An integrated approach to remove endocrine-disrupting chemicals bisphenol and its analogues from the aqueous environment: a review

Plastics are designed by polymerizing monomers and other components such as plastic additives (Okan et al. 2019). Additives are chemical substances that are added to a plastic polymer to offer desired qualities or to assist in plastic production and that are intentionally added during the manufacturing process to improve the performance of plastic products in terms of resistance to ozone, temperature, light radiation, mould, bacteria, and moisture, as well as mechanical, thermal, and electrical resistance (Gunaalan et al. 2020). Chemical additives like toxic BPA, phthalates, and brominated flame retardants, which are frequently used in the processing of plastics, also induce endocrine disruption when ingested or inhaled and seem to be present in household products and food packaging materials (Thompson et al. 2009). Most of these chemicals are not chemically bound. Therefore, they can leach out of materials at certain temperatures thus providing an increasingly emerging contaminant threat to marine organisms due to plastic deposition on land and ocean disintegration (Hermabessiere et al. 2017).

Plastic longevity estimates range from hundreds to millions of years based on the physical and chemical characteristics of the polymer materials. However, this is expected to be significantly enhanced at depths where oxygen levels are low, and light is non-existent (Barnes et al. 2009), leading to a loss of structural stability (Biber et al. 2019). Wind speeds, current flow, shoreline nature, and human influences such as urban centres and shipping routes all contribute to the spread of plastic debris in the sea (Born & Brüll 2022). Another key aspect of the process for the fragmentation of plastic debris is photodegradation produced by sunlight. UV radiation from the sun induces oxidation of the polymer chain, which leads to chemical bond disruption (Yousif & Haddad 2013). The plastic polymer materials are categorized based on their sizes, with large plastic most likely disintegrating into macroplastics (tiny plastic debris) with a size of 5–10 mm, microplastics with a size range <5 mm, nanoplastics with a size range from 1 to1 mm (Peng et al. 2020) and macroplastics with greater than 5 mm (Lebreton et al. 2019). With the finding of these materials, microplastics derived from the macroplastics have been discovered in the marine environment and they gained much attention because they can enter the environment through wastewater, storms, leaching, and natural disasters, which can transport materials of all types, including plastics, into the ocean waters (Schmaltz et al. 2020). Primarily microplastics are present in various packaging plastics, bottling plastic material (particularly bottled water), food processing containers (Aragaw 2021), as well as pharmaceuticals and personal care items (Cheung & Fok 2017). One of the most frequently discussed types of primary microplastics is the scrubber, which is present in exfoliating hand cleansers and cosmetic scrubs easily absorbed by human bodies. Over a thousand plastic microbeads are found in each daily-used personal care product, including toothpaste and other things (Mhiret Gela & Aragaw 2022). This subsequently became a part of a discharge from residential wastes and sewage. Secondary microplastics are generated in the environment due to plastic fragmentation caused by various physiological, bio, and chemical methods that reduce plastic stability (Debroy et al. 2022).

The physical structure of microplastic is minute in size, so it can be easily trapped or ingested by ocean species, which shows that it could be utilized to chemically transmit pollutants to the food supply chain and marine life (Li et al. 2016). It is well-accepted that marine aquatic species are exposed to plastic-related substances in greater quantities due to microplastics. Several synthetic chemicals released into the natural world were once considered relatively harmless, but researchers gradually became aware of their negative impacts on the environment and human health (Fang et al. 2019). Some of chemical compounds may be restricted or banned, and alternative counterparts frequently replace them. For example, BPA is a commonly utilized manufacturing chemical that acts as an endocrine disruptor in the environment. It is widely used in manufacturing products like polycarbonate polymers, adhesives, and surface coating for the lining of metallic food and beverage cans (Cooper et al. 2011). There is widespread awareness about the potentially hazardous effects of BPA leaching into meals and beverages and crossing the permissible limits from food packaging and storing containers, owing to the regulatory pressure, and it affects human endocrine systems. BPA is being assessed by the European Chemicals Agency (ECHA) to be identified, categorized, and used by the Registration, Evaluation, Authorization, and Restriction of Chemicals (REACH) regulation. All consumer goods supplied in the European Union must comply with the REACH regulation, which limits the use of chemicals and heavy metals. BPA was added to the ECHA's authorization list as a substance of very high concern due to its impact on human endocrine function. Since January 2020, its use in thermal paper has been limited. Just a small quantity of BPA (0.05 mg/kg) is permitted to leach from products intended for use in food contact materials. All food packaging, containers, and BPA utensils are prohibited in France. According to the Toy Safety Directive (TSD), 0.04 mg/L of BPA is the migration limit for BPA in toys (Brandsma et al. 2022). Based on the findings of the expert panel on food contact materials, enzymes, and processing aids, CEP panel's reevaluation of the health risks of BPA, the European Food Safety Authority (EFSA) published a draught opinion on December 5, 2021, proposing a reduction in the tolerable daily intake (TDI) of BPA from 4 g/kg/bw/day to 0.04 ng/kg/bw/day; this is the updated assessment by 2022 (Eaton et al. 2022).

BPA is a class comprising anthropogenic chemicals made up of two phenolic rings joined by a bridging carbon or other chemical structure. It is employed as an intermediate for synthesizing 8 billion pounds of epoxy resins and polycarbonate polymers each year. Restricting BPA manufacturing and use has led to the development of BPs analogues such as BPS, BPF, BPE, and BPAF, as BPA substitutes for industrial applications (Yang et al. 2014). The synthesis of BPA and its analogues BPAF, BPF, and BPS includes a phenol condensation process with the appropriate solvent and catalyst like acetone, hexafluoroacetone, formaldehyde, and sulphur trioxide, respectively (Vasiljevic & Harner 2021). According to research, analogous chemicals have been identified in several environmental assemblages, such as indoor dust, sediments, fresh and ocean water, and sewage effluent at levels equal to or higher than that of BPA in the atmosphere (Chen et al. 2016a).

BPA was first synthesized in 1891, and its widespread industrial application began in the 1950s as a tool for producing epoxy resins and polycarbonates. BPA-containing epoxy resins are additionally utilized in materials, including bottle caps, water supply pipelines, and food containers. It can penetrate into packaged foods due to thermal processing during manufacturing, raising food safety issues (Tzatzarakis et al. 2017). Furthermore, it is used in materials that come into contact with food and in fabricating currency notes, thermal printing papers, compact discs, powder paints, and adhesives. These substances might build up in the environment because it is unfavourable for biodegradability (Tajik et al. 2020). As a result, there has been an increasing awareness in recent years of the possible detrimental effects on humans and animals from exposure to endocrine-disrupting chemicals (EDCs) (Gore et al. 2015). EDCs are chemicals that interfere with the action of hormones within the human body causing diseases. Some significant impacts of EDCs in humans are reproductive system issues, hypothyroidism, stroke, cancers, and obesity. Regarding vitellogenin and hatchability levels, the reproductive system of wildlife may be impacted (Kasonga et al. 2021). BPA is one of the typical EDCs, according to toxicology research, which replicates oestrogen's activity. Also, it is linked with an increased risk of all-cause mortality, cardiovascular illness, and high blood pressure in both experimental and epidemiological research (Moon et al. 2021). Also, there is a growing concern about the manufacturing and use of BPA analogues due to their disruptive effects and ecological implications.

BPA is naturally susceptible to entering the environment (Fromme et al. 2002), with quantities from 0.0005 to 0.41 mg/L in surface water, 0.018 to 0.702 mg/L in sewage effluents, 0.01 to 0.19 mg/kg in sediments, and 0.004 to 1.363 mg/g in sewage sludge, according to measurements. It is also found in tap water samples, ranging from 3.5 to 59.8 ng/L (Santhi et al. 2012). BPs are major ecological contaminants in municipal wastewater (Wang et al. 2019). Using an LC-MS analyzer, Chiriac et al. (2021) found the presence of BPs (BPA, BPB, BPC, BPE, BPF, and BPS) in influent, effluent, and surface water. The total number of analytes found in influent samples ranged from 1,337 to 16,118 ng/L, while in effluent samples it was 15–96 ng/L). In surface water, the total chemical concentration ranged from 34 to 240 ng/L. As previously stated, comparing three decades has revealed that BP contamination in the aqueous system has increased parts per million (PPM) mg/L to parts per billion (PPB) ng/L, indicating that BP levels in the aquatic system are increasing at an alarming rate year after year.

