Mineralization Of Bisphenol A Research Articles

Catalytic activation of persulfate by nanoscale zero-valent iron-derived supported boron-doped porous carbon for bisphenol A degradation.

In this study, boron-doped porous carbon materials (BCs) with high surface areas were synthesized employing coffee grounds as carbon source and sodium bicarbonate and boric acid as precursors; afterward, nanoscale zero-valent iron (nZVI) and BCs composites (denoted as nZVI@BCs) were further prepared through reduction of FeSO4 by NaBH4 along with stirring. The performance of the nZVI@BCs for activating persulfate (PS) was evaluated for the degradation of bisphenol A (BPA). In comparison with nZVI@Cs/PS, nZVI@BCs/PS could greatly promote the degradation and mineralization of BPA via both radical and non-radical pathways. On the one hand, electron spin resonance and radical quenching studies represented that •OH, SO4•-, and O2•- were mainly produced in the nZVI@BCs/PS system for BPA degradation. On the other hand, the open circuit voltages of nZVI@BCs and nZVI@Cs in different systems indicated that non-radical pathway still existed in our system. PS could grab the unstable unpaired electron on nZVI@BCs to form a carbon material surface-confined complex ([nZVI@BCs]*) with a high redox potential, then accelerate BPA removal efficiency via direct electron transfer. Furthermore, the performances and mechanisms for BPA degradation were examined by PS activation with nZVI@BC composites at various conditions including dosages of nZVI@BCs, BPA and PS, initially pH value, temperature, common anions, and humid acid. Therefore, this study provides a novel insight for development of high-performance carbon catalysts toward environmental remediation.

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.

Effects of cobalt salts on biomass conversion to functional carbon-based catalysts for peroxymonosulfate activation

Metal functionalization is an effective structure-engineering strategy for preparing biomass-derived carbon materials, whereas the influences of different metal precursors on the structure and catalytic performance remain unclear. Herein, an investigation of four typical cobalt salts for pyrolytic biomass conversion is performed. The melting points and anion species of cobalt salts are found to be critical factors. Co-salts (cobalt nitrate (Co(NO3)2), cobalt acetate (Co(OAc)2), cobalt acetylacetonate (Co(acac)2)) melted at low temperatures (≤165 °C) could promote mesopore formation and catalyze the graphitization process of a biomass flower during the carbonization, finally forming mesoporous graphitic carbon matrixes with Co@graphitic-C nanoparticles and trace isolated Co atoms as active catalytic sites (denoted as Co@C-NO3, -Ac, -acac). By comparison, high-melting-point (735 °C) CoSO4/biomass pyrolysis produces an amorphous carbon/Co9S8 nanoparticle composite (denoted as Co9S8@C-SO4), with Co9S8 as active sites. Co@C-NO3 and Co9S8@C-SO4 demonstrated excellent activities with the reaction rates of 0.21 and 0.29 min−1, respectively, in peroxymonosulfate (PMS) activation for bisphenol A (BPA) degradation with distinct catalytic mechanisms. Co@C-NO3/PMS shows multiple nonradical/radical pathways with 40.9% mineralization of BPA, while Co9S8@C-SO4/PMS demonstrates a selective sulfate radical-based reaction pathway to achieve 99.8% mineralization of BPA. Co@C-NO3 and Co9S8@C-SO4 presented excellent performance for multiple organic pollutant removal (100%) in real water and good regeneration ability by thermal treatment of the reclaimed samples at 400 °C. This study provided a novel insight into rational design of biomass-derived carbon-based catalysts with desired active sites to meet a different catalytic demand.

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.

