Degradation Of Bisphenol Research Articles

Highly Efficient Activation of Peroxymonosulphate by Co and Cu Co-Doped Sawdust Biochar for Ultra-Fast Removal of Bisphenol A

The rapid, efficient, and thorough degradation of Bisphenol A (BPA) is challenging. In this study, we prepared an effective peroxymonosulphate (PMS) activation catalyst derived from sawdust containing calcium carbonate. The Co and Cu co-doped sawdust biochar (CoO/CuO@CBC) catalyst could activate PMS quickly, and the degradation rate of BPA reached 99.3% in 5 min, while the rate constant was approximately 30 times higher than in the CBC/PMS and CoCuOx/PMS systems. Moreover, the interaction between CoO, CuO, and CBC endows the CoO/CuO@CBC catalyst with excellent catalytic performance under different conditions, such as initial pH, temperature, water matrix, inorganic anions, and humic acid, which maintained fast PMS activation via the cyclic transformation of Cu and Co for BPA degradation. The results demonstrated that both the radical (•O2− and •SO4−) and non-radical (1O2) pathways participate in the degradation of BPA in the CoO/CuO@CBC/PMS system. The efficient and stable degradation over a wide range of pH, temperature, and aqueous matrices indicates the potential application of the CoO/CuO@CBC catalyst.

Peroxydisulfate Activation by Biochar from Banana Peel Promoted with Copper Phosphide for Bisphenol S Degradation in Aqueous Media

In this work, the decomposition of bisphenol S (BPS) by biochar derived from banana peel (BPB) promoted by copper phosphide (Cu3P) was examined. Different materials with Cu3P loadings from 0.25 to 4.00 wt.% on biochar were synthesized, characterized using the Brunauer–Emmett–Teller (BET) method, X-ray diffraction (XRD) and a scanning electron microscope (SEM) equipped with an energy dispersive spectrometer (EDS), and evaluated. Nearly all of the synthesized materials exhibited low to moderate adsorption capacity, attributable to their limited surface area (<3.1 m2/g). However, in the presence of sodium persulfate (SPS), the 2%Cu3P/ΒPB/SPS system was capable of removing 90% of 500 μg/L BPS in less than 10 min. The system’s performance was enhanced under inherent pH, and the reaction rate followed pseudo-first-order kinetics with respect to BPS and persulfate concentrations. Interestingly, the presence of 250 mg/L of sodium chloride had a negligible effect, while low to moderate inhibition was observed in the presence of bicarbonates and humic acid. In contrast, significant retardation was observed in experiments performed in real matrices, such as secondary effluent (WW) and bottled water (BW). According to scavenging experiments, both radical and non-radical mechanisms participated in the BPS degradation. Four transformation products were identified using the UHPLC/TOF-MS system in negative ionization mode, with two of them having higher molecular weights than BPS, while the other two TBPs involved the ring-opening reaction, and a BPS decomposition pathway was proposed.

Hydrochar supported strategy for nZVI to remove bisphenol A and Cr(VI): Performance, synergetic mechanism, and life cycle assessment

To comprehensively overcome the shortcomings and extend the application of nanoscale zero-valent iron (nZVI), a promising hydrochar supported strategy was provided. nZVI/Eupatorium adenophorum hydrochar (nZVI/EaHC) composite was attained under relatively mild reaction condition, and life cycle assessment revealed that the greenhouse gases emission, ecotoxicity, and resource consumption of nZVI/EaHC fabrication processes largely reduced in comparison with nZVI and pyrolysis biochar supported nZVI (nZVI/EaBC). Moreover, nZVI/EaHC exhibited an outstanding potential in reduction and immobilization of Cr(VI) as well as degradation of bisphenol A (BPA) via Fenton-like system. The static experiment showed that the removal efficiency achieved 99.21 % within 1 h for Cr(VI) and 97.9 % within 1 min for BPA, which significantly exceeded the performance of nZVI/EaBC, accompanied by a significant detoxification to non-harmful level and mineralization of 87.9 % within 10 min. The dynamic continuous flow column experiment indicated that 90 % Cr(VI) was removed within 40 min and 90 % BPA within 180 min under ultra-low-dosage of catalyst and H2O2. Furthermore, hydrochar supported strategy may reduce the economic cost and avoid secondary pollution due to the outstanding stability under aerobic condition and recyclability in magnetic field. The synergetic mechanisms were further revealed, the abundant oxygen-containing functional groups on EaHC facilitated the generation of electron-rich/poor centers via chemical bond bridge (COFe) and Fe-π interaction, which further enhanced the electron transfer to reduce Cr(VI) or promote the production of multiple reactive species including OH, O2–, and 1O2 to degrade BPA, additionally, persistent free radicals on EaHC also contributed to the degradation of BPA. Therefore, this efficient, applicable, and sustainable strategy may have a greatly practical outlook on nZVI application together with a comprehensive control and utilization of biomass including invasive plants.

