and Brodie on acetaminophen (Jollow et al. 1973; Mitchell et al. 1973). The covalent binding of drugs to proteins has been greatly studied in hepatotoxicity, which is a clinical and pre-clinical problem.

The pharmaceutical sector has made considerable contributions to the field of healthcare, thereby enhancing the overall quality of life and preserving human lives on a global scale. However, the management of pharmaceuticals has given rise to apprehensions pertaining to their ecological impact and influence on various ecosystems, particularly with regard to water reservoirs (Haider 2023). The detection of pharmaceutical substances in water reservoirs has emerged as a prominent obstacle, bearing potential repercussions for both the environment and human well-being (Bharti & Bora 2023). The intricate nature of the pharmaceutical industry, encompassing the processes of research, production, and disposal of medicinal drugs, has consequently facilitated the release of pharmaceutical compounds into the environment. In turn, this has instigated concerns regarding the plausible ecological and health hazards linked to the presence of pharmaceuticals within ecosystems and water sources (Li 2023; Haider 2023).

Pharmaceuticals have a considerable ecological influence, particularly when they infiltrate the ecosystem via various channels such as wastewater and inappropriate disposal. The extensive utilization of pharmaceuticals has resulted in their presence in the environment through multiple pathways, mainly through excretion, improper disposal, and manufacturing procedures. Consequently, these compounds permeate into water bodies, soil, and even the food chain. These pharmaceuticals can accumulate in the environment and attain toxic levels for animals and plants, thereby causing detrimental effects on ecosystems and biodiversity (Giunchi 2023; Giunchi et al. 2023). Research has underscored the potential hazards linked to the existence of pharmaceutical residues, encompassing the emergence of antibiotic-resistant bacteria (ARB), disturbance of aquatic ecosystems, and potential harm to human health due to indirect exposure (O'Flynn et al. 2021; Giunchi et al. 2023).

The presence of pharmaceuticals in surface waters can lead to difficulties in growth and reproduction for aquatic flora and fauna (Paut Kusturica et al. 2022). Endeavours have been made to evaluate country-specific environmental perils and identify pharmaceuticals posing the highest risk to the environment. These data can spur regulatory actions towards more environmentally friendly drug utilization and disposal practices (Çalışkan et al. 2023). To mitigate the levels of pharmaceuticals in the environment, preventive measures are recommended, including judicious pharmaceutical consumption, the prescription of eco-friendly drugs, and the proper collection and disposal of unused pharmaceuticals. Additionally, understanding the impact of pharmaceuticals on microbial communities is crucial, as it can have implications for public health and the equilibrium of ecosystems (Pinto et al. 2022).

The management of pharmaceuticals in the environment encounters various difficulties. An important challenge lies in identifying and measuring pharmaceutical compounds in diverse environmental samples, such as water, wastewater, and soil. The intricate composition of these pharmaceuticals and the extensive volume of drugs consumed on a global scale present a fundamental challenge in their management. The intricacy of these samples, coupled with the limited empirical relationships between pharmaceutical compounds and sample characteristics, renders detection arduous (Bharti & Bora 2023). Another challenge pertains to the potential adverse effects of pharmaceutical compounds on the environment and living organisms. These effects encompass the emergence of antibiotic resistance in bacteria, the disruption of biological processes in non-target organisms, and the occurrence of ecotoxicological predicaments (Bali 2022; Sapingi et al. 2023). Furthermore, the fate and degradation of pharmaceuticals in the environment have not been adequately studied, necessitating further research to comprehend their impact on living organisms and their elimination from water samples. Traditional wastewater treatment facilities are ill-equipped to effectively eliminate these compounds, leading to their persistence in water bodies (Çalışkan et al. 2023). Additionally, the absence of comprehensive regulations and standardized methods for monitoring and controlling pharmaceutical disposal contributes to their accumulation in the environment. The challenges associated with managing pharmaceuticals in the environment encompass the detection, adverse effects, destiny, and elimination of these compounds (Khasawneh et al. 2023).

Strategies aimed at mitigating the existence of pharmaceuticals in the environment encompass a variety of approaches, including prevention, proper disposal, and remediation methods. In order to hinder the release of pharmaceuticals into the environment, several preventive actions can be pursued. These measures encompass promoting rational pharmaceutical consumption, encouraging the prescription of greener drugs, and designing pharmaceuticals that are easily biodegradable. Additionally, strategies such as improving disease prevention, personalized medicine, enhanced dimensioning of pack sizes, and establishing marketplaces for the redistribution of unused pharmaceuticals can also contribute to the prevention of environmental contamination caused by pharmaceuticals (Paut Kusturica et al. 2022).

The proper disposal of unused or expired medications is of utmost importance in addressing the issue of pharmaceutical contamination. To achieve this, community programs, pharmaceutical take-back initiatives, and guidelines for safe disposal play a crucial role. By implementing these measures, the release of pharmaceutical substances into water systems can be prevented effectively. In addition, it is crucial to educate healthcare professionals and the public about the proper methods of disposal, as this knowledge is vital in reducing environmental contamination caused by pharmaceuticals. Hence, endeavours should be made to circulate information on proper disposal methods to guarantee that waste does not reach the environment. This includes emphasizing the importance of proper collection and disposal of unused pharmaceuticals (Bali 2022).

Advancements in treatment technologies are vital in effectively removing pharmaceutical residues from water bodies. Different methods have demonstrated potential in decreasing pharmaceutical levels in water, including AOPs, membrane filtration, and activated carbon adsorption. These techniques aid in the removal of pharmaceuticals, thus contributing to the mitigation of their presence in water bodies. Furthermore, remediation methods such as phytoremediation and advanced oxidative processes can also be employed to treat pharmaceutical products in water bodies, further enhancing the remediation efforts (Khan & Barros 2023).

To address the issue of pharmaceutical contamination comprehensively, it is recommended to focus on increasing awareness, promoting green and sustainable pharmaceutical practices, and improving existing remediation methods. These steps are crucial in alleviating the problem (Sammut et al. 2021). Additionally, green manufacturing practices, efficient management of medication stock, and patient education on safe disposal also play significant roles in mitigating PCs in the environment. Therefore, by adopting a holistic approach, comprehensive mitigation actions can be taken throughout the entire pharmaceutical life cycle. These actions should encompass various stages, including design, synthesis, production, prescription, sales, and waste handling. By addressing each stage of the life cycle, it is possible to minimize the environmental impact of pharmaceuticals and promote sustainable practices in the industry (Caban & Stepnowski 2021).

Antibiotics are chemical substances that are used to kill or inhibit the growth of bacteria. These bacteria can be commensalistic or pathogenic causing various kinds of infectious diseases. The origin of antibiotics can be described as natural, semi-synthetic, or synthetic. The first antibiotics discovered were natural antibiotics such as Penicillin, which was derived as a secondary metabolite produced by the mold Penicillium notatum (Kovalakova et al. 2020). Semi-synthetic antibiotics are also derived from natural antibiotics, but they are chemically altered to enhance their efficacy. Example of a semi-synthetic antibiotic is Clarithromycin. Other antibiotics are completely synthetic. They are manufactured from scratch through chemical synthesis. An example is iboxamycin. Based on their chemical structures, antibiotics are classified into different groups such as β-lactams, Macrolides, Aminoglycosides, Fluoroquinolones, Tetracyclines, and Sulfonamides. Based on their spectrum or range of activity, antibiotics can also be divided into narrow-spectrum, broad-spectrum, or extended-spectrum antibiotics. They can also be classified according to their mechanisms of action into bactericidal (killing bacteria) or bacteriostatic (inhibiting the growth of bacterial cells) (Yang et al. 2021a, b).

Antibiotics play a crucial role in managing bacterial infections in both human and veterinary medicine. Their widespread use extends to disease treatment, prevention, and the promotion of growth in livestock and fish farming (Kovalakova et al. 2020). The rising demand for animal protein has led to a substantial increase in antibiotic consumption within these industries. This heightened usage is intended to bolster animal health and is anticipated to persist in the unforeseeable future alongside the growing global population (Yang et al. 2021a, b). Projections suggest an alarming trajectory, with an expected 200% surge in global antibiotic consumption by the year 2030 (Scaria et al. 2021). Antibiotics, extensively employed in human and animal settings, are now acknowledged as emerging environmental pollutants due to their considerable persistence. Detected in various concentrations across seawater, groundwater, surface water, and even drinking sources, these drugs and their metabolites contribute to ongoing ecological contamination and the proliferation of antibiotic-resistant bacterial strains (Alduina 2020). This trend underscores the pressing need for strategic interventions in pharmaceutical practices to curtail antibiotic misuse to minimize environmental pollution and preserve their efficacy.

Sulfonamides are frequently used antibiotics for the treatment of bacterial diseases in animals and humans. Its usage is associated with the excretion of a high fraction of the drug without metabolism through the urine or faeces, into the environment (Ovung & Bhattacharyya 2021). The inactive N4-acetylsulfamethoxazole first-step metabolite of the Sulfonamide, Sulfamethoxazole, which is the most prescribed antimicrobial in human medicine, is known to be excreted in very large quantities (Ovung & Bhattacharyya 2021). In lower rates, 20 and 13%, the second-step metabolites of the macrolide clarithromycin, 14-OH-(R)-clarithromycin and 14-OH-(R)-N-demethyl-clarithromycin, respectively, are excreted after undergoing hydroxylation and N-demethylation.

