Photocatalytic degradation of bisphenol A in aqueous media: A review

Clearing the path: Unraveling bisphenol a removal and degradation mechanisms for a cleaner future

Bisphenol A (BPA) is a prevalent chemical found in a range of consumer goods, which has raised worries about its possible health hazards. Comprehending the breakdown pathways of BPA is essential for evaluating its environmental consequences and addressing associated concerns. This review emphasizes the significance of studying the degradation/removal of BPA, with a specific focus on both natural and artificial routes. It explores natural processes such as photolysis, hydrolysis, and biodegradation, as well as manmade methods including advanced oxidation processes (AOPs) and enzymatic degradation. Examining the decomposition of BPA helps to understand how it behaves in the environment, providing valuable information for managing risks and addressing pollution. Furthermore, comprehending degradation mechanisms aids in the creation of more secure substitutes and regulatory actions to reduce BPA exposure and safeguard human health. This review emphasizes the need of promptly addressing this environmental and public health concern through the research of BPA degradation.

Fabrication of close-contact S-scheme Cr2Bi3O11-Bi2O3/Fe3O4@porous carbon microspheres based on in-situ reaction: Enhanced photo-Fenton wastewater treatment

Low photo-induced carrier recombination rate, exceptional light absorption, and advantageous recycling performance are crucial attributes of semiconductor photocatalyst for wastewater purification. Herein, based on in-situ reaction, close-contact S-scheme bismuth chromate/bismuth oxide/ferroferric oxide@porous carbon microspheres (Cr2Bi3O11-Bi2O3/Fe3O4@PCs) (F-CBFP) was fabricated using alginates as precursor. Due to the abundance of functional groups on the porous carbon (PCs), Bi2O3 and Cr2Bi3O11 nanoparticles (NPs) are in situ deposited onto the highly conductive 3D magnetic porous Fe3O4@PCs microsphere surface, which not only form tight interfacial contacts and reduces interfacial potential barriers but also prevent agglomeration or shedding of the NPs during photocatalytic reactions. Moreover, density functional theory (DFT) calculations further confirm that the formation of a robust built-in electric field (BIEF) within F-CBFP prompts photo-induced electrons in the conduction band (CB) of Bi2O3 to combine with holes in the valence band (VB) of Cr2Bi3O11, effectively constructing a S-scheme heterojunction system. Also, Fe3O4 can act as a Fenton catalyst, activating the H2O2 generated by Cr2Bi3O11 under illumination. In wastewater treatment, the obtained F-CBFP shows remarkable photo-Fenton degradation (towards methyl orange (97.8 %, 60 min) and tetracycline hydrochloride (95.3 %, 100 min)) and disinfection performance (100 % E. coli inactivation), and exceptional cyclic stability.

Bisphenol A (BPA) toxicity assessment and insights into current remediation strategies

Bisphenol A (BPA) raises concerns among the scientific community as it is one of the most widely used compounds in industrial processes and a component of polycarbonate plastics and epoxy resins. In this review, we discuss the mechanism of BPA toxicity in food-grade plastics. Owing to its proliferation in the aqueous environment, we delved into the performance of various biological, physical, and chemical techniques for its remediation. Detailed mechanistic insights into these removal processes are provided. The toxic effects of BPA unravel as changes at the cellular level in the brain, which can result in learning difficulties, increased aggressiveness, hyperactivity, endocrine disorders, reduced fertility, and increased risk of dependence on illicit substances. Bacterial decomposition of BPA leads to new intermediates and products with lower toxicity. Processes such as membrane filtration, adsorption, coagulation, ozonation, and photocatalysis have also been shown to be efficient in aqueous-phase degradation. The breakdown mechanism of these processes is also discussed. The review demonstrates that high removal efficiency is usually achieved at the expense of high throughput. For the scalable application of BPA degradation technologies, removal efficiency needs to remain high at high throughput. We propose the need for process intensification using an integrated combination of these processes, which can solve multiple associated performance challenges.

Predictive modeling for the adsorptive and photocatalytic removal of phenolic contaminants from water using artificial neural networks

Numerous harmful phenolic contaminants are discharged into water that pose a serious threat to environment where two of the most important purification methodologies for the mitigation of phenolic contaminants are adsorption and photocatalysis. Besides cost, each process has drawbacks in terms of productivity, environmental impact, sludge creation, and the development of harmful by-products. To overcome these limitations, the modeling and optimization of water treatment methods is required. Artificial Intelligence (AI) is employed for the interpretation of treatment-based processes due to powerful learning, simplicity, high estimation accuracy, effectiveness, and improvement of process efficiency where artificial neural networks (ANNs) are most frequently employed for predicting and analyzing the efficiency of processes applied for the mitigation of these phenolic contaminants from water. ANNs are superior to conventional linear regression models because the latter are incapable of dealing with non-linear systems. ANNs can also reduce the operational cost of treating phenol-contaminated water. A correlation coefficient of >0.99 can be achieved using ANN with enhanced phenol mitigation percentage accuracy generally ranging from 80 % to 99.99 %. Using ANN optimization, the maximum phenol mitigation efficiencies achieved were 99.99 % for phenol, 99.93 % for bisphenol A, 99.6 % for nonylphenol, 97.1 % for 2-nitrophenol, 96.6 % for 4-chlorophenol and 90 % for 2,6-dichlorophenol. In numerous ANN models, Levenberg-Marquardt backpropagation algorithm for training was employed using MATLAB software. This study overviews their employment and application for optimization and modeling of removal processes and explicitly discusses the important input and output parameters necessary for better performance of the system. The comparison of ANNs with other AI techniques revealed that ANNs have better predictability for mitigation of most of the phenolic contaminants. Furthermore, several challenges and future prospects have also been discussed.

Enhancing the Catalytic Activity of Laccase@Copper-Metal-Organic Framework Nanofractal Microspheres: Synergistic Contribution of the Mass Transfer and Electron Transfer Pathway

Metal-organic frameworks (MOFs) are limited by small pores and buried active sites, and their enzyme-like catalytic activity is still very low. Herein, laccase was employed as the organic component to construct laccase@Cu3(BTC)2 nanofractal microspheres. During the preparation process, laccase adsorbed Cu2+ by electrostatic attractive interaction, then combined with Cu2+ by coordination interaction, and finally induced the in situ growth of H3BTC2 in multiple directions by electrostatic repulsion. Interestingly, electrostatic repulsion was tuned efficiently by adjusting the Cu2+ concentration to obtain laccase@Cu3(BTC)2 nanofractal microspheres (nanosheet microspheres, nanorod microspheres, and nanoneedle microspheres). Laccase@Cu3(BTC)2 nanorod microspheres exhibited the highest catalytic efficiency, which was 14-fold higher than that of smooth microspheres. The mechanism of the improvement of catalytic activity in the degradation of BPA was proposed for the first time. The enhanced catalytic activity depended on the adsorption effect of the nanorod framework and dual cycle synergistic catalysis of Cu+/Cu2+ active sites, which accelerated substrate diffusion and electron transfer. The catalytic mechanism of enzyme@MOF nanofractal microspheres not only deepens our understanding of enzyme and MOF synergistic catalysis but also provides new insights into the design of catalysts.