Decoration of marigold flower-like CoMo LDH on reinforced cow manure-derived biochar as an effective peroxymonosulfate activator for degradation of Bisphenol A in water

Marigold flower-like CoMo layered double hydroxide (LDH) was decorated on biochar derived from cow manure (CoMo@BC) to act as an efficient activator for peroxymonosulfate (PMS), enabling the degradation of Bisphenol A (BPA) in water. The CoMo@BC/PMS system can eliminate up to 98% of BPA at a concentration of 0.044mM within 15min. High efficacy is sustained in the pH range of 5 to 9, underscoring the robustness and adaptability of the system. Furthermore, the catalyst exhibits excellent stability, retaining activity over five consecutive cycles. Versatility is highlighted by the capability to degrade over 88% of various organic pollutants, indicating broad-spectrum applicability in water treatment. A comprehensive mechanistic study has elucidated three distinct degradation pathways and identified six intermediates of BPA, providing valuable insights into the catalytic process. Overall, the research underscores the potential of CoMo@BC as a highly effective catalyst for advanced water treatment applications through PMS activation. Significant efficacy in eliminating organic pollutants suggests great promise for enhancing the sustainability and efficiency of water purification technologies.

Salt template-assisted polymer tethering strategy to achieve high dispersed cobalt single atoms/clusters on porous carbon catalysts for effective Fenton-like reactions

The exploration of the synthesis of porous carbon-supported metal nanocatalysts with high metal loading and dispersion for the development of heterogenous catalysts is important. However, this remains a challenging subject. In this paper, a salt template-assisted polymer tethering strategy was proposed to prepare Co single atom and ultrafine cluster anchored on porous carbon (Co-NPC) with a high-loading of 16.9wt%, thereby exposing high density of reaction sites. The obtained Co-NPC catalyst exhibited excellent catalytic performance for almost 100% degradation of bisphenol A (BPA) within 20min, which is much faster than the CoSA-NPC catalyst with only single atom sites and Co-NC without salt template added. Radical quenching experiments and electron paramagnetic resonance tests verified that both the nonradical oxidation pathway by 1O2, the electron transfer and radical oxidation pathway by •OH, SO4•- appeared during the degradation process. After 3 cycles, the removal rate of BPA did not decrease significantly. The fixed bed experiment revealed that Co-NPC could realize the continuous degradation of methylene blue (MB) with almost 100% degradation efficiency. This research indicated that the strategy by pyrolyzing metal coordinated polymer is a potential method for the synthesis of high metal loading catalyst at gram scale, meeting the requirement of practical applications.

One-step construction of defective Fe-doped MIL-68(In)–NH2 for efficient photocatalytic degradation of bisphenol A

Defective Fe-doped MIL-68(In)–NH2 (Fe-MIL68) was successfully synthesized for photocatalytic bisphenol A (BPA) degradation in one step via a simple hydrothermal method for the first time. The presence of mesoporous structure and oxygen vacancies in Fe-doped Fe-MIL68 was confirmed using modern characterization techniques, which can significantly improve its adsorption performance and electron-hole separation ability, thus enhancing its photocatalytic activity. The results confirmed the photodegradation efficiency of Fe-MIL68 for BPA under visible light could reach 92.3 % in 100 min, which was 2.1 times higher than that of MIL-68(In)–NH2.

Catalytic Degradation of Bisphenol A in Water by Non-Thermal Plasma Coupled with Persulfate

Bisphenol A (BPA) has become prevalent in the environment due to its extensive use in industrial materials, thus raising significant concerns regarding its potential toxicity and health effects. In this study, an efficient and eco-friendly non-thermal plasma (NTP) was used to catalyze persulfate (PS) for BPA decomposition, and the results showed that the integrated system could effectively degrade BPA. The best performance was attained at a PS to BPA mass ratio of 5:1, with a degradation rate of 91.3% following a 30 min treatment. The degradation rate of BPA increased with increasing input voltage and frequency; conversely, it decreased with an increase in BPA’s initial concentration. Higher BPA degradation rates could be achieved in alkaline environments. Radical quenching experiments revealed that SO4−•, OH•, O2−• and 1O2 were important active substances involved in BPA degradation. Nine intermediate products were identified by liquid chromatography–mass spectrometry (LC-MS), and four degradation pathways were deduced. Additionally, a toxicity analysis of intermediate products was performed. The significant decrease in chemical oxygen demand (COD) during the actual wastewater treatment suggested that the NTP/PS system has good applicability in actual wastewater treatment.

