Bisphenol A Degradation Research Articles

A self-cleaning thermocatalytic membrane for bisphenol a abatement and fouling removal

Thermocatalytic, ceramic microfiltration membranes for continuous micropollutants removal and simultaneous degradation of organic fouling were synthesized by integrating a Sr0.85Ce0.15FeO3 (SCF) perovskite in alumina membranes and tested for the bisphenol A (BPA) abatement under different experimental conditions. Scanning electron microscopy (SEM) and Energy Dispersive X-ray spectroscopy (EDX) characterization techniques were used to characterize the samples. The effect of water flux, BPA concentration and temperature on the BPA and fouling removal was investigated in detail. Up to 55 % of BPA was removed by filtration of a 9.6 mg L−1 BPA solution at 40 °C and a flux of 25 LMH. Degradation studies with BPA feed concentrations of 3.4, 5.5 and 9.6 mg L−1 showed higher degradation rate by the membrane with higher concentrations of BPA. Furthermore, the rate of BPA degradation increases with lower permeate flux, due to the longer retention time of pollutant in the membrane. Membranes were fouled with humic acid to study the thermocatalytic fouling removal. After fouling, membranes were rinsed to remove external, removable fouling, which was followed by 20–120 min of thermal treatment at 40 °C. This showed up to complete recovery of permeability by reduction of hydraulic resistance from the internal fouling in the membranes. No effect of heat treatment was observed for fouled non-functionalized membranes. Hence, the novel membrane studied in this article is a promising solution for simultaneous degradation of micropollutants and recovery of permeability during filtration, e.g. in wastewater treatment.

Magnetic Co-doped 1D/2D structured γ-Fe2O3/MoS2 effectively activated peroxymonosulfate for efficient abatement of bisphenol A via both radical and non-radical pathways

Iron-based catalysts have been widely used to treat refractory organic pollutants in wastewater. In this paper, magnetic Co-γ-Fe2O3 was synthesized by a facile tartaric acid-assisted hydrothermal method, and Co-γ-Fe2O3/MoS2 nanocomposite catalyst was obtained via in situ growth of MoS2 nanosheets on Co-γ-Fe2O3 nanoparticles. The nanocomposite catalysts were used to decompose bisphenol A (BPA) by activating peroxymonosulfate (PMS). It was shown that only 0.15 g/L catalyst and 0.5 mmol/L PMS degraded 10 mg/L of BPA (99.3% within 10 min) in the pH range of 3–9. PMS was activated due to redox cycling among the pairs Co(III)/Co(II), Fe(III)/Fe(II), and Mo(VI)/Mo(IV). Quenching experiments and electron paramagnetic resonance spectroscopy demonstrated that both radical and non-radical pathways were involved in BPA degradation, in which active radical sulfate radical and non-radical singlet oxygen were the main reactive oxygen species. Ten intermediates were identified by liquid chromatography-coupled mass spectrometry, and three possible BPA degradation pathways were proposed. The toxicity of several degradation intermediates was lower, and Co-γ-Fe2O3/MoS2 exhibited excellent reusability and could be magnetically recovered.

Research Progress of Methods for Degradation of Bisphenol A.

Bisphenol A (BPA), an endocrine disruptor widely used in industrial production, is found in various environmental sources. Despite numerous reports on BPA degradation and removal, the details remain unclear. This paper aims to address this gap by providing a comprehensive review of BPA degradation methods, focusing on biological, physical, and chemical treatments and the factors that affect the degradation of BPA. Firstly, the paper uses VOSviewer software (version 1.6.15) to map out the literature on BPA degradation published in the past 20 years, which reveals the trends and research focus in this field. Next, the advantages and limitations of different BPA degradation methods are discussed. Overall, this review highlights the importance of BPA degradation to protect the environment and human health. The paper provides significant insights for researchers and policymakers to develop better approaches for BPA degradation and removal.

