Efficient activation of peroxymonosulfate by magnetic Mn-MGO for degradation of bisphenol A

Sonoelectrochemical degradation of aspirin in aquatic medium using ozone and peroxymonosulfate activated with FeS2 nanoparticles

The catalytic performance of nano-FeS2 in the sonoelectrochemical activation of peroxymonosulfate (PMS) and ozone to remove aspirin (ASP) was studied for the first time. The crystal structure and Fe bonds in the catalyst were confirmed through XRD and FTIR analysis. Within 30 min, ASP (TOC) was removed by 99.2 % (81.6 %) and 98.6 % (77.4 %) in nano-FeS2/PMS and nano-FeS2/O3 sonoelectrochemical systems, respectively. Water anions, especially (almost 50 %), had an inhibitory effect on ASP removal. The probes confirmed that SO4•-and HO• were the key to ASP degradation in nano-FeS2/PMS and nano-FeS2/O3 systems, respectively. The effective activation of oxidants due to the ideal distribution of Fe2+ by catalyst was the main mechanism of ASP removal, in which electric current (EC) and ultrasound (US) played a crucial role through the recycling of Fe ions, dissolution and cleaning of the catalyst. LC-MS analysis identified thirteen byproducts in the ASP degradation pathways. The energy consumption of the proposed sonoelectrochemical systems was lower than previous similar systems. This study presented economic and sustainable hybrid systems for pharmaceutical wastewater remediation.

Activated persulfate for efficient bisphenol A degradation via nitrogen-doped Fe/Mn bimetallic biochar

To achieve the purpose of treating waste by waste, in this study, a nitrogen-doped Fe/Mn bimetallic biochar material (FeMn@N-BC) was prepared from chicken manure for persulfate activation to degrade Bisphenol A (BPA). The FeMn@N-BC was characterized by scanning electron microscopy (SEM), X-ray diffract meter (XRD), fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectrometer (XPS) and found that N doping can form larger specific surface area. Catalytic degradation experiments showed that Fe/Mn bimetal doping not only accelerated the electron cycling rate on the catalyst surface, but also makes the biochar magnetic and easy to separate, thus reducing environmental pollution. Comparative experiments was concluded that the highest degradation efficiency of BPA was achieved when the mass ratios of urea and chicken manure, Fe/Mn were 3:1 and 2:1, respectively, and the pyrolysis temperature was 800 °C, which can almost degrade all the BPA in 60 min. FeMn@N-BC/PS system with high catalytic efficiency and low consumables is promising for reuse of waste resources and the remediation of wastewater.

Remediation of phenanthrene contaminated soil by persulphate coupled with Pseudomonas aeruginosa GZ7 based on oxidation prediction model

Chemical oxidation coupled with microbial remediation has attracted widespread attention for the removal of polycyclic aromatic hydrocarbons (PAHs). Among them, the precise evaluation of the feasible oxidant concentration of PAH-contaminated soil is the key to achieving the goal of soil functional ecological remediation. In this study, phenanthrene (PHE) was used as the target pollutant, and Fe2+-activated persulphate (PS) was used to remediate four types of soils. Linear regression analysis identified the following important factors influencing remediation: PS dosage and soil PHE content for PHE degradation, Fe2+ dosage, hydrolysable nitrogen (HN), and available phosphorus for PS decomposition. A comprehensive model of "soil characteristics-oxidation conditions-remediation effect" with a high predictive accuracy was constructed. Based on model identification, Pseudomonas aeruginosa GZ7, which had high PAHs degrading ability after domestication, was further applied to coupling repair remediation. The results showed that the optimal PS dose was 0.75% (w/w). The response relationship between soil physical, chemical, and biological indicators at the intermediate interface and oxidation conditions was analysed. Coupled remediation effects were clarified using microbial diversity sequencing. The introduction of Pseudomonas aeruginosa GZ7 stimulated the relative abundance of Cohnella, Enterobacter, Paenibacillus, and Bacillus, which can promote material metabolism and energy transformation during remediation.

Hydrogel immobilized bacteria@MOFs composite towards Bisphenol A degradation and the interconnection mechanism elucidation

Bisphenol A (BPA) degradation efficiency by bacteria or by metal-organic-frameworks (MOFs) catalyzed persulfate (PMS) oxidation have been studied intensively. However, their synergistic effect on BPA degradation was less reported. In this study, we combined previously synthesized CNT-hemin/Mn-MOF with an BPA degrading bacteria SQ-2 to form a composite (SQ-2@MOFs). CNT-hemin/Mn-MOF in the composite catalyzed little PMS to promote the degradation efficiency of SQ-2 on BPA. Results indicated SQ-2@MOFs significantly accelerated BPA degradation rate than SQ-2 alone. Furthermore, SQ-2@MOFs composite was successfully immobilized in hydrogel to achieve better degradation performance. Immobilized SQ-2@MOFs could almost completely degrade 1-20 mg/L BPA within 24 h and completely degrade 5 mg/L BPA at pH 4-8. Besides, degradation byproducts also reduced by immobilized SQ-2@MOFs, which promoted the cleaner biodegradation of BPA. Metabolomics and multiple chemical characterization results revealed the interconnection mechanism between CNT-hemin/Mn-MOFs, SQ-2 and hydrogel. CNT-hemin/Mn-MOF helped SQ-2 degrade BPA into more biodegradable products, promoted electron transfer, and augmented BPA degradation ability of SQ-2 itself. SQ-2 enabled the surface electronegativity of SQ-2@MOFs more suitable for BPA contact. Meanwhile, SQ-2 avoided the loss of Fe and Mn of CNT-hemin/Mn-MOF. Hydrogel augmented the above synergistic effect. This study provided new perspective for the development of biodegradation materials through interdisciplinary integration.

Toxic effects of triclosan in aquatic organisms: A review focusing on single and combined exposure of environmental conditions and pollutants

Triclosan (TCS) is an antibacterial agent commonly used in personal care products. Due to its widespread use and improper disposal, it is also a pervasive contaminant, particularly in aquatic environments. When released into water bodies, TCS can induce deleterious effects on developmental and physiological aspects of aquatic organisms and also interact with environmental stressors such as weather, metals, pharmaceuticals, and microplastics. Multiple studies have described the adverse effects of TCS on aquatic organisms, but few have reported on the interactions between TCS and other environmental conditions and pollutants. Because aquatic environments include a mix of contaminants and natural factors can correlate with contaminants, it is important to understand the toxicological outcomes of combinations of substances. Due to its lipophilic characteristics, TCS can interact with a wide range of substances and environmental stressors in aquatic environments. Here, we identify a need for caution when using TCS by describing not only the effects of exposure to TCS alone on aquatic organisms but also how toxicity changes when it acts in combination with multiple environmental stressors.

