Removal Of Bisphenol Research Articles

Removal of BPA by Pseudomonas asiatica P1: Synergistic response mechanism of toxicity resistance and biodegradation

Bisphenol A (BPA) is a globally concerning toxic pollutant, and microbial degradation is considered an effective method to treat BPA contamination. However, the inherent microbial toxicity of BPA is often overlooked, particularly the microbial mechanisms of resistance and detoxification against BPA. This study found that under the toxic stress of BPA, cbb3-type cytochrome c oxidase (cbb3-Cox) in the cells of Pseudomonas asiatica P1 (P. asiatica P1) was the first to resist the toxicity. Genes such as ccoNOQPG showed significant upregulation with an average log2FC value of 3.56. Subsequently, genes that are related to metal ion binding, transport, and DNA repair were upregulated in the middle to later phase, which enhanced the metabolic functions of the strains and induced strain mutations to assist P. asiatica P1 in resisting the BPA toxicity. Meanwhile, three potential BPA degradation genes were identified, among which sdrP1 was crucial to the BPA degradation and detoxification. After genetic recombination, sdrP1 achieved a degradation rate of 92.52 % for BPA. Furthermore, through various methods such as alkyl interactions, sdrP1 exhibited oxidation and demethylation to form lower toxic intermediate products and complete the biological detoxification of BPA. This study provides a systematic analysis of the toxicity resistance, biodegradation, and detoxification processes in bacterial BPA removal, refines the mechanism of BPA biodegradation and contributes to a more comprehensive and systematic understanding of the overall process of microbial removal of toxic pollutants.

ZIF-derived non-bonding Cu/Zn catalysts-driven peroxymonosulfate activation via selective generation of surface-bound radicals for efficient water purification

The peroxymonosulfate-based advanced oxidation processes (PMS-AOPs) have been extensively studied in wastewater treatment due to their ability to generate various reactive oxygen species. However, the ultra-short half-lives of free radical species limit their effective transfer from the catalyst surfaces to the target organic contaminants for efficient decontamination. Thus, directed production of reactive species with longer lifetimes is challenging but belong with significant demand. In this study, a catalyst with neighboring Cu and Zn heteroatoms pairs anchored on the surface of zeolitic imidazolate framework (Cu/Zn-ZIF) was designed to selectively and sustainably generate radicals via PMS activation. Electron energy-loss spectroscopy (EELS) demonstrated the formation of non-bonding Cu-Zn heteroatom pairs. Owing to the synergistic effect of the Cu and Zn heteroatoms, the Cu/Zn-ZIF/PMS system achieved 99.5 % removal rate of bisphenol A (BPA) within 60 min. Therein, PMS was stabilized by the strongly adsorptive Cu/Zn-ZIF and activated within the nanoscale confinement of Cu sites, resulting in the directional generation of surface-bound •OH and SO4•− radicals with longer lifetimes, which facilitated the efficient removal of BPA. Significantly, it also demonstrated robust resilience against disruptions caused by intricate aquatic environments, including freshwater bodies and ionic species. These findings provide reference for theoretical research on the design of functional MOFs materials and the practical application of surface-bound radicals in AOPs

The catalytic reduction-oxidation collaborative processes for enhanced elimination of TBBPA over Pd/CeO2-R catalyst