The diverse roles of halide ions in the degradation of bisphenol A via UV/peracetic acid process at different pH values: Radical chemistry, and transformation pathways

UV/Peracetic Acid (UV/PAA), as an innovative advanced oxidation process (AOP), is employed to treat bisphenol A (BPA) in water through the generation of hydroxyl radicals (•OH) and carbon-centered radicals (R−C•). The impact of halide ions (Cl−; Br−; I−) on the efficiency of UV/PAA was investigated for the first time under varying pH levels. The presence of halide ions exerted an influence on the reactivity of •OH and R−C•, exhibiting varying degrees of impact across different pH conditions. It was discovered that pH exerts a significant influence on its efficiency, with optimal removal performance observed at a pH 9. The degradation of BPA was inhibited by Cl− through the generation of reactive chlorine species (RCS), which triggers the interconversion between •OH and R−C•. Reactive bromine species (RBS) were produced in the presence of Br−, facilitating BPA degradation and generating HOBr as a supplementary source of •OH radicals. I− primarily generate reactive iodine species (RIS) through photolysis, which facilitates the degradation of BPA. The transformation of BPA involves hydroxylation, demethylation, halogenation, and cleavage reactions to form various products and pathways. The toxicity test demonstrates that the UV/PAA treatment of BPA exhibits lower toxicity, thereby indicating its environmentally friendly.

Using Mn/Fe enriched-roots of P. Stratiotes to synthesize multi-metallic catalysts for activating peroxymonosulfate to degrade bisphenol A

Aquatic plants used for phyto-extracting toxic metals from water are often enriched in certain metals and recycling these metal-enriched plants will achieve the sustainable application of phytoremediation/phytoextraction technology. The present study systematically explores the potential recycling of Mn-enriched-roots of P. Stratiotes used in the treatment of electrolytic manganese residue leachates as catalysts for activating peroxymonosulfate [1] to degrade organics in water. The effects of heat treatment temperature and atmosphere on the catalyst activity were first investigated and the results indicate that catalyst prepared in air at 400 °C contains active Mn(IV) while Mn(IV) was not detected in the catalyst prepared in N2 at the same temperature, and thereby catalyst obtained in air under 400 °C (MF400) performs better catalytic activity in degrading bisphenol A (BPA). The removal of BPA was found to reach 99.9 % in the MF400/PMS system at 120 min. The BPA degradation pathways were inferred by density flooding calculations (DFT) and then confirmed by liquid chromatography-mass spectrometry coupled detection, indicating that the radical pathway depending on·OH, SO4− and·O2– is the mechanism for BPA degradation in the MF400/PMS system. The ECOSAR assessment reveals that most BPA degradation intermediates are less toxic than their parent molecule. This work provides a simple and effective way for recycling Mn/Fe enriched aquatic plants used in phytoextraction process.

Computational explorations of the interaction between laccase and bisphenol A: influence of surfactant and different organic solvents

ABSTRACT Bisphenol A (BPA), as an environmental endocrine disruptor can cause damage to the reproductive, nervous and immune systems. Laccase can be used to degrade BPA. However, laccase is easily deactivated, especially in organic solvents, but the specific details are not clear. Molecular dynamics simulations were used to investigate the reasons for changes in laccase activity in acetonitrile (ACN) and dimethyl formamide (DMF) solutions. In addition, the effects of ACN and DMF on the activity of laccase and surfactant rhamnolipid (RL) on the degradation of BPA by laccase were investigated. Results showed that addition of ACN changed the structure of the laccase, not only decreasing the van der Waals interaction that promoted the binding of laccase with BPA, but also increasing the polar solvation free energy that hindered the binding of laccase with BPA, so it weakened the laccase activity. DMF greatly enhanced the van der Waals interaction between laccase and BPA, and played a positive role in their binding. The addition of surfactant RL alleviated the effect of organic solvent on the activity of laccase by changing the polar solvation energy. The mechanism of surfactant RL affecting laccase activity in ACN and DMF is described, providing support for understanding the effect of organic solvents on laccase.

