Bisphenol A Degradation Research Articles

Catalytic oxidation of Bisphenol A with Co3+ rich spinel Co3O4: Performance evaluation with peroxymonosulfate activation and mineralization mechanism

Bisphenol A (BPA) is a toxic substance that is released into the environment mainly from paint, polymer, plastics and pharmaceutical industries. In this study, spinel Co3O4 consisting of Co2+/(Co3+)2O4 nanospheres with excellent specific surface properties were systematically synthesized via a simple hydrothermal approach preceded by calcination. The as-synthesized Co3O4 spinels were used for peroxymonosulfate (PMS) activation to reduce the bisphenol A (BPA). The effects of operating parameters including PMS dosage, initial pH, catalyst dosage, and co-existing ions were detected during the BPA degradation. It was observed that at neutral pH, the nano-Co3O4/PMS system effectively degrades the BPA (∼92%) with very low cobalt leaching and excellent recyclability. Control experiment analysis confirms the magnificent performance of the Co3O4/PMS system and the synergistic interaction between Co3O4 and PMS. Various characterization techniques were used to determine the thermal, textural and structural properties. A chemical quenching study confirmed that both hydroxyl radicals (•OH) and sulfate radicals (SO4•−) promotes BPA oxidation. The chloride (Cl-) ions and dihydrogen phosphate ions (H2PO4-) have little inhibition effect while adding humic acid (HA) and HCO3- inhibits the BPA oxidation. Separation techniques such as high-performance liquid chromatography (HPLC) coupled with mass spectroscopy (MS) were used to identify the oxidative by-products and the mineralization pathway of BPA reduction. First-order pseudo-kinetics were observed for BPA degradation. However, the power law model also fits nth-order kinetics models.

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.

Wood induced preparation of Fe3C decorated biochar for peroxymonosulfate activation towards bisphenol a degradation with low ion leaching

Heterogeneous iron/persulfate system suffers from the problems of high ion leaching, severe catalyst surface corrosion and low performance stability. Herein, a series of iron compound incorporated N doped biochar composite catalysts were prepared from pyrolyzing wood powder and ferric ferrocyanide mixture, which were used for bisphenol A (BPA) degradation in water through peroxymonosulfate (PMS) activation. It was found that the reducing gases released from wood powder at different pyrolysis temperature significantly affected the crystalline phase of the iron compound in the catalyst, in which pure phase iron carbide (Fe3C) decorated N doped biochar was obtained at pyrolysis temperature of 600 °C or higher. Wood powder was introduced as both Fe3C formation inductive agent and biochar precursor. Fe3C/biochar exhibited optimal BPA degradation performance, in which 0.5 g/L of catalyst could completely degrade 0.05 mM BPA within 30 min. Radical, high valent iron-oxo, and non-radical species were all generated in the reaction system by both Fe3C and N doped biochar, respectively. Moreover, the multi-valence nature of Fe in Fe3C enabled the reaction system with remarkably reduced Fe ion leaching and negligible iron sludge production since Fe3C could activate PMS through a heterogeneous mechanism. Having multiple active species generated for BPA degradation, the prepared catalyst also showed promising adaptability and recyclability. This study can provide a new solution for the design of iron based catalyst/PMS system for organic pollutant degradations with low ion release.

Exploring the effect of surfactants on the interaction between laccase and bisphenol A by molecular docking, molecular dynamics, and energy calculations