An efficient approach for the treatment of radioactive waste perfluoropolyether lubricants via a synergistic effect of thermal catalysis and immobilization

Perfluoropolyether (PFPE) lubricants are a kind of high-molecular polymer with many excellent properties. However, the use of PFPEs in the nuclear industry can lead to partial decomposition and carrying radionuclides, resulting in a large amount of radioactive waste PFPE lubricants annually. Moreover, radioactive waste PFPE lubricants are difficult to be effectively treated due to their high stability, the risk of possible leakage of radionuclides, and hypertoxic fluorine-containing by-products. In this study, without any precedent, a strategy of MnO2-catalyzed decomposition and Na2CO3-immobilized conversion was proposed for PFPE lubricant decomposition and fluorine immobilization simultaneously based on the Lewis acid-base and oxygen vacancies concept. A high fluorine conversion efficiency of 95.4% was achieved. Meanwhile, the mechanism of decomposition suggested that MnO2 mainly provided Lewis acid sites and attacked the (basic) fluorine or oxygen atoms in PFPE molecules. The decomposition of PFPE chains was proceed down and volatile fluorine-containing gas was released by partial electron transfer, intramolecular disproportionation reaction, and unzipping fashion. Subsequently, gas by-products could be further oxidized and then immobilized into fluoride salts by carbonate solid absorbents. Overall, this study provides a simple, safe, and potentially practical strategy for the harmless conversion of refractory fluorinated organic wastes, especially perfluoropolymers.

Degradation of 2, 4-dichlorophenol by peroxymonosulfate catalyzed by ZnO/ZnMn2 O4

In this study, a highly efficient peroxymonosulfate (PMS) activator, ZnO/ZnMn2 O4 , was synthesized using a simple one-step hydrothermal method. The resulting bimetallic oxide catalyst demonstrated a homogenous and high-purity composition, showcasing synergistic catalytic activity in activating PMS for degrading 2, 4-dichlorophenol (2, 4-DCP) in aqueous solution. This catalytic performance surpassed that of individual ZnO, Mn2 O3 , and ZnMn2 O4 metal materials. Under the optimized conditions, the removal efficiency of 2, 4-DCP reached approximately 86% within 60 min, and the catalytic ability remained almost constant even after four cycles of recycling. The developed degradation system proved effective in degrading other azo-dye pollutants. Certain inorganic anions such as HPO4 - , HCO3 - , and NO3 - significantly inhibited the degradation of 2, 4-DCP, while Cl- and SO4 2- did not exhibit such interference. Results from electrochemical experiments indicated that the electron transfer ability of ZnO/ZnMn2 O4 surpassed that of individual metals, and electron transfer occurred between ZnO/ZnMn2 O4 and the oxidant. The primary active radicals responsible for degrading 2, 4-DCP were identified as SO4 •- , OH• and O2 •- , generated through the oxidation and reduction of PMS catalyzed by Zn (II) and Mn (III). Furthermore, X-ray photoelectron spectroscopy (XPS) analysis of the fresh and used catalysts revealed that the exceptional electron transfer ability of ZnO facilitated the valence transfer of Mn (III) and the transfer of electrons to the catalyst's oxygen surface, thus enhancing the catalytic efficiency. The analysis of radicals and intermediates indicates that the two main pathways for degrading 2, 4-DCP involve hydroxylation and radical attack on its aromatic ring. PRACTITIONER POINTS: A bimetallic ZnO/ZnMn2 O4 catalyst was synthesized and characterized. ZnO/ZnMn2 O4 can synergistically activate PMS to degrade 2, 4-DCP compared with single metal oxide. Three primary active radicals, O2 •- , • OH, and SO4 •- , were generated to promote the degradation. ZnO promoted electron transfer among the three species of Mn to facilitate oxidizing pollutants. Hydroxylation and radical attack on the aromatic ring of 2, 4-DCP are the two degradation pathways.

Overcoming the fluorescent interference during Raman spectroscopy detection of microplastics

Owing to environmental concerns, microplastics pollution has been the object of increasing attention. Currently, the chemical composition of microplastics is commonly detected using Raman spectroscopy. Nevertheless, the Raman spectra of microplastics may be overlaid by signals derived from additives (e.g., pigment), resulting in serious interference. In this study, an efficient method is proposed to overcome the interference of fluorescence during Raman spectroscopic detection of microplastics. Four catalysts of Fenton's reagent (Fe2+, Fe3+, Fe3O4, and K2Fe4O7) have been investigated for their capacity to generate hydroxyl radical (•OH), thus potentially eliminating the fluorescent signals in microplastics. The results indicate that the Raman spectrum of microplastics treated with Fenton's reagent can be efficiently optimized in the absence of spectral processing. This method has been successfully applied to the detection of microplastics collected from mangroves, featuring a range of colours and shapes. Consequentially, after 14 h of treatment with sunlight-Fenton (Fe2+: 1 × 10-‍6 M, H2O2: 4 M), the Raman spectra matching-degree (RSMD) of all microplastics were >70.00 %. The innovative strategy discussed in this manuscript can greatly promote the application of Raman spectroscopy in the detection of real environmental microplastics, overcoming interfering signals derived from additives.

Persulfate enhanced removal of bisphenol A by copper oxide/reduced graphene oxide foam: Influencing factors, mechanism and degradation pathway

The CuO/reduced graphene oxide foam (CuO/RGF) with excellent recyclability was prepared via hydrothermal method followed by freeze drying treatment for bisphenol A (BPA) removal via activating peroxydisulfate (PDS). SEM, XRD, XPS, FT-IR, BET, and TG techniques were used to investigate the structure and property of CuO/RGF. The effect of degradation conditions (pH, PDS amount, Cl-, HCO3-, HA and FA) on BPA removal by CuO/RGF were investigated. The result presented that CuO nanosheet was inserted into the RGF carrier with three-dimensional structure. The degradation rate constant of BPA over CuO/RGF (0.00917 min-1) was 1.24 and 6.46 times higher than those of BPA over CuO (0.00714 min-1) and RGF (0.00142 min-1). More importantly, the pore structure of RGF can successfully limit the release of Cu (II) compared to pure CuO. According to quenching test as well as electron spin resonance (EPR) spectra, BPA degradation was triggered by 1O2, •OH and SO4•-, which was the combination of nonradical (1O2) and radical activation of PDS (•OH and SO4•-). The possible degradation route of BPA was proposed based on intermediates obtained by combining solid phase extraction pretreatment technique with high performance liquid-mass spectrometry. After assessing the viability of MCF-7 cells, we can see that the estrogenic activities of treated solution reduced without producing stronger endocrine disruptors.