Activation of periodate by ABTS as an electron shuttle for degradation of aqueous organic pollutants and enhancement effect of phosphate

Periodate (PI) based advanced oxidation processes (AOPs) have recently attracted much attention due to their high application potential in water purification through production of reactive species. In the study, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) was used as a representative electron shuttle, and its reaction with PI was investigated in detail. It was found that PI can be activated by ABTS via one-electron transfer to produce ABTS•+ and IO3•, cooperatively promoting oxidation of organic contaminants such as bisphenol A (BPA). Their contribution in BPA oxidation at pH 7 was estimated as 81.9% and 18.1%, respectively. With phosphate, BPA oxidation rate in the PI/ABTS process increased linearly with raised phosphate concentrations from 0 to 10 mM. The enhancement effect of phosphate is attributed to formation of PI-phosphate complexes, which facilitate PI activation by ABTS, and production of more ABTS•+ and IO3•, and additional phosphate radicals. Accordingly, the contribution of IO3• and phosphate radicals in BPA oxidation raised to 57.7% in the process with 4 mM phosphate, while that of ABTS•+ decreased to 42.3%. The reaction stoichiometry ratio of ABTS to PI was measured as 1.1 at pH 7, suggesting the little involvement of IO3• and phosphate radicals in production of ABTS•+ due to their high self-quenching. The PI/ABTS process exhibited excellent anti-interference capacity towards water matrix components (e.g. Cl−, HCO3− and natural organic matters). Moreover, an immobilized ABTS (ABTS/ZnAl-LDH) was successfully developed as a heterogeneous electron shuttle for PI oxidation, which resultantly exhibited the good catalytic activity and stability in degradation of BPA, further improving feasibility of the process in treatment of actual water. This work advances understanding on reaction of PI with ABTS from stoichiometric and kinetic aspects, and provides a high performance AOP for selective oxidation of trace organic contaminants.

Isolation and characterization of a bisphenol A-degrading strain, Pseudomonas aeruginosa DU2, from soil containing decaying plants.

Bisphenol A (BPA) is a toxic compound with broad applications in the plastics industry. BPA has harmful effects on various organisms and its efficient removal is necessary. The microbial degradation of BPA is a safe and economical approach. In this research, soil samples containing decaying plants were screened to isolate a BPA-degradable bacterial strain. Soil samples were collected from different locations in Damghan, Semnan province, Iran. To enrich BPA-degrading bacteria, the samples were cultured in a stepwise manner in a mineral medium containing increasing BPA concentrations (5 to 40 mg/L). The ability of isolated bacteria in degrading BPA was assayed by Folin-Ciocalteu and high-performance liquid chromatography methods. The biodegradation efficiency of the most efficient isolate was assayed under distinct conditions and it was identified through the sequencing of the 16S rRNA gene. Among the isolated bacteria, Pseudomonas aeruginosa DU2 (GenBank accession number: OP919484) showed the most BPA biodegradation ability. The highest BPA degradation (52.98%) was observed in the mineral medium containing 5 mg/L BPA and the inoculum size of 6 × 107 CFU/mL at pH 9 and in the presence of 0.05% (w/v) NaCl during 10 days. These results offer soil containing decaying plants as a promising source for finding BPA-degrading bacteria. P. aeruginosa DU2 has basal BPA removal ability, which could be improved by optimization of medium components and growth conditions.

Fabrication of Ti3+/N/B-TiO2@NGQDs composite photocatalyst with significantly enhanced visible light catalytic activity

A two-step hydrothermal process was used to successfully create Ti3+, N, and B co-doped TiO2 modified with nitrogen doped graphene quantum dots (Ti3+/N/B-TiO2@NGQDs (TNBTN)) composite photocatalyst for photodegradation of bisphenol A (BPA) and methyl orange (MO) under visible-light illumination. The prepared TNBTN composite demonstrated significantly enhanced visible light catalytic performance. Especially, the apparent rate constant of BPA degradation with TNBTN was approximately 56.9 times that of pure TiO2, which was attributed to broader visible light absorbance and faster transmission and separation of photoinduced charge. In addition, the mechanism of BPA and MO degradation with TNBTN was distinct.