A Comparison Study between Wood Flour and Its Derived Biochar for the Enhancement of the Peroxydisulfate Activation Capability of Fe3O4

In this study, both wood flour (WF) and wood flour-derived biochar (WFB) were used as supports for Fe3O4 to activate peroxydisulfate (PDS). The role of different carriers was investigated emphatically from the aspects of catalyst properties, the degradation kinetics of bisphenol A (BPA), the effects of important parameters, and the generation of reactive oxygen species (ROS). Results showed that both WF and WFB could serve as good support for Fe3O4, which could control the release of iron into solution and increase the specific surface areas (SSAs). The WFB/Fe3O4 had stronger PDS activation capability than WF/Fe3O4 mainly due to the larger SSA of WFB/Fe3O4 and the PDS activation ability of WFB. Both radical species (•OH and SO4•−) and non-radical pathways, including 1O2 and high-valent iron-oxo species, contributed to the degradation of BPA in the WFB/Fe3O4–PDS process. Moreover, the WFB/Fe3O4 catalyst also showed stronger ability to control the iron release, better reusability, and higher BPA mineralization efficiency than WF/Fe3O4.

Steering •OH-triggered radicalization of surface phosphate functionality and its protonated analogues to accelerate mineralization of aqueous organic wastes

Herein, iron oxide served as a host to support mono-dentate H3-XPO4X- guests (H3-XPO4X-SUP; X = 1–3), whose relative compositions were varied by calcining a synthetic intermediate at 250–450 °C. This could produce H2PO4-SUP-rich P250, HPO42-SUP-rich P350, and PO43-SUP-rich P450 catalysts, all of which were subjected to characterizations, DFT calculations, and kinetic assessments of bisphenol A (BPA) mineralization runs for justifying six compelling findings specified below. The catalysts could proceed with the overall •OH → H3-XPO4•(X-1)-SUP route consisting of heterolytic H2O2 dissection and •OH → H3-XPO4•(X-1)-SUP cycles, where the former was enabled by Lewis acidic (LA) sites to generate •OH, whereas the latter was enabled using •OH as a radicalizer of H3-XPO4X-SUP functionalities to exothermically generate H3-XPO4•(X-1)-SUP analogues. Of significance, the overall •OH → H3-XPO4•(X-1)-SUP route energetically hinged on endothermic •OH desorption from LA sites. H2PO4-SUP was most adequate to reduce LA strength, desorbed •OH in the easiest manner, thereby rendering P250 to display the smallest energy barrier (EBARRIER) among P250-P450. Of additional significance, PO43-SUP bore the largest number of P+-O- bonds available to •OH → H3-XPO4•(X-1)-SUP cycle, elevated collision frequency of •OH ↔ H3-XPO4X-SUP or H3-XPO4•(X-1)-SUP ↔ pollutant in the most efficient fashion, thus making P450 exhibit the largest pre-factors (kAPP, 0) among P250-P450. In addition, EBARRIER outweighed kAPP, 0 in dictating BPA mineralization efficiencies for P250-P450, among which P250 with the largest H2PO4-SUP composition revealed the greatest BPA mineralization rate, while sustaining BPA mineralization multiple times via electron transfer pathway. Moreover, H3-XPO4•(X-1)-SUP outperformed conventional •OH and SO4•-SUP/NO3•SUP analogues in mineralizing real wastewaters.

E-waste derived CuAu bimetallic catalysts supported on carbon cloth enabling effective degradation of bisphenol A via an electro-Fenton process

Extensive utilization and excessive accumulation of bisphenol A (BPA) has posed a serious threat to the whole ecosystem, necessitating the rational design of metal-based catalysts capable of complete mineralization of BPA via electrochemical oxidation. Considering the shortage of metals resources and ever-increasing generation of electronic waste (e-waste), converting e-waste into high-performance catalysts is highly expected to offer an economical and feasible means to achieve the degradation of BPA. To this end, CuAu bimetallic catalysts are in situ electro-codeposited on the carbon cloth (CC) support with the waste central processing unit (CPU) leachate as electrolyte. Significantly, the recovered CuAu/CC composites can be directly applied as an efficient electrocatalyst for the decontamination of BPA via the electro-Fenton process. The electrocatalytic activities of the fabricated CuAu/CC electrodes can be regulated by tuning the reduction potentials during electro-deposition process. Under the optimized operational conditions, 99.5 % of BPA (50 mg/L) is removed within 120 min at a constant cathodic potential of −1.0 V (vs Ag/AgCl) in the CuAu/CC-mediated electro-Fenton system, accompanied by 64.2 % of total organic carbon (TOC) removal, highlighting a satisfactory performance of the BPA electrochemical oxidation. In addition, the proposed CuAu/CC electrode material can be facilely regenerated and reused for at least ten cycles without significant decline in BPA removal efficiency. Our work offers valuable guidance for upcycling of bimetallic alloy catalysts from e-waste and further application in electrochemical decontamination of organic pollutants, achieving the innovative target of “using waste to treat waste.”