Floating metal phthalocyanine@polyacrylonitrile nanofibers for peroxymonosulfate activation: Synergistic photothermal effects and highly efficient flowing wastewater treatment

Highly efficient floating photocatalysis has potential applications in organic pollutant treatment but remains limited by low degradation efficiency in practical applications. By introducing the photothermal effect into a peroxymonosulfate (PMS) coupled photocatalysis system, tetracycline hydrochloride (TCH) degradation could be significantly enhanced using floating metal phthalocyanine@polyacrylonitrile (MPc@PAN) nanofiber mats. MPc@PAN nanofibers with different metal centers showed similar photothermal conversion performance but different activation energies for PMS activation, resulting in metal-center-dependent synergistic photothermal effects, i.e., light-enhanced dominated, thermal-enhanced dominated, and conjointly light-thermal dominated mechanisms. The porous structures and floating ability of the FePc@PAN nanofibers provided a fast mass transfer process, with higher solar energy utilization and superior photothermal conversion performance than the FePc nanopowders. Meanwhile, the FePc@PAN nanofibers showed excellent TCH removal stability within 10 cycles (>92%) and extremely low Fe ion leaching (<0.055 mg/L) in a dual-channel flowing wastewater treatment system. This work provides new insight into PMS activation via photothermal effects for environmental remediation.

Peroxymonosulfate activation with an α-MnO2/Mn2O3/Mn3O4 hybrid system: parametric optimization and oxidative degradation of organic dye

The present study proposed the synthesis of low-toxicity and eco-friendly spherically shaped manganese oxides (α-MnO₂, Mn₂O₃, and Mn₃O₄) by using the chemical precipitation method. The unique variable oxidation states and different structural diversity of manganese-based materials have a strong effect on fast electron transfer reactions. XRD, SEM, and BET analyses were used to confirm the structure morphology, higher surface area, and excellent porosity. The catalytic activity of as-prepared manganese oxides (MnO_x) was investigated for the rhodamine B (RhB) organic pollutant with peroxymonosulfate (PMS) activation under the condition of control pH. In acidic conditions (pH = 3), complete RhB degradation and 90% total organic carbon (TOC) reduction were attained in 60 min. The effects of operating parameters such as solution pH, PMS loading, catalyst dosage, and dye concentration on RhB removal reduction were also tested. The different oxidation states of MnO_x promote the oxidative-reductive reaction under acidic conditions and enhance the SO₄^•-/^•OH radical formation during the treatment, whereas the higher surface area offers sufficient absorption sites for interaction of the catalyst with pollutants. A scavenger experiment was used to investigate the generation of more reactive species that participate in dye degradation. The effect of inorganic anions on divalent metal ions that genuinely occur in water bodies was also studied. Additionally, separation and mass analysis were used to investigate the RhB dye degradation mechanism at optimum conditions based on the intermediate's identification. Repeatability tests confirmed that MnO_x showed superb catalytic performance on its removal trend.

Peroxymonosulfate activation by magnetic CoNi-MOF catalyst for degradation of organic dye

In this work, Fe₃O₄/CoNi-MOF was synthesized by a simple solvothermal method. The catalytic performance of 0.2-Fe₃O₄/CoNi-MOF toward PMS activation was studied by degradation of 20 mg/L methylene blue (MB). The results indicated that 0.2-Fe₃O₄/CoNi-MOF had good catalytic ability, the removal rate of MB was 99.4% within 60 min with 125 mg/L PMS and 150 mg/L catalyst. Quenching experiment and electron paramagnetic resonance (EPR) analysis revealed that the singlet oxygen (¹O₂), superoxide radical (•O₂^-) and sulfate radical (SO₄^•-) played a crucial role in the catalytic degradation process. Meantime, mechanism of PMS activation by 0.2-Fe₃O₄/CoNi-MOF was proposed, the electrons donated by Fe²⁺ can also enhance the Co-Ni cycles. In conclusion, Fe₃O₄/CoNi-MOF composite catalyst has the advantages of simple preparation, excellent catalytic activity and reusability, which is an effective catalyst for water pollution control.

Nitrogen doped bimetallic sludge biochar composite for synergistic persulfate activation: Reactivity, stability and mechanisms

As a recycling use of waste activated sludge (WAS), we used high-temperature pyrolysis of WAS to support bimetallic Fe-Mn with nitrogen (N) co-doping (FeMn@N-S), a customized composite catalyst that activates peroxysulphate (PS) for the breakdown of tetracycline (TC). First, the performance of TC degradation was evaluated and optimized under different N doping, pH, catalyst dosages, PS dosages, and contaminant concentrations. Activating PS with FeMn@N-S caused the degradation of 91% of the TC in 120 min. Next, characterization of FeMn@N-S by XRD, XPS and FT-IR analysis highlights N doping is beneficial to take shape more active sites and reduces the loss of Fe and Mn during the degradation reaction. As expected, the presence of Fe-Mn bimetallic on the catalyst surface increases the rate of electron transfer, promoting the redox cycle of the catalyst. Other functional groups on the catalyst surface, such as oxygen-containing groups, accelerated the electron transfer during PS activation. Free radical quenching and ESR analysis suggest that the main contributor to TC degradation is surface-bound SO₄^•-, along with the presence of single linear oxygen (¹O₂) oxidation pathway. Finally, the FeMn@N-S composite catalyst exhibits excellent pH suitability and reusability, indicating a solid practicality of this catalyst in PS-based removal of antibiotics from wastewater.

