Oxidation Of Bisphenol A Research Articles

Titanium carbide MXene and V2O5 composite-based electrochemical sensor for detection of bisphenol A

In recent years, 2D layered titanium carbide (Ti3C2Tx) MXene has been widely used in the electrochemical sensing of various analytes. This paper focuses on fabricating a glassy carbon electrode modified with Ti3C2Tx MXene and V2O5. The electrochemical studies for the detection of bisphenol A (BPA) have been carried out using the modified glassy carbon electrode (GCE) electrode and also the electrochemical oxidation of BPA has been described through cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS) techniques. The voltammetric behavior of the material by detecting BPA in different concentrations has been studied. The materials have been synthesized and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and Energy-Dispersive X-ray spectroscopy (EDX). The differential pulse voltammetry exhibits a linear range from 414 nM − 31.2 µM with a detection limit of 87 nM for BPA. This novel BPA sensor showed satisfactory results and also it has the potential to create a great platform in the environmental monitoring system.

Palladium nanoparticles anchored MoS2-MXene composite modified electrode for rapid sensing of toxic bisphenol A in aqueous media

Bisphenol A (BPA) is a commonly used, highly toxic organic phenolic that can damage the human nervous, reproductive, and immune systems, and thus, a rapid onsite test method is required to detect BPA in environmental samples. In this research, we coated screen-printed carbon electrodes (SPCEs) with Pd nanoparticles (NPs) anchored on a MoS2-modified MXene nanoarchitecture for the accurate onsite sensing of BPA contamination in aquatic environmental samples. Pd-MoS2-MXene-SPCEs were prepared using a one-step hydrothermal technique followed by chemical reduction. The optimized SPCE had a low Rctof 63 Ω and excellent electrocatalytic efficiency for BPA oxidation and a remarkably high current density at the lowest anodic potential (0.57 V vs. Ag/AgCl) in 0.05 M phosphate buffer (pH 7). The charge-transfer rate (ks) and the saturation absorption capacity (or surface-excess) (Γ) of the Pd-MoS2-MXene-SPCEs were 3.14 s−1 and 5.62 × 10-9 mol cm−2, respectively. Under optimal conditions, square wave voltammetry responses to BPA concentration were linear in the range 5 to 175 nM, and exhibited high sensitivity (16.205 μA nM−1 cm−2) and a detection limit of 0.12 nM (3.3 σ/s). The optimized SPCE exhibited high reproducibility, reusability, and repeatability with a relative standard deviation (RSD) of < 5.0% and excellent stability and retained 89.2% of its initial sensitivity after 30 days of storage for the onsite sensing of BPA. The prepared sensor showed excellent selectivity for the quantification of BPA even in the presence of electrochemically active interfering compounds such as drugs, pollutants, biological substances, and some common cations/anions. Real-time quantitative analysis of BPA in milk and river and lake water samples was performed, and acceptable recoveries were obtained (from 89.1 to 107.8%) with an RSD of 2.2–3.8%, demonstrating an accuracy similar to that of HPLC.

Photo, thermal and photothermal activity of TiO2 supported Pt catalysts for plasmon-driven environmental applications

TiO2+Pt plasmonic solids with 1 wt% Pt and different TiO2 supports (anatase nanoparticles (TNP), polycrystalline nanorods (a-TNR) and single-crystal anatase nanorods (TNR)) were synthesized using the wet impregnation technique and tested as photo, thermal and photothermal catalysts in gas-solid and gas-liquid-solid reactions. Due to the different charges of the TiO2 support surfaces, Pt particles with different sizes, crystallinities and degrees of interaction with the TiO2 supports were formed during the synthesis. The heights of the Schottky barrier (SBH) were 0.38 eV for the a-TNR+Pt, 0.41 eV for the TNP+Pt, and 0.50 eV for the TNR+Pt samples, respectively. The low visible-light-triggered photocatalytic activity of the TNR+Pt catalyst toward the oxidation of water-dissolved bisphenol A (BPA) is attributed to its high SBH and active site deactivation due to the adsorption of BPA and/or BPA oxidation products. The highest photothermal catalytic H2-assisted NO2 reduction rate was expressed by the TNR+Pt catalyst. This can be ascribed to the presence of a narrow particle size distribution of small Pt particles, the absence of the Pt catalysed reduction of the TNR support at higher temperatures, and the lower rate of re-injection of “hot electrons” from the TNR support to the Pt particles.