Will the photocatalytic ceramic membrane be the solution for the next generation of photocatalysis? - A comprehensive comparison between g-C3N4 powder and g-C3N4 modified ceramic membrane

To address the catalyst recovery issue in traditional photocatalysis processes, photocatalytic membrane reactors have emerged as a novel technology in recent years. However, the understanding of the differences in photocatalytic performance and mechanism between the membrane and slurry systems is missing. The current study provided a comprehensive comparison between the photocatalytic slurry system (CN-P) and membrane system (CN-M) in terms of bisphenol A (BPA) degradation and mineralization, in which the well-developed g-C3N4 was chosen as the catalyst. The fabrication of CN-M was optimized via tuning initial urea concentration, and a series of characterization technologies confirmed the successful incorporation of g-C3N4 onto the membrane. Different reaction mechanisms were proposed in two systems via the identification of contributed reactive species and the degradation products. The “sea anemone effect” in the membrane system enhanced the mass transfer between the reactive species and the BPA molecules and promoted the BPA mineralization with less toxic intermediates. Furthermore, the CN-M exhibited excellent anti-fouling and self-cleaning properties with a much lower irreversible fouling resistance than the original membrane and could be regenerated rapidly after visible light irradiation. These findings provided new insights for the CN-M system as a promising and reliable alternative to the traditional photocatalytic process, which is of great significance and importance in promoting the practical application of photocatalytic membranes in water treatment.

Oxidation of bisphenol-A by ozone microbubbles: Effects of operational parameters and kinetics study

The removal of bisphenol-A (BPA) from aqueous medium by ozone microbubbles (OMBs) was studied in this work. The removal efficiency of BPA was improved from 41 to 98% within 600 s of ozonation when the initial pH of the medium was increased from 3 to 7. The stoichiometric ratio of the moles of ozone consumed to the moles of BPA removed was found to be in the range of 0.228–0.276 at pH 7 and 0.125 mol m − 3 initial concentration of BPA. A considerably high range of ozone utilization efficiency (i.e., 52%–86%) for the complete removal of BPA was achieved by using the OMBs. Based on the TOC removal, three stages of ozonation (i.e., 0–0.6, 0.6–2.5, and 2.5–3.0 ks) were observed. Their corresponding (observed) reaction rate constants were 294.1, 1365.3, and 2477.7 dm 3 mol − 1 s − 1 , respectively. The oxidation of BPA by ozone followed a first-order kinetics with respect to both BPA and ozone, and an overall second-order kinetics. The Hatta number was low (i.e., 0.01–0.054), which proves that the mass transfer resistance was negligible, implying that the rate of mass transfer was enhanced by the OMBs. • OMBs were very efficient for the oxidation and mineralization of BPA. • Oxidation of BPA was achieved both by the direct and indirect reactions with ozone. • A high range of ozone utilization efficiency was achieved by the OMBs. • Based on the TOC removal, three stages of ozonation were observed. • The low Hatta number proved that the mass transfer resistance was negligible.