The degradation of tetrabromobisphenol A (TBBPA) was inhibited due to the existence of strong electron attraction Br. The reduction of TBBPA usually generated bisphenol A (BPA), which still do harm to the environment. Herein, we prepared Pd/CeO2 catalysts for the valid elimination of TBBPA with clean products via the catalytic hydrodebromination-oxidation (R-O) synergy processes. TBBPA suffered debromination and BPA and Br- were the products after reaction for 60min during the catalytic hydrodebromination (HDBr) processes, BPA could be degraded smoothly in the following oxidation step involved PMS activation, reflecting an excellent ability of the Pd based catalyst for the activation of H2, C-Br bond and PMS. Both Pd0 and Pdn+ played key roles for the HDBr of TBBPA, while Pd0 was the main active sites for the oxidation of BPA. HOBr generated from Br- oxidation favored the removal of BPA while the reactive species such as 1O2 generated from PMS activation further accelerated the TOC removal. The TOC removal rate was 5.2% for the direct degradation of TBBPA in the PMS/DP-Pd/CeO2-R system, while this value increased to 57.5% in the R-O synergy system. In addition, after reaction for 120min to eliminate TBBPA, the products were friendly to the aquatic organisms in the R-O synergy system, while the products remain exhibited strong toxicity in the single oxidation system, highlighting the advantages of the Pd/CeO2 catalyst triggered reduction/oxidation cooperation processes.

One-step pyrolysis of ZIF-8 after recovering rare earth elements from mining wastewater as a functional fenton-like catalyst

The management of rare earth elements (REEs) from mining wastewater has consistently a key issue. Our previous research has demonstrated the selective adsorption of REEs in mining wastewater by ZIF-8. Herein, one-step pyrolysis of ZIF-8 after recovering REEs from mining wastewater as a high-value product was further proposed. The resulting REEs-based magnetic nanoporous carbon materials (REEs-MPC) was utilized for the activation of peroxymonosulfate (PMS) in the removal of bisphenol A (BPA). Experimental results indicate substantial BPA removal efficiencies of 74.62 %, 83.57 %, and 70.06 % with REEs-MPC synthesized at different pyrolysis temperatures (700 °C, 800 °C, and 900 °C). The detailed characterizations reveal the REEs-MPC at 800 °C was obtained (REEs-MPC/800) exhibit prominent graphitic and defective characteristics. In addition, electrochemical analysis revealed that the REEs-MPC/800 demonstrate elevated conductivity and superior capacitive current, with Tafel slopes as high as 294 mV/dec. Functional theory (DFT) calculations demonstrate that the presence of graphitic-N and REEs-N species significantly enhance PMS activation. Finally, a neural network model constructed through machine learning techniques provided a comprehensive overview of the structure–property relationship. Overall, the proposal to synthesize a high-value product using mining wastewater has been put forward. This initiative is expected to contribute to the advancement of the green economy within the rare earth mining industry.

Self-assembled flower-like spherical Bi2WO6/BiOBr S-scheme heterojunction: Improved charge transfer and excellent photocatalytic activity

The suppression of expeditious complexation of photoexcited carriers and the enhancement of light harvesting are two extraordinarily momentous elements for boosting the catalytic activity of synthesized semiconductor photocatalyst. Herein, a sequence of visible-light-induced self-assembled flower-like spherical Bi2WO6/BiOBr S-scheme heterojunctions were successfully fabricated by two-step solvothermal process. The fabricated Bi2WO6/BiOBr hybrids possessed the splendid capacity to catalyze the degradation of bisphenol A (BPA) in water without the addition of surfactant compared to monocomponent photocatalyst. The optimized Bi2WO6/BiOBr (FBBH-16) possessed the most prominent photocatalytic activity, acquiring a conspicuous degradation efficiency of 91.97 % ± 1.51 % for BPA after 60 min illumination. The rate constant k (0.04078 ± 0.0009985 min−1) of FBBH-16, which was approximately 4.0 and 3.5 times that of bare Bi2WO6 and BiOBr, respectively. Such strengthening mechanism was chiefly ascribed to the establishment of S-scheme heterojunction, which efficaciously impeded the complexation of photoexcited charge pairs and noteworthily heightened the light harvesting. Furthermore, the forceful interfacial interactions between Bi2WO6 and BiOBr afforded much more active sites for BPA removal. The quenching experiments confirmed that ·OH and ·O2− are the principal active species for BPA degradation over Bi2WO6/BiOBr hybrids. Ultimately, two possible photodegradation pathways of BPA over Bi2WO6/BiOBr heterojunctions are also come up with on the grounds of the identification of intermediate products. This work furnishes fresh insights into the fabrication of highly efficacious and stable bismuth-based S-scheme heterojunctions for treating the actual wastewater by integrating nanostructure and microscopic morphology.