Bisphenol A (BPA), an endocrine disruptor, has potential threat to human health due to its widespread use as a plasticizer in many industrial products. Laccase (Lac) can degrade BPA well and the intervention of some surfactants can further improve the degradation of BPA by Lac, but the exact details are not known. In this paper, focused on the Lac and BPA, as well as the surfactants rhamnolipid (RL) and polyethylene glycol (PEG) as research objects, we construct nine research systems by molecular docking, and study the effect of these two surfactants on the interaction of Lac-BPA at the molecular level through molecular dynamics (MD) simulation and MM-PBSA prediction. The results showed that these two surfactants aggregated and encapsulated the enzyme in different degrees during the MD simulations, which separated the surface part of the enzyme from the solvent, thereby weakening the environmental influence on Lac activity and changing the local residues conformation of Lac, leading to the reduction of polar solvation free energy and changing the binding state of Lac-BPA. RL promotes the binding of Lac-BPA primarily by influencing the free energy of polar solvents, while PEG weakens the binding free energy of Lac-BPA complex. These results explain the reason for the lower degradation rate of BPA with the addition of PEG than with the addition of RL in the same system under the appropriate conditions. Our work elucidates the mechanism of action by which two surfactants RL and PEG affect the Lac-BPA interaction which will provide a strong basis for improving the degradation of BPA by Lac at the molecular level.

FexO4-enhanced degradation of bisphenol A in visible light/peroxydisulfate system: production of singlet state oxygen

In this study, ferrous composites (FexO4) were prepared by microreactor to activate peroxydisulfate (PDS) for the degradation of bisphenol A (BPA) with visible (Vis) light irradiation. X-ray diffraction (XRD), energy-dispersive spectrometry (EDS), X-ray photoelectron spectroscopy (XPS), and scanning electron microscope (SEM) were used to characterize the morphology and crystal phase of FeXO4. Photoluminescence (PL) spectroscopy combined with amperometric tests were used to determine the role of PDS on the performance of photocatalytic reaction. The main reactive species and intermediates for BPA removal were determined by electron paramagnetic resonance (EPR) measurement and quenching experiments. The result indicated that singlet state oxygen (1O2) contributed more to the BPA degradation than that of other reactive radicals (·OH, SO4·- and ·O2-); these reactive radicals and 1O2 formed by the reaction between photo-generated electrons (e-) and holes (h+) of FexO4 and PDS. During this process, the consumption of e- and h+ also improved their separation efficiency and thus enhanced the degradation of BPA. In addition, the photocatalytic activity of FexO4 in Vis/FexO4/PDS system was 3.2-fold and 6.6-fold higher than that of single FexO4 and PDS under Vis light, respectively. The Fe2+/Fe3+ cycle could effectively drive the photocatalytic activation of PDS through indirect electron transfer and the formation of reactive radicals. This work illustrated that the degradation of BPA was rapidly in Vis/FexO4/PDS system mainly through 1O2, which further improve our understanding on the efficient removal of organic contaminants in the environment.

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.

Unraveling the instability of Nitrogen-Doped carbon during BPA treatment by peroxymonosulfate Activation: Effect of free radical grafting

Nitrogen-doped carbon has been established as an effective catalyst for peroxymonosulfate (PMS) activation to remove pollutants from water. However, the easy deactivation during the reaction process limits its potential for widespread application. In this study, nitrogen-rich carbocatalysts was synthesized by two-step pyrolysis and used to activate PMS for degradation of bisphenol A (BPA). The nitrogen-rich catalysts calcined at 900 ℃ with the amount of 2 mg degraded more than 80 % of 20 mg/L BPA in 20 min and the degradation of TOC has reached 65 %, showing excellent catalytic performance. Based on free radical quenching experiments and electron spin resonance (ESR), the non-radical process played a key role in BPA degradation. The characterization results of fresh and used catalysts suggested that the instability of the nitrogen-rich carbon materials resulted from the grafting reaction between free radicals on the graphite carbon site of the N-doped carbon materials and the intermediate degradation products of BPA, which covered the active sites of the catalysts. This new discovery elucidates the reason of N-doped carbon materials deactivation in PMS oxidation and provides a complementary for the reaction mechanism of carbon catalysis.