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.

Synthesis and characterization of plasmonic Au/TiO2 nanorod solids for heterogeneous photocatalysis

Plasmonic Au (1 wt%) catalysts deposited on hydrothermally synthesized TiO2 nanorods (TNR) were investigated in this study. Based on the duration of mixing of the Au precursor/TNR suspension during the wet impregnation synthesis and parameters of the end calcination, Au/TiO2 catalysts with different sizes of Au nanoparticles (Au NPs) were obtained. The prepared solids were thoroughly characterized by several instrumental techniques to investigate property-activity relationships. Regardless of the size of Au particles on the catalyst surface, an absorption peak at 550 nm occurred in all UV-Vis diffuse reflectance spectra of the investigated Au/TiO2 catalysts, which is characteristic of the localized surface plasmon resonance effect exerted by metallic Au NPs. By measuring the formation of reactive oxygen species under visible-light illumination using various scavengers, the production of superoxide anion radicals (O2•) and hydroxyl radicals were identified, however, the former were found to represent the main reactive oxygen species that govern the oxidation of aqueous bisphenol A (BPA) employed as a model organic pollutant. The activity of Au/TiO2 catalysts for the generation of O2• radicals (and BPA oxidation) increases by increasing the Schottky barrier height, which is due to the slow reduction of water-dissolved O2 on the catalyst surface.

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.

A single-atom Fe–N2 embedded in nitrogen-doped porous carbon as a bifunctional photocatalyst for efficient removal of marine petroleum pollutants

Petroleum and its refined products enter the marine environment during the extraction process, causing serious pollution. Herein, a bifunctional Fe–N2 single-atom embedded in nitrogen-doped porous carbon photocatalyst (FC) was fabricated for the efficient removal of marine petroleum pollutants. The combination of highly dispersed Fe–N2 active sites, large surface area, high porosity, and good conductivity results in excellent photocatalytic activities. The FC catalyst exhibited a 96.7% degradation rate in the oxidative removal of bisphenol A (BPA) and a 63.4% reduction of Cr(VI) within 1 ​h, whereas the reaction equilibrium rate constants of 0.0132 ​min−1 and 0.0505 ​min−1 were reached, respectively. FC with good stability and reusability could reach 88.3% and 53.5% removal rate of BPA and Cr(VI) after 5 cycles. Radical quenching experiments and electron spin resonance (ESR) confirmed that ‧OH and e− were the most driving active species for photo-oxidation and reduction, respectively. Besides, the FC catalyst was applied to an actual seawater system and the simulation results showed a good removal rate (82.7% of BPA and 50.9% of Cr(VI) within 1 ​h). The BPA oxidation pathway in the system was proposed and the toxicity of each intermediate was accessed. This work offers a new way to construct single-atom functionalized carbon-based catalysts for marine pollution control.

Fabrication of CuO–NiO Wrapped Cellulose Acetate/Polyaniline Electrospun Nanofibers for Sensitive Monitoring of Bisphenol-A