Granular anaerobic membrane bioreactor coupled hybrid forward osmosis − membrane distillation module for organic matter, nutrient and bisphenol A removal: Integrated assessment of performance, cost, toxicity, and risks

Bisphenol A (BPA), a compound widely produced and used worldwide, has been increasingly investigated due to its potential risk to human health and the environment. Studies and regulations have focused on its presence in materials in contact with food and children’s products; however, BPA has been detected in several aquatic matrices, reaching water bodies, mainly due to its incomplete removal in wastewater treatment plants, which may lead to even greater hazards. Therefore, this study investigated for the first time a granular anaerobic membrane bioreactor associated with a hybrid module of forward osmosis – membrane distillation (G-AnOMBR/MD) focusing on removing BPA in domestic sewage. In addition, the removal of organic matter and nutrients was evaluated concomitantly at the ecotoxicological tests, risk assessment, and cost evaluation. The results showed that the average COD, P-PO43−, and N-NH4+ removal was 95.6 %, 99.6 %, and 91 %, respectively. The removal of BPA was 94.65 % after 30 days of operation due to the granular sludge biodegradation and the higher selectivity of the FO-MD module. In addition, the system eliminated the high environmental and human health risks related to BPA, and the final effluent was non-toxic to the bacteria Aliivibrio fischeri. Finally, the estimated cost for G-AnOMBR/MD was US$ 3.91 m−3. Thus, the technology is promising for generating a high-quality and safe effluent regarding the presence of BPA and being financially competitive with other advanced systems.

Removal of bisphenol A through peroxymonosulfate activation with N-doped graphite carbon spheres coated cobalt nanoparticles catalyst: Synergy of nonradicals

Removal of bisphenol A through peroxymonosulfate activation with N-doped graphite carbon spheres coated cobalt nanoparticles catalyst: Synergy of nonradicals

Revealing the essence of anion ligands in regulating amorphous MnOx to activate peracetic acid for micropollutant removal

How the anion ligands of manganese precursors affect the catalytic activity of amorphous manganese oxides (MnOx) in Fenton-like process is poorly understood. Here, five amorphous MnOx synthesized by Mn(II) precursors with different ligands were characterized and adopted to activate peracetic acid (PAA) for bisphenol A (BPA) degradation. Although > 90 % BPA removal was achieved in the five MnOx/PAA processes via both adsorption and oxidation, the oxidation kobs greatly differentiates by the ligands types with the order of MnOx-N > MnOx-S > MnOx-Cl > MnOx-AA > MnOx-OA. Ligands types would affect the specific surface area of MnOx and their ability to adsorb BPA, however which is not the decisive factor in determining the contaminant oxidation efficiency. Multiple experimental results indicate that the generation of oxygen vacancies induced by the ligands alters the Mn(III)/Mn(IV) ratio, ultimately contributing to the different efficiency of BPA oxidation driven by the direct electron transfer mechanism. Moreover, amorphous MnOx holds the promise of practical applications in catalytic PAA of various micropollutants with good stability. This study advances the fundamental understanding of ligand-regulated amorphous MnOx-catalyzed PAA process.