Enhancing the efficient degradation of BPS using the BPNS-CdS composite catalyst under visible light

Black phosphorus nanosheets (BPNS), a novel two-dimensional nanomaterial, find extensive applications in the field of photocatalysis. With the prohibition of bisphenol A (BPA), the utilization of bisphenol S (BPS), which is more resistant to degradation than BPA, has been steadily increasing. In this study, few-layer BPNS was prepared using an improved liquid-phase exfoliation method, showcasing its commendable specific surface area and notable adsorption capacity. Subsequently, a new type of nanocomposite material, BPNS-Cadmium sulfide (CdS), was hydrothermal synthesized involving BPNS and CdS. We conducted comparative assessments of BPNS, CdS, and their composite materials to identify the most efficient catalysts. Ultimately, we found that the composite material BPNS-CdS exhibited the highest capability for degrading BPS in an alkaline environment, achieving an impressive degradation rate of 86.9%. Notably, the degradation rate remained higher in an acidic environment compared to a neutral one. Through Electron Spin Resoance (ESR) experiments, it is revealed that BPNS-CdS, when exposed to visible light, generates •O2-, •OH, and h+ as confirmed. Additionally, we tested and validated the carrier separation and migration abilities of BPNS-CdS while also calculating the band gap for each material. Building upon these results, a possible photocatalysis mechanism experiment was proposed. Finally, the degradation products were analyzed using High-Performance Liquid Chromatography-Mass Spectrometry (HPLC-MS) and put forth a plausible pathway for the BPS degradation, and it was found that 4-Phenolsulfonic acid, Ethyl protocatechuate and Isophthalic acid are the main intermediates of BPS. This study contributes to a deeper understanding of the synergy between non-metallic catalysts like BPNS and metal catalysts like CdS. It also offers new insights into the degradation mechanisms and pathways for BPS.

Construction of flake ball-shaped Bi2WO6 embedded on phenyl functionalized g-C3N4 nanosheet for efficient degradation insight of colorless pollutants and its biological application

A facile solvent-free solid-state method was adapted to synthesize the spherical-shaped Bi2WO6 engraved on phenyl-doped g-C3N4 nanosheet, i.e., Bi2WO6/Ph-gC3N4 (or BPCN) composites with varying weights of Bi2WO6. Several spectral analyses were used to characterize all the synthesized nanomaterials. The synthesized photocatalyst showed good absorption under visible light as confirmed by UV-visible DRS analysis. Morphological analyses like SEM and TEM determine the successful fabrication of binary heterocomposite. Further, the elements available in the fabricated binary nanocomposite were confirmed by XPS. The photocatalyst was used for the aerobic photocatalytic degradation of a few colorless pollutants like bisphenol A (BPA, 30 mg L-1), a microplastic constituent, and tetracycline (TC, 40 mg L-1), an antibiotic derivative to achieve the impressive results. The less intense PL signal obtained for the 20BPCN heterocomposite reveals the remarkable enhancement in e--h+ pair separation and recombination rate. The quenching study, alkaline terephthalic acid photoluminescence test (TA-PL), and NBT phototransformation study explain the formation of reactive species involved in the decomposition process. An oral cancer cell line (A-254) was tested for the anticancer activity analysis of the 20BPCN photocatalyst. Based on the obtained results, a Z-scheme electron transfer mechanism has been proposed for the photodegradation of model compounds.

Photocatalytic and electrocatalytic degradation of bisphenol A in the presence of graphene/graphene oxide-based nanocatalysts: A review

Bisphenol A (BPA), a widely recognized endocrine disrupting compound, has been discovered in drinking water sources/finished water and domestic wastewater influent/effluent. Numerous studies have shown photocatalytic and electrocatalytic oxidation to be very effective for the removal of BPA, particularly in the addition of graphene/graphene oxide (GO)-based nanocatalysts. Nevertheless, the photocatalytic and electrocatalytic degradation of BPA in aqueous solutions has not been reviewed. Therefore, this review gives a comprehensive understanding of BPA degradation during photo-/electro-catalytic activity in the presence of graphene/GO-based nanocatalysts. Herein, this review evaluated the main photo-/electro-catalytic degradation mechanisms and pathways for BPA removal under various water quality/chemistry conditions (pH, background ions, natural organic matter, promotors, and scavengers), the physicochemical characteristics of various graphene/GO-based nanocatalysts, and various operating conditions (voltage and current). Additionally, the reusability/stability of graphene/GO-based nanocatalysts, hybrid systems combined with ozone/ultrasonic/Fenton oxidation, and prospective research areas are briefly described.

Reduced and modified graphene oxide with Ag/V2O5 as a ternary composite visible light photocatalyst against dyes and pesticides

Water pollution by dyes and pesticides poses significant threats to our ecosystem. In this research, a visible-light ternary composite photocatalytic system was fabricated using graphene oxide (GO) by reducing with N2H4, modifying with KOH, and decorating with Ag/V2O5. The fabricated photocatalysts were characterized through FTIR, SEM, XRD, BET, PL, EDX, ESR, UV-vis spectroscopy, TGA, ESI-MS, and Raman spectroscopy. The point zero charge of the reduced and modified GO (RMGO/Ag/V2O5) was measured to be 6.7 by the pH drift method. This ternary composite was able to achieve complete removal of methyl orange (MO) and chlorpyrifos (CP) in solutions in 80 min under the optimum operation conditions (e.g., in terms of pollutant/catalyst concentrations, pH effects, and contact time). The role of active species responsible for photocatalytic activity was confirmed by scavenger analysis and ESR investigations. The potential mechanism for photocatalytic activity was studied through a fragmentation process carried out by MS analysis. Through nonlinear fitting of the experimental data, MO and CP exhibited the best fit results with the pseudo 1st-order kinetics (quantum yields of 1.07 × 10-3 and 2.16 × 10-3 molecules photon-1 and space-time yields of 1.53 × 10-5 and 2.7 × 10-5 molecules photon-1 mg-1, respectively). The structure of the nanomaterials remained mostly intact to support increased stability and reusability of the prepared photocatalysts even after 10 successive regeneration cycles.

Fabrication of CuFe2O4/Bi12O17Cl2 photocatalyst with intrinsic p-n junction for highly efficient bisphenol A degradation

The construction and application of novel highly efficient photocatalysts have been the focus in the field of environmental pollutant removal. In this work, a novel CuFe2O4/Bi12O17Cl2 photocatalysts were synthesized by simple hydrothermal and chemical precipitation method. The fabricated CuFe2O4/Bi12O17Cl2 composite exhibited much higher photocatalytic activity than pristine CuFe2O4 and Bi12O17Cl2 in the removal of bisphenol A (BPA) under visible-light illumination, which ascribed to the intrinsic p-n junction of CuFe2O4 and Bi12O17Cl2. The photocatalytic degradation rate of BPA on CuFe2O4/Bi12O17Cl2 with an optimized CuFe2O4 content (1.0 wt.%) reached 93.0% within 30 min. The capture experiments of active species confirmed that the hydroxyl radicals (•OH) and superoxide radicals (•O2-) played crucial roles in photocatalytic BPA degradation process. Furthermore, the possible degradation mechanism and pathways of BPA was proposed according to the detected intermediates in photocatalytic reaction process.