S-Scheme WO3/SnIn4S8 Heterojunction for Water Purification: Enhanced Photocatalytic Performance and Mechanism

Photocatalysis is a promising technology for removing micropollutants in water. However, developing efficient and stable catalysts remains a challenge. In this work, a novel step-scheme (S-scheme) heterojunction of WO3/SnIn4S8 (WSI) was constructed through the combined process of in situ precipitation with hydrothermal synthesis to simultaneously realize photocatalytic degradation of bisphenol A(BPA) and reduction of Cr(VI) in contaminated water. Results showed that the WSI S-scheme heterojuction has a synergistic effect for the removal of BPA and Cr(VI). An optimum case of the WSI-12% heterojunction exhibited the highest photocatalytic efficiency in the degradation of BPA under visible light, which is ca. 2.5 and 3.8 times more than the pure WO3 and SIS, respectively. The enhanced photocatalytic activity is attributed to the formation of the WSI S-scheme heterojunctions which facilitate the spatial separation of charge carriers and preserve strong photoredox ability. Further, the S-scheme mechanism of enhanced photocatalysis was examined by the radical-trapping experiment and ESR, and superoxide and hydroxyl radicals were determined to be the major reactive oxygen species responsible for BPA degradation and Cr(VI) reduction by WSI. This work provides a novel strategy for tailoring high-performance S-scheme heterojunctions and shows the promising application in purifying wastewater with complex pollutants.

Visible light-mediated activation of periodate for bisphenol A degradation in the presence of Fe3+ and gallic acid at neutral pH

The current study demonstrates, for the first time, the effectiveness of an innovative visible light (VL) photo-Fenton like system using periodate (PI) mediated by Fe3+ and gallic acid (GA) for bisphenol A (BPA) elimination at neutral pH. The promotion of VL irradiation and GA on the Fe2+/Fe3+ cycle in the system allowed the VL/GA/Fe3+/PI system to exhibit excellent performance for BPA removal. Complete degradation of BPA was carried out in the VL/GA/Fe3+/PI process after 30 min reaction under the optimum conditions (0.10 mM Fe3+, 0.10 mM GA, 1 mM PI, and initial pH 7.0). Electron paramagnetic resonance analysis and quenching tests confirmed that the singlet oxygen, iodate radical, and hydroxyl radical were primarily involved in the elimination of BPA with minor contribution from superoxide anion radical and high-valent iron species (Fe4+ and Fe5+). BPA abatement was slightly inhibited by the addition of Cl−, NO3−, and SO42−, whereas the addition of HCO3− obviously hindered this process. Notably, Huimic acid dramatically expedited BPA decomposition. Besides, the VL/GA/Fe3+/PI process demonstrated remarkable removal efficiency over a broad range of initial pH values (3.01–8.97). Meanwhile, based on the eight identified intermediates, the possible degradation pathways of BPA were predicted. The phytotoxicity test concluded that a decrease in toxicity of the degraded intermediates to the growth of radish seed compared to BPA. In addition, the VL/GA/Fe3+/PI system demonstrated favorable potential for application in different actual water matrices. Moreover, efficient and simultaneous abatement of various organic contaminants by the GA/Fe3+/PI process was success accomplished under natural solar light or VL. Consequently, all results implied that the VL/GA/Fe3+/PI process might be a perspective technique for the treatment of organic contaminants.