Overturned doping inert Ce into mesoporous CuO for enhanced peroxydisulfate activation and bisphenols degradation

Transition metal oxides have been recently investigated as excellent catalyst for peroxydisulfate (PDS) activation, but suffers from slow redox cycle of metal species. In this work, a novel avenue for facilitating valence cycles of Cu2+/Cu+ was proposed by overturned doping inert Ce into mesoporous CuO. Increased formation of active sites (Cu-Ce interface) and oxygen vacancy was achieved, resulting in accelerated interfacial electron transfer and facilitated valence cycles of Cu2+/Cu+. The Ce-doped mesoporous CuO (CeCuOx) exhibited greatly enhanced activity toward PDS activation and efficient removal of different bisphenols in a wide pH working range. The degradation of bisphenols followed a nonradical oxidation pathway based on electron transfer process (ETP), and CeCuOx@PDS complex was proved to be the primary reactive species. The CeCuOx/PDS system exhibited good stability and superior catalytic performance in complicated water matrix, and would be a promising catalyst for wastewater purification. This work provides a new prospect for boosting the redox behavior of metal active sites for environmental remediation.

MOF derived porous Fe-Cu@carbon catalyst for the degradation of bisphenol A through a persulfate-based advanced oxidation process

A calcination strategy based on the use of mixed MOF HKUST-1/MIL-100 as precursor was used for the obtention of a porous carbon composite (C-HKUST-1/MIL-100) containing iron-copper bimetallic particles within it. The prepared carbon was characterized by XRD, SEM, EDS spectroscopy and N2 adsorption-desorption, confirming the obtention of a micro-mesoporous carbon with Fe-Cu particles homogenously distributed within the structure. For comparison, Cu and Fe-carbons (C-HKUST-1 and C-MIL-100, respectively) were also prepared from the corresponding HKUST-1 and MIL-100 MOFs, respectively. The catalytic performance of the developed carbons as heterogeneous catalysts for persulfate-based advanced oxidation degradation of bisphenol A was evaluated. The Fe-Cu@carbon showed the best catalytic performance, leading to a total BPA degradation after just 10 min of reaction, which was closely related to the synergistic effect of iron and copper. The effect of some key parameters including initial pH value, PS concentration and catalyst dosage was investigated using the Fe-Cu@carbon. In addition, the developed carbon showed good reusability, with no apparent loss in BPA degradation, after five cycles and the ability to treat real water samples, with the advantage that the recovery process after degradation is facilitated thanks to its magnetic properties.

Construction of novel dual wave-absorbing ZnFe2O4/CNTs nanoparticles with more hotspots for enhanced microwave-induced catalytic activity：Performance and mechanism

In this study, novel dual wave-absorbing ZnFe2O4/CNTs nanoparticles were successfully fabricated using a microwave hydrothermal method and applied for enhanced microwave-induced catalytic degradation of bisphenol A (BPA) in aqueous solution. The effects of various process parameters, including Fe3+ concentration (mass ratio of ZnFe2O4 to CNTs), MW irradiation time, MW power, initial BPA concentration, and catalyst dose on the degradation process were thoroughly assessed. The results indicate that ZnFe2O4/CNTs nanoparticles effectively utilize MW energy to generate more hot spots and exhibit superior MW catalytic activity at a 1.0:10.0 mass ratio (ZnFe2O4:CNTs), due to the synergistic effect between ZnFe2O4 nanoparticles and CNTs under MW irradiation. Additionally, hydroxyl radicals (·OH) play a major role in the degradation process, while superoxide radicals (·O2−) and holes (h+) play relatively minor roles. Potential intermediates and degradation pathways in the ZnFe2O4/CNTs/MW system have also been identified. Thus, the integrated ZnFe2O4/CNTs/MW technology shows great promise for treating environmental endocrine disruptors (EEDs) in water and wastewater.