Monitoring endocrine-disrupting chemicals such as bisphenol-A (BPA) is of great concern because its exposure may lead to reproductive problems, neurotoxicity, mutagenicity, and even carcinogenicity. Herein, we reported the fabrication of an efficient electrochemical sensor based on CuO–NiO wrapped cellulose acetate/polyaniline electrospun nanofibers at a Ni foam (CuO–NiO/CA–PANI@NF) electrode for the sensitive and selective monitoring of BPA. CA–PANI-based electrospun nanofibers were selected because of their improved electrical conductivity and charge density, high binding affinity toward BPA via alternative amine and imine groups, and low cost, thus paving the way for the smooth and uniform flow of ions. However, CuO–NiO-based nanoparticles offer more exposed catalytic active species such as NiOOH/CuOOH for the fast electrocatalytic oxidation of BPA. Thus, the synergistic effect of CuO–NiO nanoparticles with electrospun nanofibers leads to high sensitivity (0.00172 μA/nM/cm2) with a low limit of detection (0.6 nM), a wide linear range (2–100 nM), and high selectivity, even in the presence of interferences, including Co2+, Cd2+, Na+ Pb2+, Ni2+, Cd2+, Ca2+, Fe3+, NO32–, SO42–, Cr6+, Br–, Mg2+, Zn2+, and Ba2+ and molecules such as bisphenol-B, bisphenol-F, and phenol. The designed electrode was successfully applied to monitor BPA from plastic bottled water with high precision, thus suggesting the reliability of our designed system.

Highly Efficient Utilization of Ferrate(VI) Oxidation Capacity Initiated by Mn(II) for Contaminant Oxidation: Role of Manganese Species.

Manganese ion [Mn(II)] is a background constituent existing in natural waters. Herein, it was found that only 59% of bisphenol A (BPA), 47% of bisphenol F (BPF), 65% of acetaminophen (AAP), and 49% of 4-tert-butylphenol (4-tBP) were oxidized by 20 μM of Fe(VI), while 97% of BPA, 95% of BPF, 96% of AAP, and 94% of 4-tBP could be oxidized by the Fe(VI)/Mn(II) system [20 μM Fe(VI)/20 μM Mn(II)] at pH 7.0. Further investigations showed that bisphenol S (BPS) was highly reactive with reactive iron species (RFeS) but was sluggish with reactive manganese species (RMnS). By using BPS and methyl phenyl sulfoxide (PMSO) as the probe compounds, it was found that reactive iron species contributed primarily for BPA oxidation at low Mn(II)/Fe(VI) molar ratios (below 0.1), while reactive manganese species [Mn(VII)/Mn(III)] contributed increasingly for BPA oxidation with the elevation of the Mn(II)/Fe(VI) molar ratio (from 0.1 to 3.0). In the interaction of Mn(II) and Fe(VI), the transfer of oxidation capacity from Fe(VI) to Mn(III), including the formation of Mn(VII) and the inhibition of Fe(VI) self-decay, improved the amount of electron equivalents per Fe(VI) for BPA oxidation. UV-vis spectra and dominant transformation product analysis further revealed the evolution of iron and manganese species at different Mn(II)/Fe(VI) molar ratios.

Biotransformation of bisphenol A in vivo and in vitro by laccase-producing Trametes hirsuta La-7: Kinetics, products, and mechanisms