Monodispersed Ag nanoparticles deposited on Ni-based coordination polymer composite with enhanced photocatalytic degradation for bisphenol A

Exploring effective methods to improve photoresponse and charge separation efficiency is the key to preparing high-performance photocatalysts. A novel Ni-based coordination polymer, namely {[Ni(TIPA)2]·2Ac·6 H2O}n (Ni-TIPA), was designed and synthesized hydrothermally using the ligand tri-(4-imidazole phenyl) amine (TIPA). The metal-to-ligand charge transfer (MLCT) of Ni-TIPA is visually demonstrated by theoretical calculations as the key to enhanced charge separation efficiency. A series of novel silver-deposited Ni-TIPA composites (Ag@Ni-TIPA-X, X = 1, 2, 3) and excellent light-driven photocatalytic activity were prepared using a simple photoreduction method at room temperature. The prepared Ag@Ni-TIPA-2 composite had excellent photocatalytic performance for degrading bisphenol A (BPA) under ultraviolet light irradiation. The excellent photocatalytic performance might be attributed to MLCT and the surface plasmon resonance (SPR) of Ag nanoparticles, which improved hole-electron separation capability, and the formation of Schottky junctions. The intermediates in the BPA degradation process were further predicted and analyzed by electrostatic potential (ESP), orbital-weighted dual descriptor (ODD), and liquid chromatography-mass spectrometry (LC-MS) technologies, and the possible degradation mechanisms were deduced deeply. The work as a new reference might be provided for the efficient optimization of photocatalysts for BPA degradation.

Facile synthesis of defect induced CeO2/MIL-53(Fe) nanocatalyst: Strategically switching the charge transfer dynamics for remarkable enhancement of photocatalytic Bisphenol A degradation and H2 evolution

This work reports the fabrication of heterojunction between defect induced CeO2 and iron based metal organic framework (MIL-53). A simple chemical redox etching methodology was adopted to narrow the band gap of pristine CeO2 through oxygen vacancy engineering. The photocatalytic efficacy of defect induced CeO2/MIL-53 (MCO-X) heterojunction was studied in Bisphenol A (BPA) breakdown and photocatalytic hydrogen generation from water splitting. The significantly improved photocatalytic application of MCO-X heterojunction could be attributed to the switching of charge dynamics mechanism from Type-1 to Type-II due to defect formation in the pristine CeO2. The optimal photocatalyst (MCO-30) displayed the highest photocatalytic BPA degradation with rate constant (0.045 min−1) and H2 evolution (3286.2 μmol.h−1. g−1) respectively. This study provides a comprehensive analysis on how defect in pristine CeO2 in MCO-X heterojunction can switch the charge transfer mechanism from Type-1 to Type-II to achieve remarkable visible light harnessing capacity and photocatalytic activity.

Efficient 1O2 production from H2O2 over lattice distortion controlled spinel ferrites

Iron-based materials are difficult to produce single oxygen (1O2) efficiently from H2O2. Herein, we demonstrate that 1O2 production from H2O2 can be manipulated by regulating the lattice distortion degrees of spinel ferrite through controlling the contents of Co and Ni in Co1−xNixFe2O4. Typically, NiFe2O4, which owns the lowest lattice distortion degree, can produce 1O2 as the dominated reactive oxygen species with·O2- as the intermediate. Due to the production of 1O2, the NiFe2O4/H2O2 system removes bisphenol A (BPA) completely within 180 min but removes only ∼ 4% of benzoic acid. In addition, the system demonstrates significant resistance to water matrix interference, as 50 mM of Cl-, NO3-, H2PO4-, and humic acid inhibited the BPA degradation by only ∼0%, ∼2%, ∼40%, and ∼3%, respectively. Our work may shed light for regulating the formation of 1O2 from H2O2 through the rational design of iron-based catalysts for Fenton-like reactions.

Plasma-assisted assembly of Co3O4/TiO2-NRs for photoelectrocatalytic degradation of bisphenol A in solution and muddy systems