Towards the assessment of exposure to bisphenols in everyday items with increased accuracy by the use of integrated calibration method (ICM)-based methodology

The most crucial purpose of the measurement is to obtain a reliable result that reflects the actual qualitative and/or quantitative features of the tested material. The overriding goal of analytical chemistry is to obtain accurate results after compensating of various interference effects as well as non-linear calibration dependence. A new approach based on an integrated calibration method (ICM) supported by H-point standard addition method (HPSAM) has been used to improve the quality of analytical results. The proposed methodological approach was extended using the step-by-step dilution procedure, and five measurement conditions were used to eliminate multiplicative, additive, and non-linear interferences. On this basis, a set of estimations is obtained to improve the quality of the analytical results. The analytical usefulness of the proposed approach was tested on the example of the determination of three compounds from the group of bisphenols (BPs) using the chromatographic technique - HPLC-DAD (high-performance liquid chromatography with diode array detection). Compared to the reference method - fluorescence spectroscopy - the obtained results were characterized by excellent accuracy (RE=3 % in most cases). The developed methodology allowed to carry out a risk assessment on BPA, BPF, and BPS present in samples of shop receipts and canned food. Store clerks have been shown to be particularly vulnerable to PBF and BPS in receipts due to skin permeation (exposure factors were equal to 308.97 µg/g for BPF and 181.89 µg/g for BPS). Consumers should also pay close attention to the BPA found in canned food samples (the average concentration was equal to 20.61 µg/mL, and the tolerable daily intake was exceeded over 165.000 times). The analytical method and the methodological approach were evaluated using the RGB model and the AGREE approach - it was shown that the method can be successfully used for other analytical purposes (the method is White) and is environmentally friendly (Significance=0.63).

Photocatalytic Antimicrobials: Principles, Design Strategies, and Applications

Nowadays, the increasing emergence of antibiotic-resistant pathogenic microorganisms requires the search for alternative methods that do not cause drug resistance. Phototherapy strategies (PTs) based on the photoresponsive materials have become a new trend in the inactivation of pathogenic microorganisms due to their spatiotemporal controllability and negligible side effects. Among those phototherapy strategies, photocatalytic antimicrobial therapy (PCAT) has emerged as an effective and promising antimicrobial strategy in recent years. In the process of photocatalytic treatment, photocatalytic materials are excited by different wavelengths of lights to produce reactive oxygen species (ROS) or other toxic species for the killing of various pathogenic microbes, such as bacteria, viruses, fungi, parasites, and algae. Therefore, this review timely summarizes the latest progress in the PCAT field, with emphasis on the development of various photocatalytic antimicrobials (PCAMs), the underlying antimicrobial mechanisms, the design strategies, and the multiple practical antimicrobial applications in local infections therapy, personal protective equipment, water purification, antimicrobial coatings, wound dressings, food safety, antibacterial textiles, and air purification. Meanwhile, we also present the challenges and perspectives of widespread practical implementation of PCAT as antimicrobial therapeutics. We hope that as a result of this review, PCAT will flourish and become an effective weapon against pathogenic microorganisms and antibiotic resistance.

Determination of tetrabromobisphenol A and its brominated derivatives in water, sediment and soil by high performance liquid chromatography-tandem mass spectrometry

Tetrabromobisphenol A (TBBPA) was typical brominated flame retardant and potential environmental endocrine disruptor, and it had persistence, bioaccumulation and chronic toxicity. Simultaneous determination of ultra-trace TBBPA, tribromobiphenol A (tri-BBPA), dibromobiphenol A (di-BBPA), monobromobisphenol A (mono-BBPA) and bisphenol A (BPA) was developed by high performance liquid chromatography-tandem mass spectrometry(HPLC-MS/MS), the parent ion charge ratios (m/z) had been optimized. The linear range was wider and the limit of detection was (LOD) 0.09 ~ 0.21 ng mL-1, which could detect trace pollutants. The extraction efficiency was improved by optimizing the parameters, HLB cartridge was used in the water sample by solid phase extraction (SPE), the recovery rates in water samples were over 80.28% with three concentration levels, the relative standard deviations (RSD) were less than 7.12%, and the minimum detection limit of the method was 0.90 ~ 2.10 × 10-3 ng mL-1. Soil and sediment samples were extracted by accelerated solvent extraction (ASE), the recovery rates in soil and sediment were over 79.40% and 75.65%, the minimum detection limit was 0.0225 ~ 0.0525 ng g-1, RSD was less than 7.19%. The proffered method was successfully utilized to detect actual samples, the residue of di-BBPA and mono-BBPA are detected in Naihe River and Shuxi River in Tai'an City, residue of di-BBPA and mono-BBPA was detected in the soil, and there was low residual amount of di-BBPA, mono-BBPA and BPA in the sediment of Shuxi River.

Bisphenol A contamination in aquatic environments: a review of sources, environmental concerns, and microbial remediation

The production of polycarbonate, a high-performance transparent plastic, employs bisphenol A, which is a prominent endocrine-disrupting compound. Polycarbonates are frequently used in the manufacturing of food, bottles, storage containers for newborns, and beverage packaging materials. Global production of BPA in 2022 was estimated to be in the region of 10 million tonnes. About 65-70% of all bisphenol A is used to make polycarbonate plastics. Bisphenol A leaches from improperly disposed plastic items and enters the environment through wastewater from plastic-producing industries, contaminating, sediments, surface water, and ground water. The concentration BPA in industrial and domestic wastewater ranges from 16 to 1465 ng/L while in surface water it has been detected 170-3113 ng/L. Wastewater treatment can be highly effective at removing BPA, giving reductions of 91-98%. Regardless, the remaining 2-9% of BPA will continue through to the environment, with low levels of BPA commonly observed in surface water and sediment in the USA and Europe. The health effects of BPA have been the subject of prolonged public and scientific debate, with PubMed listing more than 17,000 scientific papers as of 2023. Bisphenol A poses environmental and health hazards in aquatic systems, affecting ecosystems and human health. While several studies have revealed its presence in aqueous streams, environmentally sound technologies should be explored for its removal from the contaminated environment. Concern is mostly related to its estrogen-like activity, although it can interact with other receptor systems as an endocrine-disrupting chemical. Present review article encompasses the updated information on sources, environmental concerns, and sustainable remediation techniques for bisphenol A removal from aquatic ecosystems, discussing gaps, constraints, and future research requirements.