Adsorptive Removal of Bisphenol A by Polyethylene Meshes Grafted with an Amino Group-Containing Monomer, 2-(Dimethylamino)ethyl Methacrylate

The adsorptive removal of Bisphenol A (BPA) with the PE meshes photografted with 2-(dimethylamino)ethyl methacrylate (DMAEMA) was performed by varying the grafted amount, pH value, BPA concentration, and temperature, and the adsorption performance was correlated by the equilibrium, kinetic, and isotherm models. In addition, the regeneration of DMAEMA-grafted PE (PE-g-PDMAEMA) meshes was discussed from the repetitive adsorption/desorption process. The adsorption capacity had the maximum value at the grafted amount of 2.6 mmol/g and at the initial pH value of 8.0. The increase in the protonation of dimethylamino groups on grafted PDMAEMA chains and the dissociation of phenol groups of BPA present in the outer solution during the adsorption process results in the increase in BPA adsorption. The adsorption process followed the pseudo second-order equation. The BPA adsorption was enhanced by increasing the BPA concentration and the equilibrium data fit to Langmuir equation. The adsorption capacity stayed almost constant with the increase in the temperature, whereas the k2 value increased against the temperature. These results comprehensively emphasized that BPA adsorption occurred through the chemical interaction or ionic bonding of a BPA anion to a terminal protonated dimethylamino group. Desorption of BPA increased by increasing the NaOH concentration and BPA was entirely desorbed at more than 20 mM. The cycle of adsorption at pH 8.0 and desorption in a NaOH solution at 100 mM was repeated five times without loss or structural damage. These results indicate PE-g-PDMAEMA meshes can be used as a regenerative adsorbent for BPA removal from aqueous medium.

Highly efficient activation of peroxymonosulfate via KOH-activated Fe@NC for the degradation of bisphenol A.

In this study, the KOH-modified Fe-ZIF-derived carbon materials (Fe@NC-KOH-x) were designed for Fenton-like systems to enhance bisphenol A (BPA) removal from wastewater. Compared with the Fe@NC without KOH activation, the pore structure, BET (Brunner-Emmet-Teller) surface area, and oxygen-containing functional group of KOH-activated Fe@NC-KOH-x are dramatically improved, which increases the adsorption and catalytic performance. The Fe@NC-KOH-900/PMS system showed significant BPA removal reactivity across wide pH ranges and low doses of Fe@NC-KOH-900. Interestingly, our findings indicated that the removal effectiveness of BPA improved when PMS was introduced following the saturation adsorption of Fe@NC-KOH-x, as compared to the simultaneous introduction of Fe@NC-KOH-x and PMS. More particularly, through regression analysis, we found that the proportion of reactive species in the Fe@NC-KOH-x/PMS system changes with the increase of pyrolysis temperature, and there was a certain relationship between structure-function and active species in the Fe@NC-KOH-x/PMS system. O-C = O, Fe-N4, C-O, and pyrrolic N in Fe@NC-KOH-x lead to the generation of •OH, and SO4-•, C = O, Fe-N4, and defect are closely related to FeIV = O, and the formation of 1O2 is affected by Fe-N4, graphite N, C = O, and defect. Also, the density functional theory (DFT) calculation and the potential correlation between catalyst active centers and reactive oxygen species indicate that Fe-N4 is the main active site of Fe@NC-KOH-x. These outcomes of the study offer an innovation for enhanced elimination of BPA in wastewater treatment and provide a dynamic understanding of the mechanism of BPA degradation.

Unveiling bisphenol A toxicity: human health impacts and sustainable treatment strategies.

The widespread presence of bisphenol-A (BPA) in consumer goods like water bottles and eyeglass frames raises serious concerns about the chemical's ability to accumulate in human tissues. Molecular filtration and activated carbon adsorption are two of the many BPA treatment technologies that have emerged in response to these issues; both are essential in the removal or degradation of BPA from water sources and industrial effluents. To secure the long-term health and environmental advantages of BPA treatment approaches, sustainable development is essential. Both the efficient elimination or destruction of BPA and the reduction of the treatment operations'impact on the environment are important components of a sustainable approach. Different search engines like Pub-Med, MEDLINE, Google Scholar and Scopusare used for these systematic reviews and analyzed accordingly. This can be accomplished by making treatment facilities more energy efficient and using environmentally friendly materials. Greener ways to deal with BPA pollution are on the horizon, thanks to innovative techniques like bioremediation and improved oxidation processes. Reducing dependence on conventional, resource-intensive procedures can be achieved by investigating the use of bio-based materials and natural adsorbents in treatment processes. This review article tackling the health and environmental concerns raised by BPA calls for an integrated strategy that incorporates sustainable development principles and technology progress. We can reduce the negative impacts of BPA contamination, improve environmental stewardship in the long run, and ensure human health by combining cutting-edge treatment technologies with sustainable behaviours.