Efficacy and mechanism of peroxymonosulfate activation by single-atom transition metal catalysts for the oxidation of organic pollutants: Experimental validation and theoretical calculation

Single-atom catalysts can activate peroxymonosulfate (PMS) to enhance its oxidation of organic pollutants in water treatment. We synthesized a series of carbon-supported single-atom transition metal catalysts (MnN@C, FeN@C, CoN@C, NiN@C, and CuN@C) with similar compositions and structures. Their catalytic activity toward PMS activation and oxidation mechanisms were investigated using acid orange 7 (AO7) as a model pollutant. The degradation rate (min^-1·mol^-1·g·m^-2) of AO7 followed order: FeN@C/PMS (7.576 × 10³) > MnN@C/PMS (5.104 × 10³) > CoN@C/PMS (1.919 × 10³) ≫ NiN@C/PMS (0.058 × 10³) > CuN@C/PMS (0.035 × 10³). Electron transfer mediated by surface-activated PMS was found to be the main regime of AO7 oxidation in the catalytic systems. Density functional theory calculations indicated that the degradation of AO7 was promoted by the intense adsorption of PMS and the electron transfer between AO7 and the surface-activated PMS on the catalyst. The cleavage of the naphthalene ring and the azo group was the primary degradation pathway. The toxicity of the products was significantly reduced. This research provides valuable findings for preparing highly efficient single-atom transition metal catalysts for PMS-based degradation of toxic and refractory organic pollutants from water.

Vivianite-induced peroxymonosulfate activation for containment removal under dark conditions: Performance, mechanism and regeneration

The performance and intrinsic mechanism of vivianite, a natural mineral containing structural Fe(II), for peroxymonosulfate (PMS) activation and pollutant degradation under dark conditions were comprehensively explored in this study. It was found that vivianite was able to efficiently activate PMS to degrade various pharmaceutical pollutants under dark conditions, in which the corresponding reaction rate constant of ciprofloxacin (CIP) degradation was 47- and 32-fold higher than that of magnetite and siderite, respectively. SO₄^·-, ^·OH, Fe(IV) and electron-transfer processes were found in the vivianite-PMS system, while SO₄^·- was the main contributor to CIP degradation. Moreover, mechanistic explorations revealed that the Fe site on the surface of vivianite could bind PMS in the form of a bridge position, and thus vivianite could rapidly activate absorbed PMS due to its strong electron-donating ability. Additionally, it was illustrated that the used vivianite could be efficiently regenerated by either chemical or biological reduction. This study may provide an alternative application of vivianite in addition to phosphorus recovery from wastewater.

Visible light enhanced persulfate activation for degradation of tetracycline via boosting adsorption of persulfate by ligand-deficient MIL-101(Fe) icosahedron

In this work, Fe-based metal-organic frameworks (Fe-MOFs) are prepared by a simple solvothermal method, in which acetic acid/N, N-dimethylformamide (HAc/DMF) mixture solvents are employed to regulate the particle morphology, exposed facets and ligand defects. At HAc/DMF = 0/50, 5/45 and 8/42 (volume ratio), the irregular particles (MIL-53(Fe)), elongated icosahedrons (5H-MIL-101(Fe)) and icosahedrons (8H-MIL-101(Fe)) are obtained, respectively. Under visible light irradiation (λ > 420 nm) and the addition of sodium persulfate (PS), 5H-MIL-101(Fe) shows the highest degradation activity for tetracycline (TC). Specifically, 80% of TC has been removed by 5H-MIL-101(Fe) within 25 min, and the degradation kinetics rate is 3.03 times higher than that over MIL-53(Fe). The improvement of catalytic activity is mainly attributed to the active facets exposed and ligand defects of 5H-MIL-101(Fe). Density functional theory (DFT) calculation further confirms that the active facets exposed and ligand defects of 5H-MIL-101(Fe) favor the adsorption and activation of PS, benefiting the generation of •SO₄^-. Besides, a probable degradation pathway of TC is proposed based on trapping experiments and liquid chromatography-mass spectrometry (LC-MS) test. Furthermore, the toxicities of intermediates are predicted by the quantitative structure-activity relationship (QSAR) mathematical model. This work demonstrates that visible light enhanced PS activation (Vis-PSA) can more effectively degrade organic pollutants, and this work also provides a simple strategy to precisely regulate ligand defects and actively exposed facets of Fe-MOFs to enhance the adsorption and activation of PS.

Synthesis of an Environmentally Friendly Modified Mulberry Branch-Derived Biochar Composite: High Degradation Efficiency of BPA and Mitigation of Toxicity in Silkworm Larvae

In the present study, mulberry branch-derived biochar CuO (MBC/CuO) composite was successfully synthesized and used as a catalyst to activate persulfate (PS) for the degradation of bisphenol A (BPA). The MBC/CuO/PS system exhibited a high degradation efficiency (93%) of BPA, under the conditions of 0.1 g/L MBC/CuO, 1.0 mM PS, 10 mg/L BPA. Free radical quenching and electron spin-resonance spectroscopy (ESR) experiments confirmed that both free radicals ^•OH, SO₄^•- and O₂^•- and non-radicals ¹O₂ were involved in the MBC/CuO reaction system. Cl^- and NOM displayed negligible influence on the degradation of BPA, while HCO₃^- promoted the removal of BPA. In addition, the toxicity tests of BPA, MBC/CuO and the degraded BPA solution were conducted by the 5th instar silkworm larvae. The toxicity of BPA was reduced after the treatment in the MBC/CuO/PS system, and no obvious toxicity of the synthesized MBC/CuO composite was found in the toxicity evaluation experiments. This work provides a new value-added utilization of mulberry branches as a cost-effective and environmentally friendly PS activator.

The role of MnO2 crystal morphological scale and crystal structure in selective catalytic degradation of azo dye

MnO₂, as a representative manganese-based catalyst with many kinds of crystal forms, has been widely used to activate PMS. However, the role of morphological scale and crystal structures on the catalytic capability of MnO₂ still lacks further study. In this study, four different crystal forms of MnO₂ (α-MnO₂, β-MnO₂, γ-MnO₂, and δ-MnO₂) are succeeded in being fabricated via hydrothermal processes and evaluated by activating PMS for the removal of Reactive Yellow X-RG, typical azo dye. Experiment results indicate that α-MnO₂ with a one-dimensional structure exhibits the best catalytic performance among the four as-prepared MnO₂, which can be attributed to its broadest crystal interplanar distance (0.692), the highest portion of Mn (III)/Mn (IV) (4.194), and lowest value of average oxidation state AOS (2.696). Correlation analysis confirms that interplanar distance is the most relative factor with the catalytic activity of MnO₂ among the three studied factors (R² = 0.99715). Meanwhile, the morphological scale structure of α-MnO₂ can also account for its highest catalytic ability among the four as-prepared MnO₂, including its large specific area and advantageous one-dimensional nanostructure. Furthermore, according to the response surface methodology, when the dosage of PMS is 2.369 g/L, the dosage of α-MnO₂ is 0.991 g/L, and the initial dye concentration is 1025 mg/L, the maximum removal rate of Reactive Yellow X-RG is up to 97.38%.