Insights into boron accelerated Fenton-like chemistry: Sustainable and fast FeIII/FeII circulation

In this work, amorphous boron (A-Boron) as a metal-free co-catalyst was applied to address the slow kinetics of FeII regeneration and inactive FeIII accumulation in Fenton-like peroxydisulfate (PDS) activation. The A-Boron/FeIII/PDS system can rapidly degrade bisphenol A (BPA) for ten cyclic runs without performance decline. Based on chemical probing, radical quenching and in situ capturing tests, Fe(IV) and radicals (OH and SO4−) are identified as the primary reactive species, and the combined ROS can achieve universal pollutants oxidation with high PDS utilization efficiency. QSAR study unveils that the kobs values of pollutants linearly depend on their EHOMO. A-Boron can bind with FeIII species for catalytic reduction, and meanwhile, the semi-metallic surface experiences stepwise transformation. The fast dissolution of inactive surface boron oxide enabled a self-cleaned and reactive boron surface for long-lasting iron circulation. Also, BPA degradation pathways were proposed based on UHPLC-QTOF-MS tests and Fukui index calculation.

Comparison of effects of multiple oxidants with an ultrasonic system under unified system conditions for bisphenol A degradation

Bisphenol A (BPA) as a trace contaminant has been reported, due to widespread use in the plastics industry. This study applied the 35 kHz ultrasound (US) to activate four different common oxidants (H2O2, HSO5−, S2O82−, and IO4−) for BPA degradation. With increasing initial concentration of oxidants, the degradation rate of BPA increased. The synergy index confirmed that a synergistic relationship between US and oxidants. This study also examined the impact of pH and temperature. The results showed that the kinetic constants of US, US-H2O2, US-HSO5- and US-IO4−decreased when the pH increased from 6 to 11. The optimal pH for US-S2O82− was 8. Notably, increasing temperature decreased the performance of US, US-H2O2, and US-IO4- systems, while it could increase the degradation of BPA in US-S2O82− and US-HSO5-. The activation energy for BPA decomposition using the US-IO4- system was the lowest, at 0.453nullkJnullmol−1, and the synergy index was the highest at 2.22. Additionally, the ΔG# value was found to be 2.11 + 0.29T when the temperature ranged from 25 °C to 45 °C. The main oxidation contribution is achieved by hydroxyl radicals in scavenger test. The mechanism of activation of US-oxidant is heat and electron transfer. In the case of the US-IO4- system, the economic analysis yielded 271 kwh m−3, which was approximately 2.4 times lower than that of the US process.

Visible light responsive MoS2/Ag@WO3/EG photoanode with highly stable Z-scheme induced circular electron motion pioneered by Exfoliated graphite for bisphenol a photoelectrodegradation

The alarming issue of endocrine disrupting chemicals increase in aquatic environment has heightened concerns about their potential impact on human health and ecosystem. Taking cognizance of this, the current investigation focused on fabrication of effective and efficient photoanode (MoS2/Ag@WO3/EG) from molybdenum disulphide/silver@tungsten trioxide (MoS2/Ag@WO3) photocatalyst and exfoliated graphite (EG) for the photoelectrocatalytic degradation of bisphenol A (BPA). The characterization results and Density Functional Theory (DFT) calculations together affirmed a strong interfacial contact and charge transfer direction at the interface of the materials for substantial promotion of charge separation and increased photoelectrocatalytic performance. The charge separation was further increased by EG’s “give-accept or redistribution” strategy of the charge at the interface that allowed circular motion of electrons in the formed Z-scheme heterostructure. The MoS2/Ag@WO3/EG photoanode exhibited the highest photoelectrocatalytic activity for BPA degradation with efficiency of 100% at optimum experimental conditions. The high degradation efficiency was attributed to uplifted visible light absorption emanating from EG surface plasmon resonance (SPR) contribution, formation of Z-scheme for efficient charge separation, and high stability of the photoanode, which possessed renewable surface. Moreover, scavenger experiments confirmed the participation of all the radicals (●O2– >●OH > h+) in BPA decomposition. Based on XPS, DFT, and radical experiments, the Z-scheme mechanism was proposed, and this work shed light on the production of highly effective house-made photoanode for photoelectrocatalytic processes, thus this can be a good fit in the industrial setup for degradation of other pollutants like microbials.