Periodate activation with polyaniline-derived carbon for bisphenol A degradation: Insight into the roles of nitrogen dopants and non-radical species formation

Periodate-based advanced oxidation processes (PI-AOPs) activated by carbon catalysts have shown promising application prospects in the removal of emerging contaminants. Herein, a series of N-doped carbon catalysts (NC) were prepared by in-situ pyrolysis of N-containing polymers (polyaniline) to unveil the potential mechanism of N dopants on PI activation. The optimized sample NC700 showed a satisfying degradation performance, achieving 100 % removal of bisphenol A (BPA) at a concentration of 10 mg/L within 90 min in the presence of 0.1 mM PI. The impacts of various N types on PI activation were systematically investigated by dynamic fitting and density functional theory computations. These analyses highlighted the crucial role of graphitic N configuration on carbon surface, which exhibited the highest adsorption energy and a positive correlation with the normalized degradation efficiency. The chemical quenching experiments and electrochemical experiments confirmed that the BPA oxidation mechanism was primarily mediated electron transfer by [NC-PI]* complex, with singlet oxygen (1O2) /superoxide radicals (O2•–) playing a supplementary role. In situ ATR-SERAS measurement strengthened the understanding of PI activation by carbon catalyst based on electron transfer pathway. Owing to the non-radical oxidation mechanism, the NC/PI system had a broad pH adaptability and great anti-interference ability against typical wastewater components. This study provides mechanistic insights into the carbon-driven PI activation process for wastewater treatment, advancing the practical application of PI-AOPs.

Safe concentration, unsafe effects: Impact of BPA on antioxidant function in the hepatopancreas and ovarian gene expression in oriental river prawns (Macrobrachium nipponense)

This study investigated the effects of Bisphenol A (BPA), a common endocrine-disrupting chemical, on the antioxidant enzyme activities in the hepatopancreas and the expression of genes related to ovarian development in oriental river prawns (Macrobrachium nipponense). The 24hLC50 and 48hLC50 values for BPA were 80.59 mg/L and 63.90 mg/L, respectively, with a safe concentration of 12.06 mg/L. Prawns were exposed to low (4.85 mg/L), safe (12.06 mg/L), and high (30.00 mg/L) concentrations of BPA for 10 days to measure enzyme activities, and for 20 days followed by 7 days in BPA-free water to measure gene expression.Short-term exposure (12 h, 1d, 3d) to low concentration BPA did not significantly affect superoxide dismutase (SOD) activity in the hepatopancreas (P > 0.05), but long-term exposure (6d, 10d) significantly reduced SOD activity (P < 0.05). Catalase (CAT) activity showed no significant changes throughout the low concentration exposure period (P > 0.05). At safe and high concentrations, SOD and CAT activities significantly decreased after 12 h of exposure (P < 0.05).BPA affected heat shock protein 90 (HSP90) expression in the ovary, with low concentration BPA significantly upregulating HSP90 after 1 day (P < 0.05), but returning to normal levels after 10 and 20 days. At the safe concentration, HSP90 was significantly upregulated at all three sampling points (1d, 10d, 20d) (P < 0.05), while high concentration exposure led to significant upregulation only on day 10 (P < 0.05).Low concentration BPA had no significant effect on Cathepsin B (CB) and Cathepsin L (CL) gene expression in the ovaries (P > 0.05). However, safe concentration exposure promoted CB expression on days 1, 10, and 20 (P < 0.05), while high concentration exposure significantly increased CB expression on day 1 (P < 0.05), with levels returning to normal on days 10 and 20. CL expression significantly increased after 20 days of exposure to both safe and high concentrations (P < 0.05). Gene expression levels in the ovaries returned to normal after transfer to BPA-free water, with HSP90 and CB normalizing by day 1, and CL by day 7.These results indicate that even safe concentrations of BPA impose stress on the hepatopancreas and increase the expression of HSP90, CB, and CL genes in the ovaries, affecting ovarian development. And, these effects are reversible within a certain period after the removal of BPA.