New insight of Mn(III) in δ-MnO2 for peroxymonosulfate activation reaction: Via direct electron transfer or via free radical reactions

Due to the increasing of industrial plastic waste and its refractory characteristics, it is extremely urgent to develop new degradation technology and environmentally friendly catalyst for industrial plastic waste. Manganese oxides are one of the most promising candidates for the catalytic degradation of plastic wastes. However, an improved understanding of the structural properties affecting their catalytic activity is required for high-efficient wastewater treatment. We herein report the surface reactivity effects of δ-MnO₂ structural defects with regards to Bisphenol A (BPA) degradation/probe in the presence of peroxymonosulfate (PMS). Four δ-MnO_x samples with different Mn(III) contents (different Mn(III)-deficient sample) were prepared and their structural properties as well as surface reactivity were characterized by batch test, ESR and XAFS analysis. For the Mn(III)-deficient sample, BPA removal was principally affected by direct electron transfer, with the adsorbed BPA degraded following hydroxylation. In contrast, a small fraction of Mn(III) substitution in δ-MnO₂ could significantly encouraged the activation of PMS to produce SO₄^-☐and ☐OH, and a BPA degradation via beta scission. Moreover, the Mn(III)-rich δ-MnO₂ demonstrate a high BPA removal rate even with a low sample load, which performed well following a reuse of five times. Our results provide a new way for the improvement of δ-MnO₂ activity for the use of industrial plastic wastes treatment.

Nano-architecture of MOF (ZIF-67)-based Co3O4 NPs@N-doped porous carbon polyhedral nanocomposites for oxidative degradation of antibiotic sulfamethoxazole from wastewater

Co₃O₄ NPs in N-doped porous carbon (Co₃O₄ NPs@N-PC) materials were prepared by one-pot pyrolysis of a ZIF-67 powder under N₂ atmosphere and followed by oxidation under air atmosphere (200 °C) toward promotion catalytic activity and activation of peroxymonosulfate (PMS) to degradation sulfamethoxazole (SMZ). 2-methylimidazole was used as a nitrogen source and a competitive ligand for the synthesis of Co₃O₄ NPs@N-PC, which in addition to affecting nucleation and growth of the crystal, promotes the production of active Co-N sites. Co₃O₄ NPs@N-PC nano-architecture has high specific surface areas (250 m² g^-1) and is a non-toxic, effective and stable PMS activator. The effect of operating parameters including SMZ concentration, catalyst dosage, temperature and pH in the presence of Co₃O₄ NPs@N-PC was investigated. The Co₃O₄ NPs@N-PC composite showed superior performance in activating PMS over a wide range of pH (2-10) and different temperatures so that complete degradation of SMZ (50 μM, 100 mL) was achieved within 15 min. The role of Co^2+/Co³⁺ redox system in the mechanism before and after PMS activation was determined using XPS analysis. Surface-generated radicals led to the degradation of SMZ, in which the SMZ degradation rate attained 0.21 min^-1 with the mineralization of 36.8%. The feasible degradation mechanism of SMZ was studied in the presence of different scavengers and it was revealed that the degradation reaction proceeds from the radical/non-radical pathway and in this process most of the SO₄^- and OH radicals are dominant. The recoverability and reuse of Co₃O₄ NPs@N-PC were evaluated to confirm its stability and potential for SMZ degradation and it was observed that the catalyst maintains its catalytic power for at least 5 cycles.

A ZIF-8-derived copper-nitrogen co-hybrid carbon catalyst for peroxymonosulfate activation to degrade BPA

A series of copper-nitrogen co-hybrid porous carbon catalysts were prepared by pyrolysis of copper-doped ZIF-8 in argon atmosphere. Both the precursors and the corresponding pyrolysis products retained the polyhedral morphology of ZIF-8. The catalytic performance of the catalysts obtained at different Cu doping levels and pyrolysis temperatures for PMS activation was compared by bisphenol A (BPA) degradation experiment. Among them 5%Cu-NC(8) catalyst obtained by pyrolysis of 5%Cu-ZIF-8 at 950 °C showed the best catalytic performance. The catalytic mechanism of PMS activation catalyzed by 5%Cu-NC(8) was analyzed by quenching experiment, ESR and XPS. The degradation pathways of BPA in 5%Cu-NC(8)/PMS system were proposed on the basis of LC-MS analyses. Pyridine N (including Cu-N), graphite N, CO group and the valence change of Cu were recognized as the catalytic active sites for 5%Cu-NC(8). Both free radical and non-free radical processes were involved in BPA degradation, and singlet oxygen (¹O₂) was identified to be the main active substance. The stable performance and low Cu leaching rate in recycling experiment indicated that 5%Cu-NC(8) had good reusability and stability. This study provided a new insight for the design of heterogeneous copper-nitrogen co-hybrid carbon catalysts.

Elimination of bisphenol A with visible light-enhanced peroxydisulfate activation process mediated by Fe3+-nitrilotriacetic acid complex

In recent years, visible light assisted advanced oxidation processes (AOPs) are appealing in the elimination of pollutants. Herein, an innovative and eco-friendly visible light enhanced Fe³⁺-nitrilotriacetic acid system for the activation of peroxydisulfate (Vis/Fe³⁺-NTA/PDS) was proposed for the removal of bisphenol A (BPA). Fe³⁺-NTA could be dissociated through ligand-to-metal charge transfer (LMCT) to realize the generation of Fe²⁺ for the continuous activation of PDS to remove BPA. The use of 0.10 mM Fe³⁺, 0.10 mM NTA and 1.00 mM PDS led to 97.5% decay of 0.05 mM BPA and 66.3% of TOC removal in 30 min with the illumination of visible light at initial pH 3.0. The sulfate and hydroxyl radicals were proved to be the dominant species leading to BPA removal by means of radical scavenging experiments, radical probes and electron paramagnetic resonance (EPR) technique. The effects of various operating parameters, natural water constituents as well as different water matrices on BPA abatement were explored. The intermediate products of BPA degradation were identified and a possible transformation pathway was proposed. Briefly, this research provides an attractive strategy for the remediation of refractory wastewater using NTA assisted with visible light in the homogeneous Fe³⁺/PDS system.