Photocatalytic degradation of bisphenol A by temperature-sensitive magnetic hydrogel with enhanced service life

Easy diffusion and low reusability limit the practicality of photocatalysts. In this study, a hollow sphere (HS) heterojunction was synthesized based on oxygen-doped carbon nitride (OCN) and layered double hydroxides (LDHs). A thermosensitive HS hydrogel (HS Gel) was prepared by mixing HS with N-isopropylacrylamide. Bisphenol A (BPA), being widely manufactured and used in commercial and domestical products and its high toxicity, was chosen as the target pollutant to demonstrate the photocatalytic ability and practicality of the HS Gel. HS Gel presented effective BPA degradation (95% degradation in 70 mins, 4.2 × 10-2 min-1 of kobs) at ambient temperature which is much better than kobs = 1.8 × 10-2 min-1 of OCN and kobs = 0.08 × 10-2 min-1 of LDH), and increased by two-fold the recycling service life (retention of >80% degradation efficiency after 13 usage cycles) compared to other carbon-based photocatalysts (retention of >80% degradation efficiency after 5-6 usage cycles). This is due to its multifunctional characteristics (magnetic property and thermal sensitivity). Under ambient temperature, the hydrophilic HS Gel swelled in the aqueous solution, which promoted the photocatalytic reaction between HS and BPA in the gel state. After the reaction, the HS Gel was subjected to shrinkage by high temperature heating to enhance the mechanical strength for recovery. The magnetic recovery was realized by the paramagnetic properties of layered double oxide to reduce environmental interference. Detailed studies of HS gel related to enhanced service life were conducted including structural changes, catalyst leaking and magnetic changing. A new kind of type Ӏ plus Z-scheme mechanism was also proposed based on the Kubelka-Munk equation, UV diffuse reflectance spectroscopy and Mott-Schotty technique.

Dopant-driven recombination delay and ROS enhancement in nanoporous Cd1-xCuxS heterogeneous photocatalyst for the degradation of DR-23 dye under visible light irradiation

Developing an efficient heterogeneous photocatalyst for environmental remediation and treatment strategies using visible light harvesting processes is promising but challenging. Herein, Cd1-xCuxS materials have been synthesized and characterized by precise analytical tools. Cd1-xCuxS materials exhibited excellent photocatalytic activity for direct Red 23 (DR-23) dye degradation in visible light irradiation. The operational parameters, like dopant concentration, photocatalyst dose, pH, and initial concentration of dye were investigated during the process. The photocatalytic degradation process follows pseudo-first-order kinetics. As compared to other tested materials, 5% Cu doped CdS material revealed superior photocatalytic performance for the degradation of DR-23 (k = 13.96 × 10-3 min-1). Transient absorption spectroscopy, EIS, PL, and transient photocurrent indicated that adding copper to the CdS matrix improved the separation of photo-generated charge carriers by lowering the recombination rate. Spin-trapping experiments recognized the photodegradation primarily based on secondary redox products, i.e., hydroxyl and superoxide radicals. According to by Mott-Schottky curves, photocatalytic mechanism and photo-generated charge carrier density were elucidated regarding dopant-induced valence and conduction bands shifting. Thermodynamic probability of radical formation in line with the altered redox potentials by Cu doping has been discussed in the mechanism. The identification of intermediates by mass spectrometry study also showed a plausible breakdown mechanism for DR-23. Moreover, samples treated with nanophotocatalyst displayed excellent results when tested for water quality metrics such as DO, TDS, BOD, and COD. Developed nanophotocatalyst shows high recyclability with superior heterogeneous nature. 5% Cu-doped CdS also exhibit strong photocatalytic activity for the degradation of colourless pollutant bisphenol A (BPA) under visible light (k = 8.45 × 10-3 min-1). The results of this study offer exciting opportunities to alter semiconductors' electronic band structures for visible-light-induced photocatalytic activity for wastewater treatment.

MWCNTs Decorated with TiO2 as Highly Performing Filler in the Preparation of Nanocomposite Membranes for Scalable Photocatalytic Degradation of Bisphenol A in Water

Bisphenol A (BPA), an endocrine-disrupting compound with estrogenic behavior, is of great concern within the scientific community due to its high production levels and increasing concentration in various surface aquifers. While several materials exhibit excellent capacity for the photocatalytic degradation of BPA, their powdered nature and poor chemical stability render them unsuitable for practical application in large-scale water decontamination. In this study, a new class of nanocomposite membranes based on sulfonated polyethersulfone (sPES) and multiwalled carbon nanotubes decorated with TiO2 nanoparticles (MWCNTs-TiO2) were investigated as efficient and scalable photocatalysts for the photodegradation of BPA in aqueous solutions. The MWCNTs-TiO2 hybrid material was prepared through a facile and inexpensive hydrothermal method and extensively characterized by XRD, Raman, FTIR, BET, and TGA. Meanwhile, nanocomposite membranes at different filler loadings were prepared by a simple casting procedure. Swelling tests and PFG NMR analyses provided insights into the impact of filler introduction on membrane hydrophilicity and water molecular dynamics, whereas the effectiveness of the various photocatalysts in BPA removal was monitored using HPLC. Among the different MWCNTs-TiO2 content nanocomposites, the one at 10 wt% loading (sP-MT10) showed the best photoactivity. Under UV irradiation at 254 nm and 365 nm for 240 min, photocatalytic oxidation of 5 mg/L bisphenol A by sP-MT10 resulted in 91% and 82% degradation, respectively. Both the effect of BPA concentration and the membrane regenerability were evaluated, revealing that the sP-MT10 maintained its maximum BPA removal capability over more than 10 cycles. Our findings indicate that sP-MT nanocomposite membranes are versatile, scalable, efficient, and highly reusable photocatalysts for the degradation of BPA, as well as potentially for other endocrine disruptors.

Light-Driven MXene-Based Microrobots: Mineralization of Bisphenol A to CO2 and H2 O

Light-driven magnetic MXene-based microrobots (MXeBOTs) have been developed as an active motile platform for efficiently removing and degrading bisphenol A (BPA). Light-driven MXeBOTs are facilitated with the second control engine, i.e., embedded Fe2 O3 nanoparticles (NPs) for magnetic propulsion. The grafted bismuth NPs act as cocatalysts. The effect of the BPA concentration and the chemical composition of the swimming environment on the stability and reusability of the MXeBOTs are studied. The MAXBOTs, a developed motile water remediation platform, demonstrate the ability to remove/degrade approximately 60% of BPA within just 10 min and achieve near-complete removal/degradation (≈100%) within 1 h. Above 86% of BPA is mineralized within 1 h. The photocatalytic degradation of BPA using Bi/Fe/MXeBOTs demonstrates a significant advantage in the mineralization of BPA to CO2 and H2 O.

Photocatalytic degradation of bisphenol A in aqueous solution using TiO2/clinoptilolite hybrid photocatalyst

Photocatalytic degradation of bisphenol A (BPA) was investigated using commercial TiO2 P25 nanoparticles supported on natural zeolite clinoptilolite (Cli). Employing ultrasound assisted solid-state dispersion method hybrid photocatalyst containing 20 wt% of TiO2, marked TCli-20, was prepared. The structural, morphological and surface properties, and particle size distribution of TCli-20 were studied by X-ray powder diffraction, Fourier transform infrared spectroscopy, ultraviolet-visible diffuse reflectance spectroscopy, scanning electron microscopy with energy dispersive spectroscopy, atomic force microscopy, Brunner-Emmet-Teller method and laser diffraction. The results revealed a successful loading of TiO2 P25 nanoparticles on Cli surface and the preservation of both zeolitic structure and optical properties of TiO2. The influence of catalyst dose, pH value and the addition of hydrogen peroxide (H2O2) was evaluated. The optimal reaction conditions were 2 g/L of catalyst at near-neutral conditions (pH = 6.4) for complete BPA (5 mg/L) photodegradation after 180 min of exposure to simulated solar light. The addition of H2O2 was beneficial for the degradation process and led to the removal of BPA after 120 min of irradiation. BPA removal (60% for 180 min of irradiation) was reduced when TCli-20 was tested in bottled drinking water due to the presence of bicarbonate ions which acted as scavengers for hydroxyl radicals. Even though the photocatalytic activity of TCli-20 decreased after several cycles of usage, 70% of BPA was still successfully degraded during the fourth cycle. The reusability study showed easy separation, stability and good photocatalytic ability of investigated cost-effective hybrid photocatalyst.