Iron nanoparticles enhance the efficiency of single-atom Fenton-like catalyst by boosting Fe-NX activity

Single-atom catalysts (SACs) have been widely employed for the removal of organic contaminants via advanced oxidation processes (AOPs). The underlying principle involves central metal atoms that interact synergistically with surrounding atoms in specific ensembles to adsorb reactants and facilitate catalytic reactions. However, comprehensive studies exploring the ensemble effect of SACs in combination with metal nanoparticles relatively rare. In this study, we have synthesized a highly active iron single-atom catalyst (Fe@BC), which features both Fe-Nx coordination sites and iron nanoparticles. Fe@BC exhibits remarkable adsorption and degradation capabilities for bisphenol A across a wide pH range from 3.0 to 11.0. Scavenging experiments coupled with electron paramagnetic resonance analysis have revealed that •OH and O2•− are the key reactive oxygen species within the Fe@BC/PAA system, with •OH playing a crucial role in the removal of bisphenol A (BPA). Our comprehensive characterization analysis has validated the simultaneous presence of Fe nanoparticles and Fe-Nx sites, which are crucial for the catalyst's high activity. Furthermore, our experimental data highlight the importance of the synergistic effect between these two components. Density Functional Theory calculations have provided additional insights, showing that the presence of iron nanoparticles significantly boosts the Fe-Nx sites' activity. This enhancement is achieved by increasing adsorption energy, promoting electron transfer to peracetic acid (PAA), and decreasing the energy barrier for the formation of active species. These findings are vital for the strategic refinement of Fe single-atom catalysts for PAA-based advanced oxidation processes.

LaCuMnOx perovskite activating persulfate for the degradation of bisphenol A: excellent tolerance to hypersaline environment

AbstractBackgroundLaCuMnOx (LCMO) perovskite was designed as an effective catalyst to activate peroxydisulfate (PDS) to remove bisphenol A (BPA) in hypersaline wastewater.ResultsIn the LCMO/PDS system, BPA (10 mg/L) was removed completely and the mineralization degree reached 74.9% in the presence of 0.12 g/L catalyst and 1.2 mM PDS. The BPA removal efficiency was still almost 100% even after five cycles. Metal ion leakage also indicated the stability of the catalytic system. •OH, SO4•−, 1O2, and O2•− all contributed to BPA removal, and O2•− accounted for the greatest contribution. The presence of oxygen vacancies (Vo··) on the surface of the catalyst was important for PDS activation and the formation of active species. In addition, the system could still maintain outstanding performance even when [Cl−] and [SO42−] were 100 g/L. CO32− and HCO3− inhibited BPA degradation greatly, even at very low concentrations. The inhibitory effect was related to changes in the pH of the solution caused by the addition of CO32− and HCO3−. This effect could be eliminated by adjusting the pH.ConclusionThe system showed excellent catalytic performance, stability, and inorganic anion tolerance, indicating its potential for application in hypersaline wastewater treatment. © 2024 Society of Chemical Industry (SCI).