Mn2O3/Mn3O4-Cu1.5Mn1.5O4 spinel as an efficient Fenton-like catalyst activating persulfate for the degradation of bisphenol A: Superoxide radicals dominate the reaction

In this work, a Mn₂O₃/Mn₃O₄-Cu_1.5Mn_1.5O₄ spinel was fabricated and utilised as a catalyst to activate peroxydisulfate (PDS) leading to degradation of bisphenol A (BPA). The results showed that the system exhibited an excellent turnover frequency (TOF) of 2.7 × 10^-3 s^-1 and high stability. The amount of ion leaching was small and the degree of mineralisation was up to 66.2%. Superoxide radicals (O₂^-) were determined to be the dominant active species in the system. ≡Mn(II) and oxygen vacancies (V_o) were found to be the main active sites at the catalyst surface. The activation of PDS by the spinel catalyst and the reduction of dissolved oxygen both contributed to the production of O₂^- species. The synergistic effect of ≡Cu(I)/≡Cu(II) and ≡Mn(II)/≡Mn(III) redox pairs enabled the reaction to occur continuously. These results suggest the promise of this novel spinel catalyst in the removal of refractory organic compounds due to its excellent performance and stability. The catalyst may thus have great utility for environmental remediation.

Trace Iron as single-electron shuttle for interdependent activation of peroxydisulfate and HSO3-/O2 enables accelerated generation of radicals

The generation of reactive oxygen species generally requires initiators in various environmental remediation processes, which necessitates high dosage of activators and downstream treatment for eliminating the accumulation of deactivated catalysts. Herein, a coupled process was constructed using trace iron for simultaneously activating HSO₃^-/O₂ system and peroxydisulfate (PDS) oxidation system, where the iron ions (2 mg/L) transferred single-electron from the former system to the latter due to the moderate redox potential (Fe³⁺/Fe²⁺, +0.77 V) between the potentials of SO₃^·-/HSO₃^- (+0.63 V) and PDS/SO₄^·- (+2.01 V). Hence, the phenol degradation quickly occurred at a first-order kinetic constant of k₁=0.223 min^-1 due to the accelerated generation of sulfate radical (SO₄^·-) and hydroxyl radical (^·OH) in the process. The k₁ value was almost 6-fold of that in the deoxygenated condition (0.040 min^-1). Density function theory reveals that the single electron shuttle spatially separates the electron-donating activation of HSO₃^- and electron-accepting activation of PDS, while avoiding the "mutual-annihilation" of HSO₃^- and S₂O₈^2- via direct two-electron transfer. Finally, utilizing the in-situ generated electron-shuttle (dissolved iron from cast iron pipe), the HSO₃^-/PDS reagent could efficiently inactivate the chlorine-resistant pathogens and inhibits biofilm regrowth inside the distribution systems at regular intervals or infectious disease outbreak in a neighborhood.

Waste coal cinder catalyst enhanced electrocatalytic oxidation and persulfate advanced oxidation for the degradation of sulfadiazine

Waste coal cinder, a kind of waste cinder discharged from coal combustion of thermal power plants, industrial and civil boilers, and other equipment, was rich in metal oxides with catalytic activity. In this work, waste coal cinder was used to enhance electrochemical coupling peroxymonosulfate (PMS) advanced oxidation degradation of sulfadiazine (SD). The surface morphology, elemental composition, and electrocatalytic activity of waste coal cinder were characterized by various characterization instruments. The results show that compared with simple electrocatalytic oxidation, electrocatalytic oxidation + waste coal cinder and electrocatalytic coupled persulfate oxidation, electrocatalytic oxidation + PMS advanced oxidation + waste coal cinder has the largest removal efficiency (99.95%) and mineralization rates (90.16%) of SD in 90 min, indicating that the introduction of waste coal cinder greatly increases the degradation efficiency. •OH and SO₄^-• were detected during the process of degradation. The optimal degradation process parameters were explored through different voltage, pH, plate spacing, aeration flow rate, potassium peroxymonosulfate sulfate complex salt dose, and Na₂SO₄ dosage. Cycling experiments show waste coal cinder has good structural stability. Through the analysis of triple quadrupole liquid chromatography-mass spectrometry (LC-MS), we put forward three possible ways of SD degradation. This research will provide a novel vision for water treatment.

Nonradical electron transfer-based peroxydisulfate activation by a Mn-Fe bimetallic oxide derived from spent alkaline battery for the oxidation of bisphenol A

Mn-Fe bimetallic oxide has been employed as an outstanding peroxydisulfate (PDS) activator, but the underlying mechanism is still controversial. In this work, Mn_0.27FeO_4.55 (MFBO) was synthesized using the recovered waste alkaline battery and its catalytic activity and mechanism for PDS activation were explored in detail. Results show that MFBO exhibited a higher catalytic activity than the individual single metal oxides (FeO_x and Mn₂O₃) due to the synergistic effect between Fe and Mn elements. The removal efficiency of bisphenol A (BPA) with an initial concentration of 10 mg/L reached 97.8% within 90 min in the presence of 0.5 g/L MFBO and 2.0 mM PDS. Moreover, the MFBO maintained high stability and reusability even after being recycled for five times. With the aid of a series of experiments and ex-situ/in-situ characterizations, a non-radical PDS activation mechanism was proposed, in which organic contaminants would be oxidized through a direct electron transfer pathway mediated by the metastable reactive complexes (MFBO-PDS*). Notably, the MFBO/PDS system revealed selective oxidation towards different organic pollutants and the reaction rates were closely related to their structures and properties. The research provided an effective alternation process for application of the waste battery, as well as developed a novel perspective for removal of recalcitrant aqueous contaminants through a nonradical mechanism.

Performance of a Three-Dimensional Electrochemical Reactor (3DER) on Bisphenol A Degradation

This study constructed a three-dimensional electrochemical reactor (3DER) using meshed stainless steel sheets and titanic magnetite particles (TMP) to investigate bisphenol A (BPA) degradation through the synergistic action of electrical current and TMP. We examined some TMP characteristics, such as particle size, specific surface areas, X-ray diffraction, surface imaging, elemental constituents, and electrical resistivity. It was found that TMP was a micron-level material with excellent electrical conductivity, and it could be regarded as a magnetite-based material comprising Fe(II) and Fe(III). The single-factor experiment determined the optimal conditions for BPA removal in 3DER, specifically by introducing 200 ml of BPA-simulated wastewater (10 mg L⁻¹) into 3DER. At the initial pH of 9.00, current and electrodes gap of 300 mA and 15 mm, respectively, and adding 1 ml of 0.5 M potassium peroxymonosulfate and 1 g TMP, > 98% of BPA was removed after 55 min of electrochemical reaction. In addition, liquid chromatography–mass spectrometry identified the intermediates formed during the BPA treatment, showing two possible pathways for BPA degradation. The final degradation intermediates were chain organics with simple molecular structures. This research provided an understanding of the potential application of 3DER for BPA removal in water.