The ability of BPs to disrupt the endocrine system has also stimulated research into the consequences of prolonged exposure to male and female hormone levels, insulin levels, and hormonal imbalances (Bousoumah et al. 2021). Furthermore, it was noted that elevated BPA levels could have negative consequences, most notably on reproductive capacities such as female fertility, male low sperm count, quality, and changes in sex hormone concentrations (Wu et al. 2018). BPA was also detected in significant proportions in mother milk samples, with an average of 34.18 ng/mL, according to de Siqueira et al. (2023). Also, mothers' BPA concentrations were enhanced by consuming meals in plastic packaging, particularly after the plastic materials were warmed. The typical weekly consumption of BPA among nursing newborns was 19.5 g/kg/day, and the 95th percent of body weight consumed was 28.5 g/kg/day, exceeding the extreme normal amount recommended by the European Council for Food Standards (ECFS). This shows an elevated level of BPA in women's breastmilk, which could be attributed to using plastic containers as food/drink packaging. Akgül et al. (2019) also reported that human urine and blood frequently contain BPA, indicating a high exposure to these chemicals. The Food and Drug Administration (FDA) prohibited the use of BPA in children's sippy cups and baby bottles. BPS has overtaken BPA as the most popular alternative in North America, Asia, and Europe (Chen et al. 2016b). BPS is structurally similar to BPA due to including a sulphonyl ring between two phenolic sites. BPS appears to behave similarly to EDCs, by utilizing the same metabolic disposal pathway and exhibiting oestrogenic characteristics. Shortly after BPA rules were strengthened, statistical studies discovered that average BPS consumption was roughly 0.009 g/kg/day. In parallel with its expanding use as an industrial plasticizer, BPS exposure has increased. The European Chemical Association (ECA) estimates that 10,000 million metric tons of BPS are produced and imported in Europe annually. According to research, BPS is detected in biological fluids with 97% accuracy in the US and 100% in Japan. Several in-vitro studies comparing BPS, BPF, and BPAF to BPA revealed that they have comparable or even stronger estrogenic effects (Jin et al. 2018). As a result, BPS and BPF were found in the abiotic environment and bodily fluids in similar concentrations but slightly lower than BPA. The average daily intake of BPs from breast milk was 531 ng/kg/day in BPA, 53 ng/kg/day for BPS, and 24–27 ng/kg/day for BPAF. BPA and its analogues in municipal wastewater are important sources of environmental contamination. BPs are more persistent in sediments (t^1/2 = 135–1,621 days) than in soil (t^1/2 = 30–360 days) or water (t^1/2 = 15–180 days).

Because of the widespread production and high toxicity of BPs, researchers have been looking into effective methods for removing BPs from the environment for a long time, utilizing various treatment technologies made of sustainable materials. Several methods, including adsorption, photocatalytic degradation, membrane separation, and electrochemical procedures, have been developed to remove BPs from water and wastewater. Adsorption and photocatalytic degradation are advantageous to other methods due to their simple design, low investment, startup costs, and land requirement. This review article provides a detailed overview of the adsorption, photocatalytic degradation, and synergistic effects of the two techniques on different types of BPs.

BPs are colourless solids that are soluble in most major organic solvents but have a very low solubility in water. The ability of BPs to move, transform, and spread in the environment is indicated by their octanol–water partition coefficient (log K_ow) value. Low K_ow values are thought to be highly hydrophilic, which means they have high water solubility and a low adsorption coefficient (K_oc values). A common bioconcentration factor in aquatic species and the acid dissociation constant (pKa) show whether a compound will be protonated or deprotonated based on the correlation between the (pKa) of a mixture and the pH of a solution. The mixture will be protonated if the pH is lower than the pKa. The combination will deprotonate if the pH exceeds the pKa (Lintelmann et al. 2003). Table 1 displays physiochemical data of octanol–water partition coefficient (Log K_o/w), acid dissociation constant (pKa), and some physical-chemical properties of BPs.

Several treatment strategies have traditionally been used for the removal of endocrine-disrupting substances. The most promising treatment processes are adsorption, photocatalytic degradation, electrochemical, and membrane separation. Adsorption is regarded as one of the most efficient contaminant removal techniques due to its many advantages including ease of operation, low investment in terms of both initial costs and a wide variety of adsorbents that are appropriate for pollutant removal; the only consequence is the need for adsorbent regeneration (Blinová & Sirotiak 2021). A photocatalytic approach has the advantage of removing both metal ions and organic contaminants simultaneously at the same time. However, low visible light utilization, rapid charge recombination, and the limited ability of photo-generated electrons and holes to migrate are some limitations of current photocatalytic systems that limit their industrial applications. As a result, noble metals, transition metals, nonmetals, and metalloids (graphene, carbon nanotubes, and carbon quantum dots) are doped into the photocatalyst as co-catalysts to improve photodegradation performance (Sadegh & Ali 2018). Electrochemical oxidation does have a few advantages for pollution prevention and remediation. It is eco-friendly because it incorporates a pure reagent, the electron, and requires minimal or no chemical addition. Similarly, electrochemical oxidation is distinguished by its simple equipment, convenient operation, and short retention time. Other benefits include robustness, adaptability, and automation capabilities. The main disadvantage of this procedure is its high operating cost due to increased energy consumption (Anglada et al. 2009). In the membrane separation process, various commercial membranes from multiple manufacturers are available, many applications and module configurations are available, and a small amount of space is required. Even at high concentrations, it is simple, quick, and efficient, producing high-quality treated effluent with no chemicals. Although little solid waste is generated, the investment costs can be prohibitively high for small and medium-sized businesses (Morin-Crini et al. 2019). Though, we consider a cost-effective, sustainable approach, the adsorption and photocatalytic degradation show the synergistic benefits on material sizeable interfacial area, negative zeta potential, and simplified charge separation, which are primarily responsible for the integrated system's substantial improvement (Liu et al. 2017).

Adsorption is a surface phenomenon used in primary treatment methods to address hazardous pollutants at low concentrations measured in parts per million (ppm) (Figure 1). It has been identified as a suitable technology for water and wastewater treatment due to its high efficiency in diluted solutions, operating elasticity, versatile strategy, comfort handling, and cost-effectiveness. Compared to different treatment approaches, the adsorption method has shown the most favourable results for removing dissolved inorganic and organic pollutants from the aqueous phase (Miriyam et al. 2022). However, several variables affect both the financial and technical aspects of adsorption operation, such as adsorbent material properties, target adsorbate, accessibility, moisture, operating parameters, adsorbent recovery, and disposal methods (Barquilha & Braga 2021). Adsorption happens when an absorbable solute solution contacts a solid with a highly porous surface structure. It is based on developing an adsorbed phase that differs from the bulk fluid phase in composition (Rathi & Kumar 2021). Organic contaminants seem very resistant to several water-based treatment processes because of their hydrophobic nature and low molecular mass. In adsorption, unstable molecules are attracted to adsorbent material surfaces by diffusing from the group of the solution to the functional sites of adsorbent materials (Zango et al. 2020). One of the desirable properties of adsorbent materials is the physical characteristics of the adsorbent condition, typically in the form of powder, cake, or beads. Adsorption processes are influenced by factors such as solubility, molecular size, molecular weight, and pKa, in addition to the physical properties of the adsorbents (Moreno-Castilla 2004). The adsorbate molecules that have been adsorbed must be desorbed to renew and reuse the adsorbent for another cycle. During the desorption process, the solid adsorbent has the potential to be one of the most impactful ways to treat and remove organic pollutants from wastewater (Rajabi et al. 2018). The reversal of adsorption occurs when molecules that have adhered to the adsorbent are released back into the solution. Regenerating and reusing adsorbents in adsorption procedures significantly reduces industrial wastewater treatment costs (Vakili et al. 2017). In desorption, acid and alkali solutions are commonly used to restore waste material (Duan et al. 2020). As a result, investigating the adsorption method for removing BPs from wastewater is essential (Duan et al. 2014).

Cost analysis is one of the most important things to consider when choosing a water treatment system. The cost of the adsorbent determines the cost of the adsorbent used in the process. Researchers seek readily available, cost-effective adsorbents to remove EDCs and turn wastes into wealth. Organic chemicals and low-cost by-products from the agricultural, domestic, and industrial sectors have all been identified as viable wastewater treatment options. They facilitate the detoxification of pollutants from the effluent and its reduction, recovery, and subsequent utilization (De Gisi et al. 2016). The use of inexpensive adsorbents to treat BPs has been the topic of numerous research studies.