Sulfonamide drugs were also found to exist in low but detectable levels in the edible tissues of meat-producing animals treated with Sulfonamide drugs (Kalpana et al. 2022). These poorly metabolized antibiotics also accumulate within the soil, which can impact soil microbial communities and functions (Wang et al. 2021; Zhao et al. 2023). Trace determination Sulphonamides in animal feeds, human urine, and wastewater (aquatic environment) using different techniques have been variously reported (Conde-Cid et al. 2020; Lyu et al. 2020; Jia et al. 2023). The environmental behaviour of Sulphonamides is such that their metabolites can bioaccumulate in the environment causing varying levels of environmental pollution.

The presence of tetracycline and its subtypes in the environment has been previously reported (Scaria et al. 2021; Xu et al. 2021). It was found in by-products of livestock farming such as animal manure, which is being used extensively in crop cultivation as an organic fertilizer. As such, the direct introduction of these antibiotics into the environment ensues due to the large-scale usage of animal manure for soil enrichment purposes. Tetracycline subtypes such as oxytetracycline and chlortetracycline were found to be highly pervasive in contaminated soils where the highest concentration was found in raw and treated manure (Ghirardini et al. 2020). Tetracycline and its derivatives have widespread usage due to their low cost, effectiveness against bacterial infections, and as growth promoters in livestock. However, a higher proportion of tetracycline is recovered in the environment such as in soil and waste-streams due to its very low biodegradability and, as such, it poses a severe threat to environmental ecology and human health (Ahmad et al. 2021).

Macrolides are a class of broad-spectrum antibiotics of large molecular size. The class includes erythromycin, clarithromycin, and azithromycin, among others (Yuan et al. 2022). Macrolides are divided into categories based on their chemical structure. Erythromycin and clarithromycin exhibit 14-membered lactone rings, with clarithromycin distinguished by a methoxy group, replacing the hydroxyl group at Position 6 on the carbon ring compared to erythromycin. Azithromycin, categorized as an azalide subclass, features a 15-membered ring. Notably, it contains a methyl-substituted nitrogen at the Position 9 on the aglycone ring instead of a carbonyl group, a structural variation preventing metabolism by the conventional mechanisms observed in other macrolides (Lenz et al. 2021).

However, several studies have reported the frequent setection of macrolides and their metabolites in sewage, surface water, seawater, and even groundwater (Hernández et al. 2019; Anh et al. 2021). Macrolide toxins represent a vast catalogue of chemical substances with varying levels of toxicity in the environment, especially in the marine environment (Lenz et al. 2021). Other classes of antibiotics and their metabolites such as Beta-lactam antibiotics and Aminoglycosides are heavily used and subsequently find their way into the environment (Timm et al. 2019; Polianciuc et al. 2020). The environmental pollution associated with these antibiotics favours the natural selection of ARB that are quite difficult to eradicate.

In the contemporary landscape, antibiotics find application not solely within healthcare and veterinary practices but also in diverse human activities globally, including fish farming, aquaculture, agriculture, and livestock management. Consequently, wastewater stemming from these activities – agricultural, hospital, farm, or urban treatment plant effluents – increasingly harbours a spectrum of antibiotics. These compounds eventually infiltrate environmental domains previously unexposed to such substances, facilitated by water seepage or soil fertilization. Due to their intricate molecular compositions, numerous antibiotics exhibit resistance to degradation, persisting notably in polluted environments (Alduina 2020). This underscores the imperative for strategic interventions to mitigate their environmental impact.

The introduction of antibiotics has unquestionably sparked a revolution in the field of medicine, resulting in a significant improvement in healthcare on a global scale. However, the extensive utilization of antibiotics has resulted in their presence within wastewater, presenting a notable ecological threat. Various sources such as hospitals, industrial activities, and improper disposal contribute to the release of antibiotics into wastewater. Consequently, this has led to the pollution of aquatic systems and the potential emergence of antibiotic resistance (Mohamed et al. 2023). WWTPs serve as crucial reservoirs for ARB and antibiotic-resistant genes (ARGs), making them critical control points for preventing the release of antibiotics into the environment. To address this issue, the development of innovative wastewater treatment technologies that possess the ability to efficiently eliminate antibiotics from water sources is imperative (Marutescu et al. 2023).

Several studies have investigated innovative technologies for wastewater treatment that aim to eliminate antibiotics from wastewater. One such technology is algae treatment, also known as phycoremediation, which has emerged as a promising and sustainable option for cost-effective wastewater treatment. Algae-based technologies employ various mechanisms, including bioadsorption, bioaccumulation, and biodegradation, to effectively remove antibiotics from wastewater (Khan et al. 2020). Moreover, the integration of algae with bacteria consortia and other microorganisms has been found to be highly effective in the treatment of antibiotics (Matviichuk et al. 2022). Additionally, the combination of algal treatment with oxidation processes can further enhance the elimination of antibiotics and the degradation of refractory organic compounds present in wastewater (El Semary 2023). Notably, certain algal consortia, such as Chlorella protothecoides and Chlorella vulgaris, have demonstrated the ability to remove antibiotics, including sulfamethoxazole and ofloxacin, from wastewater samples (Ndlela et al. 2023). Nevertheless, there is still a lack of comprehensive understanding regarding the relationship between antibiotic exposure and the selection of resistance in bacterial communities found in the environment.

Various processes and factors have been explored in the investigation of biological treatment options for the remediation of antibiotics from wastewater. Recent progress in this area has been summarized, encompassing the classification of antibiotics, their detection, and their presence in the environment (Tripathy et al. 2023). Biological treatment methods, such as aerobic activated sludge and biofilm-based wastewater treatment, offer promise for the elimination of antibiotics from wastewater. In the context of domestic wastewater, improving the effect of activated sludge treatment on antibiotic removal has been emphasized (Chen et al. 2022a, b, c). In the case of aerobic activated sludge, the majority of antibiotics can be effectively treated, although the presence of certain antibiotics, such as lincomycin, may still be observed in the effluent (Chen et al. 2023a, b). Conversely, biofilm-based processes have demonstrated the ability to exploit metabolism and co-metabolism induced by functional microorganisms for the biodegradation of antibiotics (Wang et al. 2023). Core microbial communities, including proteobacteria, bacteroidetes, firmicutes, and actinobacteria, have been identified as possessing antibiotic-degrading capabilities in biofilm-based reactors (Tripathy et al. 2023). Moreover, novel biotechnological approaches, such as the utilization of TiO₂ photocatalyst, have exhibited successful outcomes in the removal of antibiotics from wastewater under visible light (Ata et al. 2022).

METs have been investigated as a viable alternative to conventional wastewater technologies in the context of eliminating antibiotics (Zakaria & Dhar 2022). METs have demonstrated significant promise in remediating ECs owing to their economically feasible operation, eco-friendly nature, and compatibility (Wu et al. 2023). In contrast to electrochemical technologies (ETs), METs have exhibited superior efficiency in eliminating ECs (Orimolade et al. 2023). Furthermore, electrochemical methods such as photoelectrocatalysis, electro-Fenton, electrocoagulation, and electrochemical oxidation have been established as effective techniques for completely eliminating fluoroquinolone antibiotics from wastewater. All in all, both METs and ETs present potential solutions for eliminating antibiotics and other ECs from wastewater (Priyadarshini et al. 2022). Various other remediation techniques, including electrocoagulation, photocatalysis, Fenton process, sonocatalysis, ozonation, membrane filtration, adsorption, and ionizing irradiation, have demonstrated varying degrees of effectiveness in removing antibiotics from wastewater (Akhil et al. 2021).

Research and development have focused on advanced treatment technologies for antibiotics in wastewater. Numerous methods have been explored, including biological treatment options, electrochemical oxidation technology (EOT), and advanced biotechnological approaches. EOT has gained recognition for its environmentally friendly, efficient, and user-friendly advantages in medical wastewater treatment (Zhang et al. 2022a). Moreover, the removal of ARGs and ARB from wastewater has been extensively studied, with a specific emphasis on minimizing the risk associated with contaminated water containing ARGs (Ezeuko et al. 2021). The elimination of ARGs and ARB from wastewater is a crucial concern for public health and environmental considerations.

Traditional WWTPs serve as reservoirs for ARB, ARGs, and antibiotic residues, which are not effectively eliminated during treatment (Kalli et al. 2023). Additional treatments, such as AOPs, show promise in removing ARB and ARGs while minimizing the production of toxic by-products (Liu et al. 2022). Novel materials, such as ZnO/AC alginate beads, have been developed and have exhibited excellent capacities for removing ARB and ARGs (Jiang et al. 2023). Electrochemical disinfection (ED) has also proven effective in removing ARB and ARGs, with beta-lactamase resistance genes playing a prominent role in cross-resistance to antibiotics and electrochemical oxidation (Zheng et al. 2023). The electro-peroxone (EP) process, which generates hydrogen peroxide through cathodic oxygen reduction during ozonation, demonstrates moderate efficiency in inactivating ARB and degrading ARGs compared to ozonation alone. Ozone-based continuous flow systems have proven effective in inactivating ARB, DNA molecules, and ARGs in hospital wastewater (Azuma et al. 2023). These studies provide valuable insights into the development and implementation of advanced treatment technologies for antibiotics in wastewater.