Bisphenol A (BPA) is a ubiquitous endocrine disruptor that poses adverse human health risks. Herein, biotransformation kinetics, products, and mechanisms of BPA undergoing a laccase-producing Trametes hirsuta La-7 metabolism were for the first time reported. Strain La-7 could completely biotransform ≤0.5 mmol·L−1 BPA within 6 d in vivo. Notably, its extracellular crude laccase solution (ECLS) and intracellular homogenized mycelium (HM) only required 6 h to convert 85.71% and 84.24% of 0.5 mmol·L−1 BPA in vitro, respectively. The removal of BPA was noticeably hampered by adding a cytochrome P-450 inhibitor (piperonyl butoxide) in HM, disclosing that cytochrome P-450 monooxygenase participated in BPA oxidation and metabolism. BPA intermediates were elaborately identified by high-resolution mass spectrometry (HRMS) combined with 13C stable isotope ratios (BPA: 13C12-BPA = 0.25: 0.25, molar concentration). Based on the accurate molecular mass, isotope labeling difference, and relative intensity ratio of product peaks, 6 versatile metabolic mechanisms of BPA, including polymerization, hydroxylation, dehydration, bond cleavage, dehydrogenation, and carboxylation in vivo and in vitro, were confirmed. Germination index values revealed that inoculating strain La-7 in a BPA-contaminated medium presented no phytotoxicity to the germinated radish (Raphanus sativus L.) seeds. In vivo, Mg2+, Fe2+, Fe3+, and Mn2+ were conducive to BPA removal, but Cd2+ and Hg2+ significantly obstructed BPA elimination. Additionally, strain La-7 also exhibited high-efficiency metabolic ability toward estrone (E1), 17β-estradiol (E2), and 17α-ethinylestradiol (EE2), with more than 96.13%, 96.65%, and 100% of E1, E2, and EE2 having been converted, respectively. Our findings provide an environmentally powerful laccase-producing fungus to decontaminate endocrine disruptor-contaminated water matrices by radical polymerization and oxidative decomposition.

Electrochemical sensor based on confined synthesis of gold nanoparticles @ covalent organic frameworks for the detection of bisphenol A

Covalent-organic frameworks (COFs), a kind of conjugate crystalline polymers, has great potential for high performance electrochemical sensors due to high porosity, controllable pores and structure, and large specific surface area, etc. Herein, we developed an electrochemical sensor based on confined synthesis of gold nanoparticles @ 1,3,5-triformylphloroglucinol (Tp) and benzidine (BD) connected COFs (Au NPs@TpBD-COFs) for electrochemical detection of bisphenol A (BPA). Firstly, Au NPs were grown on the surface and in the pores of COFs by confinement synthesis strategy, which aimed to improve the conductivity and catalytic activity of COFs. Then, this composite was used to constitute electrochemical sensor for the oxidation of BPA, resulting a good electrocatalytic activity in the phosphate buffer solution (pH 7.4). Due to high conductivity of Au NPs and TpBD-COFs recognize BPA via π–π stacking interactions and hydrogen bonds, the proposed sensor for the detection of BPA has the linear range of 5–1000 μM and the detection limit of 1 μM. Finally, the proposed sensor was used to measure the content of BPA in real water samples with a satisfactory recovery from 98.6 to 106.9%. Those good results confirmed that the proposed electrochemical sensors for monitoring of BPA in the application of COFs provided a significant guidance.

Photo-Fenton Catalyzed by Cu2O/Al2O3: Bisphenol (BPA) Mineralization Driven by UV and Visible Light

This work aimed to demonstrate Cu2O/Al2O3 as a catalyst of the photo-Fenton process in the UV and visible spectra. Cu2O nanoparticles were synthesized by laser ablation in liquid and supported on Al2O3. The catalytic activity of the resulting solid was assessed in the mineralization of bisphenol A (BPA). The studied variables were type of Al2O3α and γ, Cu content (0.5 and 1%), and H2O2 concentration (1, 5, and 10 times the stoichiometric amount). The response variables were BPA concentration and total organic carbon (TOC) removal percentage. The presence of Cu2O nanoparticles (11 nm) with an irregular sphere-like shape was confirmed by transmission electron microscopy (TEM) and their dispersion over the catalytic surface was verified by energy-dispersed spectroscopy (EDS). These particles improve ·OH radical production, and thus a 100% removal of BPA is achieved along with ca. 91% mineralization in 60 min. The BPA oxidation rate is increased one order of magnitude compared to photolysis and doubles that for H2O2 + UV. An increase of 40% in the initial oxidation rate of BPA was observed when switching from α-Al2O3 to γ-Al2O3. 4-hydroxybenzaldehyde, 4-hydroxybenzoic acid, acetaldehyde, and acetic acid are the BPA oxidation by-products identified using LC/MS and based on this a reaction pathway was proposed. Finally, it was also concluded that the synthesized catalyst exhibits catalytic activity not only in the UV spectrum but also in the visible one under circumneutral pH. Therefore, Cu2O/Al2O3 can be recommended to conduct a solar photo-Fenton reaction that can degrade other types of molecules.