Visible light-driven NH2Cl activation by g-C3N4 photocatalysis producing reactive nitrogen species to degrade bisphenol A

The photolysis of monochloramine (NH2Cl), a widely used disinfectant, under UVC irradiation produces different radicals for the micropollutant degradation. For the first time, this study demonstrates the degradation of bisphenol A (BPA) via the NH2Cl activation by graphitic carbon nitride (g-C3N4) photocatalysis using visible light-LEDs at 420 nm, termed as the Vis420/g-C3N4/NH2Cl process. The process produces •NH2, •NH2OO, •NO and •NO2 via the eCB−- and O2•−-induced activation pathways and •NHCl and NHClOO• via the hVB+-induced activation pathway. The produced reactive nitrogen species (RNS) enhanced 100% of the BPA degradation compared with the Vis420/g-C3N4. Density functional theory calculations confirmed the proposed NH2Cl activation pathways and further demonstrated that eCB−/O2•− and hVB+ induced the cleavage of N–Cl and N–H bonds in NH2Cl, respectively. The process converted 73.5% of the decomposed NH2Cl to nitrogen-containing gas, compared with that of approximately 20% in the UVC/NH2Cl process, leaving much less ammonia, nitrite and nitrate in water. Among different operating conditions and water matrices tested, of particular significance is natural organic matter of 5 mgDOC/L only reduced 13.1% of the BPA degradation compared against that of at least 46% reduction in the UVC/NH2Cl process. Only 0.017–0.161 µg/L of disinfection byproducts were produced, two orders of magnitudes lower than that in the UVC/chlorine and UVC/NH2Cl processes. The combined use of visible light-LEDs, g-C3N4 and NH2Cl significantly improves the micropollutant degradation and reduces the energy consumption and byproduct formation of the NH2Cl-based AOP.

BPA degradation using biogenic manganese oxides produced by an engineered Escherichia coli with a non-blue laccase from Bacillus sp. GZB

Bisphenol A (BPA), an endocrine disruptor that is often found in a variety of environmental matrixes, poses a serious health risk. One of the most effective methods for completely degrading BPA is biological oxidation. This study used a non-blue laccase to develop an engineer Escherichia coli strain for the synthesis of biogenic manganese oxides (BMO). The recombinant strain LACREC3 was utilized for the efficient production of BMO. The LACREC3 strain developed the erratic clumps of BMO after prolonged growth with Mn2+, as shown by scanning electron microscopy (SEM) and energy-dispersive X-ray (EDS) tests. After 12 days of incubation under liquid culture conditions, a total of 51.97 ± 0.56% Mn-oxides were detected. The Brunauer-Emmett-Teller (BET) surface areas, X-ray diffraction (XRD), Fourier transform infrared (FT-IR), and X-ray photoelectron spectroscopy (XPS) experiments were further used to characterize the purified BMO. Data revealed that Mn(IV)-oxides predominated in the structure of BMO, which was amorphous and weakly crystalline. The BPA oxidation assay confirmed the high oxidation efficiency of BMO particle. BMO degraded 96.16 ± 0.31% of BPA in total over the course of 60 min. The gas chromatography and mass spectroscopy (GC-MS) identified BPA-intermediates showed that BPA might break down into less hazardous substances that were tested by Photobacterium Phosphoreum in an acute toxicity experiment. Thus, employing BMO generated by a non-blue laccase, this study introduces a new biological technique of metal-oxidation and organic-pollutant degradation.