Fabrication of an in situ-grown TiO2 nanowire thin film and its enhanced photocatalytic activity

TiO2 is a promising photocatalyst used in practical environmental remediation. TiO2 photocatalysts are usually implemented in two forms: suspended powder and immobilized thin films. A simple technique for fabricating TiO2 thin film photocatalyst was developed in this work. The fabricated TiO2 thin film photocatalyst featured a homogeneous nanowire layer grown in situ on the parent Ti plate. The optimized fabrication protocol was to soak the ultrasonically cleaned and acid-washed Ti plate in 30% H2O2 solution containing 3.2 mM melamine and 0.29 M HNO3 at 80 °C for 72 h and then anneal at 450 °C for 1 h. TiO2 nanowires with uniform diameters were homogeneously arrayed on the Ti plate surface. The thickness of the TiO2 nanowire array layer was 1.5 μm. The pore properties of the TiO2 thin film were close to those of P25. The band gap of the fabricated photocatalyst was 3.14 eV. The photocatalytic activity of the fabricated photocatalyst toward 10 mg/L RhB and 1 mg/L CBZ demonstrated greater than 60% degradation under 2 h UVC irradiation. The RhB and CBZ degradation efficiencies remained at a good level after 5 consecutive cycles. Mechanical wearing, such as 2 min sonication, will not lead to significant suppression of the photocatalytic activity. Photocatalytic RhB and CBZ degradation using the fabricated photocatalyst favored an acidic > alkaline > neutral environment. The presence of Cl- slightly suppressed the photocatalytic degradation kinetics. However, RhB and CBZ photocatalytic degradation kinetics were promoted in the copresence of SO42- or NO3-.

Enhancing Visible Light Photocatalytic Degradation of Bisphenol A Using BiOI/Bi2MoO6 Heterostructures

With the growing population, access to clean water is one of the 21st-century world's challenges. For this reason, different strategies to reduce pollutants in water using renewable energy sources should be exploited. Photocatalysts with extended visible light harvesting are an interesting route to degrade harmful molecules utilized in plastics, as is the case of Bisphenol A (BPA). This work uses a microwave-assisted route for the synthesis of two photocatalysts (BiOI and Bi₂MoO₆). Then, BiOI/Bi₂MoO₆ heterostructures of varied ratios were produced using the same synthetic routes. The BiOI/Bi₂MoO₆ with a flower-like shape exhibited high photocatalytic activity for BPA degradation compared to the individual BiOI and Bi₂MoO₆. The high photocatalytic activity was attributed to the matching electronic band structures and the interfacial contact between BiOI and Bi₂MoO₆, which could enhance the separation of photo-generated charges. Electrochemical, optical, structural, and chemical characterization demonstrated that it forms a BiOI/Bi₂MoO₆ p-n heterojunction. The free radical scavenging studies showed that superoxide radicals (O₂•^-) and holes (h⁺) were the main reactive species, while hydroxyl radical (•OH) generation was negligible during the photocatalytic degradation of BPA. The results can potentiate the application of the microwave synthesis of photocatalytic materials.

One-Step Fabrication of the ZnO/g-C3N4 Composite for Visible Light-Responsive Photocatalytic Degradation of Bisphenol E in Aqueous Solution

The ZnO/g-C₃N₄ composite was successfully synthesized by a simple one-step calcination of a urea and zinc acetate mixture. The photocatalytic activity of the synthesized composite was evaluated in the degradation of bisphenol E (BPE). The morphology, crystallinity, optical properties, and composition of the synthesized composite were characterized by using various analytical techniques such as scanning electron microscopy (SEM), transmitted electron microscopy (TEM), field emission-electron probe microanalysis (FE-EPMA), nitrogen adsorption and desorption isotherm measurement, Fourier-transform infrared (FTIR) spectroscopy, X-ray powder diffraction (XRD), diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectroscopy, electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA). The degradation rate of BPE with the ZnO/g-C₃N₄ composite was 8 times larger than that obtained with pure g-C₃N₄ at the optimal conditions. The excellent photocatalytic activity was attributed to the synergistic effect between the g-C₃N₄ and ZnO, which enhanced the efficiency of charge separations, reduced the e^-/h⁺ pairs recombination, and increased the visible light absorption ability. The radical scavenger studies indicated that the ^•O₂ ^- and h⁺ species were mainly responsible for the degradation of BPE. The stability test suggested the chemical and photostability of the synthesized composite. Two possible photocatalytical mechanisms have been suggested.

Mechanism of visible light enhances microbial degradation of Bisphenol A

Bisphenol A (BPA) is a toxic endocrine disruptor detected in various environments. Microbial metabolic/enzymatic degradation has been thought to be the main pathway for BPA attenuation in natural environments. In this study, we found that under visible light conditions, superoxide produced by bacteria was the main reason for the rapid removal of BPA, accounting for 57 % of the total removal rate. With visible light, the bacteria degraded BPA at a rate of 0.22 mg/L/d, and the total removal within 8 days reached 85 %, which is 4.7 times compared with that of dark culture. The intermediate product 4-iso-propenylphenol, which was considered as an end-product of microbial degradation of BPA in previous reports, was detected in large quantities at 24 h in culture but gradually decreased in our experiment. Community analysis suggested bacteria with aromatic hydrocarbon degradation ability were more enriched under light incubation. Moreover, the bacteria showed well degradation ability to various pharmaceutically active but nonbiodegradable compounds including diclofenac and fluoxetine, with a removal rate of 88 % and 20 %, respectively. Our study revealed the organic pollutant transformation pathway under the combined action of light and microorganisms, providing new insights into the microbial treatment of aromatic hydrocarbon pollutants.

Construction of dual Z-scheme Bi2WO6/g-C3N4/black phosphorus quantum dots composites for effective bisphenol A degradation

In this work, a novel dual Z-scheme Bi₂WO₆/g-C₃N₄/black phosphorus quantum dots (Bi₂WO₆/g-C₃N₄/BPQDs) composites were fabricated and utilized towards photocatalytic degradation of bisphenol A (BPA) under visible-light irradiation. Optimizing the content of g-C₃N₄ and BPQDs in Bi₂WO₆/g-C₃N₄/BPQDs composites to a suitable mass ratio can enhance the visible-light harvesting capacity and increase the charge separation efficiency and the transfer rate of excited-state electrons and holes, resulting in much higher photocatalytic activity for BPA degradation (95.6%, at 20 mg/L in 120 min) than that of Bi₂WO₆ (63.7%), g-C₃N₄ (25.0%), BPQDs (8.5%), and Bi₂WO₆/g-C₃N₄ (79.6%), respectively. Radical trapping experiments indicated that photogenerated holes (h⁺) and superoxide radicals (•O₂^-) played crucial roles in photocatalytic BPA degradation. Further, the possible degradation pathway and photocatalytic mechanism was proposed by analyzing the BPA intermediates. This work also demonstrated that the Bi₂WO₆/g-C₃N₄/BPQDs as effective photocatalysts was stable and have promising potential to remove environmental contaminants from real water samples.