Facile synthesis of CoOOH@MXene to activate peroxymonosulfate for efficient degradation of sulfamethoxazole: performance and mechanism investigation

Using MXene as substrate, CoOOH@MXene with different mass content of CoOOH were prepared and used to active peroxymonosulfate (PMS) for the sulfamethoxazole (SMX) degradation. The sample characterizations demonstrated the successful preparation of CoOOH@MXene. CoOOH@MXene possessed much higher BET surface area (183.82 m2/g) than CoOOH (85.36 m2/g) and MXene (6.89 m2/g) due to the good dispersibility of CoOOH particles on MXene. Due to its large surface area, 1.3CoOOH@MXene displayed the best catalytic performance for the degradation of SMX. With 0.2 g/L of 1.3CoOOH@MXene and 0.5 mM of PMS, 20 μM of SMX was completely eliminated in 10 min. The degradation followed pseudo-first-order kinetic model well, with rate constants of 0.33 min-1 for 1.3CoOOH@MXene and 0.054 min-1 for CoOOH. Influencing factors of initial pH, catalyst dosage, PMS concentration, SMX concentration, and co-existing anions on SMX degradation were assessed systematically. Recycling tests verified the excellent reusability and stability of the catalyst. Quenching experiments and electron paramagnetic resonance analysis substantiated that 1O2 played a leading role. Moreover, the intermediates were identified, and degradation pathways and activation mechanism of CoOOH@MXene for PMS were proposed. This work may highlight the application of MXene with transition metals in PMS activation.

Degradation of atrazine in water by Bi2MoO6 and visible light activated Fe3+/peroxymonosulfate coupling system

In this study, the effects of ferric ion (Fe³⁺) on the degradation of atrazine (ATZ) in Bi₂MoO₆/peroxymonosulfate (PMS) system under visible light irradiation was investigated. With the addition of Fe³⁺, ATZ in the visible light/Bi₂MoO₆/PMS system degraded rapidly after 20 min treatment (removal rate > 99%). The enhancement of ATZ removal can be attributed to the role of Fe³⁺. As an electron transfer mediator, Fe³⁺ not only inhibits the recombination of photo-charges and prolongs the life of photogenerated carriers, but also promotes the activation of PMS by accelerating the electron transfer from Bi₂MoO₆ to PMS. The generation of ^•OH and SO₄^•- in the system was determined via electron paramagnetic resonance (EPR) technology and quenching experiments. Furthermore, the characterization of Bi₂MoO₆ before and after reaction, influence of the reaction parameters (i.e., catalyst and PMS dosages, Fe³⁺ and ATZ concentration, initial pH), influence of inorganic anions and humic acid, and the recyclability of catalyst in the vis/Bi₂MoO₆/PMS/Fe³⁺ system was also investigated. Additionally, the existence of Fe³⁺ also exhibits a wide selectivity for the degradation of different pollutants and high treatment efficiency. In general, the vis/Bi₂MoO₆/PMS/Fe³⁺ system demonstrated the potential as an efficient, economical, and environment-friendly water treatment process.

Aluminum-based layered metal oxides activating peroxymonosulfate for bisphenol A degradation via surface-bound sulfate radicals and singlet oxygen

In this study, a series of aluminum-based layered metal oxide with various divalent metals (M²⁺Al-LMOs) were prepared and employed in activation of peroxymonosulfate (PMS) for bisphenol A (BPA) degradation. The BPA removal rates of M²⁺Al-LMOs were ordered as: CoAl(100%) > MnAl(75.6%) > CuAl(63.2%) > NiAl(9.0%) > MgAl = ZnAl-LMO(0%). CoAl-LMO showed the highest kinetic constant (k = 1.329 µmol^-1g_cat^-1s^-1), which was 3.95 times of MnAl-LMO, 5.36 times of CuAl-LMO, 88.6 times of NiAl-LMO and 443 times of MgAl-LMO and ZnAl-LMO, respectively, and also exhibited the highest TOC removal rate (83.3%). The surface-bound sulfate radical (SO₄^·-) and singlet oxygen (¹O₂) were elucidated as the dominant reactive oxygen species (ROS) for BPA degradation. The M²⁺Al-LMOs/PMS system not only displayed wide applicability in different pH and inorganic anions environments, but also had excellent stability and reusability. This work provides a novel family of M²⁺Al-LMOs to activate PMS for water treatment.

Enhanced visible light photo-Fenton-like degradation of tetracyclines by expanded perlite supported FeMo3Ox/g-C3N4 floating Z-scheme catalyst

In the conventional Fenton system, the relatively low efficiency of Fe (II) regeneration is a significant drawback. To address this shortcoming, a novel floating Z-scheme photo-Fenton catalyst FeMo₃O_x/g-C₃N₄/EP was prepared by a facile dip-calcination method, in which iron and molybdenum oxides with mixed valence states (FeMo₃O_x) and graphitic carbon nitride (g-C₃N₄) were loaded on the expanded perlite. The removal efficiencies reached the maximum at 98.0%, 93.1% and 97.1% for tetracycline, oxytetracycline and chlortetracycline, respectively, after 60 min dark adsorption and 60 min photo-Fenton process. The aid of dual ion (Fe and Mo) synergy system and photoreduction by Z-scheme photocatalyst enhanced the Fe (II) regeneration, resulting in the excellent performance. Radical scavenger experiment, electron spin resonance spectra (ESR) and X-ray photoelectron spectra (XPS) were used to confirm the mechanism of free radicals' formation and Fe/Mo redox cycling. ·OH, ·O₂^- and ¹O₂ played important roles in the pollutant's degradation, while the generation of ·O₂^- was enhanced due to the floatability in this system. The possible degradation pathways of TC were put forward according to the results of mass spectrum and Orbital-Weighted Fukui Function. Overall, this work provides new insights on the cooperation between iron-based mix oxides and semiconductor in the photo-Fenton system.