Highly Efficient Copper Doping LaFeO3 Perovskite for Bisphenol A Removal by Activating Peroxymonosulfate

A series of copper doping LaFeO3 perovskite (LaCuxFe1−xO3, LCFO, x = 0.1, 0.4, 0.5, 0.6, 0.9) are successfully synthesized by the sol-gel method under mild conditions. In this study, it is applied for the activation of peroxymonosulfate (PMS) for bisphenol A (BPA) removal. More than 92.6% of BPA was degraded within 30 min at 0.7 g/L of LCFO and 10.0 mM of PMS over a wide pH range with limited leaching of copper and iron ions. The physical–chemical properties of the catalysts were demonstrated by using X-ray diffraction (XRD), N2 adsorption–desorption isotherms, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). Furthermore, the effects of catalyst dosage, PMS concentration, initial pH value, and inorganic anions on the LCFO/PMS system were fully investigated. Quenching experiments were performed to verify the formation of reactive oxidant species, which showed that the radical reaction and mechanisms play a great role in the catalytic degradation of BPA. The perovskite LCFO is considered a stable, easy to synthesize, and efficient catalyst for the activation of PMS for wastewater treatment.

Preparation of Fe-Cu bimetal from copper slag by carbothermic reduction–magnetic process for activating persulfate to degrade bisphenol A

BackgroundFe-Cu bimetal (Fe-Cu) was prepared from copper slag via a carbothermic reduction–magnetic separation process, and used as persulfate (PS) activator to degrade bisphenol A (BPA). MethodsThe characteristic of Fe-Cu was detected by XRD, SEM-EDS, and XPS. Significant findingsThe Fe-Cu is mainly composed of copper containing metallic iron, iron containing metallic copper, and copper-iron sulfide. The batch experiments results showed that the Fe-Cu offered highly effective BPA removal up to 400 mg/g in the presence of PS within 60 min, and the degradation of total organic carbon was 72.32% under optimal conditions, which proved that Fe-Cu is a highly active PS activator. Electron paramagnetic resonance and radical scavenging experiments showed that sulfate radical (SO4•−) and hydroxyl radical contributed to the degradation of BPA, and SO4•− was dominant. The reuse experiments showed that the degradation efficiency of BPA was still as high as 96.92% after the fourth use. Moreover, the possible BPA degradation pathway was proposed on the basis of intermediates analyzed by gas chromatography–mass spectrometry. This study offers a novel idea for preparing Fe-Cu and suggests that the Fe-Cu/PS system has good potential for removing refractory organic pollutants in wastewater.

Laccase encapsulation immobilized in mesoporous ZIF-8 for enhancement bisphenol A degradation.

Endocrine disruptors (EDCs) such as bisphenol A (BPA) have many adverse effects on environment and human health. Laccase encapsulation immobilized in mesoporous ZIF-8 was prepared for efficient degradation of BPA. The ZIF-8 (PA) with highly ordered mesopores was synthesized using trimethylacetic acid (PA) as a template agent. On account of the improvement of skeletal stability by cross-linking agent glutaraldehyde, ZIF-8 (PA) realized laccase (FL) immobilization within the mesopores through encapsulation strategy. By replacing the template agent, the effect of pore size on the composite activity and immobilization efficiency by SEM characterization and kinetic analysis were investigated. Based on the physical protection of ZIF-8(PA) on laccase, as well as electrostatic interactions between substances and changes in surface functional groups (e.g. -OH, etc.), multifaceted enhancement including activity, stability, storability were engendered. FL@ZIF-8(PA) could maintain high activity in complex systems at pH 3-11, 10-70°C or in organic solvent containing system, which exhibited an obvious improvement compared to free laccase and other reported immobilized laccase. Combined with TGA, FT-IR and Zeta potential analysis, the intrinsic mechanism was elaborated in detail. On this basis, FL@ZIF-8(PA) achieved efficient removal of BPA even under adverse conditions (removal rates all above 55% and up to 90.28%), and was suitable for a wide range of initial BPA concentrations. Combined with the DFT calculations on the adsorption energy and differential charge, the mesoporous could not only improve the enrichment performance of BPA on ZIFs, but also enhance the interaction stability. Finally, FL@ZIF-8(PA) was successfully applied to the degradation of BPA in coal industry wastewater. This work provides a new and ultra-high performances material for the organic pollution treatment in wastewater.