Aerobic degradation of bisphenol A by Pseudomonas sp. LM-1: characteristic and pathway

Bisphenol A (BPA) has been widely used in the manufacture of polymeric materials. BPA is regarded as an endocrine disrupting chemical, posing a great threat to the public health. In this study, a bacterial strain LM-1, capable of utilizing BPA as the sole carbon and energy source under aerobic conditions, was originally isolated from an activated sludge sample. The isolate was identified as Pseudomonas sp. based on 16S rRNA gene sequence analysis. Strain LM-1 was able to completely degrade 25-100 mg/L BPA within 14-24 h, and it also exhibited high capacity for BPA degradation at a range of pH (6.0-8.0). (NH₄)₂SO₄ and NH₄NO₃ were the suitable nitrogen sources for its growth and BPA biodegradation, and the BPA degradation could be accelerated when exogenous carbon sources were introduced as the co-substrates. Metal ions such as Zn²⁺, Cu²⁺, and Ni²⁺ could considerably suppress the growth of strain LM-1 and BPA degradation. According to the analysis of liquid chromatography coupled to Q-Exactive high resolution mass spectrometry, hydroquinone, p-hydroxybenzaldehyde, and p-hydroxybenzoate were the predominate metabolites in the BPA biodegradation and the degradation pathways were proposed. This study is important for assessment of the fate of BPA in engineered and natural systems and possibly for designing bioremediation strategies.

Performance and mechanism of a novel S-scheme heterojunction sonocatalyst CuS/BaWO4 for degradation of bisphenol A by ultrasonic activation

A novel CuS/BaWO₄ heterojunction catalyst was prepared and characterized. Taking bisphenol A as the target pollutant for catalytic degradation, the sonocatalytic activity of CuS/BaWO₄ composite was evaluated, and the combination with persulfate improved the sonocatalytic degradation of bisphenol A. The results showed that CuS/BaWO₄ composite had good sonocatalytic degradation activity for bisphenol A, and the degradation rate was 70.99% ± 1.46%. After combined with persulfate, the degradation rate was further increased to 95.34% ± 0.10%, and the reaction time was relatively shortened. The results of the trapping experiment and calculated energy band positions showed that the formation of S-scheme heterojunction and the formation of hydroxyl radicals and holes were the key to the catalytic degradation of bisphenol A by CuS/BaWO₄ composite. In this study, a new CuS/BaWO₄ heterojunction sonocatalyst was synthesized. The catalyst can efficiently remove bisphenol A from the water environment and can be used as a potential solution for endocrine disruptor pollution in the water environment.

Current progress in treatment technologies for plastic waste (bisphenol A) in aquatic environment: Occurrence, toxicity and remediation mechanisms

Bisphenol-A (BPA) is a type of endocrine disrupting compound (EDC) that is being widely used in the production of polycarbonate and epoxy resins. In the last few years, human exposure to BPA has been extensively high due to the continuous increment in the Annual Growth Rate (AGR) of the BPA global market. The presence and transportation of BPA in the environment could cause serious damage to aquatic life and human health. This paper reviewed the literature on the exposure and toxicity mechanisms of BPA and advanced analytical techniques for the detection of BPA in the environment and human beings. The study indicated that BPA can cause damaging effects on numerous tissues and organs, including the reproductive system, metabolic dysfunction, respiratory system, immune system and central nervous system. On the basis of reported studies on animals, it appears that the exposure of BPA can be carcinogenic and responsible for causing a variety of cancers like ovarian cancer, uterine cancer, prostate cancer, testicular cancer, and liver cancer. This review paper focused mainly on the current progress in BPA removal technologies within last ten years (2012-2022). This paper presents a comprehensive overview of individual removal technologies, including adsorption, photocatalysis/photodegradation, ozonation/advance oxidation, photo-fenton, membranes/nanofilters, and biodegradation, along with removal mechanisms. The extensive literature study shows that each technology has its own removal mechanism and their respective limitations in BPA treatment. In adsorption and membrane separation process, most of BPA has been treated by electrostatic interaction, hydrogen boning and π-π interations mechanism. Whereas in the degradation mechanism, O* and OH* species have played a major role in BPA removal. Some factors could alter the removal potential and efficiency of BPA removal. This review paper will provide a useful guide in providing directions for future investigation to address the problem of BPA-containing wastewater treatment.

Laccase-coupled photoelectrocatalytic system for highly efficient degradation of bisphenol A

In the present work, a hybrid advanced oxidation process that combined laccase with photoelectrocatalysis (PEC) was explored for highly efficient degradation of bisphenol A (BPA). Visible light-responsive BiVO₄ film electrode with good optical and photoelectrochemical properties was prepared via an electrodeposition method and employed as photoanode for PEC degradation of BPA. After laccase was facilely introduced into the PEC system, the BPA removal efficiency was significantly promoted, attributed to the synergistic effect of enzymatic catalysis and PEC processes. To obtain the optimum operation conditions, the effects of initial pH and applied bias potential were investigated systematically. Radicals trapping experiments revealed that •O₂^- dominated the biophotoelectrocatalytic degradation process, and the possible degradation pathway for BPA was proposed by identifying intermediates using liquid chromatography-mass spectrometry.

Synthesis and characterization of SSM@NiO/TiO2 p-n junction catalyst for bisphenol a degradation

Photocatalyst immobilization on support materials is essential for large-scale applications. Here, we describe growth of a p-n junction catalyst (NiO/TiO₂) on a stainless-steel mesh (SSM) support using a facile hydrothermal method. The morphological superiority of the composite over previously reported NiO/TiO₂ catalysts was probed using scanning and transmission electron microscopy. Flower petal-like NiO grew uniformly on SSM, which was evenly covered by TiO₂ nanoparticles. Theoretical and experimental X-ray diffraction patterns were compared to analyze the development of the composite during various stages of synthesis. The photocatalytic activity of a powdered catalyst and SSM@catalyst was compared by measuring bisphenol A (BPA) degradation. SSM@NiO/TiO₂ achieved the highest rate of BPA degradation, removing 96% of the BPA in 120 min. Scavenging experiments were used to investigate the charge separation and degradation mechanism. SSM@NiO/TiO₂ showed excellent reusability potential, achieving and sustaining 91% BPA removal after 10 rounds of cyclic degradation. Reusability performance, composite resilience, apparent quantum yields, and figures of merit suggest that SSM@NiO/TiO₂ has excellent utility for practical applications.

Photocatalytic degradation of bisphenol a from aqueous solution using bismuth ferric magnetic nanoparticle: synthesis, characterization and response surface methodology-central composite design modeling

PURPOSE

Bisphenol A (BPA), as endocrine-disrupting compound (EDC), is extensively used as an important chemical in the synthesis of polycarbonate polymers and epoxy resins. BPA absorption into the body can result in the development of metabolic disorders such as low sex-specific neurodevelopment, immune toxicity, neurotoxicity and interference of cellular pathway. Therefore, the presence of BPA in the body and the environment can create hazards that must reach standards before being discharged into the environment.