Cellulose / waste Cu2+-activated carbon composite: A sustainable and green material for boosting laccase activity and degradation of bisphenol A in wastewater

Low enzyme activity is one of the disadvantages of immobilized laccase. In this study, waste Cu2+-loaded activated carbon (Cu-AC) was successfully used in preparing a novel composite support，cellulose / Cu2+-loaded activated carbon beads (C / Cu-AC)， and effectively boosted immobilized laccase activity. To achieve optimum conditions for immobilization of laccase, the immobilization time, pH and laccase concentration were examined. The highest immobilized laccase activity (34.21 U/g) was achieved under optimum conditions (T = 4 h, pH = 4, C = 5 g/L), which was increased by 35.86 % compared to control. In addition, the immobilized laccase showed an outstanding performance in thermostability and reusability compared to free laccase. Moreover, the degradation of BPA by immobilized laccase was carried out, and the optimum degradation conditions were explored. Under such conditions: concentration of BPA was 75 mg / L and pH = 4, t = 1 h, T = 50 °C，the removal yield of BPA reached a maximum of 79.88 %. Therefore, the utilization of waste Cu-CA is a powerful method to boost immobilized laccase activity and creating a new way to high value treatment of waste Cu-CA.

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.

Mn3O4-FeS2/Fe2O3 composite as peroxidase-mimics for the degradation of Bisphenol A

Due to the benefits of artificial peroxidase-like enzymes, Flower-like Mn3O4-FeS2/Fe2O3 composites with multiple active sites prepared by a one-step solvothermal method.The synergistic cyclic reaction between Mn and Fe on the catalyst surface enhances the generation of active radicals, which together promote the efficient degradation of BPA. In the presence of hydrogen peroxide (H2O2), Mn3O4-FeS2/Fe2O3 could generate hydroxyl radicals (·OH) and superoxide radicals (·O2-) in buffer solution of pH=4.5 and catalyze the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) to blue oxidation products (ox TMB). The steady-state kinetic constants (Km) of TMB and H2O2 were obtained by Michaelis-Menten and Lineweaver-Burk models, which are 1.34 mM and 1.00 mM, respectively. This reveals the nice catalytic efficiency of Mn3O4-FeS2/Fe2O3 as enzyme mimics. Under the condition of 10 mg Mn3O4-FeS2/Fe2O3 catalyst, 100 μL H2O2 and pH = 4.5, the degradation efficiency of Bisphenol A (BPA) reaches 100 % when treating 40 mL of 50 mg L−1 BPA for 30 min at room temperature. Moreover, after 5 cycles of degradation, the BPA degradation efficiency of 85.8 % was still maintained. Therefore, the as-prepared Mn3O4-FeS2/Fe2O3 sample could potentially be applied in wastewater treatment.

Electrochemical oxidation of bisphenol A with a Fe-N-C/persulfate three-dimensional electrochemical system

In this study, an effective three-dimensional (3D) electrochemical system based on persulfate was developed, utilizing Fe-N-C compostie as the particle electrodes, and its electrocatalytic performance for the oxidation of bisphenol A was evaluated. With the synergetic effect of Fe-N-C catalyst and electric current, peroxydisulfate is activated to generate highly oxidative sulfate radicals (SO4•−) and hydroxyl radicals (•OH), and the •OH playing a leading role in the oxidation of BPA. In this process, the redox cycle of Fe2+/Fe3+ acts as the main catalytic active center to produce SO4•−, •OH and O2•−, while pyridine N and graphite carbon cooperate to catalyze the formation of 1O2 and promote direct electron transfer, with their reduction by 37.19 % and 3.34 %, respectively, highlighting their crucial role in these processes. During the degradation of bisphenol A, coupling polymerization occurred at the same time, which may be due to the stabilization and instantaneous resonance of the intermediate on the surface of the catalyst caused by direct electron transfer, which induced the polymerization of oxide intermediate. 1O2 not only oxidizes BPA into low molecular weight products, but also extracts hydrogen atoms to form phenoxy free radicals. The coupling of these free radicals promotes the formation of macromolecular polymers and separation from water. This parallel treatment mechanism of degradation and polymerization effectively reduces the emission of CO2 and the mineralization of organic matter. Based on the above findings, the E/PDS/Fe-N-C system has broad potential in the treatment of environmental pollutants.