Mechanistic study of oxidative removal of bisphenol A by pristine nanocatalyst Mn3O4/peroxymonosulfate

• Mn 3 O 4 nanocatalyst showed excellent mineralization of BPA. • 1 O 2 was the dominant reactive oxygen species in BPA degradation. • Oxygen vacancy played a vital role in generation of 1 O 2 . • β-scission reaction was the main transformation pathway for the degradation of BPA. • 13 transformation products were decreased while 4 were increased. In recent years, activation of persulfate via Mn-based composites has gained interest due to extraordinary kinetics and performance for the degradation of organic contaminants. However, the potential of pristine manganese oxides (Mn 3 O 4 ) in removing organic compounds and its mechanism has not been comprehensively explored yet. This study systemically investigated the Mn 3 O 4 based peroxymonsulfate (PMS) activation to effectively mitigate bisphenol A (BPA) in different real water matrixes. Substantial mineralization (75.9%) with efficient removal of BPA (96.7%) has been achieved at optimum conditions in 60 min. A long-term performance, eight cycles of reusability, has shown merely an 11% reduction in BPA removal, highlighted the higher stability of Mn 3 O 4 . The oxidizing contributions of reactive oxygen species (ROS) were in the order of 1 O 2 > O 2 •- > SO 4 •- > • OH. The different water matrixes have influenced BPA degradation by<10%. Linear changes in BPA aromatic contents were recorded using log-transformed ultraviolet (UV) spectra and fluorescence excitation-emission matrix (EEM). Total 17 transformation products (TPs) were detected in Mn 3 O 4 /PMS/BPA system, with 13 decreasing concentrations and 4 TPs in increasing concentration with the β-scission reaction as the main pathway for the degradation of BPA. The toxicity of BPA after degradation was also significantly suppressed measured by the activated sludge inhibition method.

Mechanism of peroxymonosulfate activation and the utilization efficiency using hollow (Co, Mn)3O4 nanoreactor as an efficient catalyst for degradation of organic pollutants

Development of efficient catalysts for peroxymonosulfate (PMS) activation and further understanding its mechanism on organic pollutants degradation is of significant importance for advanced oxidation processes (AOPs). Herein, hollow (Co, Mn)3O4 catalysts were synthesized by calcination of Co, Mn containing metal-organic frameworks (MOFs) and further used to evaluate the effectiveness of organic pollutants (Bisphenol A (BPA), atrazine (ATZ), and diethyl phthalate (DEP)) degradation by PMS activation. The PMS utilization efficiency in (Co, Mn)3O4/PMS system (36.4%) was estimated to be 28.0% and 43.8% higher than that of Co3O4/PMS and Mn5O8/PMS system, respectively. Notably, the metal leaching in (Co, Mn)3O4/PMS system was significantly suppressed. The utilization efficiency also reveals an inverse proportionality relationship with BPA mineralization but decreases with increasing initial pH value. A synergy between oxides of Co and Mn was perceived to enhance PMS utilization efficiency and BPA degradation. The results indicate enhanced catalytic performance with (Co, Mn)3O4 compared to Co3O4 derived from Co-MOF and other reported catalysts, with 99% of BPA degradation within 4 min. The oxidation mechanism was then proposed based on the electron paramagnetic resonance (EPR) and XPS results. Our findings might have contributed to designing heterogeneous catalysts for efficient PMS utilization in AOPs.

ZnO-CdO nanocomposites incorporated with graphene oxide nanosheets for efficient photocatalytic degradation of bisphenol A, thymol blue and ciprofloxacin

The widespread existence of different organic contaminants mostly phenolic compounds, organic dyes and antibiotics in water bodies initiated by the various industrial wastes that raised great scientific concern and public awareness as well recently owing to their prospective capability to spread these contaminants resistant gene and pose hazard to human. In the present study, a series of nanostructured ZnO-CdO incorporated with reduced graphene oxide (ZCG nanocomposites) were successfully synthesized by a simple refluxing method and characterized by using the X-ray diffraction (XRD), Raman spectroscopy, FT-IR spectroscopy, photoluminescence spectroscopy, field emission-scanning microscope (FE-SEM) and UV–visible diffused reflectance spectroscopy (DRS) for the photocatalytic degradation of bisphenol A (BPA), thymol blue (ThB) and ciprofloxacin (CFn) with illumination of UV light. The maximum degradation and mineralization of BPA, ThB and CFn was achieved around 98.5%, 98.38% and 99.28% over the ZCG-5 nanocomposite photocatalyst after UV light irradiation for 180 min, 120 min and 75 min, respectively. The superior photocatalytic activity of ZCG-5 ascribed to enhance adsorption capacity, effective separation of charge carriers consequential for the production of more ROS after incorporation of RGO nanosheets with ZnO-CdO in photocatalyst. The conceivable photocatalytic degradation mechanism of BPA, ThB and CFn was elucidated through ROS identification and the assessment of photocatalyst stability by reusability, EEO (kwh/m3order) and UV light dose (mJ/cm2) were evaluated. The plausible photocatalytic degradation pathways were proposed for the degradation of BPA, ThB and CFn via GC-MS analysis. The present work investigates the efficient removal of BPA, ThB and CFn using ZCG nanocomposites as photocatalyst.