AOPs are water treatment processes executed at pressure and temperature at normal environmental conditions, which involve the production of radicals in adequate quantity to interact with the organic compounds of the solution in order to degrade them (Cuerda-Correa et al. 2020). The common conventional processes employed in treating wastewater may not sufficiently degrade some organic pollutants because of their low biodegradability (e.g. antibiotics) but radicals involved in AOPs, which are referred to as reactive oxygen species (ROS), such as hydroxyl radicals (OH•), superoxide radicals (O ⁻•), and sulphate radicals (SO₄). These radical species are generated from water through the use of some compounds such as hydrogen peroxide (H₂O₂), ozone (O₃), and peroxy sulphates (O₂-SO₄) (Kurian 2021; Mangla et al. 2022). The degradation of these organic substances commonly called contaminants can be partial or complete. In the partial degradation, contaminants are converted to more hydrophilic and biodegradable intermediates, while the complete degradation involves mineralization of the whole organic substances (Ghime & Ghosh 2020).

There are so many methods under AOP and they can be classified based on the following: (1) method of generating reactive radicals especially the energy source such as photochemical (UV/light), sonochemical (sonicator), electrochemical (electrolysis), and chemical (reactions with or without catalyst) and (2) the reactive phase, which may be either homogeneous or heterogeneous (Stanton et al. 2022; Lupu et al. 2023). Most of the methods of generating reactive radicals are non-photochemical such as ozonation, fenton/fenton-like process, wet air oxidation, and ozone/hydrogen peroxide process, while the remaining ones are photochemical. The photochemical ones are mostly accompanied by catalysts and are mostly classified as homogeneous and heterogeneous (Brillas 2020; Giwa et al. 2021).

Reaction (8) is a fast side reaction that reduces the efficiency of OH• radical generation, which may lead to the reduction of the oxidation potential of the process (Cuerda-Correa et al. 2020; Akbari et al. 2021; Mahdi et al. 2021).

The major challenge of the Fenton process despite its high efficiency is that it produces iron-rich sludge at alkaline conditions that are difficult to dispose and this reduces its efficiency. This gives rise to the Fenton-like process where catalysts are added at various conditions. Substances like iron minerals, such as goethite, ferrite, schorl, and zerovalent iron, can be used in an homogeneous reaction while metals/metallic salt like Pd, Mn²⁺, TiO₂, and MnO₂ are useful in heterogeneous reactions (Wang et al. 2019a; Hafeez et al. 2020; Ivanets et al. 2020).

The generation of more radicals makes the process more effective (Kurian 2021; Ortiz et al. 2021; Lupu et al. 2023).

The reaction is faster and more feasible in the alkaline region and high concentration of H₂O₂ (Cuerda-Correa et al. 2020; Kurian 2021; Lupu et al. 2023).

When fenton reaction is photonized by UV, there is an increase in degradation of contaminants. The UV rays photolyse the two chemicals involved, namely, H₂O₂ and Fe (II).

The following equations show the interactions of light and fenton reagent:

The main advantages of this method are the non-production of sludge and the circular usage of Fe²⁺ (Cuerda-Correa et al. 2020; Mahdi et al. 2021).

Semi-conductors are used as photocatalysts and they include ZnO, ZnS, WO₃, SnO₂, TiO₂, C₃N₄, BiVO₄, graphene, sulphide, Ag₃O₄, and BiOCl, but the common and effective one is TiO₂, which is very stable and does not produce secondary pollutants (Hou et al. 2019; Li et al. 2019a, b; Poulopoulos et al. 2019; Shandilya et al. 2019; Tilley 2019; Hojamberdiev et al. 2020; Li et al. 2020a).

The capability of AOPs largely depends on the efficiency of hydroxyl radicals. These radicals are mostly useful within the group of potent oxidants because they meet some requirements, as follows:

• Non-generation of additional waste;

• A very short lifetime and being non-toxic;

• Not corrosive to pieces of equipment and usually produced by assemblies that are simple to manipulate.

The emergence of photocatalytic antibiotics degradation has garnered significant attention in recent times (Guo et al. 2023; Nie et al. 2023). This is due to its potential of addressing the shortcomings of the conventional remediation methods. The degradation of antibiotics through photocatalysis involves the use of nanomaterials to generate electron–hole pairs when exposed to light (Bagheri et al. 2017). Theses electron–hole pairs generated provided the electrons needed for the redox reactions, leading to the breakdown of the antibiotics. The ability of photocatalysts to absorb solar energy positions the photocatalysis as an environmentally sustainable and economically feasible solution for the degradation of persistent antibiotic pollutants. The use of photocatalysis in antibiotic degradation not only mediates the removal of the antibiotics from the environment but also addresses the issues of AMR and the long-term consequences of the pollution to human health (Bai et al. 2022). Table 1 presents some of the important catalysts used in antibiotics remediation from contaminated media.

The most important mechanism of photocatalytic degradation of antibiotics is the generation of electron–hole pairs in the nanomaterials upon exposure to light. This reaction occurs when photons from the electromagnetic spectrum of solar radiation strike the surface of the nanomaterials, generating sufficient energy to free electrons from the VB to the conduction band (CB), creating electron–hole pairs for the redox reaction (Hassaan et al. 2023). The nanomaterial's ability to generate and sustain these electron–hole pairs is dependent on its bandgap energy. Bandgap is the distance between the VB of electrons and the CB, a necessary factor that determines the energy edge for the excitation of electrons. For a material to serve in photocatalysis, it must have a bandgap energy that corresponds to the UV or visible portion of the electromagnetic spectrum (1.63–5 eV) (Liu et al. 2016; Haruna et al. 2020). For example, titanium oxide possesses a bandgap energy that corresponds to the UV portion of the electromagnetic spectrum (3.2 eV), zinc oxide exhibits a broader spectrum of electromagnetic spectrum (3.1–3.4 eV), and bismuth ferrite possesses a bandgap energy within the visible portion of the electromagnetic spectrum (2.07 eV).

Comparing the two pre-eminent nanomaterials available for photocatalytic degradation of antibiotics – zinc oxide and titanium oxide (Bouyarmane et al. 2021; Mohammad et al. 2021; Wang et al. 2022; Al-Khadhuri et al. 2023; Deng et al. 2023; Yu et al. 2023), titanium oxide has been extensively studied and utilized due to its non-toxicity, stability, and high photocatalytic activity. However, its major drawback lies in its bandgap energy, where it can only utilize UV irradiation and is irresponsive to visible light, which constitutes 41% of the solar spectrum. Zinc oxide, conversely, exhibits a lower bandgap energy, allowing it to absorb a broader range of light, including visible light. This feature improves its photocatalytic activity under both UV and visible light, increasing its applicability in situations where UV light might be unworkable. Furthermore, zinc oxide possesses good electron mobility, aiding efficient charge separation, a vital factor in the overall effectiveness of photocatalysis. Therefore, it is important to always look for a semi-conductor material that can utilize the visible region of the electromagnetic spectrum when embarking on photocatalytic studies.

The use of nanostructured semi-conductors for photocatalytic degradation of antibiotics has demonstrated a commendable progress in the remediation of the environmental impact of pollutants. However, as with any flourishing area of research, undeniable challenges occur, requiring dedicated efforts to push the field forward and make photocatalytic degradation a more feasible and effective solution for large-scale treatment. Among the primary challenges is the stability of the nanomaterials over extended time. Some of the nanomaterials undergo deactivation or degradation due to agglomeration, photo-corrosion, and surface fouling (Kusworo et al. 2022; Khader et al. 2023). To overcome these, researchers need to discover new strategies to increase the durability and stability of nanomaterials. This may involve the development of coatings or modifications that can prevent photo-corrosion and increase the overall lifespan of the photocatalytic materials. Additionally, understanding the important mechanisms of catalyst degradation under different states is important for formulating targeted solutions. Another challenge is the complexity of pollutant matrices where various organic and inorganic pollutants can interfere with the photocatalytic degradation of the antibiotics (Cai et al. 2022; Zhang et al. 2022b). Hence, future research should endeavour to focus more on the comprehensive understanding of the matrix effects on photocatalytic degradation. This can be done by studying the interactions between the antibiotics under study and the multitude of components present in the pollutant matrices. Also, pre-treatment can be done to remove other pollutants to enhance the robustness of the photocatalytic processes. Furthermore, while titanium oxide and zinc oxide have been extensively used for photocatalytic degradation of antibiotics, discovering novel photocatalytic materials with improved properties remains a current challenge (Anucha et al. 2022). Novel materials may offer enhanced absorption in the visible light spectrum, increased selectivity for specific antibiotics and higher catalytic activity. Therefore, future research should explore the discovery and characterization of new photocatalytic materials and the enhancement of the known ones through doping, co-catalysis, and formation of heterojunctions.

The semi-conductors synthesized from metal oxide have been employed as pristine photocatalysts either independently or in combination with other substances to aid in the breakdown of organic contaminants such as pesticides, dyes, and polycyclic aromatic hydrocarbons (PAHs) (Djurišić et al. 2020). Notably, there is a growing focus among researchers on utilizing metal oxide-based photocatalysts to degrade antibiotics, thanks to their strong light absorption when using UV, visible light, or the combination of both, as well as their biocompatibility, safety, and resilience when introduced to diverse environmental states (Shurbaji et al. 2021; Zeng et al. 2021; Soni et al. 2022).