Dehghani et al. (2016) studied the effectiveness of BPA removal utilizing two different chitosan samples, a commercial chitosan sample purchased commercially, and a chitosan adsorbent made from waste seafood shell that is safe and environmentally friendly, non-toxic, and naturally occurring polymeric compound. In this investigation, the most excellent BPA adsorption removal rate was found at pH 5, with a 75-min contact period, and an adsorbent dosage of 0.06 g/L. The greatest sorption capacity was achieved at 34.48 and 27.02 mg/g for synthetic chitosan (SC) and commercial chitosan (CC). To remove BPF and BPS, Wang et al. (2021) utilized heteroatom (N/S) doped porous carbon-based materials manufactured from chicken feathers as a sustainable precursor. These materials were fabricated as a dual activation process to produce dual-doped heteroatoms with a 3D hierarchically porous structure (MZ-NSPC), within 30 min of equilibrium time it reached maximum sorption capacity at 308.7 mg/g for BPS and 295.8 mg/g for BPF. The adsorbent material reusability efficiency reduction after five repeats is 6.15%. Balci & Erkurt (2017) investigated Eucalyptus camaldulensis bark/magnetite composite (EBMC) as a low-cost adsorbent for BPA removal. At pH 7 and 50 °C, the combined eucalyptus camaldulensis bark and magnetite were shown to have a maximum sorption capacity of 290.6 mg/g. The Freundlich isotherm model better represented the adsorption process than the Langmuir, Dubinin-Radushkevich, Jovanovic, and Vieth-Sladek isotherm models. The adsorption capacity of the EBMC increased significantly from 57.08 to 290.6 mg/g when the adsorbent dosage was reduced from 0.7 to 0.1 g. The increase in adsorption capability with decreasing EBMC dosage is due to a concentration gradient between the concentration of BPA in the solution and on the surface of EBMC. It was also discovered that increasing the adsorbent mass from 0.1 to 0.7 g enhanced the percentage of BPA removal efficiency from 72.6 to 99.8%. This is due to the increase in the availability of surface-active sites with increasing doses of EBMC. It was also observed that 0.2 g EBMC was enough to eliminate 200 mg/L BPA with a 90% effectiveness. The activated carbon (AC) from fruit bunch waste is a superior, low-cost bio-adsorbent modifying with ZnCl₂ as a chemical reacting agent and assessing its ability to eliminate BPA from an aqueous solution was studied by Wirasnita et al. (2014). Throughout the 96 h, the optimum adsorption equilibrium was achieved after 48 h, with a percentage BPA elimination of 96.1% and an adsorption ability of 19.3 mg/g. Because of the abundance of readily available sites, the adsorption process began rapidly within 18 h, followed by slower adsorption over the initial 18–48 h. After 48 h, a peak was noticed, proving that the AC was saturated. While having significant adsorption capacity for adsorption, EFB-AC has a drawback. To reach equilibrium, the EFB-AC requires a more extended adsorption period. Lazim et al. (2015) examined the BPA removal from water using an agro-based low-cost adsorbent like coir pith, durian peel, and coconut shell (CP, DP, CS) treated with H₂SO₄. In comparison to DP and CS, the CP shows the highest sorption potential of 4.308 mg/g with 72% removal for 24 h, followed by 70% removal of DP with 4.178 mg/g and CS with 69% removal of 4.159 mg/g, asserting the ability of modified phyto-waste as the best option as an alternative adsorbent. Vidovix et al. (2021) provide a basic summary of how babassu-AC has great potential for usage in dirty water restoration. Under ideal experimental conditions with 318 K, 1 g/L adsorbent concentration, and 720 min equilibrium duration the maximum adsorptive capacity was achieved at 49.61 mg/g, therefore the empty fruit bunch is a good choice as a cost-effective bio-adsorbent for EDCs removal. Fibric peat was treated with hexadecyltrimethylammonium bromide (HTAB), and its effectiveness as a low-cost sorbent for removing BPA was examined by Zhou et al. (2011). At an initial concentration of 45 mg/L, the maximum sorption capacity of 31.40 mg/g was attained. Freundlich isotherm perfectly describes BPA sorption to HTAB-modified peat, while Langmuir isotherm best describes BPA sorption to untreated peat. Unlike unmodified fibric peat, the modified peat removed more BPA molecules and had a much lower desorption rate. According to research, the major mechanism is improved hydrophobic interaction and chemical modification of the peat surface, dramatically boosting sorption capacity towards organic compounds dissolved in water. According to the observations, the feasible usage of low-cost adsorbents has yielded positive results in removing EDCs (Hacıosmanoğlu et al. 2019).

Carbon materials derived from porous carbohydrates or natural polymers are popular nowadays due to their superior properties, such as extremely high surface area, promising chemical stability, and high electrical conductivity (Wang et al. 2020). Adsorbent materials such as graphene oxide (Xu et al. 2013), carbon nanotubes (Naeemullah & Tuzen 2019), porous carbon materials (Bhadra et al. 2018), and AC (Sotelo et al. 2013) have long sparked the curiosity of researchers due to their chemical stability, large pore size distribution, and mass production feasibility (Tagliavini et al. 2017). In recent decades adsorbents made of natural polymers (Crini 2005), carbon materials, mainly ACs and their composite have acquired significant recognition as ubiquitous adsorbents due to their abundant resources like favourable physical and chemical properties, strong sorption capacity, and surface reactivity by the presence of various functional groups. Eventually, some techniques have been considered to produce more practical and cost-effective results. Carbons derived from various sources, including tea leaves (Ahsan et al. 2018a, 2018b), walnut shells (Dovi et al. 2021), coffee waste (Naganathan et al. 2021), rice husks (Balarak et al. 2019), and peanut shells (Chu et al. 2017), have all been used to treat wastewater and remove EDCs, according to investigation.

(Soni & Padmaja 2014) found that BPA adheres to palm shell activated carbon (PSAC) through p-p interactions and hydrogen bonding with an adsorption capacity of 62.5 mg/g. After 8 h, the BPA adsorption equilibrium was attained. The ability of BPA to connect to PAC was significantly influenced by basic pH, this is likely because both BPA and PAC zero-point charge (ZPC) deprotonated at this pH. Similarly, it was shown that the ability to absorb BPA was not greatly affected by adding 0.5 M NaCl. Film diffusion is the stage that determines the rate in the intraparticle and film diffusion process, and both of these have been discovered to regulate adsorption kinetics. According to observations of Andreia (Alves et al. 2019), chemically treated coffee grounds AC has a specific surface area (1,039 m²/g) higher than physical AC making it more effective for adsorption. The Langmuir isotherm and pseudo-second-order model were used to analyze the BPA adsorption data, showing that chemical AC had a 123.22 mg/g highest sorption potential. The outcomes demonstrated that chemically treated might be a viable sorption material waste for water treatment. Guo et al. (2011) produced magnetic composites made of chitosan, fly ash cenospheres, and iron oxide (CTS/-Fe₂O₃/FACs) to remove BPA quickly. The CTS/-Fe₂O₃/FACs that were produced had a perfectly spherical shape, thermal stability, and saturation magnetization. The monolayer adsorption capacities for BPA and 31.92 mg/g, at 298 K, respectively. The Langmuir isotherm model had the best fit with the equilibrium compared to other models. For kinetic, the pseudo-second-order equation provided a good description for CTS/-Fe₂O₃/FACs adsorbents. With rising concentration and temperature, intraparticle diffusion (ki) and film diffusion increased, whereas pore diffusion decreased. According to the Scanning electron microscopic (SEM) images, the imprinted layer efficiently covered a considerable section of the KLT/Fe₃O₄. The adsorption capacity decreased considerably from pH 7.0 to 10.0 due to its pKa value of 10.23, making it easier to dissociate under alkaline conditions. At increasing pH, the electrostatic repulsive interactions between BPA and adsorbents get stronger and finally outnumber the binding affinity. Using magnetite and the adsorption technique, Orimolade et al. (2018) investigated the effectiveness of eliminating BPA from water. At a pH 6, the optimum adsorption parameter was 0.2 g dosage, at 50 ppm of BPA, with 60 min of contact time. Iron nanoparticle-doped magnetic ordered mesoporous carbon (Fe/OMC) was created by carbothermal reduction and impregnation techniques and employed for the highly efficient adsorption and degradation of BPA (Tang et al. 2016).

Batch studies were carried out to investigate the decontamination performance. The findings revealed that with an initial BPA concentration of 200 mg/L, the adsorption capacity had achieved 311 mg/g. The kinetic investigation indicated that it concurred well with the pseudo-second-order model. Ahsan et al. (2018a, 2018b) described a simplified method to produce sulphonic acid that contacts with a carbonaceous adsorbent derived from tea leaves (TW-SO₃H). At 25 °C, BPA has been removed by TW-SO₃H with a sorption capacity of 236.80 mg/g. Park & Jhung (2021) investigated the adsorptive purification of BPS-polluted water using metal-organic frameworks (MIL-101-NH₂). At pH 7, it had a maximum sorption at 513 mg/g. Additionally, the MOF is reusable, with just a little performance following ethanol washing. Second, good adsorption is mostly explained by H-bonding between the BPS and the applied MOF. Fang et al. (2018) showed that a magnesium ascorbyl phosphate non-shell graphene-based monolith (MAP-GBM) is a viable adsorbent for the efficient and cost-effective removal of low-concentration EDCs. MAP-GBM has a maximum sorption capacity of 324 mg/g, with 100% removal of BPS from solution at low concentrations of 50 mg/L. Soaking the material in methanol for 24 h may be readily replenished, and after five regenerations, the adsorption efficacy stays as high as 88%. Multi-walled carbon nanotubes coated with CoFe₂O₄ nanoparticles improved the sorption and characterization of their abilities, according to an investigation done by Al-Musawi et al. (2022). The highest sorption capacity of MWCNTs/CoFe₂O₄ fits with the Langmuir model for BPA adsorption which was 416.6 mg/g, significantly higher than earlier reports using adsorbents for the same purpose. Bhatia & Datta (2019) studied the adsorption performance of amine-modified multiwall carbon nanotubes in batch studies and discovered that the equilibrium duration for batch adsorption tests was 45 min and the optimal adsorbent dosage was 1.6 g/L.