Ultrasound-activated peroxydisulfate process with copper film to remove bisphenol A: Operational parameter impact and back propagation-artificial neural network modeling

Combining the ultrasound and peroxydisulfate (US-PDS) process, offers a promising advanced oxidation method to remove organic compounds from aqueous solutions. This study evaluated the activation of PDS by US irradiation based on bisphenol A (BPA) degradation experiments; the effect of copper film (CF) as a metal catalyst was also tested. The BPA degradation efficiency of PDS as an oxidizing agent was compared to H2O2 under US irradiation; PDS was effectively activated by ultrasound and through ultrasound-derived heat. The presence of CF in the system was also observed to significantly enhance BPA degradation. The performance of three single systems (US, PDS, and CF), three dual systems (US-PDS, US-CF, and PDS-CF), and one triple system (US-PDS-CF) were compared. It was found that the US-PDS-CF triple system exhibited the highest BPA degradation of 99.51% within 30 min. The effect of operating parameters on degradation efficacy was investigated; BPA degradation was stimulated by the elevation of ultrasound power (38.87–97.17 W), temperature (30–70 °C), and initial PDS concentration (1.71–17.11 mM). Artificial neural network modeling was utilized to determine the significance of these operational parameters in BPA degradation. It was estimated that the importance of these parameters was, in order, temperature (46.83%) > initial PDS concentration (40.54%) > ultrasound power (12.63%). Furthermore, BPA mineralization was studied in the US-PDS and US-PDS-CF systems. These findings facilitate an understanding of the US-PDS process to degrade organic compounds.

A novel photon-enzyme cascade catalysis system based on hybrid HRP-CN/Cu3(PO4)2 nanoflowers for degradation of BPA in water

Inspired by the multi-enzymes cascade catalysis, a novel photon-enzyme cascade catalysis system described as hybrid HRP-CN/Cu3(PO4)2 nanoflowers was constructed successfully for the first time. It not only exhibits excellent immobilized enzyme enzymatic properties but also has better tolerance to extreme acid, alkali and high temperature compared with the free HRP. Moreover, the encapsulation yield of HRP reaches up to 36.2% and the residual activity after 5 cycles still has 83.6% over HRP-CN/Cu3(PO4)2 catalyst. Specifically, the HRP-CN/Cu3(PO4)2 showed excellent degradation performance for bisphenol A (BPA), which reached up to 72.98% far more than that of CN/Cu3(PO4)2 (41.89%) and HRP/Cu3(PO4)2 (4.71%). Those unique advantages are mainly owing to the introduction of photocatalyst (g-C3N4), which not only increases the encapsulation yield of HRP, but also realizes the complete mineralization of BPA. The photon-enzyme cascade catalysis system could replace the traditional system composed of glucose oxidase and horseradish peroxidase (GOx&HRP) for the harmless treatment of BPA, providing a new strategy for HRP in wastewater treatment.