New processes employing bismuth-based catalysts have emerged for breaking down antibiotics. Bismuth-based photocatalysts, mainly with a bandgap less than 3 eV, have gained recent attention, particularly Bi₂O₃ and BiVO₄. Bi₂O₃, a common photocatalyst, demonstrates remarkable performance in water treatment due to its bandgap of 2.1 to 2.8 eV, enabling efficient absorption of visible light. While these bismuth-based photocatalysts show promise in using visible light effectively, there is a need to focus on parameters such as stability and solubility (Bai et al. 2022).

Researchers have explored the use of various silver photocatalysts such as Ag-X (where X = Cl, Br, I), Ag₂O, Ag₃PO₄, and Ag₂CO₃ for photocatalytic degradation. However, challenges exist with certain photocatalysts such as pristine Ag₂CO₃, which tends to become unstable and photo-corrosive due to potential transformations from Ag+ ion to metallic Ag when exposed to acquired photoelectrons within the process (Liu et al. 2019a; Li et al. 2019a, b). Similarly, pristine Ag₂O faces issues related to poor stability and quick electron–hole recombination (Tian et al. 2018). Despite these challenges, their effectiveness in degrading antibiotics stems not only from reduced electron–hole recombination but also from their capacity for broad and strong absorption in the visible spectrum, attributed to localized surface plasmon resonance effects induced by Ag nanoparticles (Djurišić et al. 2020; Khanam & Rout 2022).

The metal-organic frameworks (MOFs) are structured coordination polymers formed from metal ions and organic ligands, showing promise in effectively degrading antibiotics in solutions (Du et al. 2021). While various MOF-based materials have been used for antibiotic removal, enhancing their efficiency remains a primary challenge. Improving active sites, surface areas, and functionalization is crucial (Du et al. 2021; Dong et al. 2022). MOFs, functioning akin to semi-conductors under light exposure, hold potential as powerful photocatalysts for antibiotic degradation due to their robust stability, structural qualities, and semi-conductor-like behaviour (Du et al. 2021).

Graphitic–carbon–nitride (g-C₃N₄), a semi-conducting material, holds promise for photo-driven catalytic applications. With a bandgap of about 2.7 eV, it has been well known for photocatalytic water splitting. However, its use in degrading antibiotics under visible light was limited due to a weak oxidation ability, requiring surface modifications. Noble metal ion doping has been found to enhance photocatalytic performance by improving electron–hole separation. Ongoing research focuses on modifying g-C₃N₄ to design nanomaterials with optimized properties for efficient antibiotic removal through photocatalysis (Bai et al. 2022).

Tetracycline's presence in water raises environmental concerns due to its ecological impact and potential toxicity. Various studies have explored photocatalytic materials for its removal. The introduction of AgI/BiVO₄, a hetero-structured photocatalyst, shows excellent performance in eliminating tetracycline under visible light compared to bare BiVO₄ and AgI (Chen et al. 2016).

Ciprofloxacin, a potent antibiotic, is widely used for various infections but poses environmental and health risks due to its impact on plant growth and human health. Modified photocatalysts have been explored for more efficient degradation of ciprofloxacin. Zn-doped Cu₂O particles exhibit superior photocatalytic performance over undoped Cu₂O, degrading 94.6% of ciprofloxacin, and maintaining 91% efficiency after five cycles (Yu et al. 2019a, b). Meanwhile, a Z-scheme CeO₂–Ag/AgBr photocatalyst demonstrated enhanced degradation using visible light due to faster charge transfer (Malakootian et al. 2020). Additionally, it was found that exfoliated nano g-C₃N₄ significantly improved photocatalytic activity, degrading 78% of ciprofloxacin in a solar-exposed solution, showcasing its efficient charge separation and high surface area (Pattnaik et al. 2019).

Norfloxacin, a widely used antibiotic for treating urinary tract infections, has become a concerning pollutant in wastewater, particularly in hospital settings due to its high concentration. Environmental concerns around fluoroquinolone antibiotics, including norfloxacin, have surged due to their widespread usage and potential ecological impact. Various studies have investigated different materials for photocatalytic degradation of norfloxacin. For instance, an immobilized TiO₂/Ti film with exposed {001} facets displays excellent photocatalytic performance by mainly involving •OH in norfloxacin degradation (Sayed et al. 2016). Additionally, high degradation efficiency was achieved using a Z-scheme Ag/FeTiO₃/Ag/BiFeO₃ photocatalyst under visible light that was stable and could also be reused (Tang et al. 2016). Copper-doped BiOBr was synthesized and the results showed enhanced light absorption and charge separation, maintaining 95% of its activity after five cycles (Lv et al. 2020.). Similarly, Bi₂WO₆ was proposed as a catalyst, the results showed an increased norfloxacin degradation when used in a TX100/Bi₂WO₆ dispersion under visible light, especially at the critical micelle concentration of TX100 (CMC = 0.25 mM) (Bai et al. 2022).

Amoxicillin, a widely used antibiotic, has been the focus of studies exploring various photocatalytic materials for its degradation. Balarak et al. (2021) utilized graphene oxide–loaded titanium dioxide nanoparticles under UV light, noting significant influences from factors such as pH, dosage, UV intensity, and initial amoxicillin concentration, achieving over 99% degradation under specific conditions. Mirzaei et al. (2019) developed a magnetic fluorinated graphitic-carbon-nitride catalyst with enhanced surface area, exhibiting improved photocatalytic activity and mineralization for amoxicillin degradation compared to bulk g-C₃N₄. Additionally, Huang et al. (2021) created carbon-rich g-C₃N₄ nanosheets with excellent stability and efficacy under solar light for amoxicillin degradation.

Photocatalysis is the reaction brought about by the induction of photon, which is dependent on the specific energy band structure of the photocatalytic material (Yuju et al. 2023). The specific energy band structures of photocatalysts are low energy VB and high energy CB. The energy difference between conduction and valence bands is known as the bandgap width of the photocatalyst (Kou et al. 2017). The charge carrier in the VB is known as the hole, while the charge carrier in the CB is the electron. Semi-conductors with a predominantly electron conductivity are n-type semi-conductors, while semi-conductors with a hole conductivity are p-type semi-conductors. For example, tungsten trioxide (WO₃) is an n-type semi-conductor. Various materials have been used to achieve the antibiotics photocatalytic degradation, and this includes graphene, metal semi-conductors, mixtures of the two such as TiO₂@g-C₃N₄ (Wang et al. 2017), and MOFs (Du et al. 2021).

In recent studies, photocatalysis has been successfully applied in antibiotic remediation with notable results. For instance, Heris et al. (2023) demonstrated the efficient degradation of tetracycline in wastewater using titanium dioxide (TiO₂) as a photocatalyst under UV light. The study reported that more than 90% of tetracycline was degraded within 180 min, with mineralization rates exceeding 70%, indicating the effective breakdown of the antibiotic into harmless by-products. The researchers highlighted the role of hydroxyl radicals generated during the photocatalytic process, which played a crucial role in oxidizing the tetracycline molecules. Similarly, a study by Van Thuan et al. (2022) explored the use of graphitic–carbon–nitride (g-C₃N₄) for the degradation of ciprofloxacin under visible light irradiation. The research demonstrated that over 93.8% of the antibiotic was removed within 120 min, showcasing the potential of non-UV photocatalysis in real-world applications where energy efficiency is critical. The study further emphasized the recyclability of the g-C₃N₄ photocatalyst, which retained its activity after multiple cycles, suggesting its potential for sustainable and cost-effective wastewater treatment. These examples demonstrate the promising application of photocatalysis in mitigating antibiotic pollution, offering significant advantages over conventional methods.

The mechanism of photocatalysis involves the incident of light energy on a photocatalyst, which in turn brings about the transition of electron from the valence energy level to the conduction energy level with a trail of hole behind. The reaction of the photocatalyst electron–hole transition with its surrounding substances in water, which includes dissolved oxygen molecules, ions, and added Fenton reagents, leads to free energy generation (Du et al. 2021). The substances in the surrounding water capture exited electron to form free radicals and propagate through a series of redox reactions. This finally leads to breakage of the bonds within the antibiotic molecule and eventually leads to the complete mineralization into CO₂ and H₂O. These final products of degradation of antibiotics, for example, of tetracycline (TC), ciprofloxacin (CIP), and doxorubicin (DOX), are demonstrated in the works of Chen et al. (2020) and Racles et al. (2019).

h⁺ + antibiotics → H₂O + CO₂ + degradation products.

Metal doping, composite materials with heterojunctions, and Fenton reagents can be used to optimize the photocatalytic degradation of antibiotics. Metal doping was used to optimize the mechanism of MOF photocatalytic degradation of tetracycline (TC) (Cao et al. 2018). Upon the incidence of the light energy, the organic part of MOFs generates free electrons, which are transferred to the Zirconium-oxo (Zr-O) metal cluster through ligand-to-metal electron transfer (LMCT) to produce Zr³⁺, or the electron flow could also flow from Zr³⁺ to Co atoms through metal-to-metal electron transfer (MMCT) to produce Co²⁺. This transfer of the electron flow from Zr³⁺ or Co²⁺ leads to production of superoxide radical (⁠⁠) from dissolved oxygen molecule (O₂), which effects the degradation of the TC.