For the column study, increased bed height and lowered flow rate promote BPA adsorption. However, BPA concentrations are more significant at 40 mg/L, and temperatures greater than 323 K reflect unfavourable adsorption conditions. Although it has multiple regeneration properties in batch mode, the adsorbent is ineffective for BPA removal. The pseudo-second-order kinetic model best fitted the adsorption data, whereas the equilibrium data best fit the Toth and Sips isotherm models for the column test. Goyal et al. (2018) used hydrothermal treatment and surfactant HDTMA-Br modification to create a nano-zeolite secondary mobil-5 (NZSM-5). The functionalized nano-zeolite FNZSM-5 was utilized for rapid removal of BPS from the aqueous phase. The FNZSM-5 removed BPS higher than NZSM-1 with an efficiency of (95–36%). The electrostatic effect of solution pH from 2 to 4 significantly impacted BPS adsorption onto the produced adsorbent with optimum removal of 95%. The best match for the kinetic data was a pseudo-second-order kinetic model that represents the occurrence of chemical adsorption in the sorption system. The thermodynamic properties revealed that BPS adsorption was more beneficial at low temperatures. Zhang et al. (2013) investigated the removal and recovery of BPF using multiwall carbon nanotubes and discovered that the removal percentages of BPF could reach up to 96.2% in 4 min at pH 4–10. The kinetics of BPF adsorption was rapid, with the equilibrium reached in 4 min using the pseudo-second-order model and measured rate constants (k) at varied temperatures. Multi-walled carbon nanotubes modified with iron oxide and manganese dioxide (MWCNTs-Fe₃O₄MnO₂) were employed as an adsorbent to eliminate BPA (Guo et al. 2020). The maximum adsorption capacity and contact time to achieve equilibrium of initial concentrations were determined to be 132.9 mg/g and 150 min, respectively. According to the scanning electron microscopic (SEM) images, the imprinted layer efficiently covered a considerable section of the KLT/Fe₃O₄. The adsorption capacity decreased considerably from pH 7.0 to 10.0 due to its pKa value of 10.23, making it easier to dissociate under alkaline conditions. At increasing pH, the electrostatic repulsive interactions between BPA and adsorbents get stronger and finally outnumber the binding affinity. Consequently, when the pH increased above 7.0, the adsorption capacity of BPA for both MMIPs and MNIPs dropped considerably compared to the alterations observed under acidic conditions. Joseph et al. (2011) investigated the sorption behaviour of BPA from landfill leachate onto single-walled carbon nanotubes (SWCNTs). Solutions of artificial seawater, brackish water, and a combination of these two fluids were generated by previously published composition data. The higher removal efficiency of BPA is 75–80%, owing to a higher log K_ow value. Single-walled carbon nanotubes were successfully used to adsorb BPA from aqueous environments before and after the treatment of SWNTs and tSWNTs (Zaib et al. 2012). After a 72-h contact time at 315 K, 14.3 mg/g of BPA was adsorbed on SWNTs and 5.1 mg/g on tSWNTs. Naeemullah & Tuzen (2019) evaluated the efficiency of carbon nanotubes functionalized with tetra ethylene pentamine for surface adsorption. The monolayer adsorption capacity of the functionalized tetra ethylene pentamine immobilized on the surface of multi-wall carbon nanotubes for BPA was found to be 45.5 mg/g at pH 6.5 at 30 °C with a contact time of 40 min. As a result, carbon and polymer-based absorbents can give high adsorption capacity and may eliminate EDCs within a short contact time.

Biosorption has long been considered an excellent approach for removing a broad spectrum of organic contaminants. The word ‘biosorption’ refers to any system in which a solid surface of a biological matrix interacts with a sorbate, decreasing the sorbate concentration in the solution (Fomina & Gadd 2014). The adsorption of BPA from aqueous solutions using biosorbent materials such as peat, rice husk, bagasse, and sawdust was examined by Zhou et al. (2011) in contrast to the other materials taken into consideration. The surface of the peat developed a selectivity for BPA after being treated with alkyl ammonium. Modified peat had a slightly higher sorption capacity of 1.71 mg/g than AC of 1.67 mg/g under specific conditions with a BPA concentration of 2 mg/L. Ahsan et al. (2018a, 2018b) demonstrates synthesizing a simple sulphonation method to produce sulphonated coffee waste with superior biosorption potential for a wide range of emerging pollutants. This biosorbent was used in wastewater to remove endocrine disruptors such as BPA and sulphamethoxazole (SMX) medications. The biosorption capacities of CW-SO₃H for BPA and SMX removal were 271 and 256 mg/g, respectively. BPA adsorption from an aqueous solution on inactivated lichen biomass (Pseudoevernia furfuracea) was investigated by Şenol et al. (2020). The maximum removal occurs at pH 5 for 3 h, then an adsorbent dosage with an initial concentration at 40 mg/L,9 mg/g, and 150 rpm. Sorption capacity reached 82% after eight cycles, with a 5% reduction in the regaining rate. Li et al. (2017) examined the effect of ash concentration on BPA sorption utilizing various agricultural waste as adsorbents like silkworm dung, corncob eucalyptus globulus, and pomelo peel, observed that the acid treatment substantially enhanced BPA adsorption capacity. Biosorbent material has effectively removed EDC contaminants from the aqueous environment.

AC is a mesoporous carbon-containing material that has become a commonly used sorbent material because of its large surface area, inexpensive, and excellent charge-holding capabilities, as well as the capacity to produce multiple functional groups which could be responsible for the effective removal of a wide range of contaminants from water-soluble or gaseous media (Sabzehmeidani et al. 2021). AC is available in granular, powdered, and fibrous forms, all of which are widely used in water remediation methods (Jjagwe et al. 2021). Because of its excellent adsorption capacity, AC has been successfully used to remove pollutants such as colours, CO₂, and phenolic and organic chemicals (Kalderis et al. 2008). According to Tagliavini et al. (2017), AC is one of the most effective adsorbents. Still, it has various disadvantages, such as being flammable and difficult to regenerate, limiting its usage in wastewater treatment.

Sudhakar et al. (2016) examined the use of activated rice husk (RHA) as an adsorbent for BPA recovery from aqueous solution and contrasted its performance to that of granular activated carbon (GAC). RHA had the best values at a concentration of 100 mg/L and the dosage at 30 g/L with a contact time of 3 h for RHA. In contrast, the optimum parameters of GAC were found to be 20 g/L of dosage with a contact time of 2 h. The Freundlich and Temkin models pseudo-second-order model, and the pseudo-second-order model provided the best fits for the isotherm data and the adsorption kinetic data, respectively. It was discovered that the BPA adsorption onto GAC and RHA was endothermic. AC combined with constructed wetlands (CWs) was used as an adsorbent for BPA, BPS, and BPF pollutants. The findings indicate that the fundamental mechanism of the AC-CW's efficient and stable removal of EDCs was a two-step process in which EDCs were initially adsorbed onto the AC and subsequently eliminated by the sizeable bacterial population on the AC.AC-CW totally and sustainably eradicated all EDCs 98–100%. The addition of AC as a component of the CW medium could increase EDC removal (Wirasnita et al. 2018). To eliminate BPA from aqueous solutions, iron oxide goethite particles with activated carbon (GPAC) have been suggested by Koduru et al. (2016). At the initial concentration of 10 ppm at pH 7, BPA was promptly removed at 100 min; equilibrium was slowly restored after 200 min of shaking. XRD patterns of pure iron oxide and AC/iron oxide goethite composites revealed the crystalline nature of goethite. The capacity of AC to remove BPS by adsorption from deionized water has been widely demonstrated by Zhao et al. (2022). This ability is strongly inclined through environmental factors such as temperature and pH. The research reveals that BPs adsorption is more significant in deionized water than in tap water, making it harder for AC aquatic filters to recover BPS from tap water. After pH 6, the removal rate and adsorption capacity progressively declined. The contact time was around 50 min, with the amount of adsorption capacity of 83.19 mg/g. Chemically treated AC was more successful than physically treated AC in BPA removal due to its greater surface area. The pseudo-second-order model for kinetics computed the BPA adsorption data, and the Langmuir model for isothermal study, revealing a maximum chemical AC adsorption capacity occurred at 123.22 mg/g. Rice straw-AC can potentially remove BPA from the environmental matrices investigated (Chang et al. 2012). The adsorbent was prepared using potassium hydroxide KOH to convert waste biomass into AC. The AC absorbs BPA quickly due to its maximum surface area and adsorptive capacity of 181.19 mg/g. Reaching equilibrium at 90 min at 30 °C. BPA sorption capability in babassu-AC was investigated by Ahamad et al. (2019) developed a highly permeable N/S-modified magnetic carbon nanocomposite (N/S-MCA) from sugarcane bagasse-based cellulose and utilized it for BPA removal. According to the findings, the mechanism of synergistic adsorption of BPA using N/S-doped magnetic carbon aerogel would be an essential guideline in developing a carbon-based adsorbent for the high-efficiency adsorption of environmental pollutants.

