One of the most important problems that the world is currently facing in terms of its impact on the environment is figuring out how to properly manage textile effluents. Photocatalysis has been shown to be successful in the removal of intractable chemicals and is regarded as a viable wastewater treatment technology. This work focused on the photocatalytic degradation of rhodamine-B (RB) in an aqueous solution, as well as the photocatalytic behavior of niobium pentaoxide (Nb2O5) as a photocatalyst was tested. It is important to note that good photocatalytic efficiency is highly dependent on the operating conditions. There are several process parameters that influence RB photocatalytic degradation, including the amount of photocatalyst (Nb2O5) used, the concentration of RB at the start of the reaction, and the pH of the solution optimized under visible-light irradiation. According to the findings, the conditions in which the greatest amount of RB was degraded were those in which the concentration of the catalyst was 10 mg/l, the dosage of the catalyst was 1 mg/l, and the pH was 11. The results also revealed that after utilizing the catalyst three times in a row, catalyst efficiency was maintained, and the degradation rate was maintained at a greater level.
Photocatalytic degradation of rhodamine-B (RB) using niobium pentaoxide (Nb2O5) as a photocatalyst was tested.
Effects of different process parameters have been studied.
The result shows that the maximum degradation of RB was observed at 10 mg/l RB concentration, 1 mg/l catalyst (Nb2O5) dose, and the pH was 11.
This work will provide some context and guidelines for those who are new to the field of photocatalytic degradation of RB.
Dyes are widely used in the fabric/textile industry so major sources of environmental pollution are dye wastewater pollutants (Al-Kahtani 2017). Fabric/textile industry wastewater produced intensive organic dyes and the toxicity of these dyes has become a worldwide problem for the aquatic system (Ucker et al. 2021). The greater durability of modern synthetic dyes with their complicated aromatic structure makes biological treatment approaches ineffective (Yang et al. 2012). For the treatment of dye wastewater, currently some other physical and chemical techniques such as coagulation, ultra-filtration, adsorption, and membrane separation are available with limited success (Prado et al. 2008; Zhang et al. 2008; Qamar & Muneer 2009). Rhodamine-B (RB), one of the most important dyes, is used in many industrial processes for dyeing paper and producing a dye laser (Liang & Guo 2010; Topare et al. 2015). It has been experimentally proven that RB is harmful to animals and human beings which causes respiratory tract, irritation of the eyes, and skin. Thus, keeping the harmful effects and hazardous nature of RB, it was measured important to make efficient efforts to degrade RB from an aqueous solution (Akpan & Hameed 2009; Zhou et al. 2011).
The use of advanced oxidation processes (AOPs), in the degradation of the organic pollutants using the photocatalyst, has shown the potential to completely remove the organic and inorganic pollutants apart from the other major technologies available which concentrate the dye on an adsorbent that involves the transfer of the pollutant from a liquid phase to another phase (Kaviyarasu et al. 2013; Fairooz & Ali 2016; Santos et al. 2019). The material's photocatalytic activity and other properties are significantly affected by its crystalline structure (Nunes et al. 2020). In addition, it is common knowledge that the synthesis pathway approach possibly prominent role in determining the structural properties that are ultimately produced (Prado et al. 2021).
The photodegradation of pollutants may benefit from the implementation of an innovative new approach, which makes use of the Nb2O5 catalyst. This approach can be applied to a wide variety of semiconductors; in particular, metal oxide semiconductors have high surface areas and unique optical and electrical properties that make them ideal for use in photocatalytic applications. Thermodynamically stable and highly corrosion-resistant, niobium pentoxide (Nb2O5) has the potential to be used as a catalytic oxidation catalyst for organic molecules in aqueous conditions (Hashemzadeh et al. 2013; Osman et al. 2021). Nb2O5 has strong corrosion resistance and low toxicity, which has piqued the interest of the research community. This compound has a wide range of uses, including catalysis, solar cells, gas sensors, and electrochromic, to name a few. It has also been the subject of some recent studies (Brites et al. 2011; Carvalho et al. 2020). Dehydration, hydration, etherification, hydrolysis, condensation, alkylation, dehydrogenation, and oxidation are only a few of the many processes for which Nb2O5 is utilized as a catalyst (Topare et al. 2013; Jesus et al. 2021).
Visible-light irradiation photocatalyst development and comparison of photocatalytic activity of various photocatalysts for dye degradation have been the subject of substantial research in recent years (Moreira & Borges 2018). One of the prospective photocatalysts, Nb2O5, which has a band gap energy of 3.4 eV and is comparable to that of TiO2, demonstrates strong photocatalytic activity in the process of dye photodegradation (Reeta et al. 2018). This makes it one of the most promising photocatalysts. The use of Nb2O5 for the photodegradation of pollutants, on the other hand, is not widely investigated in the published research (Paris et al. 2020; Troncoso & Tonetto 2021). In the present study, Nb2O5 was used as a photocatalyst and the photocatalytic activity of this material on RB dye was investigated when it was exposed to visible light. To determine the optimal conditions for photocatalytic degradation of RB, the study examined how several parameters, including the starting concentration of RB, the dosage of the catalyst (Nb2O5), and the pH of the solution, impacted the process.
MATERIALS AND METHODS
RB is widely used in dyeing the fabric used for experimental work. The molecular formula of RB is C28H31ClN2O3 and has a molar mass of 479.02. RB dye chemical structure is given in Table 1. The photocatalyst was used as the analytic grade of Nb2O5 (99.9%). Various reagent solutions were made up in double-distilled water for the experiments. To control the acidity and alkalinity of the solutions, 0.1 N HCl/0.1 N NaOH was utilized.
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System requirements (photocatalytic reactor)
RESULTS AND DISCUSSION
Impact of the various process parameters
The experiments were carried out by employing Nb2O5 as a photocatalyst onto RB when exposed to visible light. The degradation efficiency was evaluated by the influence of process parameters including catalyst (Nb2O5) dosage (0.25, 0.5, 0.75, 1.0, and 1.25 g/l), initial RB concentration (10, 20, 30, and 40 mg/l), and the solution pH (3, 5, 7, 9, and 11) were studied.
Impact of the catalyst dosage (Nb2O5)
Impact of RB initial concentration
Impact of pH
In the degradation of RB, the Nb2O5 was used as a catalyst. The degradation of RB is facilitated in the presence of a catalyst as experimental results confirmed. With an increase in catalyst dose up to an optimum loading, the initial rate of degradation of RB increased. Further, it showed no effect on the degradation of RB, as a result of an increase in the catalyst dose. As the rate of degradation of RB decreased, the initial RB concentration increased. It also shows that the maximum degradation of RB was observed at optimal conditions, i.e. RB initial concentration is 10 mg/l, catalyst (Nb2O5) dosage is 1 mg/l, and the pH is 11.
DATA AVAILABILITY STATEMENT
All relevant data are included in the paper or its Supplementary Information.
CONFLICT OF INTEREST
The authors declare there is no conflict.
This research work was funded by Institutional Fund Projects under grant no. (IFPIP:1296-961-1443). The authors gratefully acknowledge the technical and financial support provided by the Ministry of Education and King Abdulaziz University, DSR, Jeddah, Saudi Arabia.