Herein, Co3O4/TiO2-NRs electrodes with excellent photoresponse have been prepared via the plasma-assisted modification of Co3O4 on TiO2. With the combination of Co3O4 and TiO2, the composite electrode exhibited a red-shift phenomenon and the absorption of UV and visible light were enhanced to improve the light utilization efficiency. The Mott-Schottky diagram showed that a P–N heterojunction was successfully formed between Co3O4 and TiO2 on the electrode, which inhibited the recombination of electrons and holes, and had a high photocurrent density. In our photoelectrocatalysis (PEC) degradation experiments, the degradation rates of bisphenol A (BPA) by Co3O4/TiO2-NRs electrode in Na2SO4 and simulated seawater system reached 69.44 and 100%, respectively. The important role of ·O2−, ·OH, h+, and active chlorine (Cl·, HClO/ClO−, and Cl2) on the Co3O4/TiO2-NRs electrode during the degradation of BPA in simulated seawater was revealed. In addition, PEC combined with electrokinetic (EK) studies with the Co3O4/TiO2-NRs electrode were used for the degradation of BPA in muddy water, initially expanding the application scope of the PEC performance of the Co3O4/TiO2-NRs electrode for pollutants degradation, and had great potential for the subsequent treatment of muddy water pollutants.

Enhanced mineralization of bisphenol A by electric arc furnace slag: Catalytic ozonation

The catalytic ozonation of bisphenol A (BPA) was performed using an industrial solid waste as catalyst: electric arc furnace slag (EAFS). The characterization of the catalyst (SEM/EDS, XRD, surface area, pHPZC and Mössbauer spectroscopy) showed low surface area, alkaline nature and a composition rich in Fe, Ca, Si, C oxides, with minor content of Mg, Mn and Al. Ozonation experiments were carried out in a semi-batch reactor at room temperature at different initial pH conditions: from alkaline (natural pH 10.5) to acidic (controlled pH 3) aqueous media. Catalytic ozonation experiments showed complete BPA removal and remarkable total organic carbon conversions (62–80 %) over the broad pH range explored. The highest mineralization levels were obtained under basic pH, which was attributed to the generation of hydroxyl radical given by the presence of OH− and precipitation reactions of intermediates promoted by Ca oxides. Under acidic conditions the presence of EAFS notoriously enhanced BPA mineralization compared to single ozonation, due to the activity of leached species. The stability of the material was tested in 4 ozonation cycles. EAFS activity was mostly sustained under acidic conditions while a reduction was observed under uncontrolled pH condition, which was associated with a marked pH decrease. However, the residual activity still allowed complete BPA degradation and high mineralization levels (> 50 %). EAFS is a low-cost material that exhibits high activity and reasonable stability in catalytic ozonation of BPA. The valorization of this waste constitutes a technological alternative that could benefit both metallurgical and water treatment plants.

Insights into the fundamental role of Mo doping in facilitating the activation of peroxydisulfate by iron-based catalysts: Accelerating the generation of sulfate radicals

Electron-rich Fe sites in iron-based catalysts provide sufficient electrons to activate peroxydisulfate (PDS) for organic pollutants degradation, whereas catalyst activity is restricted by the inert Fe(III)/Fe(II) conversion. Herein, we synthesized Fe and Mo co-doped carbon (Fe/Mo@C) catalysts to explore the effect of Mo doping on Fe(III)/Fe(II) cycling during PDS activation process. Compared to the sole Fe loaded carbon (Fe@C), the introduced Mo converted the iron to a lower valence state (Fe0 and Fe(II)) during the catalysts preparation. Bisphenol A (BPA) was completely degraded within 10 min in Fe/Mo@C-PDS system with the degradation rate of 0.70 min−1, which was 26 times higher than that in Fe@C-PDS system. Mechanism studies indicated that the introduction of Mo promoted the cycling of Fe(II)/Fe(III) in catalytic-oxidation system and accelerated the generation of more SO4•−, resulting in a significant improvement of the catalytic activity. Density functional theory (DFT) calculations revealed that Mo doping facilitated PDS adsorption onto Fe/Mo@C and accelerated the O-O breaking in PDS to produce more SO4•− for BPA degradation. Besides, the intermediates formed during the BPA degradation in Fe/Mo@C-PDS system exhibited lower bio-toxicity than the pristine BPA and those in Fe@C-PDS system. This work elucidates the mechanism of Mo doping to improve the catalytic activity of iron-based catalysts in sulfate-based advanced oxidation processes, providing a new strategy for solving the blockage of Fe(II)/Fe(III) cycle.