Activation of peroxymonosulfate by CuFe2O4-CoFe2O4 composite catalyst for efficient bisphenol a degradation: Synthesis, catalytic mechanism and products toxicity assessment

In this research, the CuFe2O4-CoFe2O4 metallic oxides catalyst (donated as CCF) was synthesized by solvothermal method and applied to degrade bisphenol A (BPA) by activating peroxymonosulfate (PMS). The different influences containing initial PMS concentration, pH, catalyst dosage, coexisting ions and reaction temperature on the degradation efficiency of BPA were systematically investigated. The CCF exhibited 99.3% removal efficiency and 72.5% mineralization of BPA. Notably, compared with the reported metallic catalysts, CCF exhibited much lower amount of metal leaching during the degradation process. The superior catalytic activity and stability of CCF was attributed to the synergistic effects of Co2+/Co3+, Cu+/Cu2+ and Fe2+/Fe3+ redox cycles. The SO4•− and •OH were detected by chemical scavenging and electron paramagnetic resonance (EPR) tests while SO4•− might play a dominant role for BPA degradation. Furthermore, the catalytic mechanism was proposed and analyzed the toxicity of reaction system. The toxicity of BPA and its oxidation intermediates were predicted by ECOSAR model and activity inhibition experiments to demonstrate that BPA was ultimately mineralized as a non-toxic product. This study suggests that the prepared CCF is an efficient and environmentally friendly catalyst for activating PMS, which has an enormous potential application in practical waste water treatment.

Efficient catalytic ozonation of bisphenol A by three-dimensional mesoporous CeOx-loaded SBA-16

Herein, we demonstrated the construction of three-dimensional (3D) cerium oxide (CeOx)/SBA-16 nanocomposites for efficient removal of bisphenol A (BPA) via a catalytic ozonation, with a high BPA mineralization up to 60.9% in 90 min. On one hand, the CeOx/SBA-16 mesoporous structured materials presented large surface area and uniform pore distribution, which was conducive to the adsorption of transformation by-products (TBPs) and then, the mass transfer. On the other hand, CeOx/SBA-16 could enhance the ozone utilization efficiency and meanwhile facilitate the formation of OH, the main reactive oxygen species. Through the exploration of dissoluble organic matters and the identification of the reaction intermediates, two BPA degradation pathways were proposed. This approach reported here will benefit the design and construction of mesoporous structured materials for catalytic elimination of hazards to remediate the environment.

Anodic oxidation of bisphenol A by different dimensionally stable electrodes.

Bisphenol A (BPA) is a known endocrine disrupter and was detected in surface waters. We investigated the mineralization of BPA by electrochemical oxidation. Six different types of electrodes, including the boron-doped diamond (BDD), platinum (Pt), and mixed metal oxide (MMO) electrodes; RuO2-IrO2, RuO2-TiO2, IrO2-Ta2O5, and Pt-IrO2, were compared as the anode material. Total organic carbon (TOC) was analyzed to monitor the mineralization efficiency of BPA. BDD achieved 100% BPA mineralization efficiency in 180 min and at a current density of 125 mA/cm2, whereas the TOC removal efficiency of Pt was 60.9% and the efficiency of MMO electrodes ranged between 48 and 54%. BDD exhibited much lower specific energy consumption, which corresponds to a lower energy cost (USD63.4 /kg TOC). The effect of operational parameters showed that the BDD anode was much more affected by the current density, initial BPA concentration, and electrolyte concentration than the other parameters such as the stirring speed and interelectrode distance.

Oxidative degradation and mineralization of the endocrine disrupting chemical bisphenol-A by an eco-friendly system based on UV-solar/H2O2 with reduction of genotoxicity and cytotoxicity levels