Surface active agents are surfactant compounds that can modify the surface energy between the substances (Tamjidi et al. 2021). This property is related to its dipolar molecular structure, which contains amphiphilic or amphipathic molecules that contain polar (the hydrophilic portion that is soluble in a particular fluid, such as water) and nonpolar (the hydrophobic element that is insoluble in water). The term ‘amphi’ is derived from the Greek word which means ‘both’ (Belhaj et al. 2020). Adsorbents with a modified surfactant base were a great option. As a result, it has been demonstrated that using surfactants as a modifier for removing organic contaminants significantly improves the ability of diverse materials to adsorb pollutants (Lawal et al. 2019).

The adsorption of BPA onto natural bentonite modified hexadecyl trimethylammonium chloride (HDTMA) was investigated by (Genc et al. 2019). Due to a neutral molecular form of BPA and the hydrophobic surface produced by the loaded surfactant molecules, BPA removal was accelerated under acidic pH conditions. When the ionic strength was increased, the BPA adsorption on modified bentonite was improved, and the adsorption capacity was attained at 15.63 mg/g. Tang et al. (2017) investigated a one-step technique that dispersed AC-AB, CTAB and synthesized AC-AB-CTAB prepared for the BPAF removal from wastewater. The one-step method outperforms the synthesized adsorbents with a maximum reduction of BPAF of about 284.6 mg/g. Kinetic investigations and adsorption isotherms revealed that the one-step adsorption of BPAF on AC-AB could be represented by a pseudo-second-order model and a Dubinin-Ashtakhov (D-A) isotherm, respectively. Bamboo fibre powders were recognized by Hartono et al. (2015) as a promising low-cost sorbent with superior adsorption properties for eliminating hazardous organic chemicals in aqueous systems. Treating the bamboo powders with alkali and surfactants seemed to be enhancing the BPA sorption performance with 39% removal obtained for bamboo treatment with the cationic surfactant with an adsorbent dosage of 4 g/L. Zheng et al. (2013) investigated Organo Arizona SAz-2 Ca-montmorillonite generated by direct ion exchange with different surfactant (DDTMA and HDTMA) loadings to remove BPA. The monolayer pattern with minimal surfactant loading, hydrophobic phase (0.5 CEC), and positively charged surface produced by the loaded surfactant molecules enhances the BPA adsorption. The values for DDTMA slightly increased from 1.94 to 2.03 nm as the CEC from 1.0 to 2.0, showing that the arrangement of DDTMA molecules in the interlayer space changes from monolayer to bilayer and that longer chain surfactant intercalated in organoclays has a better capacity for BPA adsorption even in alkaline conditions. Furthermore, the molecular conformation of the intercalated surfactant is significantly influenced by the surfactant chain length and surfactant loading. A Langmuir isotherm revealed that the highest sorption capacity for organo clays on removing BPA was 151.52 mg/g. Surfactant cetylpyridinium bromide (CPB) modified natural zeolites (SMNZs) were prepared by Li et al. (2014). BPA was effectively removed from the aqueous solution using monolayer and bilayer SMNZs. The monolayer SMNZs for BPA adsorption gained somewhat when pH climbed from 4 to 9 but reduced dramatically as pH increased from 9 to 11. The bilayer SMNZs for BPA adsorption were achieved between pH 9 and 10 and declined when it was reduced between 9 and 4 or increased between 10 and 11. The hydrophobic interaction and hydrogen bonding are the mechanisms for BPA adsorption onto the monolayer SMNZ at pH 4–11. Organic partitioning and hydrogen bonding are two pathways for BPA adsorption on the bilayer SMNZ at pH 4–8. At pH 8–11, electrostatic attraction, hydrogen bonding, and organic partitioning are the methods through which BPA adheres to the bilayer SMNZ. Kuang et al. (2019) studied to build a novel graphene oxide (GO)-based adsorbent by loading the cationic surfactant HDTMA to adsorb BPA from aqueous solution simultaneously. BPA adsorption capacities were 141.0 mg/g for the synthesized adsorbents. BPA adsorption procedures were fast, with 100% removal achieved in 2 h, respectively. Raising the pH favoured the adsorption of the BPA adsorption. The results show that by customizing the surface coverage of HDTMA on GO, adsorption of the target species may be accomplished. The summary and overview of adsorbents to be used for the adsorption of BPs are given in Table 2.

The adsorbent and BPs properties are among the most significant causes of sorption inhibition at high pH, while other variables can also impact (Miriyam et al. 2022). Other important parameters involved in BPs elimination are initial concentration, contact period, dosage, pH, and the temperature that affect BPs compounds to remove from an aqueous solution. Adsorption performance can be increased by extending contact duration due to abundant vacant active sites on the adsorbent surface. The availability of BPA to the active sites on the adsorbent surface would be constrained with increased contact duration, resulting in a decrease in adsorption effectiveness (Balarak et al. 2019). When the concentration of BPA was low, the number of adsorption sites increased in parallel with a rise in adsorbent dosage. If the concentration were too high, the adsorbent would quickly attain saturation. As a result, contaminant retention would be terminated (Martín-Lara et al. 2020). The weakening of the hydrogen bonding interaction caused a reduced adsorption capacity for pH. This is due to its particles forming bisphenolate anions and releasing protons in an alkaline solution. Hydrophobicity, hydrogen bond, electrostatic and π–π interactions were the main BPs sorption mechanisms onto an adsorbent (Hamadeen & Elkhatib 2022). Due to the protonated effect of functional surface molecules like amino, carboxyl, thiol, and others, the AC surface gets wholly charged. This may increase the normally hydrophobic interactions between BPs and sorbent material by adding electrostatic attractions. The neutral charge of the adsorbent and adsorbate inhibits the formation of any further sorbed mechanisms other than hydrophobic interactions. The creation of aqua-complexes, which hinder adsorption, is brought on by an increase in hydroxyl ions at basic pH. Temperature is another important component that influences adsorption capability. Endothermic process refers to a process where adsorption increases as temperature rises. Increased temperature improves the mobility of organic pollutants, resulting in quicker adsorption owing to easier access of adsorbate to adsorbent. Exothermic processes are those in which adsorption capacity reduces with increasing temperature, greater the temperature, lower the adsorptive forces between adsorbate and adsorbent has been occurring (Saxena et al. 2020).

Table 2 lists the readily accessible adsorbent raw materials (such as agricultural wastes, clays, polymer materials, chitosan, nanoparticles, graphene, and carbon nanotubes) used in adsorption processes.

• (a) Agricultural waste materials: Agro-waste materials are dumped in the soil without any use. Still, they but they contain several essential elements such as lipids, lignin, cellulose, hemicellulose, hydrocarbons, extracts, proteins, starch, simple carbohydrates, and water, as well as a variety of functional groups that present in the binding process and can sequester pollutant. Agricultural wastes are inexpensive in cost, easily accessible, and have plenty of assets and distinctive chemical structures, so they frequently get used to examining the removal of contaminants from water-based solutions (Lazim et al. 2015). Using chemical activation with the agricultural waste is found to be more expensive than the raw agro-waste adsorbents, since the adsorption capacity is more in chemically activated than physical method.

• (b) Clays: Clay minerals have historically been prominent in their function as an adsorbent for hazardous chemical disposal and storage to protect as an adsorbent for hazardous chemical disposal and storage for the protection of the environment. They are a naturally occurring substance with particles ranging from 2 m down, resulting in substantial surface areas suited for high-efficiency pollution removal. Compared with AC, organic/inorganic, and composite materials, clays and modified clay-based adsorbents are the most effective clarifying agents and low cost for organic contaminants removal (Mundkur et al. 2022).

• (c) AC: AC is a broad term for a variety of carbonized materials with a high degree of porosity and surface area. The materials that are calcined at a particular temperature in a muffle furnace are known to be an AC. Commercially available AC is found to be more expensive than synthesized carbon. Among all the natural adsorbents, AC has been found to be the most effective for organic contaminant removal; however, its use is restricted due to its high regeneration cost (Heidarinejad et al. 2020).