Facile pyrolysis synthesis of Pt-PtFe nanoparticles/3D porous N-doped carbon nanoflowers for highly sensitive detection of hydrazine and bisphenol A

It is still challenging for synthesis of advanced nanomaterials and explores their electrocatalytic detection of hydrazine (N2H4) and bisphenol A (BPA). Herein, Pt-PtFe nanoparticles/three-dimensional (3D) porous N-doped carbon nanoflowers (Pt-PtFe/N-CNFs) were successfully prepared by high-temperature pyrolysis. The structures and properties of the nanocomposite were strictly investigated by various characterization techniques. The Pt-PtFe/N-CNFs displayed high-efficiency electrocatalytic activity for oxidation of N2H4 and BPA. Under the optimal conditions, the Pt-PtFe/N-CNFs based sensor exhibited the wide linear ranges: 0.5–559.5 μM and 559.5–2659.5 μM for detection of N2H4 with a limit of detection (LOD) of 0.19 μM (S/N = 3), coupled with a broad scope of 0.3–70 μM and a LOD of 0.043 μM for BPA. The developed sensor has promising applications in environmental and industrial samples.

Derivatives of two-dimensional MXene-MOFs heterostructure for boosting peroxymonosulfate activation: Enhanced performance and synergistic mechanism

Integrating the merits of the substrate and active sites with the water matrix is of significant importance to design novel catalysts for peroxymonosulfate (PMS)-based advanced oxidation processes. A sandwich-like heterostructure catalyst (MCoO@Co-N-C) were fabricated via anchoring zero-dimensional metal-organic frameworks (MOFs)-derived CoO nanoparticles on two-dimensional Ti3C2Tx MXene nanosheets. Benefiting from the distinctive structure, the resultant catalysts achieved excellent decontamination performance under high salinity conditions (200 mM). Nearly 100% efficiency of bisphenol A (BPA) was degraded within 10 min only using 0.05 g L−1 catalyst and 0.1 g L−1 PMS, with exceptional high turnover frequency (TOF) value (8.64 min−1) which was 22.5 times higher than that of MOFs derived catalysts without MXene. A mediated-electron transfer mechanism is found to be conducive to the oxidation of BPA. This work provides a new approach to novel catalysts designed for removing trace organic contaminants (TrOCs) in saline water.

Applying a novel advanced oxidation process of biochar activated periodate for the efficient degradation of bisphenol A: Two nonradical pathways

Periodate based advanced oxidation processes (PI-AOPs) exhibited promising future for the abatement of emerging contaminants, yet the underlying mechanism of carbon materials for PI activation was still unclear. In this study, a metal-free biochar (BCx, x represents the pyrolysis temperature) catalyzed PI-AOPs system was established and explored for the degradation of bisphenol A (BPA), one of the endocrine disrupting compounds (EDCs) that was ubiquitously detected in natural ecosystems. Biochar catalysts clearly boosted BPA degradation, suggesting a distinct synergistic effect between PI and biochar. Interestingly, BC350 and BC800 exhibited distinct behaviors for PI activation. Specifically, BC350 performed moderate PI activation, which was believed to be a surface hydroxyl group (OH)-induced nonradical pathway. A unique COOIO3 complex was formed and served as the reactive oxidant responsible for the BPA oxidation. On the other hand, BC800 showed a significant PI activation ability, which was preferentially proved to be a carbon-mediated electron-transfer mechanism. A high potential metastable carbon activated PI complexes (C-PI*) was elucidated to be the dominant oxidative species through electrochemical characterizations and galvanic oxidation process (GOP) experiments. The electron-transfer between adsorbed BPA (electron donor) and C-PI* (electron acceptor) was a crucial step in this pathway. Density functional theory (DFT) calculations confirmed that the interaction between PI and carbon surface was probably caused by the van der Waals force and a part of strong attraction between the interface of PI and BCOH. These findings provide new insights into nonradical pathways in biochar catalyzed PI-AOPs and promote the development and application of PI-AOPs in environmental remediation.