Sustainable hydrochar as an efficient persulfate activator for cost-effective degradation of bisphenol A

This study explored Mason pine-derived hydrochar (MPHC) as an effective adsorbent and persulfate (PS) activator for degrading bisphenol A (BPA). Increasing MPHC dosage from 0.25 to 2.0 g L−1 raised BPA removal from 42% to 87%. Similarly, at the same MPHC dosage range and fixed PS concentration (8 mM), BPA removal by MPHC/PS increased from 66% to 91%. Additionally, at a fixed MPHC dosage (1.0 g L−1), higher PS concentrations (2–32 mM) resulted in an overall BPA removal increase from 78% to 99%. The optimal pH for BPA removal by MPHC was at pH 3, while for MPHC/PS was at pH 9. BPA degradation by MPHC was optimal at pH 3, whereas MPHC/PS was at pH 3 and pH 9. Additionally, pH 7 favored BPA adsorption for both MPHC and MPHC/PS. The study also considered the influence of coexisting anions and humic acid (HA). PO43− and NO3− influence adsorption on MPHC, but these anions' effect on MPHC/PS is limited. Furthermore, the existence of HA had minimal influence on BPA removal by MPHC/PS. The contributions of different reactive species by MPHC for BPA degradation are as follows: electron-hole (h+) 2%, singlet oxygen (1O2) 7%, superoxide radicals (O2•–) 13%, electron (e–) 2%, hydroxyl radical (•OH) 3%, whereas the remaining 48% removal was the contribution of adsorption. For MPHC/PS, adsorption accounted for 39 %, more reactive species were involved in degradation, and the donations are (h+) 3%, sulfate radicals (SO4•–) 3%, (1O2) 19%, (O2•–) 15%, (e–) 2%, and (•OH) 2%. Additionally, the performance of MPHC remains stable after three operational cycles. The preparation cost of MPHC is 3.01 € kg−1. These results highlight the potential of MPHC as an environmentally friendly material for activating PS and removing organic pollutants, suggesting its promising application in future environmental remediation efforts.

Bismuth niobate/g-C3N4 heterojunction for maximised visible light photocatalytic removal of Bisphenol A

The occurrence of xenobiotic pollutants in the aquatic environment troubling the present and future generation. Persistent Organic Pollutants (POPs) is one such class of xenobiotic that was dominant in that category. In the present paper, a competent visible light driven heterojunction photocatalyst combining Bismuth niobate and g-C3N4 was developed for the effective removal of Bisphenol A (BPA), a notable POP. Before constructing the heterostructure the calcination temperature for bismuth niobate synthesis was optimised for achieving most proficient photocatalysis. A phase change in the crystal structure of bismuth niobate was apparent. The Bi3NbO7 at 300–500 °C transformed to Bi5Nb3O15 at 600–700 °C and to orthorhombic BiNbO4 at 900 °C as the temperature was enhanced. With the increment in the temperature the light absorbance of the materials enhanced in UV and reduced in visible light. Thus, the bismuth niobate obtained by calcining at 500 °C demonstrated highest BPA removal under sunlight was chosen for heterojunction construction. After the heterojunction construction with g-C3N4 the crystal lattice strain was observed to be reduced for all composites, and a greater mobility of charge carriers was observed within the composite. The presence of either of the materials resulted in a different band structure and thus Type II and Z-scheme pathway was inferred. A commendable photocatalytic activity was observed for B1.5G and BG1.5 under sunlight and LED light respectively. Hight amount of g-C3N4 in the BG1.5 resulted in maximum absorbance in LED light. Superoxide radicals (*O2−) radicals were observed as major radicals for B1.5G composite, whereas both *O2− and holes (h+) were the major radicals in case of BG1.5.

A novel visible light-driven oxygen doped C3N4/Bi12O17Cl2/ferrate(VI) system for Bisphenol A degradation: Radical and nonradical pathways