• (d) Chitosan: Chitosan has a high affinity for hydroxyl and amino groups. Because of its inexpensive cost and high adsorption potential, it is employed as an adsorbent for contaminant removal. Chitosan has also been combined with other substances, including as graphene and zeolite, to create composite materials that have better adsorption capabilities. Commercially available chitosan is more expensive than the synthesized chitosan due to its pretreatment processes (Zhang et al. 2021).

• (e) Nanoparticles: Nanoparticles exhibit distinct chemical, physical, visible, electrical, magnetic, and biological properties because of their extraordinarily high specific surface area and minimized surface defects (Chen et al. 2017b). Plant extract-derived nanoparticles have different surface morphologies than routinely manufactured nanoparticles, contributing to the adsorption process.

The possibility of utilizing solar energy seems quite attractive (Ferdous et al. 2016) (Figure 2). The catalytic activities initiated by light energy are known as photocatalytic activity. Because of its high mineralization efficiency, low toxigenicity, and ideal end products of carbon dioxide, water, and inorganic mineral ions, this is considered among the most promising approaches (Sharma & Vaish 2021). An advanced oxidation process (AOP) called photocatalysis is used to purify aqueous systems, and light degrades hazardous chemicals. AOP may successfully oxidize numerous organic contaminants found in aqueous systems. Though diverse reaction systems are active, all AOPs have the same essential feature forming radicals (•OH) through a multi-step process. Because of their solid oxidative capacity reduction potential, HO• radicals exhibit minimal attack selectivity and may oxidize a wide range of organic contaminants (Zhai et al. 2022). The significance of photocatalysis implies that a photocatalyst offers both an oxidation and a reduction simultaneously. Heterogeneous catalysis has effectively decomposed various hazardous compounds (Kumar 2017). When a semiconductor absorbs photons with an energy equal to or greater than its band gap, heterogeneous photocatalysis typically begins. The electrons are then excited from the semiconductor's valence band (VB, the highest energy band occupied by electrons) to the conduction band (CB, the lowest energy band without electrons at the ground state), generating electron (e⁻) hole (h⁺) pairs. As electrons and holes are transported to the semiconductor's surface, electrons react with acceptors to form reduction products, whereas holes interact with donor species to produce oxidation products; if holes and electrons are not depleted rapidly, they may recombine, resulting in energy loss.

The following is an explanation of the general mechanism of photocatalytic degradation of organic compounds:

The semiconductor typically absorbs photons with energy equal to or more than its band gap to begin heterogeneous photocatalysis. The formation of electron (e⁻) hole (h⁺) pairs occurs when electrons are stimulated from the semiconductor's valence band (VB, the highest energy band filled by electrons, to the conduction band CB, the lowest energy band devoid of electrons at the ground state). When electrons and holes are transported to the semiconductor surface, they react with acceptors to form reduction products and with donor species to produce oxidation products. But the holes and electrons could recombine and lose energy if not rapidly released (Yuan et al. 2021). Photocatalysis is low-cost, non-toxic, and easy to fabricate to degrade organic pollutants like EDCs. Throughout the last several decades, various photocatalysts have been created to address the difficulties of water pollution, particularly photocatalysis on semiconductor catalysts such as TiO₂ (Katančić et al. 2020), CuS₂ (Bahadoran et al. 2021), ZnO (Javid & Malakootian 2017) and MoS₂ (Kumar & Bansal 2013) has shown effectiveness in degrading a variety of organic contaminants into biodegradable or less harmful organic compounds. Doping of TiO₂ with precious metal (Pt), metal oxides such as ZnO, Fe₂O_3, and inorganic components such as N for extended visible light activities has been successfully conducted by Mühlberg (2020). Unfortunately, the poor solar energy conversion efficiency, simple aggregation, and difficult post-separation of these inorganic catalysts prevent their widespread use (Wang et al. 2016). RongChang et al. (2009) summarized BPA removal by photocatalytic degradation using TiO₂ as a catalyst along with the experimental circumstances that explain how BPA molecules and by-products can bind to the surface of the TiO₂ for their subsequent degradation, which represents the first stage of the process and in the second stage all adsorbed substrates will be broken down. The following presumptions apply to TiO₂ catalyst for BPA photocatalytic degradation on kinetic model:

• (1)

  In Equation (8), the hydroxyl groups that are absorbed by the surface of the TiO₂ particles destroy organic molecules and associated intermediates, and the interaction with hydroxyl molecules is the rate-limiting phase in photocatalytic degradation.

• (2)

  The formation of •OH radicals is shown in Equation (9) should be primarily derived from the adsorbed H₂O molecule as the reaction of H₂O/OH with photo-induced gap h⁺ to generate hydroxyl reversibly.

• (3)

  In the process involving h⁺, H₂O, and OH, the Equation (10) shows the rate of hydroxyl production is far faster than the rate of h⁺/e⁻ combination, and the concentration of H₂O/OH available to combine with h⁺ is much higher than that of H⁺.

• (4)

  In Equation (11) the concentration of hydroxyl radicals remains constant at a steady state (Bodenstein steady-state assumption).

TiO₂ is a highly effective photocatalyst due to its photocatalytic activity, chemical and physical durability, affordability, and convenience. TiO₂ generates photoinduced positive holes (h⁺) and electrons (e⁻). The surface is illuminated by UV rays 380 nm. These species can then form hydroxyl free radicals (•OH), potent oxidants contributing to the breakdown of pollutants into CO₂ and H₂O.Mei et al. (2020) showed photocatalytic degradation of BPS using a TiO₂/C₃N₄ composite produced hydrothermally. To achieve adsorption equilibrium, a 450 W Xe arc lamp was swirled for 3 min in the dark with 50 mL of 20 ppm of BPA solution at pH 6. The regeneration tests were performed in the following order, after the first photodegradation experiment, TiO₂/g-C₃N₄ was filtered and centrifuged. The samples were oven dried for 12 h to remove the adsorbed TiO₂/g-C₃N₄ water. The second photodegradation experiment was carried out using the dried catalyst solid. The photodegradation period was set at 60 min in the five-cycle trials. The effects of CD with TiO₂ photocatalytic degradation of BPE were studied by Wang et al. (2006) utilizing a 250-W metal halide lamp with 365 nm. The concentration of BPE ranges from 2.5 to 20.0 mg/L, following pseudo-first-order. Compared to systems with only TiO₂, BPE reaction rate constant is higher with CD and TiO₂. By analyzing with UV, after 40 min of irradiation, CD could enhance photodegradation efficiency by around 26% for 10 mg/L of BPE. Bechambi et al. (2015) Examined the hydrothermal synthesis of carbon-doped ZnO with varied molar ratios of carbon content. As a persulphate activator, amino-functionalized metal-organic frameworks degrade BPF. The C-ZnO catalysts showed photocatalytic solid activity in the degradation of BPA with the presence of hydrogen peroxide and UV light. After 24 h of UV exposure, C-ZnO achieved 100% BPA breakdown and 70% BPA mineralization under optimal conditions. The photocatalytic degradation efficiency of BPA removal using TiO₂/reduced graphene oxide nanocomposites was investigated by Luo et al. (2017). At pH 5, 50.42% removal efficiency was reached in 120 min using an XPA-7 photochemical reactor (XueJiang Electromechanical Factory, China) with 12 quartz tubes around a 20 W UV lamp 254 nm, 50 mL of BPA solution and 1 g/L of catalyst. Bismuth Nitrate Bi (NO₃)₃.5H₂O as a Bismuth source for enhancing the photocatalytic performance by facile method at room temperature to remove BPA (Jamil & Mansor 2018). The removal efficiency of BiOBr, BiOI, and BiOI was 55, 79, and 93%, respectively, after 120 min irradiation with a 1.0 g/L dose of photocatalysts at pH 10. As a result, heterostructure is regarded as a viable way to enhance pure photocatalysts for the breakdown of organic contaminants in water. For BPE degradation, Orona-Návar et al. (2021) prepared rare-earth doping (Gd³⁺) to increase the efficiency of BiVO₄ photocatalysis The breakdown of BPA, BPS, and BPAF in water was used to assess how different Gd³⁺ concentrations affected the process. When the photocatalyst with the greatest Gd³⁺ concentration was utilized, using a hydrothermal method, the breakdown percentages of BPs were 77.02, 44.36, and 74.11%, respectively, after 3 h of processing. Reactive species were identified using total antioxidant tests and further kinetic studies.