METHODS

In this study, bismuth ferric nanomagnetic (BFO NMPs) were successfully synthesized via sol-gel method and developed as photocatalysts for BPA removal under visible light irradiation. FE-SEM, TEM, PL, XRD, UV-Vis DRS, VSM, EDX, and FTIR were used to characterize the BFO NMPs.

RESULTS

RSM model (R2 = 0.9745) showed a good correlation between experimental and predicted removal efficiency of BPA. The investigation of four independent variables indicated that pH had the most significant positive effect on the degradation of BPA. Under optimal conditions (pH = 4.042, catalyst dose = 7.617 mg, contact time = 122.742 min and BPA concentration = 15.065 mg/L), maximum degradation was calculated to be 98.7%. After five recycles, the removal of BPA remained >82%, which indicated the proper ability to reuse the catalyst.

CONCLUSION

In conclusion, it can be stated like BPA, the prepared BFO NMPs is a promising photocatalyst for practical application in organic pollutant decomposition.

Effects of the COVID-19 pandemic on the environment, waste management, and energy sectors: a deeper look into the long-term impacts

The COVID-19 pandemic not only has caused a global health crisis but also has significant environmental consequences. Although many studies are confirming the short-term improvements in air quality in several countries across the world, the long-term negative consequences outweigh all the claimed positive impacts. As a result, this review highlights the positive and the long-term negative environmental effects of the COVID-19 pandemic by evaluating the scientific literature. Remarkable reduction in the levels of CO (3 - 65%), NO2 (17 - 83%), NOx (24 - 47%), PM2.5 (22 - 78%), PM10 (23 - 80%), and VOCs (25 - 57%) was observed during the lockdown across the world. However, according to this review, the pandemic put enormous strain on the present waste collection and treatment system, resulting in ineffective waste management practices, damaging the environment. The extensive usage of face masks increased the release of microplastics/nanoplastics (183 to 1247 particles piece-1) and organic pollutants in land and water bodies. Furthermore, the significant usages of anti-bacterial hand sanitizers, disinfectants, and pharmaceuticals have increased the accumulation of various toxic emerging contaminants (e.g., triclocarban, triclosan, bisphenol-A, hydroxychloroquine) in the treated sludge/biosolids and discharged wastewater effluent, posing great threats to the ecosystems. This review also suggests strategies to create long-term environmental advantages. Thermochemical conversions of solid wastes including medical wastes and for treated wastewater sludge/biosolids offer several advantages through recovering the resources and energy and stabilizing/destructing the toxins/contaminants and microplastics in the precursors.

Recent developments in photocatalysis of industrial effluents ։ A review and example of phenolic compounds degradation

Industrial expansion and increased water consumption have created water scarcity concerns. Meanwhile, conventional wastewater purification methods have failed to degrade recalcitrant pollutants efficiently. The present review paper discusses the recent advances and challenges in photocatalytic processes applied for industrial effluents treatment, with respect to phenolic compounds degradation. Key operational parameters including the catalyst loading, light intensity, initial pollutants concentration, pH, and type and concentrations of oxidants are evaluated and discussed. Compared to the other examined controlling parameters, pH has the highest effect on the photo-oxidation of contaminants by means of the photocatalyst ionization degree and surface charge. Furthermore, major phenolic compounds derived from industrial sources are comprehensively presented and the applicability of photocatalytic processes and the barriers in practical applications, including high energy demand, technical challenges, photocatalyst stability, and recyclability have been explored. The importance of energy consumption and operational costs for realistic large-scale processes are also discussed. Finally, research gaps in this area and the suggested direction for improving degradation efficiencies in industrial applications are presented. In the light of these premises, selective degradation processes in real water matrices such as untreated sewage are proposed.

Comment on "Efficient removal of plastic additives by sunlight active titanium dioxide decorated Cd-Mg ferrite nanocomposite: Green synthesis, kinetics and photoactivity"

In this comment paper, some critical shortcomings and errors in the original paper [Chemosphere, 290, 133,307] are discussed. The authors have not adhered to the 12 Principles of Green Chemistry by incorporating the highly toxic metal Cd in their ferrite nanocomposite photocatalyst, despite its synthesis being described as green. Neither the necessity nor the effectiveness of Cd addition in relation to catalytic activity were explained. Although adsorption of the substrates on the catalyst is necessary for the photocatalytic process, excessive adsorption may give a false impression of efficient removal as opposed to true degradation or mineralization. This issue is extremely important for experimental design when the solubility of the substances is very low. The authors have disregarded the solvent effect of organic scavengers for the reactive species, potentially attributing a greater contribution of the degradation of substances to hydroxyl radicals. Some suggestions are also provided to improve their work in the field of photocatalysis.

Construction of nitrogen vacant g-C3N4 nanosheet supported Ag3PO4 nanoparticle Z-scheme photocatalyst for improved visible-light photocatalytic activity

The superior photocatalytic activity of semiconductor-based photocatalytic materials has attracted great attention. In this work, a series of novel Ag3PO4/g-C3N4-x (APO/CNx) composites with the Z-scheme structure were fabricated through a facile precipitation method. B naphthol, a typical phenolic compound, was selected to evaluate the photocatalytic activity of all as-prepared photocatalysts. The obtained APO/CNx composites exhibited excellent photocatalytic activity for degradation of B naphthol under visible-light irradiation. Experimental results showed that the degradation rate toward B naphthol could reach to 90.5% for 180 min, which was almost 3.66 times higher than pure g-C3N4, indicating that the presence of nitrogen vacancies and Z-scheme structure could efficiently improve the photocatalytic performance of pure g-C3N4. Furthermore, the results of trapping experiments and electron spin resonance (ESR) spectroscopy manifest that •O2- and •OH radicals were the predominant active substances for B naphthol degradation, and the possible mechanism of improved photocatalytic performance was elucidated. This work will provide an innovative perspective for constructing Z-scheme photocatalysts for the application of photocatalytic in the field of wastewater treatment.

A critical review of presence, removal and potential impacts of endocrine disruptors bisphenol A

Bisphenol A (BPA) is a synthetic organic compound that is mainly used in the production of polymer materials polycarbonate and epoxy resin. Widespread use and irregular processing methods have led to BPA being detected globally, raising concerns about its environmental and health effects. This review outlines an overview of the presence and removal of BPA in the environment and consumer products. We also summarized the endocrine-disrupting toxicity of BPA, and the relatively less summarized neurotoxicity, cytotoxicity, reproductive toxicity, genotoxicity, and carcinogenicity. Human exposure data show that humans have been exposed to low concentrations of BPA for a long time, future research should focus on the long-term exposure and the migration of BPA from consumer products to humans and the possible health risks associated with human exposure to BPA. Exploring economical and effective methods to reduce and remove BPA from the environment is imperative. The development of safe, functional and reproducible BPA analogs and the study of its degradation products can be the focus of subsequent research.