In another study, Yang et al. (2019a, b) demonstrated the mechanism of photodegradation by composite material with heterojunction (BiOBr/UiO-66-NH₂). Their major inferences were that both materials synergistically improve the photon absorption, the structure of the nanocomposite material was receptive to the pollutants, and the heterojunction maintained the separation of electron–hole pair from instant recombination.

In the study of Askari et al. (2020), their ternary composite material was made up of a double Z-shaped heterojunction with very good electron conduction or flow properties. However, not all composite materials elicit the mechanism of photodegradation through only heterojunction, Zhang et al. (2020) demonstrated with the ternary composite UiO-67/CdS/rGO that heterojunction is formed between UiO-67 and CdS, and rGO acts as a co-catalyst thereby improving the hole–electron separation.

The role of Fenton reagents as important factors in photodegradation mechanism as demonstrated with the photoexcitation of MIL-100(Fe) and activation of the persulfate had a synergistic effect mainly through the cycling of Fe(II) and Fe(III) (Yin et al. 2020).

The application of antibiotics is a global thing, in the treatment of humans and animals, with residues released into the environment, especially water bodies, which poses a dangerous situation to both man and other living things in the environment (Yang et al. 2021a, b; Shang et al. 2022) The quest for a clean and sustainable environment will be achieved not only when there is a shift in the use of fossil fuels to other sources of renewable energy but also when toxic antibiotics are removed from the environment (Hemavibool et al. 2022). Different popular approaches are biological, chemical, and physical, used in the treatment and removal of pollutants from the environment. The reports of Akyon et al. (2019) and Zhang et al. (2019) showed that the use of microorganisms as biological means and advanced oxidation of antibiotic removal is to an extent effective. However, they do not give complete mineralization of the residual antibiotics. Adsorption and photocatalysis have competitive advantages over other removal techniques that have been used: they are promising choices, cheaper, simple to construct, more efficient, user as well as environmentally friendly, safe, and lend to complete degradation (Du et al. 2021; Qin et al. 2021; Yang et al. 2021a, b; Zhu et al. 2021; Shang et al. 2022; Zambrano et al. 2022).

The design, fabrication, as well as reuse of the photocatalysts after some cycles are some of the limitations facing the effectiveness of photocatalysts (Yang et al. 2019a, b). For instance, titanium oxide (TiO₂) is limited by poor photocatalytic activity under visible light. It is only excited when exposed to harmful UV light. Graphitic carbon has poor absorption of visible light. Hence, there is a need to synthesize photocatalysts that will be able to utilize visible light.

The introduction of non-metal graphitic nitride (g-C₃N₄) similar to graphene commands a lot of attention in photocatalysis due to its narrow bandgap suitable for visible light absorption, physicochemical stability, harmlessness, and environmental friendliness as well as simple fabrication method and cheapness (Jo & Tonda 2019; Niu et al. 2020). Notwithstanding, g-C₃N₄ has a few limitations such as loss of the generated electrons, the recombination of charged reactive species needed for photocatalytic activity, as well as poor visible light absorption. These can be overcome by compositing formation with other suitable materials for the synthesizing of the photocatalysts such as Bi₂S₃/g-C₃N₄, TS/g-C₃N₄, MoO₃/Ag/C₃N_4, and Ag/D/2D-g-C₃N₄/TS-1 (Adhikari et al. 2020; Yang et al. 2021a, b; Wu et al. 2022).

Furthermore, to overcome these challenges and improve photocatalytic efficiency, some modifications such as composite formation with other semi-conductor materials, and structural enhancement by the addition of suitable ligands, and by the integration of co-catalysts, have been carried out. Different combination techniques have been used to improve the removal efficiency of photocatalysts. These include variants of heterojunctions, exposing active sites, and the use of porous materials, tailoring morphology, and exposing active facets have been used to enhance the photocatalytic removal efficiency (Guo et al. 2019; Hailili et al. 2019; Hu et al. 2019; Jiang et al. 2019; Lyu et al. 2019; Wang et al. 2019b, 2021; Phakathi et al. 2022; Lee et al. 2023).

It is this demand that birthed the introduction of graphite carbon (g-C₃N₄), bismuth sulfide, and silver (Ag) in photocatalysis. These materials exhibit narrow bandgaps and have strong visible light absorption when composited with other semi-conductors and noble metals. The use of g-C₃N₄ in the photocatalysis of antibiotics has numerous advantages such as chemical stability, cost-effectiveness, ease of production, and user friendliness (Singh et al. 2019; Mao & Jiang 2019; Qin et al. 2021).

To facilitate reuse of nanomaterials after some cycles, a three-dimensional (3D) framework MoS₂ nanosheet/graphene aerogel was synthesized by hydrothermal method. The fabricated 3D MoS₂NS/GA exhibited high removal efficiency of concentrated tetracycline hydrochloride under visible light. The constructed aerogel photocatalyst is economical in usage, and enhances degradation of antibiotics due to its large area and porous nature, and improves visible light absorption (Yang et al. 2019a, b; Lee et al. 2023). It retains its photocatalytic activities after some cycles. The immobilization of the powdered catalyst is a challenge to the recovery of the catalysts. Hence, there is a need to immobilize the catalysts on stationary objects such as ceramics and stainless steel. However, the use of 3D nanostructures may serve as an alternative support. Additionally, their high activity and large surface area may enhance photocatalytic activities.

Novel composite photocatalysts MoO₃/Ag/C₃N₄, Bi₁₂O₁₇Cl₂/Ag/AgFeO_2, Ag₃PO₄/TiO₂, and TiO₂/g-C₃N₄ were improved by Z-scheme technique and fabricated using different methods such as hydrothermal and borohydride reduction, ultrasound-assisted ethanol reduction of silver ion, and simple two-step method (Liu et al. 2019a). These z-scheme photocatalyst composites degraded ofloxacin, tetracycline, and ciprofloxacin two, three, and six times better than individual semi-conductors under visible light (Wu et al. 2020). The major reactive species involved in the degradation are hydroxyl (OH⁻), holes (h⁺), and superoxide (O²⁻), though these reactive species' photoactivity varies from one photocatalyst to another. Z-scheme improves the morphology, increases surface area, and separates photogenerated radicals, which increases the absorption of visible light by the photocatalysts. The fabricated composite was more efficient in the photodegradation of antibiotics than when graphene layers were embedded in either TiO₂, g-C₃N_4, or g-C₃N₄/TiO₂. The interactive synergy among the three components of the photocatalyst resulted in improved separation and the release of the electrons from g-C₃N₄ to initiate reduction activity. Z-scheme fabricated photocatalysts are economical due to their reusability (Wu et al. 2020).

Integration of co-catalysts that are mostly noble metals into semi-conductor photocatalysts has been used to modify the effectiveness of their activity. The composite exhibits a lower energy bandgap, making it suitable for the absorption of visible light from the sun. It also prevents the recombination of the photogenerated reactive species and creates more reactive sites due to enlarged surface areas thereby improving the photodegradation of residual antibiotics (Zhao et al. 2021).

Doping or coupling of semi-conductors with metals such as silver, magnesium, copper, cobalt, iron, chromium, manganese, and zinc, or with non-metals such as nitrogen, carbon, and sulfur, are effective methods to enhance the photocatalytic activity of semi-conductors. It improves the durability of the photocatalyst as well as lowers the bandgap and enhances visible light absorption (Djurišić et al. 2020; Gautam et al. 2020; Das et al. 2021; Bai et al. 2022). However, the challenge of photo-corrosion can limit the application of metals as doping agents and the recombination of reactive species at higher concentrations, thereby reducing its removal efficiency.

A doped composite of zinc oxide was fabricated with cerium as a photocatalyst to degrade antibiotics and remove ARB. It was noted that the composite, ZnO-Ce, was faster and more effective in the degradation of trimethoprim and sulfamethoxazole than other established composites such as TiO₂-P₂S and ZnO. The novel photocatalyst composite Ce-ZnO is not expensive or difficult to synthesize, but it is reusable, making it economical and user-friendly unlike TiO₂-P₂S (Zammit et al. 2019).

A novel nanoparticle photocatalyst was fabricated by double doping the metals copper and iron with a composite that consisted of titanium oxide (TiO₂) and silicon oxide (SiO₂). The composite semi-conductor has a large surface area and is active under sunlight. The fabricated composite exhibits efficient photocatalytic degradation. It has a removal efficiency of 98% for the photocatalyzed antibiotics. Doping TiO₂-SiO₂ with either metals or non-metals results in a nanocomposite that can utilize sunlight, making it environmentally friendly. The composite exhibited a reusability up to the seventh cycle (Rani et al. 2021).

Titanium oxide and zinc oxide were doped with nitrogen and sulfur and composited with chitosan. All three photocatalysts, NS-TiO₂ (NST), NS-ZnO (NSC), and chitosan blended (NST/CS and NSZ/CS), were used in the degradation of tetracycline, with a removal efficiency of 91% after 20 min exposure to visible light. The NST composite when blended with the chitosan had a removal efficiency for tetracycline that was twice that of the composite only. The composite has a high recoverability, hence it is a reusable photocatalyst that can be used in the removal of tetracycline from water (Farhadian et al. 2019).