Mn(III)-mediated bisphenol a degradation: Mechanisms and products

Bisphenol A (BPA) is a high production volume chemical with potential estrogenic effects susceptible to abiotic degradation by MnO2. BPA transformation products and reaction mechanisms with MnO2 have been investigated, but detailed process understanding of Mn(III)-mediated degradation has not been attained. Rapid consumption of BPA occurred in batch reaction vessels with 1 mM Mn(III) and 63.9 ± 0.7% of 1.76 ± 0.02 μmol BPA was degraded in 1 hour at circumneutral pH. BPA was consumed at 1.86 ± 0.09-fold higher rates in vessels with synthetic MnO2 comprising approximately 13 mol% surface-associated Mn(III) versus surface-Mn(III)-free MnO2, and 10–35% of BPA transformation could be attributed to Mn(III) during the initial 10-min reaction phase. High-resolution tandem mass spectrometry (HRMS/MS) analysis detected eight transformation intermediates in reactions with Mn(III), and quantum calculations proposed 14 BPA degradation products, nine of which had not been observed during MnO2-mediated BPA degradation, suggesting mechanistic differences between Mn(III)- versus MnO2-mediated BPA degradation. The findings demonstrate that both Mn(III) and Mn(IV) can effectively degrade BPA and indicate that surface-associated Mn(III) increases the reactivity of synthetic MnO2, offering opportunities for engineering more reactive oxidized Mn species for BPA removal.

Tramates trogii biomass in carboxymethylcellulose-lignin composite beads for adsorption and biodegradation of bisphenol A.

Tramates trogii biomass was immobilized in carboxymethyl cellulose-lignin composite beads via cross-linking with Fe(III) ions (i.e., Fe(III)-CMC@Lig(1-4)@FB). The composite beads formulations were used for the adsorption and degradation of bisphenol A (BPA) using the free fungal biomass as a control system. The maximum adsorption capacity of the free fungal biomass and Fe(III)-CMC@Lig-3@FB for BPA was found to be 57.8 and 95.6, mg/g, respectively. The degradation rates of BPA were found to be 87.8 and 89.6% for the free fungal biomass and Fe(III)CMC@Lig-3@FB for 72h in a batch reactor, respectively. Adsorption of BPA on the free fungal biomass and Fe(III)CMC@Lig-3@FB fungal preparations described by the Langmuir and Temkin isotherm models, and the pseudo-second-order kinetic model. The values of Gibbs free energy of adsorption (ΔG°) were - 20.7 and - 25.8kJ/mol at 298K for BPA on the free fungal biomass and Fe(III)-CMC@Lig-3@FB beads, respectively. Moreover, the toxicities of the BPA and degradation products were evaluated with three different test organisms: (i) a freshwater micro-crustacean (Daphnia magna), (ii) a freshwater algae (Chlamydomonas reinhardti), and (iii) a Turkish winter wheat seed (Triticum aestivum L.). After treatment with the Fe(III)CMC@Lig-3@FB formulation, the degradation products had not any significant toxic effect compared to pure BPA. This work shows that the prepared composite bioactive system had a high potential for degradation of BPA from an aqueous medium without producing toxic end-products. Thus, it could be a good candidate for environmentally safe biological methods.