Novel PtCu/MIL-101(Cr) for efficient degradation of bisphenol A: Photothermal synergism promoted by the localized surface plasmon resonance effect

Semiconductor photocatalysis is one of the most useful methods to solve environmental pollution problems. Herein, nanomaterial PtCu/MIL-101(Cr) was produced by an improved hydrothermal technique. The composite exhibited excellent photocatalytic performance with 99.7 % BPA degradation under 100 min visible light irradiation. First, the PtCu alloy has the effect of the local surface plasmon resonance effect, which can convert the photons to hot electrons and increase the reaction temperature. The synergistic effect (1+1>2) between photocatalysis and thermocatalysis significantly improved the photocatalytic efficiency. Second, the bimetallic alloying lowered the metals' work function and reduced the Schottky barrier between the PtCu alloy and MIL-101(Cr), which effectively promoted the carrier transfer. The ·O2-, ·OH and h+ were dominant reactive substances in the degradation process. The intermediates and degradation pathways of BPA were analyzed by 3D-EEM. The reaction mechanism was proposed based on theoretical calculations and experimental analysis. This work provides new directions for designing photothermal synergistic green catalysts and purifying the environment.

Rapid and Highly Selective Fe(IV) Generation by Fe(II)-Peroxyacid Advanced Oxidation Processes: Mechanistic Investigation via Kinetics and Density Functional Theory.

High-valent iron (Fe(IV/V/VI)) has been widely applied in water decontamination. However, common Fe(II)-activating oxidants including hydrogen peroxide (H2O2) and persulfate react slowly with Fe(II) and exhibit low selectivity for Fe(IV) production due to the cogeneration of radicals. Herein, we report peroxyacids (POAs; R-C(O)OOH) that can react with Fe(II) more than 3 orders of magnitude faster than H2O2, with high selectivity for Fe(IV) generation. Rapid degradation of bisphenol A (BPA, an endocrine disruptor) was achieved by the combination of Fe(II) with performic acid (PFA), peracetic acid (PAA), or perpropionic acid (PPA) within one second. Experiments with phenyl methyl sulfoxide (PMSO) and tert-butyl alcohol (TBA) revealed Fe(IV) as the major reactive species in all three Fe(II)-POA systems, with a minor contribution of radicals (i.e., •OH and R-C(O)O•). To understand the exceptionally high reactivity of POAs, a detailed computational comparison among the Fenton-like reactions with step-by-step thermodynamic evaluation was conducted. The high reactivity is attributed to the lower energy barriers for O-O bond cleavage, which is determined as the rate-limiting step for the Fenton-like reactions, and the thermodynamically favorable bidentate binding pathway of POA with iron. Overall, this study advances knowledge on POAs as novel Fenton-like reagents and sheds light on computational chemistry for these systems.

Green synthesis of TiO2@g-C3N4 nanocomposites for the photocatalytic degradation of pesticides and toxic organics present in water and wastewater

To address the environmental challenges caused by toxic organics in aquatic systems, photocatalytic degradation is a promising option. This study investigates the green synthesis of TiO2@g-C3N4 nanocomposites by coupling Titanium dioxide (TiO2) and graphitic carbon nitride (g-C3N4) in different mass ratios through solvothermal technique due to their photocatalytic properties. Leaf extract from the Ziziphus jujube plant was utilized as a green template making the synthesis environmentally friendly, utilizing renewable resources, and employing facile and cost-effective methods. The nanocomposites were characterized using various analytical techniques including UV–Vis Diffuse reflectance spectroscopy (UV–Vis DRS), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and energy dispersive X-ray spectroscopy (EDS) to analyze the structural and morphological properties. The wavelength ranged from 385 to 454 nm and band gap energies ranged from 3.22 to 2.73 eV for the synthesized materials. The pure green TiO2 showed the highest band gap energy while pure g-C3N4 showed the lowest band gap energy among the synthesized materials. The photocatalytic activity of the synthesized nanocomposites was evaluated through the degradation of Bisphenol A and Malathion pesticide under UV light irradiation. The results indicated 71 % degradation of Bisphenol A with the 50 % TiO2@g-C3N4 nanocomposites exhibiting 1.422 x 10-2 min−1 rate constant and 74 % degradation of Malathion degraded over 20 % TiO2@g-C3N4 which depicted rate kinetics of 1.022 x 10-2 min−1. Moreover, both showcased higher performance than the individual TiO2 and g-C3N4 nanostructured materials.