Enhanced photocatalytic degradation of bisphenol A by magnetically separable bismuth oxyiodide magnetite nanocomposites under solar light irradiation

Bismuth oxyiodide/magnetite (BiOI/Fe₃O₄) nanocomposites were synthesized by a hydrothermal reaction. The synthesized BiOI/Fe₃O₄ was used to remove bisphenol A (BPA) from an aqueous solution under simulated solar light. The molar ratio of Bi to Fe in BiOI/Fe₃O₄ significantly affected BPA degradation, with the optimal BiOI/Fe₃O₄ (2:1) ratio in the composites. Optimum operating conditions such as a catalyst dosage of 1.0 g/L, an initial BPA concentration of 10 mg/L, and pH 7 gave a complete degradation of completely removed BPA within 30 min. The primary reactive oxygen species were verified as superoxide radicals and holes in oxidative species experiments. The magnetic BiOI/Fe₃O₄ could be easily collected from an aqueous solution by an external magnet, and its reusability was successfully demonstrated through recycling experiments. Furthermore, the derivatives in BiOI/Fe₃O₄ photocatalytic reactions were investigated, and a possible BPA degradation pathway was proposed. These results show that BiOI/Fe₃O₄ nanocomposites have great potential for BPA removal from water and wastewater treatment systems.

Zinc-doped hydroxyapatite: an UVA light photocatalyst for the removal of bisphenol A

Zinc-doped hydroxyapatite obtained by a simple co-precipitation method achieved a photocatalytic removal > 80% of Bisphenol A.

Efficient degradation of organic pollutants by novel titanium dioxide coupled bismuth oxide nanocomposite: Green synthesis, kinetics and photoactivity

Herein, a green and facile methodology was used for the structural design of semiconductor nanomaterials and employed as efficient photocatalyst to resolve the environmental issues of water pollutants. Titanium oxide coupled with bismuth oxide (TiO₂@Bi₂O₃) nanocomposite was synthesized by employing the seed extract of Sapindus mukorossi (commonly found plant in India) and subsequently used for the elimination of toxic, and persistence industrial pollutants namely bisphenol A (BPA) and methylene blue (MB). Microscopic and spectroscopic techniques revealed particle size of synthesized nanocomposite found less than 50 nm along with high crystallinity. Appearance of stretching vibrations at 459 cm^-1 for Bi-O-Ti in the IR spectra of nanocomposite has established the coupling of TiO₂ with Bi₂O₃. The parameters of degradation were optimized by varying the pollutant concentration, catalytic amount and pH in the presence of natural sunlight. The nanocomposite TiO₂@Bi₂O₃ showed maximum degradation (MB: 94% and BPA: 91%) at a minimum concentration of pollutant (50 mgL^-1) with catalyst amount (35 mg), neutral pH and reduces half-life of pollutants (BPA: 1h, MB: 0.5h). Owing of higher surface area (80 m²g^-1), lower band gap (2.5 eV), and more negative zeta potential value (-40.3 mV) results into excellent photocatalytic properties. The breakage of S-N conjugated system in MB results into rapid degradation as compare to BPA. The degradation followed first-order kinetics and Langmuir adsorption in both the cases. Presence of active radicals during the photocatalysis process was responsible for quick degradation and strongly supported by scavenger analysis. GC-MS analysis revealed the degradation of toxic pollutants into safer metabolites and finally mineralized. Multiple times (n = 8) reusability of green photocatalyst advocated sustainability and appropriate for industrial applications.

Efficient mineralization of TBBPA via an integrated photocatalytic reduction/oxidation process mediated by MoS2/SnIn4S8 photocatalyst

Currently, Tetrabromobisphenol A (TBBPA) has been regarded as an emerging organic pollutant and efficient TBBPA elimination technology has been attracting increasing attention. In this work, a novel photocatalyst, MoS₂/SnIn₄S₈, was synthesized through hydrothermal method by introducing few-layer MoS₂ nanosheets and then employed to establish an integrated photocatalytic reduction/oxidation system for the remediation of TBBPA under visible light. The characterization results demonstrated that the few-layer MoS₂ nanosheets were well combined with SnIn₄S₈ and significantly lowered the recombination rate of the photo-induced electron and holes, leading to outstanding photocatalytic performance of MoS₂/SnIn₄S₈ composite. Besides, the MoS₂/SnIn₄S₈ composite also exhibited excellent reusability (over 10 runs) and stability. The TBBPA degradation experiments showed that the integrated photocatalytic reduction/oxidation system was able to completely degrade TBBPA and mineralize its byproducts (60.2 ± 2.9%). In the photocatalytic reduction, due to the cleavage of C-Br bonds by photo-induced electrons, TBBPA underwent stepwise debromination and finally transferred into BPA in 6 h. In the following photocatalytic oxidation, under the attack of reactive oxygen species (¹O₂, h⁺,OH and O₂^-), BPA was first decomposed into aromatic products (such as phenol, benzoic acid, p-hydroxybenzyl alcohol and so on) via C-C bond cracking and hydroxylation, and then further oxidized into organic acids like maleic acid and muconic acid through ring-opening, and finally mineralized into CO₂ and H₂O. What was noteworthy was that the final effluent from the photocatalytic reduction/oxidation system showed no toxicity to the luminescent bacteria.

Comparison of Quantitative Detection Methods Based on Molecular Fluorescence Spectroscopy and Chromatographic Techniques Used for the Determination of Bisphenol Compounds

Analytical methods using the fluorescence properties of bisphenols (BPA, BPF and BPS) and their complexes with β-cyclodextrin and methyl-β-cyclodextrin were developed. The methods were applied for the analysis of thermal paper and canned food. Their performance was compared with a standard HPLC approach with a diode array and fluorescence detections. For comparison purposes, basic validation parameters (linear range, limit of detection, sensitivity, precision) were evaluated. It was concluded the developed methods facilitate fast and cost-effective determination of three bisphenol species in liquid samples, similar to the HPLC performance. They are also environmentally friendly. BPA, BPF and BPS can be routinely determined with the presented approach.

ZnO-Co3O4/N-C Cage Derived from the Hollow Zn/Co ZIF for Enhanced Degradation of Bisphenol A with Persulfate

The zeolitic imidazolate framework (ZIF)-67 microcrystal was employed as a precursor to synthesize the hollow ZIF-8/ZIF-67 composite via the epitaxial growth of ZIF-8 on ZIF-67, in situ self-sacrifice, and excavation of ZIF-67. The hollow ZIF-8/ZIF-67 composite was successfully transformed to the ZnO-Co₃O₄/N-C cage by thermal treatment, which was further used as the catalyst for the oxidative degradation of bisphenol A (BPA) in the presence of potassium persulfate (PS). In comparison with the Co₃O₄/N-C and Co₃O₄ obtained from pure ZIF-67 and cobalt nitrate, the ZnO-Co₃O₄/N-C cage demonstrated a more than four fold-higher activity and robust reusability. Based on structural analysis, the enhanced catalytic performance could be ascribed to the small, highly dispersed cobalt oxide particles, the hollow structure that facilitated the transportation of the molecules, and the synergistic effect between cobalt oxide and nitrogen-doped carbon in the composite. Besides, the effect of dosage of PS, BPA, and the co-existing components such as chloride ion, methanol, and t-butyl alcohol was carefully investigated to propose the possible mechanism. This study would give new insights into the design of functional composite materials from metal organic frameworks and the development of their application in environmental pollution disposal.