Sahu et al. (2021) synthesized exfoliated graphitic carbon nitride exfoliated (GCN, EGCN) by treating it with acid. When exposed to short-duration visible light >420 nm, EGCN exhibits substantial valance band hole transfer for the photocatalytic mineralization of BPA. Due to the production of OH⁻ radicals, EGCN could remove 99% of BPA. Lv et al. (2021) synthesized a Z-scheme heterojunction BiOI/B4C (BOBC) for BiOI activation of peroxymonosulphate. Under ideal conditions, the BOBC could remove 90.4% of bisphenol S (BPS) in 30 min. At the same time, experiments revealed that the synergistic effects show higher activity than individual peroxymonosulphate system. Wang et al. (2022) developed a poryphyrinic ziroconim metal-organic framework (PCN-223) to effectively remove BPF from saline water using a visible light approach. By creating ionic connections with Zr, coexisting anions increase the conductivity of electrons, enhancing light-induced electron transfer under visible light. A novel Co₃O₄-Bi₂O₃ catalyst was produced by Hu et al. (2018) with microwave, and its response properties were investigated using XRD and SEM. The activity of the synthesized photocatalyst was tested for its ability to degrade BPA as a peroxymonosulphate (PMS) activator. The findings show that the catalyst accelerated BPA degradation with catalytic conditions of 0.1 g/L and five molar ratios of PMS/BPA, exhibiting 100% BPA degradation within 15 min. While the pH of the solution ranged from 3 to 11, the dual-loaded catalyst system demonstrated better activity. By activating peroxymonosulphate (PMS) to create free radicals, amorphous boron (A-boron) can be employed as a metal-free catalyst for the efficient degradation of BPS, according to research by Shao et al. (2017). It demonstrated remarkable catalytic activity and superior stability compared to carbon-based catalysts made from metal. Zhang & Chu (2022) used physical mixing to create a dual photocatalyst of Zn-TiO₂ and Cu-TiO₂ for BPS degradation. The Zn-TiO₂ and the hydrolysis of persulphate in the system both produce superoxide radicals, which can speed up the Cu(II)/Cu(I) redox cycles and have a synergistic effect and it provided an efficient way of improving the reaction by merely combining two catalysts, as well as the mechanism underlying the synergistic benefit. Wu et al. (2020) developed several iron and nitrogen co-doped porous carbon catalysts (Fe-N/C) by pyrolyzing Fe-doped zeolitic imidazolate framework-8. The breakdown of BPF by activation of PMS, the doped catalytic performance, was assessed. The optimal 1.0% of Fe-N/C showed exceptional performance for PMS activation, outperforming the traditional catalyst Co₃O₄. Also, it was determined that single oxygen was the dominating reactive species, displaying specific selectivity for organic pollutants and high resilience to the pH and water matrices in the 1.0% Fe-N/C-PMS system. The photocatalytic degradation of BPs is outlined in Table 3.

The benefit of combining photocatalysis and adsorption is a feature of synergistic processes. Such benefits consist of high efficiency, inexpensive, widespread availability of adsorbates, superior recoverability, and reduced secondary pollution. The adsorption process can aid in reducing contaminant accumulation on the catalyst surface caused by wastewater, thereby improving photocatalytic degradation efficiency. Photocatalysis can eventually mineralize contaminants to H₂O and CO₂ when exposed to light at room temperature, trying to replicate the catalyst's surface for the next adsorption process. As a result, this synergistic adsorption and photocatalytic degradation will provide useful insights for developing highly efficient and sustainable wastewater clean-up materials (Xu et al. 2020). Photogenerated electron and hole (e⁻/h⁺) pairs are produced by photocatalysts when exposed to radiation (Chen et al. 2016b). The pairs participate in a subsequent process that generates active species such as superoxide and hydroxyl radicals (Li et al. 2012). Radicals that are created react with pollutants to transform them into less harmful molecules. Semiconductors with a broad bandgap, high photosensitivity, and photochemical stability, such as ZnO, TiO₂, ZnS and BiOBr, are good options for use in photocatalysis (Ahmed et al. 2021). Some semiconductors having less quantum efficiency due to the fast recombination of e⁻/h⁺ pairs. In order to overcome this constraint, numerous compounds have been doped into catalysts as electron scavenging agents (Sudhaik et al. 2018) like Ba, Ag, non-metal dopant such as C, N, carbon dots, Mn, Cu, hydrogels, carbon nanotubes, AC, graphene-like nanomaterials, and chitosan for the catalyst support. Incorporating materials on catalysts enhances the catalyst efficiency by scavenging electrons, strengthening surface absorption of impurities, assisting as a photosensitizer, and improving visible light absorption (Brandsma et al. 2022). By providing more surface area, it has been discovered that surface area plays a crucial role in the degradation of organic pollutants in a synergistic method (Natarajan et al. 2018). Organic contaminants like EDCs were easily adsorbed onto the photocatalyst surface with a high probability, were rapidly degraded (Kanan et al. 2020).

Meng et al. (2017) demonstrated that under visible light, a zirconium-porphyrin metal-organic framework (MOF) catalyst could control photodegradation and adsorption and allow for kinetic separation. This synergistic effect increases photocatalytic efficiency and confirms that catalysis occurs within the pores of the MOF rather than in solution. Even with very high sorption uptake 487.6 mg/g, efficient photodegradation could be observed < 20 min. Zhang et al. (2018) developed an effective titanium dioxide 3D graphene hydrogel (TiO₂-rGH) to remove BPA from wastewater using a simple one-pot method. The TiO₂-rGH has a porous structure that promotes the attachment of extra nanoparticles with defined surface areas and active regions larger than those of the thin film electrode. Because graphene has high conductivity, the TiO₂-graphene hydrogel conducts charges quickly and solves the low conductivity problem. In 5 h, the synergistic effect of the TiO₂-rGH electrode destroyed the 20 mg/L of BPA. After 10 cycles with self-regeneration properties, removal capacity is still greater than 90%. Without filters, it is easy to accomplish quick separation and regeneration. The Fe₃O₄-biochar (Fe₃O₄-BC) heterogeneous catalyst with peroxymonosulphate (Fe₃O₄-BC/PMS) was prepared by (Cui et al. 2021) examined the mechanism of sorbent to eradicate BPA and it reached 100% in 90 min at pH 3.0, with PMS at 5 mM, Fe₃O₄-BC load at 2.0 g/L, and BPA at 20 mg/L. The Fe₃O₄-BC catalyst retained its high activity after five recycles with an iron loss of just 2.13 mg/L at pH 3.0, highlighting its catalyst's excellent potential for reuse and appropriateness for various applications. Zhu et al. (2018) used a hydrogel catalyst (P(HEA-co-HAM)-CdS) to eliminate BPA from aqueous. Under 500W visible light irradiation, the BPA breakdown rate of developed hydrogel reached 92% in 3 h. Photocatalytic oxidative radicals detecting investigations demonstrated that both holes h⁺ and O₂⁻ play a significant part in such systems, with the degradation rates of BPA reaching 47%. Luo et al. (2017) produces a titanium dioxide/molybdenum disulphide-reduced graphene oxide ternary hybrid (TiO₂-MoS₂-RGO) photocatalyst for BPA removal. At a catalyst dosage of 0.5 g/L and an initial BPA concentration of 10 mg/L, the breakdown was observed at pH 5. The BPA had adsorption removal ratios of TiO₂, TiO₂-MoS₂, TiO₂-RGO, and TiO₂-1MoS₂-RGO was 0.75, 0.79, 2.30, 24.00, and 22.10%, respectively. The results indicated that TiO₂ hydrophilic nature limits its capacity to adsorb hydrophobic BPA when subjected to UV irradiation. When those catalysts are combined, it improves the effectiveness of both adsorption and degradation. Qu et al. (2012) investigated the behaviour of poplar leaves to eliminate EDCs by heating poplar leaves in air to 450 °C. Carbon nanotubes (CNTs) were created by heating poplar leaves in air to 723.15 k. CNTs had outer and inner diameters of roughly 77.5 and 40.1 nm, respectively, and were made up of C, O, Na, Zn, Cu, Ca, K, Cl, and S. The statistics show that without CNTs, BPA degradation was about 24.5–4.7% 180 min with solar light irradiation. The total equilibrium period of BPA adsorption/desorption onto the surface of CNTs was less than 30 min, and CNTs absorbed approximately 19.7% of BPA. Following that, the photodegradation efficiency of BPA was enhanced to 74.8 by combining CNTs and light irradiation for 180 min. The photocatalytic activity of the Ag/AC-ZnO was evaluated for the breakdown of BPA in a study by (Intarasuwan et al. 2018) under visible light irradiation. The results showed that Ag/AC-ZnO demonstrates more photocatalytic activity than AC-ZnO and pure ZnO. According to (Chen et al. 2017c), reduced graphene oxide encapsulates AgBr, creating a composite known as AgBr@rGO that may be introduced into graphene to create hydrogels with 3D network topologies (rGH-AgBr@rGO). When exposed to light, the 3D graphene nanosheets of rGH-AgBr@rGO quickly absorbed BPA. They swiftly decomposed to AgBr@rGO nanoparticles, proving the synergy between adsorption and photocatalytic degradation may greatly increase pollutant removal efficiency. Therefore, synergistic mechanisms produce better outcomes than other techniques, making them a promising strategy for eliminating EDCs. The integrated approach results for BPs removal are outlined in Table 4.