Study on Genomics of the Bisphenol A-Degrading Bacterium Pseudomonas sp. P1

As a widespread pollutant, bisphenol A (BPA) has created a serious threat to ecosystem and human health. Therefore, expanding the available microbial resources used to screen highly efficient BPA-degrading bacteria with BPA as the sole carbon source is very important for the removal of this pollutant from the environment. In this study, the BPA degradation rate of Pseudomonas sp. P1 to 30 mg/L was 96.89% within 120 h. Whole genome sequencing showed that the genome of strain P1 was composed of a single circular chromosome with a full length of 6.17 Mb, which contained 5636 predicted coding genes. Comparative genomic analysis showed that strain P1 contained 210 functional genes related to BPA degradation. It was confirmed that BPA degradation genes ferredoxin (bisdA), P450 (bisdB), CotA and Lac in strain P1 were highly expressed under the induction of BPA. Combined with the identification of metabolites, the route of BPA degradation by Pseudomonas was proposed. A new metabolite, 4-vinylphenol, was detected for the first time in pathway Ⅰ. In pathway Ⅱ, BPA is directly oxidized to phenol and 4-isopropenyl phenol in the presence of laccase, which is rarely reported in the process of bacterial degradation of BPA. This study confirmed that strain P1 had good tolerance to various environmental factors at the gene level and enriched the degradation mechanism of BPA.

Application of a new lignin/cellulose carbon xerogel/ZnO/Bi2O3/Bi° composite photocatalyst for the degradation of bisphenol-A under sunlight

This work proposed the study of a new lignin/cellulose carbon xerogel/ZnO/Bi2O3/Bi° composite photocatalyst for the degradation of bisphenol-A under sunlight. The reasoning behind the application of each component is based on the formation of multiple heterojunctions (p-n heterojunction between semiconductors, metal-semiconductor heterojunction, and carbon-semiconductor heterojunction) to hinder the recombination of photogenerated charges during the photocatalytic process. The lignin/cellulose carbon xerogel was employed as both a solid electron mediator and a reducing agent, promoting the reduction of the bismuth oxide into metallic bismuth. The results obtained from the characterization tests confirm the formation of all the intended phases in the hybrid photocatalyst. Furthermore, the inclusion of the carbon xerogel led to morphological modifications such as the formation of plate-like particles and the increase of specific surface area. The efficient formation of the heterojunctions between the composing phases of the hybrid composite led to an enhanced photocatalytic activity for the degradation of the bisphenol-A (BPA) molecule, under both simulated sunlight and visible light. The optimized composite achieved 84% degradation of the BPA under simulated sunlight and 27% under visible light irradiation, which is a great improvement in comparison to the pure ZnO, which obtained 55% degradation under simulated sunlight and 19% degradation under visible light. The enhanced photocatalytic activity of the lignin/cellulose carbon xerogel/ZnO/Bi2O3/Bi° composite was further verified by chronoamperometry tests, which evidenced its greater photocurrent generation capabilities.

Fabrication, characterization, and performance evaluation of Bi2WO6/TiO2/Fe3O4 photocatalyst responding to visible light for enhancing bisphenol A degradation.

A novel magnetic Bi2WO6/TiO2/Fe3O4 photocatalyst was synthesized by a hydrothermal approach. The pattern, structure, elemental composition, light-absorbing properties, and magnetism of Bi2WO6/TiO2/Fe3O4 were characterized and analyzed. The performance, influencing factors, and mechanism of Bi2WO6/TiO2/Fe3O4 towards bisphenol A (BPA) degradation were investigated and deduced. BPA removal up to 95% was achieved with the addition of 1.25g/L Bi/Ti/Fe2 (molar ratio of Bi2WO6:TiO2:Fe3O4 = 2:1:0.17) in the solution containing 10mg/L BPA at pH 5.6. The performance of Bi/Ti/Fe2 was stable for five cycles at least after extracted from the reacted solution by magnet. Photoexcited h+, •OH, and •O2- formed in the reaction mainly contributed to BPA degradation. The Bi/Ti/Fe2 composite was composed of a three-layer petal structure from outside to inside to be Bi2WO6, TiO2, and Fe3O4. This structure was conducive in forming a heterojunction between TiO2 and Bi2WO6, inhibiting the merging of photoexcited e- and h+, and improving the photocatalytic efficiency.