A doped porous composite of chloride and graphene nitride (Cl-g-C₃N₄) was synthesized using a facile bottom-up synthetic route. The composite photocatalyst was effective in the degradation of tetracycline under visible light with a removal efficiency of 92% at an exposure time of 2 hours. The doped composite was twice better in photocatalytic degradation than g-C₃N₄. The Cl-doped graphene nitride improved the structure of the graphene nitride, which makes the composite have a large surface area, and subsequently many active sites. The recombination of the generated holes–electrons as inhibited leads to improved photocatalytic mineralization of tetracycline (Guo et al. 2019).

Besides the use of two semi-conductors being used by different researchers, a novel model of three semi-conductors, capable of using solar light to photocatalyze the degradation of tetracycline has been reported. The combined semi-conductors exhibited a suitable narrow bandgap, which gave an improved visible light absorption, leading to better photocatalytic degradation of antibiotics at an optimized condition of pH 9.0, catalyst dosage of 0.02 g/L, an antibiotic concentration of 30 mg/L, and exposure time of 20 min. The reactive species O₂⁻ and holes created during the excitation of electrons were responsible for the degradation of the antibiotics. Removal efficiency according to the authors was 98% (Doosti et al. 2022).

Heterojunction photocatalysis involves the use of types such as normal heterojunctions that consist of type I, II, and III heterojunctions, p-n heterojunctions, surface heterojunctions, direct Z-scheme, and step scheme Schottky (He et al. 2021). The heterojunction photocatalyst is usually formed when two semi-conductors of different materials are combined, to enhance the photocatalytic activity and removal of the photocatalyst (Calik et al. 2022).

One of the major problems of the photocatalytic process is the recombination of generated species such as electrons and holes that are needed for the mineralization of the antibiotics. However, the photocatalysts fabricated through heterojunction methods have removed this limitation. The heterojunction composite of the semi-conductors prevents the recombination, by separating and facilitating the movement of electron–hole pairs.

Furthermore, several methods have been adopted in recent times to improve the photocatalytic degradation of antibiotics through composite formation. Different approaches in the design and fabrication of photocatalysts have been used. One such is the combination of Z-scheme and heterojunction compositing synthesized using facile hydrothermal and a liquid ultrasonic route in sequence. The composite created TCPP/rGO/Bi₂O₆ with an improved morphology, as well as visible light absorption, efficient charges separation, large surface area that gives more active sites and better tetracycline degradation was reported to be better in removal efficiency than individual composites BWO, rGO/BWO, and TCPP/Bi₂WO₆. Both holes (h⁺) and superoxide radicals (O²⁻) were mainly involved in the degradation of tetracycline within the composites system that was designed. The synthesized photocatalyst was found to be more stable and reusable after five cycles. It has a removal efficiency of 79.27% (Hu et al. 2019).

The construction of hetero-jointed photocatalysts has helped to solve the problem of well-documented semi-conductors, such as oxides and sulfides of bismuth, cadmium, and iron and graphene nitride. They are used to efficiently separate reactive species generated during photocatalysis from recombining (Qiu et al. 2020). Graphene nitride suffers from poor utilization of visible light and the recombination of electrons and holes generated thereby limiting its use in photocatalytic activity. The heterojunction method has been used to synthesize improved photocatalysts that include BiOCl/g-C₃N₄, TiO₂/g-C₃N₄, Bi₂MoO₆/g-C₃N₄, Al₂O₃/g-C₃N₄, Ag₃PO₄/g-C₃N₄.

Another technique used to improve photocatalytic efficiency is p-n heterojunction, which increases the visible light potential of the catalyst as well as prevents the recombination of the reactive species needed for photocatalytic activity. A modified photocatalyst BiOCl/BiVO₄ was synthesized using Fe₃O₄ quantum dots by a facile strategy. The photocatalyst exhibited improved morphology with quantum dot Fe₃O₄, large surface area mobile charge carrier, and enhanced visible light absorption. The photocatalyst F₃O₄ QD@BiOCl/BiVO₄ is capable of photodegrading four different types of antibiotics when the synthesized photocatalysts are exposed to visible light for 90 min. It has two-times better removal efficiency than either BiOCl or BiVO₄. The improved photocatalyst can be reused with mineralization activity retained up to the fourth cycle, making it efficiently economical in use. However, a lot of time and energy is dispensed in the fabrication of p-n hetero-jointed BiOCl and BiVO₄. This limitation can be removed by adopting a one-step hydrothermal method in the synthesis of the photocatalyst (Jiang et al. 2019).

A composite (Bi₂S₃/g-C₃N₄) was developed using a low-temperature technique and ultrasound. This has enhanced the separation of generated carriers electrons/holes (e⁻/h⁺), thereby improving photocatalytic analysis of the composite (Hao et al. 2020). The heterojunction composite of Bi₂S₃/g-C₃N₄ has its limitations, the preparation is demanding, the mechanisms of carrier separation are not well understood, and there is uncertainty about whether the composite is responsible for the photocatalysis (Truc et al. 2019).

The integration of two-dimensional materials like g-C₃N₄ into two-dimensional/two-dimensional (2D/2D) in a ternary heterojunction composite has been used to overcome the limitations of graphitic nitride (g-C₃N₄) as a photocatalyst. It has improved multiple charge transfer and separation of charges resulting in enhanced visible light absorption and photocatalytic activity (Jo & Tonda 2019).

Zirconium-based porphyrin metal-organic framework (Zr-pMOF) has a large surface area, making it have many active sites and be water and chemical stable. It is a better visible light absorber and aids in enhanced photocatalytic degradation. The addition of metal sulfide to Zr-pMOF improves the suitability of the Zr-pMOF for photocatalytic degradation of antibiotics. The synthesis of ZIS/MOF-525 was achieved by solvothermal. The composite, a type of heterojunction-modified photocatalyst, possesses enhanced generation of electrons (e⁻) and holes (h⁻) as well as inhibits the recombination of the reactive species. Ordinarily, MOF-525 removal efficiency was as low as 37.2%, 70% when Zn/n2S4 while hetero-jointed semi-conductors gave a removal efficiency of 93.8%. All the reactions were under visible light. The composite is economical as it was still active after the fifth cycle (Zhang et al. 2023).

Bismuth tungstate (Bi₂WO₆) has been reported to be effective in the removal of antibiotics from water bodies. It is non-toxic, with low bandgap energy, is easy to fabricate, and is a good absorber of visible light. Bismuth tungstate can be modified by improving its morphology, doping, as well as by heterojunction formations (Orimolade et al. 2021).

To eliminate the challenges of light absorption by the semi-conductors, MOFs were created. MOFs are crystalline substances formed by the aggregation of metal ions and organic ligands. When metal ions and organic ligands cluster together, a metal-organic framework is formed. MOFs have large surface areas with several absorption sites, and porous structures making them reputable for good visible light absorption. MOFs are good visible light absorbing materials, as well as showing efficient photocatalytic activity due to their porous nature, stability, and morphology post-synthetic modification by the addition of metal ions or functional groups (Du et al. 2021).

Before the advent of MOFs, other materials were used, but they suffered some limitations such as poor light absorption and non-reusability. MOFs have a large surface area, better porosity, many active sites, and physicochemical stability. All these features make MOFs a better light absorber of visible light. The porosity of MOFs has been improved by structure directing agents that modulate the formation of macroporous leading to meso and macroporous hierarchical zeolithic imidazole framework-8, and composited with ligands and subjected to post-synthetic modification. However, these methods are expensive or inefficient. The degradation of antibiotics using visible light-excited MOFs is a promising and efficient means of removing residual antibiotics from the environment. A non-metal (S) was doped on Bi-based MOF. The hetero-composite was reported to have a removal efficiency of 62.9%, and was more efficient than individual Bi-based MOFs (non-doped Bi-MOF). There was an increase in oxygen radicals that generated a reduction in bandgap energy from 3.57 to 3.37 ev resulting in enhanced visible light absorption in the degradation of tetracycline. The reusability of the fabricated Bi-MOF-0.0S makes it economical to use (Chen et al. 2019).

A MOF nanocomposite Bi₂S₃/MOF808 was synthesized using a simple quick method using Bi₂S₃ and MOF-808 that possessed a large surface area and remarkable stability. The photocatalyst had a good removal efficiency of 80.8% when exposed to visible light, and it was higher than the individual degradation obtained with either MOF-808 or Bi₂S₃. The nanoparticles' closeness of the composite improves the transfer of the generated electrons and holes thereby increasing visible light absorption and resulting in improved photocatalytic degradation of tetracycline, which was carried out mainly by reactive species hydroxyl.

MOFs were doped with two different semi-conductors, which were fabricated by solvothermal technique. The composite Co/Fe-MOF, Cu/Fe-MOF, and Mg-MOF were crystalline structurally with improved surface area, porosity, as well as improved light absorption that resulted in efficient photocatalytic degradation, and removal efficiency that ranged between 85 and 92% after 120 min light exposure (Thi Kim Ngan et al. 2022). The introduction of second metal ions into the framework structure to produce a double metal-organic framework has been mentioned to improve the photocatalytic activity of the composite (Al Zoubi et al. 2020).