Activation of sodium percarbonate with Fe3O4 @MXene composite for the efficient removal of bisphenol A

Sodium percarbonate (SPC) has been considered as a promising substitute of H2O2 in Fenton reaction due to its lower cost and higher safety, while the frequently-applied homogeneous activation of SPC by metal ions still faces the recovery difficulties. Herein, a Fe3O4 @MXene composite was prepared by anchoring Fe3O4 onto the surface of Ti3C2-based MXene, to heterogeneously activate SPC for bisphenol A (BPA) degradation. The performance of Fe3O4 @MXene/SPC process was evaluated under varies conditions. The results indicated that BPA could be effectively degraded by Fe3O4 @MXene/SPC process, which exhibited much higher organic degradation rate comparing to other heterogeneously activated SPC processes with iron-bearing materials. The introduction of MXene as substrate into the composite not only increased the dispersibility and stability of Fe3O4, but enhanced the Fe(II)/Fe(III) cycle, which promoted the SPC activation. Multiple reactive oxygen species including •OH, CO3•–, and 1O2 were involved in the BPA oxidation while the major contributing species varies with the pH. Additionally, the process worked well in real water matrices, while exhibiting higher selectivity toward organics containing benzene ring. This work provides a prospective heterogeneous material for SPC activation and will facilitate the application of SPC in wastewater treatment.

Phase transformation-driven persulfate activation by coupled Fe/N–biochar for bisphenol a degradation: Pyrolysis temperature-dependent catalytic mechanisms and effect of water matrix components

Fe–N co-doped biochar is recently an emerging carbocatalyst for persulfate activation in situ chemical oxidation (ISCO). However, the involved catalytic mechanisms remain controversial and distinct effects of coexisting water components are still not very clear. Herein, we reported a novel N-doped biochar-coupled crystallized Fe phases composite (Fe@N-BC800) as efficient and low-cost peroxydisulfate (PDS) activators to degrade bisphenol A (BPA), and the underlying influencing mechanism of coexisting inorganic anions (IA) and humic constituent. Due to the formation of graphitized nanosheets with high defects (AI index>0.5, ID/IG = 1.02), Fe@N-BC800 exhibited 2.039, 5.536, 8.646, and 23.154-fold higher PDS catalytic activity than that of Fe@N-BC600, Fe@N-BC400, N-BC, BC. Unlike radical pathway driven by carbonyl group and pyrrolic N of low/mid-temperature Fe@N–BCs. The defective graphitized nanosheets and Fe-Nx acted separately as electron transfer and radical pathway active sites of Fe@N-BC800, where π-π sorption assisted with pyrrolic N and pore-filling facilitated BPA degradation. The strong inhibitory effects of PO43− and NO2− were ascribed to competitive adsorption of phosphate (61.11 mg g−1) and nitrate (23.99 mg g−1) on Fe@N-BC800 via electrostatic attraction and hydrogen bonding. In contrast, HA competed for the pyrrolic-N site and hindered electron delivery. Moreover, BPA oxidation pathways initiated by secondary free radicals were proposed. The study facilitates a thorough understanding of the intrinsic properties of designed biochar and contributes new insights into the fate of degradation byproducts formed from ISCO treatment of micropollutants.