In this study, visible light-activated photocatalyst oxygen-doped C3N4@Bi12O17Cl2 (OCN@BOC) and Fe(VI) coupling system was proposed for the efficient degradation of bisphenol A (BPA). The comprehensive characterization of the OCN@BOC photocatalyst revealed its excellent photogenerated carrier separation rate in heterogeneous structures. The OCN@BOC/Fe(VI)/Vis system exhibited a remarkable BPA removal efficiency of over 84% within 5 min. Comparatively, only 37% and 59% of BPA were degraded by single OCN@BOC and Fe(VI) in 5 min, respectively. Reactive species scavenging experiments, phenyl sulfoxide transformation experiments, and electron paramagnetic resonance experiments confirmed the involvement of superoxide radicals (⋅O2−), singlet oxygen (1O2), as well as iron(V)/iron(IV) (Fe(V)/Fe(IV)) species in the degradation process of BPA. Furthermore, density functional theoretical calculations and identification of intermediates provided insights into the potential degradation mechanism of BPA during these reactions. Additionally, simulation evaluations using an ecological structure activity relationship model demonstrated that the toxicity of BPA to the ecological environment was mitigated during its degradation process. This study presented a novel strategy for removing BPA utilizing visible light photocatalysts, highlighting promising applications for practical water environment remediation with the OCN@BOC/Fe(VI)/Vis system.

Removal of bisphenol A (BPA) from aqueous solution by potassium carbonate modified wetland plant biochars

Bisphenol A (BPA) is a known endocrine disruptor that is acutely toxic to the living organisms. In this study, the wetland plants Phragmites australis and Typha orientalis were subjected to carbonize at 500 °C for different durations (4, 5, and 6 h) and varying mass ratios of wetland plants to potassium carbonate (1:2, 1:1, and 2:1). The prepared modified biochars were used to treat BPA in solution to explore the effect of contact time and initial concentration of BPA on adsorption performance. Both adsorption kinetic models and isotherm models were also studied. The results demonstrated a gradual increase in the adsorption capacity of Phragmites australis and Typha orientalis biochars for BPA with prolonged contact time. Furthermore, an enhancement in the adsorption capacity was observed with increasing initial BPA concentration. The modified biochars significantly enhanced BPA removal and adsorption capacities for BPA compared to the unmodified biochars. L55C (Phragmites australis carbonized at 500 °C for 5 h with a mass ratio of 2:1) and X54C (Phragmites australis carbonized at 500 °C for 4 h with a mass ratio of 2:1) exhibited the largest total surface areas, total pore volumes, microporous surface areas and microporous volumes, and achieved maximum adsorption capacities of 8.547 and 8.117 mg/g, respectively. The adsorption processes were fitted with pseudo-second-order adsorption kinetic models and Langmuir models. The adsorption processes were monolayer chemical adsorption.

Enhanced activation of peroxymonosulfate with cobalt-doped manganese-iron oxides for contaminant degradation: Regulation of oxygen vacancy defects

Peroxymonosulfate (PMS) based on heterogeneous catalytic reaction was a promising advanced oxidation process (AOP) to remove refractory contaminants. However, the contaminant degradation efficiency was challenged by the limited number of catalytic active site and low capacity for durable electron transfer. In this study, cobalt-doped manganese-iron oxides (CoxMn1-xFe2O4) rich in oxygen vacancy (Ov) were synthesized using a microwaved hydrothermal method and applied to activate PMS for bisphenol A (BPA) degradation, which achieved the complete removal of BPA within 30 min. In all samples, Co0.5Mn0.5Fe2O4 exhibited good catalytic activity for PMS, which was approximately 21.10 times higher than that of MnFe2O4. The results of density functional theory calculations and in-situ characterization demonstrated that the enhanced performance was ascribed to the generation of Ov and the enrichment of active site, which significantly accelerated the cycling of redox pairs and improved the PMS adsorption, which was more favorable to the formation of active specie in the electron transport process. The oxidation process involved both free radical and non-radical mechanisms, with main reactive species of O2−, and 1O2 being responsible for BPA degradation. In addition, the effects of different aqueous matrices, the results of reusability experiments, and ecotoxicity assessment experiments demonstrated the viability of the Co0.5Mn0.5Fe2O4/PMS system for real sewage purification. This research revealed a structural regulation method to enhance the catalytic activity of the material and offered new perspectives on the engineering of rich Ov.