Recently, a mechanothermal method that is non-expensive and non-toxic was used to synthesize a heterogeneous composite photocatalyst (ZnWK-5) that is capable of completely mineralizing ampicillin from wastewater using sunlight. The photocatalytic activity of the composite zinc oxide-tungstate kaolinite was attributed to the presence of W⁵⁺, although further analysis showed the generated hole (h⁺) and superoxide O²⁻ are actively involved in the photocatalytic degradation of the antibiotics. When the photocatalyst was thermally treated, its removal efficiency improved, with a 98% degradation of ampicillin after exposure to sunlight for 5 hours. The performance of the photocatalyst is higher than that of the commercially available P25 Degusa. The composite photocatalyst retains its photoactivity even after five cycles, making it economical to use (Alfred et al. 2022).

A composite of titanium oxide (TiO₂) nanotubes and copper I oxide (Cu₂O) was fabricated to improve the photocatalytic degradation of tetracycline. The composite created exhibited a low bandgap of 2.58 eV, making it absorb visible light. Also, a large surface area with more active sites enhanced the photocatalytic activity of the nanotubes composite with an approximately 100% removal of tetracycline when exposed to visible light for 60 min. The composite retains its activity after being used five times, making it economical to use. The reactive charges such as superoxide and hydroxyl radicals were responsible for the photodegradation activity (Sharma et al. 2022).

Copper oxide and iron were synthesized using the leaf extract of Psidium guajava, which was reported to possess a suitable band gap, making it a good absorber of visible light. The method of production is simple, not expensive, and environmentally friendly. The synthesized nanocomposite photocatalyst had a better performance of removing tetracycline with 88% removal efficiency than individual iron oxide or copper oxide nanoparticles. The photocatalytic degradation of the antibiotic was attributed to the hydroxyl radicals generated from the nanoparticles during photoreaction (Kaushal et al. 2023).

Nanostructured semi-conductors are attractive in the photocatalytic degradation of antibiotics in wastewater. For example, nanophotocatalysts of bismuth have some unique characteristics such as narrow bandgaps, suitable morphology, and better visible light absorption due to large surface area, more active sites, and good separation capacity of reactive species needed for the reaction. It is more competitively advantageous than the common titanium and zinc oxide-based semi-conductors (Oladipo & Mustafa 2023). Nanostructured bismuth photocatalysts are composited of semi-conductors such as FeO₃, MoO₆, VO₄, WO₆, and S₃. The composite has been modified to effectively degrade residual antibiotics under visible light.

The application of magnetic nanoparticles composite semi-conductors with a heterojunction model of copper–iron oxide and methyl cellulose was used to mineralize ciprofloxacin. The removal efficiency of the antibiotic was achieved at pH 7.0, at 3 mg/L concentration, and a loading catalyst of 0.2 g, with an exposure time of 90 min. The photocatalyst remains stable after the fourth cycle, making it reusable (photo-1-Cu-FeO₂-methyl cellulose) (Tamaddon et al. 2020).

To enhance adsorption of semi-conductors used in photocatalytic degradation of antibiotics, three different materials were fabricated and they include carbon nanotubes, graphene oxides, and sodium alginate. These three composite materials formed a strong adsorptive surface using hydrogen peroxide and L-cysteine producing better-structured carbon nanotubes/L-cysteine- graphene oxide/sodium alginate (CNT/L-Cys-Go/SA) with improved adsorption, better than individual materials (Ma et al. 2020).

The construction of a nano-heterojunction photocatalyst composite was fabricated using the facile sonochemical method. The introduction of silver oxide (AgFeO₂) nanospheres is closely knitted to zinc oxide nanoparticles. This resulted in a large surface area, with more active sites and enhanced photocatalytic activity. The reactive species h⁺ and OH⁻ are responsible for the degradation. The composite is economical in use, the magnetic nature of the silver oxide nanoparticles makes the photocatalyst recoverable and reusable. The AgFeO₂-ZnO nanoparticles have more than 98% recovery even after they have been used up to the sixth cycle, with an insignificant reduction in removal efficiency of 90.3% at the first cycle to 7% at the sixth cycle (Janani et al. 2021).

A novel nanocomposite was synthesized using reduced graphene oxide-zinc sulfide-copper sulfide (rGO-ZnS-CuS) as fabricated using a straightforward surfactant-free in situ micro method. The nanocomposite photocatalyst was used in the photocatalytic degradation of antibiotics. Photocatalysis results in the formation of reactive species superoxide and hydroxyl that are used in the degradation of ofloxacin. The addition of rGO to the ZnS-CuS nanoparticles enhances its photocatalytic degradation of ofloxacin. There is a synergy between the two semi-conductors that aids the transfer of electrons produced, and charge separation that prevents their recombination. The synthesized photocatalyst nanoparticles were more efficient in ofloxacin degradation compared to the ordinary zinc sulfide (Mahalingam et al. 2023).

The introduction of artificial intelligence (AI) into photocatalysis marks a transformative step in enhancing the efficiency and scope of this technology. The optimization of photocatalytic processes for specific outcomes can be complex due to the many variables involved, including catalyst material, light intensity, reaction conditions, and the nature of the target pollutants or substrates. Therefore, AI brings a powerful toolset to this field by enabling the automation and optimization of experimental design, data analysis, and process control. Machine learning algorithms, a subset of AI, can analyze large datasets generated from photocatalytic experiments, identifying patterns and predicting optimal conditions much more quickly and accurately than traditional methods. AI-driven models can also be used to simulate photocatalytic processes, allowing researchers to explore new catalyst designs and reaction pathways without extensive laboratory testing. In addition to optimizing performance, AI can assist in identifying novel materials for photocatalysis by predicting the properties of new or existing compounds. This accelerates the discovery of more efficient, cost-effective, and environmentally friendly photocatalysts.

By integrating AI, the field of photocatalysis stands to benefit from improved reaction efficiencies, lower operational costs, and greater adaptability to complex and dynamic environmental challenges, positioning it as a key tool in sustainable development and environmental protection.

Applications of photocatalysts in the removal of antibiotics from wastewater have garnered a lot of attention and significant progress recently due to their capacity to remove antibiotic residues from wastewater in an efficient and environmentally friendly manner (Davies et al. 2021; Sayadi et al. 2023). However, more efforts need to be made to improve the efficiency and reusability of photocatalysts to enable widespread use of the technology (Gadore et al. 2023). Different modification techniques, such as doping, heterojuction, and surface and morphology modifications, are usually employed to improve the performance and efficiency of photocatalysts (Zia & Riaz 2021; Chen et al. 2022a, b, c). Doping, particularly with metal dopants, is commonly used to increase the photocatalytic activity of a photocatalyst. At higher concentrations, however, metal dopants may act as recombination centres, which could decrease the efficacy of a photocatalyst. Therefore, future studies should concentrate on alternative approaches, such as doping with non-metals such as phosphorus, sulfur, nitrogen, and boron (Chen et al. 2021; Bai et al. 2022).

Metal oxide semi-conductor photocatalysts such as ZnO, TiO₂, and CeO₂ are reported to display superior photodegradation performance over organic photocatalysts. However, they have disadvantages of poor charge separation, high charge recombination, lower stability, and limited application in sunlight (Joshi et al. 2020; Kumar 2023; Mohamed et al. 2023). To overcome these challenges, it is absolutely essential to modify the metal oxide semi-conductors by hybridizing them with other materials (Dutta et al. 2022; Kaushal et al. 2023). The hybrid composites offer superficial photocatalytic performance in the photodegradation of antibiotics when compared with naked photocatalysts. The use of bio-inspired materials such as food and agricultural waste, plant extracts, proteins, enzymes, natural gums, and others in the synthesis of metal oxide and other photocatalysts is gaining prominence due to their improved photocatalytic activities, environmental friendliness, availability, and cost-effectiveness (Chandra et al. 2021; Gadore et al. 2023; Govindasamy et al. 2022). Hybridization of metal oxide photocatalysts with bio-inspired materials will enhance their catalytic performance by increasing the absorption of visible light, enhancing the generation of photogenerated electron–hole pairs, and producing more superoxide and hydroxyl radicals (Chen et al. 2023a, b; Gadore et al. 2023). Therefore, developing eco-friendly, non-toxic, cost-effective, and readily available biological catalysts for efficient photocatalytic degradation of antibiotics in wastewater is paramount to supporting the SDGs (Luo et al. 2023).

Moreover, most of the synthetic methods used in the preparation of photocatalysts used in the photodegradation of antibiotics in wastewater, such as hydrothermal, co-precipitation, sol-gel, solvothermal, and hydrolysis, among others, are usually prepared through series reactions with the use of toxic and expansive reagents or equipment (Wu et al. 2021). Green and cost-effective methodologies, such as biotemplating and biomimetic technologies, should be considered in the development of future photocatalysts for the sustainable removal of antibiotics from wastewater (Yu et al. 2019a, b; Kumar et al. 2021; Chin et al. 2023).