Silver and g-C3N4 co-modified biochar (Ag-CN@BC) for enhancing photocatalytic/PDS degradation of BPA: Role of carrier and photoelectric mechanism

Photocatalytic property of nano Ag is weak and its enhancement is important to enlarge its application. Herein, a novel strategy of constructing silver g-C3N4 biochar composite (Ag-CN@BC) as photocatalyst is developed and its photocatalytic degradation of bisphenol A (BPA) coupled with peroxydisulfate (PDS) oxidation process is characterized. Characterization result showed that silver was evenly embedded into the g-C3N4 structure of the nitrogen atoms format, impeding agglomeration of Ag by distributing stably on biochar. In optimum condition, BPA of 10 mg/L could be degraded completely at pH of 9.0 with a 0.5 g/L photocatalyst, 2 mM PDS in Ag-CN@BC-2 (Ag/melamine molar ratio of 0.5)/PDS system (99.2%, k = 4.601 h−1). Ag-CN@BC shows superior mineralization ratio in degrading BPA to CO₂ and H₂O via active radical way, including holes (h⁺), superoxide radicals (•O2⁻), sulfate radicals (SO4•⁻), and hydroxyl radicals (•OH). Proper amount of silver can be dispersed effectively by gC3N4, which is responsible for improving the visible-light absorbing capability and accelerate charge transfer during activation of PDS for BPA degradation, while biochar as carrier in the composite is supposed to enhance the photoelectric degradation of BPA by reducing the band gap and increasing the photocurrent of Ag-CN@BC catalyst. Ag-CN@BC exhibits excellent catalyst stability and photocatalytic activity for treatment of toxic organic contaminants in the environment.

Ethylene glycol-assisted microwave synthesis of bismuth-rich oxychlorides photocatalysts with oxygen vacancies for efficient degradation of bisphenol A and oxidation of arsenite

The bismuth-rich strategy, which involves increasing the bismuth content within the BiOCl structure, offers an effective approach for tailoring the physicochemical and optoelectrical properties of BiOCl photocatalysts for enhanced photocatalytic performance. In this study, BiOCl, Bi12O15Cl6, and Bi12O17Cl2 were selectively synthesized using the ethylene glycol (EG)-assisted microwave irradiation method by regulating the pH of the reaction solution. Photocatalytic performance was evaluated by studying bisphenol A (BPA) degradation and arsenite (As(III)) oxidation under visible-light irradiation. The energy structures and bandgaps of the materials were tuned according to their chemical compositions, affecting their photocatalytic activity. Bi12O17Cl2 (EG-pH 9) exhibited superior photo-efficiency: 85.4 % of BPA and 97.6 % of As(III) were removed by Bi12O17Cl2 (EG-pH 9) at rates 17.7 and 18.4 times higher than those of BiOCl (EG-initial pH 3), respectively. This superior performance attributed to the synergistic effect between the bismuth-rich nature and oxygen vacancies (OVs) induced by EG, along with the presence of OH− ions in the reaction solution. The increased number of OVs in Bi12O17Cl2 led to enhanced photocurrent density and charge transfer efficiency. Trapping experiments, DMPO-ESR spin-trapping, nitroblue tetrazolium transformation, terephthalic acid photoluminescence probing, and o-tolidine oxidation experiments identified holes (h+), superoxide radicals (•O2−), superoxide radicals (•OH) and electrons (e−) as the reactive species. Density functional theory calculations further highlight the OV of Bi12O17Cl2 as the active site for O2 adsorption. This study not only developed an effective method for fabricating bismuth-rich oxychlorides with OVs but also demonstrated the potential of these photocatalysts for wastewater treatment.

Interlayer synergistic reaction of radical precursors for ultraefficient 1O2 generation via quinone-based covalent organic framework

Singlet oxygen (1O2) is important in the environmental remediation field, however, its efficient production has been severely hindered by the ultrafast self-quenching of the as-generated radical precursors in the Fenton-like reactions. Herein, we elaborately designed lamellar anthraquinone-based covalent organic frameworks (DAQ-COF) with sequential localization of the active sites (C═O) at molecular levels for visible-light-assisted peroxymonosulfate (PMS) activation. Theoretical and experimental results revealed that the radical precursors (SO5·-) were formed in the nearby layers with the migration distance less than 0.34 nm, via PMS donating electrons to the photogenerated holes. This interlayer synergistic effect eventually led to ultraefficient 1O2 production (14.8 μM s-1), which is 12 times that of the highest reported catalyst. As an outcome, DAQ-COF enabled the complete degradation of bisphenol A in 5 min with PMS under natural sunlight irradiation. This interlayer synergistic concept represents an innovative and effective strategy to increase the utilization efficiency of ultrashort-lived radical precursors, providing inspirations for subtle structural construction of Fenton-like catalysts.