A solar-driven advanced oxidation process at a lab scale was studied for the degradation and mineralization of the known endocrine disrupting chemical (EDC), bisphenol A (BPA). Preliminary tests were performed varying the irradiation source, BPA/H2O2 ratio, temperature, initial H2O2 concentration, initial solution pH, and initial BPA concentration, then, the operational conditions of the UV-solar/H2O2 were optimized by a response surface methodology (RSM), providing the following responses: UV-solar/H2O2 process at pH 3.0, [BPA]0 = 25 mg L−1, [H2O2] = 350 mg L−1, T = 50 °C, achieving BPA degradation of 77.4% and BPA mineralization of 38.2%, H2O2 consumption of 230 mg L−1. From the optimized condition, different pH ranges were tested (3.0; 5.0; 7.0; 9.0; and 11.0), where, at solution pH 5.0 the best removal rates were achieved (89.2% BPA degradation and 49.0% BPA mineralization). The BPA amount in solution was monitored by High Performance Liquid Chromatography (HPLC) and a study of the intermediate reaction by-products was performed by Gas Chromatography–Mass Spectrometry (GC–MS) analyses, highlighting the lower amount of by-products identified when the solution pH 5.0 was employed, rather than the solution pH 3.0. Genotoxicity tests with Zebrafish (Danio rerio) and cytotoxicity tests with Allium cepa were performed aiming to evaluate errors in the cells and nuclear abnormalities of the tested organisms induced by BPA raw samples, as well as by the BPA samples treated by the UV-solar/H2O2 process. Therefore, the bio-toxicity levels for an animal and a vegetal bio-indicator were reduced by applying a renewable source of energy as the irradiation source for the UV/H2O2 process, representing an efficient and eco-friendly alternative for BPA treatment in aqueous solutions.

Sonochemical degradation of bisphenol A using persulfate activated by hematite nanoparticles.

In this study, hematite nanoparticles (HNPs) were used as the persulfate (PS) activator for the sonocatalytic degradation of bisphenol A (BPA). The physicochemical properties of the synthesized HNPs were investigated using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). The effect of different operational parameters (pH, nanoparticle dosage, persulfate concentration, and ultrasonic power) on catalytic activity were evaluated. The BPA degradation rate was improved when ultrasonic (US) irradiation was used simultaneously with HNPs for activating PS. According to the results, 98.94% of BPA (10 mg/L) was degraded within 15 min of reaction time at 4 mM persulfate and 0.01 g/L HNPs under ultrasonic irradiation of 250 W. The degree of mineralization of BPA was measured using chemical oxygen demand (COD), and 36.98% was achieved under optimum conditions. Quenching tests were done using different scavenger compounds; these showed that both hydroxyl and sulfate radicals were reactive species in BPA degradation. According to the results of reusability tests, the degradation efficiency decreased to 86.34%, indicating that HNPs can be recycled several times. All of the anions tested, but mainly hydrogen phosphate, had an inhibitory effect on BPA degradation. The results showed that the US/HNPs/PS process is effective for the degradation of the organic pollutants.

Heterogeneous activation of peroxymonosulfate for bisphenol A degradation using CoFe2O4 derived by hybrid cobalt-ion hexacyanoferrate nanoparticles

A facile coprecipitation-thermal method is reported to prepare spinel cobalt ferrites CoFe2O4 nanoparticles (NPs) with a well-defined mesoporous dominated structure using hybrid cobalt-ion hexacyanoferrate (CoFeHCF) NPs as a template. The properties of the synthesized catalysts are evidenced by various characterization methods. And the effects of time, pH, catalyst/oxidant/BPA dosage, coexisting ions and natural organic matter (NOM) on catalytic degradation of bisphenol A (BPA) are investigated. The as-prepared CoFe2O4 shows a high catalytic performance of 97% elimination for 45 μM BPA in 40 min. The excellent catalytic performance could be attributed to the large specific surface area (66.18 m2/g) and high content of cobalt (the atomic ratio of Fe/Co is 1.86) of CoFe2O4 NPs. Slightly alkaline pH, higher catalyst dosage and anions including Cl− and CO32−/HCO3− are favorable for BPA degradation. Especially, 81.57% mineralization of BPA could be achieved in 60 min under the optimization system. The catalytic capacity of CoFe2O4 could be regenerated by simple washing and drying at 200℃, which is much lower than the crystal temperature. SO4∙− and HO∙ are the primary reactive species responsible for BPA oxidation while SO4∙− might play a dominant role. This work provides a novel method to produce CoFe2O4 nanocatalysts for contaminant degradation and encourage the extended application of CoFeHCF in the environment.