Despite the fact that photocatalysts exhibit remarkable efficiency and photocatalytic performance after modification, only a few studies report on the fate and safety of photocatalysts after their applications. Therefore, studying the photocatalytic degradation pathways and mechanisms at the atomic level would offer a valuable guide to the fate and transformation of antibiotics during the photocatalytic degradation processes. Photocatalytic degradations of antibiotics are usually accompanied by the release of different intermediates. An in-depth investigation of such intermediates is absolutely necessary for improving catalyst performance. Another key issue with photocatalysts for antibiotic removal is their recyclability and reusability. The recycling capacity of a photocatalyst is an important indicator for determining its cost-effectiveness and viability for practical application in antibiotic degradation (Wang & Zhuan 2020). It is, therefore, critical to develop photocatalysts that are simple to separate and recycle in order to prevent losing any valuable components during the photocatalytic process. One way to streamline and enhance the recyclability and reusability of photocatalysts is through the magnetization of the photocatalysts that have no magnetic properties. Magnetisms can be induced to improve separation after use by simply adding an external low-strength magnetic field (Silva et al. 2021; Wang & Chen 2022).

Finally, almost all investigations on photocatalytic wastewater treatment are conducted on a laboratory scale. The transition from laboratory to industrial scale is required to comprehend the real-world applicability of photocatalytic wastewater treatment (Liu et al. 2020; Bai et al. 2022). To address the practical challenges of scaling up photocatalysis for industrial use, several factors must be considered. First, the availability and cost of photocatalytic materials, such as titanium dioxide (TiO₂), can significantly impact the economic feasibility of large-scale implementation. While TiO₂ is widely used due to its efficiency and stability, alternative photocatalysts such as graphitic-carbon-nitride (g-C₃N₄) and doped metal oxides may offer more cost-effective or energy-efficient solutions. Additionally, the energy requirements for activating photocatalysts, particularly under UV or visible light, pose a challenge in terms of both operational costs and sustainability. For industrial-scale applications, integrating photocatalytic systems with renewable energy sources, such as solar power, could mitigate some of these energy concerns. Furthermore, considerations regarding reactor design, such as optimizing the surface area for light exposure and ensuring uniform flow rates in large volumes of wastewater, are essential for maintaining high degradation efficiency. Overall, while photocatalysis shows great promise, addressing these scalability issues is crucial for its widespread adoption in industrial wastewater treatment.

The SDGs are a comprehensive collection of 17 ambitious objectives that were unanimously endorsed by all member states of the United Nations in 2015. These goals serve as a global appeal to take decisive action in order to eradicate poverty, safeguard the environment, and promote overall well-being of all individuals by the year 2030 (Aremu 2021). They tackle the interrelated difficulties of our world, acknowledging the necessity for comprehensive solutions that encompass social, economic, and environmental aspects. According to UN (2023), the 17 interconnected objectives can be categorized as follows: eradication of poverty, promotion of good health, preservation of terrestrial ecosystems, elimination of hunger, establishment of gender equality, provision of quality education, fostering of economic growth, ensuring access to clean water, reduction of inequality, promotion of affordable energy, development of sustainable communities, protection of marine ecosystems, promotion of responsible production and consumption, mitigation of climate change, fostering of partnerships for achieving the goals, promotion of peace, and development of industry, innovation, and infrastructure.

This study focusing on pharmaceutical wastewater treatment is essential for the attainment of various SDGs. Directly, this study is relevant to SDG 6, whose focus on the goal of clean water and sanitation aims to guarantee universal access to safe and affordable drinking water and sanitation by the year 2030. The process of water treatment is essential in ensuring the removal of detrimental impurities from water sources, rendering them suitable for human use. This study is also related to SDG 3, which is ensuring optimal health and well-being. Uninterrupted access to uncontaminated water is crucial for preserving optimal health and mitigating the prevalence of waterborne illnesses, particularly among children and marginalized communities. Effective water treatment safeguards populations against disease and enhances overall life span (Silva 2023). Indirectly, this study is relevant to SDG 2, which deals with zero hunger. Water plays a crucial role in agriculture, and implementing effective water treatment methods can encourage the sustainable use of water in farming, hence enhancing food security and mitigating water scarcity (Obadeen et al. 2022). It is also related to SDG 14, which focuses on life below water. The release of untreated wastewater contaminates marine areas, causing harm to ecosystems and aquatic organisms. Water treatment mitigates this pollution, bolstering the well-being of seas and the biodiversity they uphold. This study is also indirectly relevant to SDG 7 consisting of affordable and clean energy. Certain water treatment systems necessitate use of energy, but others have the capability to produce energy from wastewater. Attaining equilibrium in this domain can aid in achieving objectives related to both the purity of water and the generation of sustainable energy.

Generally speaking, water treatment plays a crucial role in accomplishing numerous SDGs as follows: by enhancing the well-being of the general population and promoting cleanliness and hygiene, advocating for the implementation of environmentally conscious practices in water resource management, preserving and safeguarding ecosystems and biodiversity, enhancing food security and increasing agricultural production, facilitating economic growth, and alleviating poverty. Hence, it is imperative to allocate resources towards the development of efficient and cost-effective water treatment technologies in order to establish a more sustainable and egalitarian future for everyone.

Drawing inference from Crini et al. (2023) and Nasirian et al. (2022), utilizing photocatalytic methods to purify antibiotic-contaminated wastewater has substantial ramifications for many SDGs, especially SDG 6 (Clean Water) and SDG 14 (Life Below Water), hence, promoting a healthier world and a more sustainable future.

• Through the efficient elimination of antibiotics, photocatalysis guarantees the availability of uncontaminated and hygienic water suitable for consumption and sanitation purposes. This enhances the overall well-being of the general population and mitigates the occurrence of waterborne illnesses.

• Safeguarding of freshwater sources and ecosystems from the harmful effects of antibiotic pollution. This, in turn, supports sustainable water management and the preservation of resources.

• By decreasing the presence of antibiotics in water, the potential for antibiotic resistance, which poses an increasing danger to worldwide health, is minimized. This provides individuals with protection against infections that are more resistant to treatment.

• The enhancement of water quality contributes to the enhancement of overall health and well-being by diminishing exposure to detrimental pollutants, resulting in decreased healthcare expenses.

• By eliminating antibiotics from wastewater, their release into aquatic habitats is prevented, hence safeguarding marine life and biodiversity. This fosters robust fish populations and sustains fisheries in an environmentally responsible manner.

• Enhanced water quality diminishes the likelihood of algal blooms and other ecological harm resulting from antibiotic contamination, hence protecting the well-being of aquatic ecosystems.

• Photocatalysis harnesses solar energy or easily accessible UV light, reducing dependence on dangerous substances and advocating for environmentally acceptable wastewater treatment.

• The utilization of solar energy for photocatalysis facilitates the adoption of renewable energy sources and diminishes reliance on fossil fuels.

• The implementation of effective antimicrobial wastewater treatment systems helps create cleaner urban environments, leading to enhanced public health and improved quality of life in densely populated places.

• Photocatalysis safeguards terrestrial ecosystems and biodiversity by impeding the infiltration of antibiotics into soil and groundwater.

The widespread availability of antibiotics in the environment, resulting from improper disposal of unused or expired drugs and effluents from WWTPs, poses serious threats to water resources, microbial communities, ecosystems, and even contributes to climate change. The persistence of these pollutants has become a critical issue that requires innovative solutions. The AOPs, particularly photocatalysis, have emerged as highly effective and sustainable technologies for addressing the presence of antibiotics in wastewater. Photocatalysis, in particular, offers several advantages over traditional methods due to its cost-effectiveness, versatility, simplicity, and environmental friendliness. It allows for diverse designs and modifications to enhance its applicability in various settings.

Recent advancements in the field of photocatalysis are particularly noteworthy, with researchers focusing on improving the efficiency of photocatalytic materials. Strategies such as doping with noble metals, non-metals, and multi-metal combinations have significantly improved the performance of photocatalysts, particularly under visible light conditions. The development of heterojunctions and MOFs has further enhanced the photocatalytic activity, making it a viable solution for large-scale applications. The use of nanoparticles is gaining momentum due to their enhanced surface area and reactivity, which accelerate the degradation of antibiotics. Additionally, the integration of AI in designing models to optimize photocatalytic processes is an emerging field that promises to further improve the efficiency of antibiotic removal from wastewater.

The application of photocatalysis aligns with global sustainability efforts, contributing to several SDGs, particularly SDG 6 (Clean Water and Sanitation) and SDG 14 (Life Below Water). By mitigating antibiotic pollution, photocatalysis not only protects water quality but also helps in preserving aquatic ecosystems and addressing broader environmental health concerns. Furthermore, photocatalytic systems can potentially reduce the formation of ARB, which is a major public health threat. While the potential of photocatalysis is evident, challenges remain in scaling up the technology for industrial use. These challenges include the economic feasibility of large-scale deployment, the availability and cost of photocatalytic materials, and the energy demands for UV or visible light activation. Future research should focus on addressing these barriers, exploring renewable energy integration, and optimizing reactor designs for enhanced performance and sustainability.

Conclusively, photocatalysis represents a transformative approach to mitigating antibiotic pollution in the environment. The continuous advancements in material design, AI integration, and system optimization provide a pathway towards more efficient, scalable, and cost-effective wastewater treatment solutions. As this technology matures, it holds the potential to significantly reduce the environmental impact of pharmaceutical pollutants and contribute to global sustainability efforts, offering a hopeful and environmentally friendly solution for the future.

All relevant data are included in the paper or its Supplementary Information.

The authors declare no conflict of interest.