Simultaneous removal of bisphenol A and Cr(Ⅵ) by Pd–TiO2: Significantly improve the photocatalytic activity through synergistic effect

The synergistic effect of heavy metal ions and organic pollutants can enhance the photocatalytic performance and provides a new idea for environmental governance, so it has important research value. In this work, we prepared Pd–TiO2 composites by ascorbic acid reduction method, and obtained the crystal structure, morphology and surface state information of the composites through a series of characterizations, which verified the successful preparation of the composites. It was used for simultaneous photocatalytic removal of bisphenol A (BPA) and Cr(Ⅵ), and it was found that the photocatalytic removal efficiency was significantly improved compared to their individual removal. This can be attributed to the synergistic effect between BPA and Cr(Ⅵ), where they enhance the separation efficiency of photogenerated electron-hole pairs and prolong the lifetime of photogenerated carriers. In addition, the effects of BPA concentration and Cr(Ⅵ) concentration on photocatalytic removal efficiency were also investigated. The mechanism of photocatalytic degradation of BPA by Cr(Ⅵ) coupling system was discussed by changing the experimental conditions, it is proved that the photocatalytic products of BPA can improve the removal efficiency of Cr(Ⅵ).

Catalytic ozonation of bisphenol A by Cu/Mn@γ-Al2O3: Performance evaluation and mechanism insight

Herein, an alumina-based bimetallic catalyst (Cu1Mn7@γ-Al2O3) was synthesized for bisphenol A (BPA) degradation in the catalytic ozonation process. The catalytic ozonation system could degrade 93.9% of BPA within 30 min under the conditions of pH = 7.0, 10 mg L−1 O3 concentration, and 24 g L−1 catalyst dosage compared to ozone alone (21.0%). The enhanced BPA degradation efficiency was attributed to the abundant catalytic sites and synergistic effects of Cu and Mn. The results revealed that the synergistic interaction between Cu and Mn effectively accelerated the electron transfer process on the catalyst surface, thus promoting the generation of reactive oxygen species (ROS). Further studies indicated that the BPA degradation in Cu1Mn7@γ-Al2O3/O3 system predominantly followed the ·OH and O2·- oxidation pathway. Based on the density functional theory (DFT) calculations and intermediates detected by LC-MS analysis, two pathways for BPA degradation in the Cu1Mn7@γ-Al2O3/O3 system were proposed. The toxicity estimation illustrated that the toxicity of BPA and its byproducts was effectively reduced in the Cu1Mn7@γ-Al2O3/O3 system. This work provides a new protocol for O3 activation and pollutant elimination through a novel bimetallic catalyst during water purification.

Immobilization of laccase on magnetic PEGDA–CS inverse opal hydrogel for enhancement of bisphenol A degradation in aqueous solution

Endocrine disruptors such as bisphenol A (BPA) adversely affect the environment and human health. Laccases are used for the efficient biodegradation of various persistent organic pollutants in an environmentally safe manner. However, the direct application of free laccases is generally hindered by short enzyme lifetimes, non-reusability, and the high cost of a single use. In this study, laccases were immobilized on a novel magnetic three-dimensional poly(ethylene glycol) diacrylate (PEGDA)–chitosan (CS) inverse opal hydrogel (LAC@MPEGDA@CS@IOH). The immobilized laccase showed significant improvement in the BPA degradation performance and superior storage stability compared with the free laccase. 91.1% of 100 mg/L BPA was removed by the LAC@MPEGDA@CS@IOH in 3 hr, whereas only 50.6% of BPA was removed by the same amount of the free laccase. Compared with the laccase, the outstanding BPA degradation efficiency of the LAC@MPEGDA@CS@IOH was maintained over a wider range of pH values and temperatures. Moreover, its relative activity of was maintained at 70.4% after 10 cycles, and the system performed well in actual water matrices. This efficient method for preparing immobilized laccases is simple and green, and it can be used to further develop ecofriendly biocatalysts to remove organic pollutants from wastewater.