The sorption isotherm represents the sorption rate (q_e) versus concentration at equilibrium (Ce). It is common to use the Langmuir, Freundlich, Tempkin, and Dubinin Radshkevich (D-R) isotherm to describe the equilibrium behaviour of the adsorption process (Qayoom et al. 2017).

C₀ is the initial metal ion concentration (mg/L), and b is the Langmuir constant. The absorption process will be unfavourable, favourable and linear, favourable and reversible, and irreversible for RL > 1, RL = 1, and RL = 0. The parameters K_f (mg/g) and n in the non-linear Freundlich equation are described as adsorption capacity and heterogeneity. The Tempkin isotherm denotes that the K_T and b are the Temkin isotherm equilibrium binding constant, Temkin constant, for the D-R isotherm, ε and β represent the Polanyi potential and activity coefficient, respectively (Clara et al. 2004). Table 2 lists numerous adsorbents studied for BP adsorption isotherms, including carbon-based materials, nanocomposites, agricultural waste, AC, and surfactant-modified adsorbents. Among various isotherms, Langmuir isotherm is the most widely observed because it is one of the simplest adsorption isotherms accurately characterized by several real-time systems. Several commercial adsorbents have uneven surfaces that favour adsorption at a particular spot. This explains that the adsorbate affinity is equal at all sites, with no adsorbate transmigration in the surface plane. Each molecule possesses sorption activation energy and constant enthalpies with no steric hindrance or lateral contact between the adsorbed molecules (Table 5) (Al-Ghouti & Da'ana 2020).

Adsorption kinetics are studied by looking at the adsorbent's change in adsorptive capacity or adsorptive rate (Singh et al. 2017). Table 6 shows the most often used kinetic models using linear and nonlinear equations for BPs removal (Zafar et al. 2015).

Table 6

Kinetic relations between linear and non-linear

Models .	Linear Equation .	Non-linear equation .	Mechanism .
Pseudo first-order			Physisorption limits the adsorption rate of the particles onto the adsorbent. The rate of adsorption site occupancy is related to the number of vacant sites on the adsorbent.
Pseudo second-order			It relates to the chemisorption process. The quantity of active surface sites and adsorbate ions on the adsorbent's surface determines the adsorption rate.
Intraparticle diffusion model			An intraparticle diffusion rate parameter has been used to describe the diffusion rate after the initial adsorption stages. The rate parameter has been calculated using several variables, including adsorbent mass, initial concentration, and particle size.
Elovich			With more advanced adsorption, the reaction rate falls exponentially.

Models .	Linear Equation .	Non-linear equation .	Mechanism .
Pseudo first-order			Physisorption limits the adsorption rate of the particles onto the adsorbent. The rate of adsorption site occupancy is related to the number of vacant sites on the adsorbent.
Pseudo second-order			It relates to the chemisorption process. The quantity of active surface sites and adsorbate ions on the adsorbent's surface determines the adsorption rate.
Intraparticle diffusion model			An intraparticle diffusion rate parameter has been used to describe the diffusion rate after the initial adsorption stages. The rate parameter has been calculated using several variables, including adsorbent mass, initial concentration, and particle size.
Elovich			With more advanced adsorption, the reaction rate falls exponentially.

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Where qe and q represent the adsorption capacities (mg/g) at equilibrium time with time t (h), k₁ is the pseudo-first-order model rate constant (h), k₂ (g/mg. h) is the rate adsorption constant, q_e (mg/g) represents the equilibrium adsorption capacity, q_t (mg/g) represents the amount adsorbed at time t. The slope and intercept of the plot (qt vs. t^1/2) determine the k_p (mg/g/min) and C rate constants, β which reveal the adsorption constant (mg/g) throughout every experiment, the q_t shows the concentration of the solute adsorbed at time t, α and the speed constant (mg/g/min). Table 2 depicts the sorption process utilizing practically all adsorbents, which is the pseudo-second-order kinetic model. This is because pseudo-second-order (PSO) applies throughout a prolonged duration. In contrast, the pseudo-first-order (PFO) only applies to the beginning stage of the adsorption process (Hubbe et al. 2019). Fe₃O₄ magnetic nanoparticles (MNPs) were used to break down BPA, which was investigated by (Huang et al. 2012). With 15 min of contact time, the BPA was removed, usually occurring under all pH levels and following a pseudo-first-order kinetic response. With an R² of 0.99, the PSO model was to be optimal for the sorption process, demonstrating that the chemisorption interaction between the active sites on the adsorbent and the BPA anion is the primary source of adsorption. Using a co-precipitation technique (Zhang et al. 2014) they prepared reduced graphene oxide (rGO) nanosheets with MNPs. The equilibrium is reached between 4 and 6 h of contact time, which follows PSO, implying that sorption relies on the quantity of solute adsorbed on the adsorbent's surface and the amount adsorbed at equilibrium. Zhou et al. (2013) investigated the process of binding metal-organic framework adsorbents for BPA removal. The BPA molecules get diffused to the sorbent's outer surfaces before crossing the boundary layer and entering the cover. After entering the microporous framework was created by terephthalic acid with Al ions by intra-particle diffusion, BPA molecules were finally eliminated by reacting with the benzene ring and Al-OH on the sorbents. Therefore, whereas intra-particle diffusion is crucial near the end of the sorption, boundary layer diffusion governs the sorption rate of sorption in the beginning phase. So, it concludes that the metal-organic framework for BPA removal exhibits an intra-particle diffusion model. To characterize chemical adsorption mechanisms in nature. Wu et al. (2009) explained the Elovich equation frequently employed in adsorption kinetics. Here, the adsorption kinetics characteristic curves were described using the Elovich equation (RE) equilibrium parameter.

ΔG⁰ at various temperatures indicates the feasibility of the process and the spontaneous nature of the adsorption. However, the negativity of ΔG⁰ decreases with the increase in temperature, which suggested that the sequestration of adsorbate by adsorbent is unfavourable at elevated temperature. Negative G⁰ and H⁰ values indicate that the absorption process is feasible and exothermic. Also, a negative ΔS⁰ value shows that the irregularity of the solid/solution interface is reduced. ΔG⁰ at various temperatures, indicating the viability of the method and the spontaneous nature of the adsorption. Yet, the negative of ΔG⁰ reduces as the temperature rises. This revealed that adsorbate sequestration by adsorbent is unfavourable at increased temperatures (Heiba et al. 2018). Table 7 summarizes recent thermodynamic studies on BPs removal with various adsorbents. According to Table 7, almost all adsorbents have negative H and G values, implying that the sorption mechanism is exothermic and spontaneous. As the temperature rises, the adsorption process's efficiency will decrease, and it provides E_a negative value by using Equations (14)–(16). The negative activation energy in sorption processes exhibits exothermic nature and occurs at lower temperatures. The endothermic nature implies that adsorbate species become more soluble as temperature rises. As a result, the adsorbate is harder to adsorb because the forces of interaction between the adsorbate and solvent are more significant than those between the adsorbate and adsorbent (Lombardo et al. 2019).

The cost per mass of the raw materials used in the synthesis process is the factor that determines whether an adsorbent build is economically viable. This can be calculated using the cost of raw materials, amortized cash flow, the cost of adsorbent per gram of adsorbate removed, annual investment and operating expenditures (CAPEX and OPEX), and the cost of the adsorbent use in an adsorption process (Ighalo et al. 2022).

The adsorbent raw materials are made from agricultural waste, nanomaterials, clays, graphene polymer materials, and ACs. Whereas commercially available ACs are more expensive than ACs prepared from agricultural waste materials.

Water contamination caused by toxic BPs has become one of the world's foremost significant environmental concerns. Several intriguing treatments for removing BPs from aqueous systems have been established, including adsorption, photocatalytic degradation, electrochemical approaches, and membrane technologies. Although there are several options for treating BPs, each has positive and negative impacts. Adsorption and photocatalysis have much potential in water treatment applications regarding cost-effectiveness and sustainable development. Adsorption techniques have been comprehensively investigated using low-cost adsorbents, surfactant-modified adsorbents, carbon-based adsorbents, and biological adsorbents. Several photocatalytic degradation support mechanisms have been studied for the eradication of BPs. Furthermore, it was reported that an adsorption-photocatalysis synergetic technique might significantly reduce BPs in wastewater compared to an individual approaches. Overall, the optimum ratio composite exhibits good adsorption and photocatalytic activity. This article reviewed the effectiveness and significance of adsorption, photocatalytic degradation, and the synergy between the two treatment methods for removing EDCs from aqueous environment. Although these methods can treat BP's effluent, the appropriate one depends on several factors, notably the initial concentration, financial investment, industrial performance, maintenance cost, and ecological impact (Massoud et al. 2009).

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

The authors declare there is no conflict.