Contribution of different reactive species in the oxidation of bisphenol A by permanganate combined with 1-hydroxybenzotriazole

1-Hydroxybenzotriazole (HBT), as one of the synthetic redox-mediators, significantly accelerates the oxidation of bisphenol A (BPA) during treatment with permanganate (Mn(VII)). The reaction between Mn(VII) and HBT produces HBT radical and MnO2 intermediates which can accelerate BPA oxidation by reacting with the organic contaminants in parallel with Mn(VII). This study aimed at quantifying the relative contributions of the reactive species in oxidizing BPA at different pH conditions. At pH ≤ 6, the relative contributions (R) ranked as R(HBT radical) > R(Mn(VII)) > R(in-situ formed MnO2), but at higher pH conditions the order switched. At pH ≥ 7, R(Mn(VII)) > R(HBT radical) and in-situ formed MnO2 contributed negligibly. These findings fill a critical knowledge gap and provide mechanistic insights into organic contaminant treatment processes combining permanganate with redox-mediators like HBT.

Graphene-anchored conductive polymer aerogel composite for the electrocatalytic detection of hydrogen peroxide and bisphenol A

An aerogel composite of reduced graphene oxide (rGO) anchored on amine groups of conductive polyterthiophene (p(APT-rGO) aerogel is synthesized for the first time, using a hydrothermal method. The electrocatalytic performance of the composite electrode was explored for bisphenol A (BPA) oxidation and hydrogen peroxide reduction. The surface of catalyst was found to possess numerous active sites owing to exposed edges and large surface area of a three-dimensional aerogel. Additionally, incorporation of rGO into poly(aminopyrimidyl terthiophene) (pAPT) is found to enhance the catalytic performance and stability. The p(APT-rGO) aerogel coated screen printed carbon electrode (SPCE) displayed a superior catalytic performance for the BPA detection with two dynamic ranges of 5–500 nM and 1–200 µM with the detection limit of 4.28 ± 0.75 nM. Otherwise, the dynamic ranges of H2O2 detection were 100 nM-100 µM and 200 µM-3 mM with the detection limit of 9.12 ± 1.03 nM. The catalytic active site of the composite aerogel was investigated for BPA oxidation and H2O2 reduction. The proposed sensor demonstrated an excellent analytical performance for the determination of BPA extracted from commercial polycarbonate bottles and trace amounts of H2O2 released from living cells by drug stimulation.

Inhibition mechanisms of Fe2+/Fe3+ and Mn2+ on fungal laccase-enabled bisphenol a polyreaction

Bisphenol A (BPA) is regarded as an endocrine disruptor associated with negative health effects in animals and humans. Laccase from white-rot fungus can enable BPA oxidation and auto-polymerization to circumvent its biotoxicity, but the work concerning the effect mechanisms of divalent and trivalent metal ions (MIs) on BPA polyreaction have rarely been reported. Herein, Trametes versicolor laccase-started BPA conversion within 1 h followed pseudo-first order kinetics, and the rate constant (kprcs) and half-life were respectively 0.61 h−1 and 1.14 h. The presence of Ca2+, Mg2+, Cu2+, Pb2+, Cd2+, Zn2+ and Al3+ exhibited insignificant impact on BPA removal, whereas Fe2+, Fe3+ and Mn2+ had a strong inhibiting effect. Compared with MI-free, the kprcs values of BPA respectively lowered 34.4%, 44.3% and 98.4% in the presence of Fe2+, Fe3+ and Mn2+. Enzymatic activity and differential absorption spectrum disclosed that the inhibitory actions were accomplished by two different mechanisms. One is Fe2+ was preferentially oxidized into Fe3+ that restrained laccase activity at the initial stage of reaction, and subsequently, the formed Fe3+ complex bound with laccase T1-Cu site and thus impeded the single-electron transfer system. The other is Mn2+ was instantly oxidized by laccase to generate Mn3+-citrate complex, which completely consumed the dissolved O2 in solution and consequently terminated BPA removal. Considering environmental bioremediation, T. versicolor laccase-enabled auto-polymerization is a simple and convenient candidate to eliminate BPA in enzymatic wastewater treatment, however the effects of Fe2+/Fe3+ and Mn2+ on BPA decontamination should be cautiously assessed.