Peptide-mediated green synthesis of the MnO2@ZIF-8 core-shell nanoparticles for efficient removal of pollutant dyes from wastewater via a synergistic process

The MnO₂@ZIF-8 core-shell nanoparticles for highly efficient dye degradation have been synthesized with a green method. ZIF-8 crystals with controlled morphology and size are first synthesized by using peptide to modulate the crystal growth. MnO₂ is then coated on ZIF-8 via in situ reaction. The surface MnO₂ density can be controlled by the dosage of KMnO₄. The MnO₂@ZIF-8 nanoparticles work as photocatalyst to degrade rhodamine B in a Fenton-like process, giving a degradation ratio of > 96.0%. The degradation kinetics comply well with the Pseudo-second-order model and the experimental equilibrium data meet the Langmuir model best. The specific hierarchical structure of MnO₂@ZIF-8 assures a synergistic enhancement of the catalytic degradation performance from several aspects. First, anchoring of the MnO₂ nanoparticles on ZIF-8 allows their well disperse to provide more active surface area. Second, highly porous ZIF-8 can adsorb dye molecules to accumulate them at the surface reactive sites. Third, the MnO₂/ZIF-8 nano-heterojunctions enhance charge carrier transfer and accelerate the production of free oxidative radicals. The study demonstrates a green method for fabrication of hierarchical hybrid structures, paving the way for designing novel photocatalysts with potential applications for wastewater treatment.

Amlodipine removal via peroxymonosulfate activated by carbon nanotubes/cobalt oxide (CNTs/Co3O4) in water

Amlodipine (AML) is an effective drug that has been widely used for hypertension and angina. However, AML is frequently detected in aqueous environments, posing potential risks to human and ecological health. In this study, the degradation of AML via peroxymonosulfate (PMS) activated by CNTs/Co₃O₄ was investigated. CNTs/Co₃O₄ was prepared via a facile method, and multiple characterizations suggested that Co₃O₄ were uniformly dispersed on the surface of MWCNTs-COOH. Experimental results indicated that complete removal of 10 μM AML was achieved within 30 min by using 2 mg/L CNTs/Co₃O₄ and 4 μM PMS at 25 °C in PBS buffered solution (pH 7.0). The observed pseudo-first-order rate constant was calculated to be 0.1369 min^-1. Interestingly, the presence of 100 mM Cl^- resulted in a slight enhancement of AML removal rate from 0.0528 to 0.0642 min^-1. The addition of 100 mM HCO₃^-, 5 mg/L Pony Lake fulvic acid (PLFA), or Suwannee River humic acid (SRHA) retarded AML degradation by 15.5, 0.7, and 1.6 times, respectively. As per the quenching experiments, SO₄^⦁- rather than ⦁OH were verified to be the dominant reactive oxygen species (ROS). Additionally, ten major intermediates were identified using TOF-LC-MS and three associated reaction pathways including ether bond broken, H-abstraction, and hydroxylation were proposed. We outlook these findings to advance the feasibility of organic contaminants removal via CNTs/Co₃O₄ + PMS systems that have extremely low-level PMS.

Fast Generation of Hydroxyl Radicals by Rerouting the Electron Transfer Pathway via Constructed Chemical Channels during the Photo-Electro-Reduction of Oxygen

A strategy for the fast generation of hydroxyl radicals (HO·) via photo-electro-reduction of oxygen by rerouting the electron transfer pathway was proposed. The rate-determining step of HO· production is the formation of H₂O₂ and the simultaneous reduction of H₂O₂. Engineering of F-TiO₂ with single atom Pd bonded with four F and two O atoms favored the electrocatalytic 2-electron oxygen reduction to H₂O₂ with as high as 99% selectivity, while the additional channel bond HO-O···Pd-F-TiO₂ facilitates the photogenerated electron transfer from the conduction band to single atom Pd to reduce Pd···O-OH to HO·. The optimized HO· production rate is 9.18 μ mol L^-1 min^-1, which is 2.6-52.5 times higher than that in traditional advanced oxidation processes. In the application of wastewater treatment, this proposed photoelectrocatalytic oxygen reduction method, respectively, shows fast kinetics of 0.324 and 0.175 min^-1 for removing bisphenol A and acetaminophen. Around 93.2% total organic carbon and 99.3% acute toxicity removal were achieved. Additionally, the degradation efficiency was less affected by the water source and pH value because of the evitable usage of metallic active sites. This work represents a fundamental investigation on the generation rate of HO·, which would pave the way for the future development of photoelectrocatalytic technologies for water purification.

Catalytic ozonation of chloramphenicol with manganese-copper oxides/maghemite in solution: Empirical kinetics model, degradation pathway, catalytic mechanism, and antibacterial activity

The composite material of manganese-copper oxide/maghemite (Mn_xCu_yO_z/γ-Fe₂O₃) was synthesized by the co-precipitation-calcination method. With the initial concentration of 0.2 g/L Mn_xCu_yO_z/γ-Fe₂O₃ and 10 mg/L O₃, the chloramphenicol (CAP, 10 mg/L) could be completely degraded, which was about 2.22 times of that treated with ozonation alone. The contribution of O₃ and hydroxyl radical (•OH) for CAP degradation in the catalytic process was 6.9% and 93.1%, respectively. According to the effects of catalyst dosage, ozone dosage, and pH on the catalytic performance of Mn_xCu_yO_z/γ-Fe₂O₃, a predictive empirical model was developed for the ozonation with the Mn_xCu_yO_z/γ-Fe₂O₃ system. The HCO₃^-/CO₃^2- and phosphates in solution could inhibit the degradation of CAP with the inhibition ratios 8.45% and 13.8%, respectively. The HCO₃^-/CO₃^2- could compete with CAP and react with •OH, and the phosphates were considered as poisons for catalysts by blocking the surface active sites to inhibit ozone decomposition. The intermediates and possible degradation pathways were detected and proposed. The catalytic ozonation could effectively control the toxicity of the treated solution, but the toxicity was still not negligible. Furthermore, Mn_xCu_yO_z/γ-Fe₂O₃ could be easily and efficiently separated from the reaction system with an external magnet, and it possessed excellent reusability and stability.

Manganese oxide OMS-2 loaded on activated carbon fiber: a novel catalyst-assisted UV/PMS process for carbamazepine treatment in water

A novel catalyst was prepared by loading OMS-2 onto activated carbon fiber (ACF) via a one-step hydrothermal method, which was further adopted for carbamazepine treatment.

Synthesis, Property Characterization and Photocatalytic Activity of the Ag3PO4/Gd2BiTaO7 Heterojunction Catalyst under Visible Light Irradiation

A new type of Gd2BiTaO7 nanocatalyst (GBT) was synthesized by a high-temperature solid-phase method, and a heterojunction photocatalyst, which was composed of GBT and silver phosphate (AP), was prepared by the facile in-situ precipitation method for the first time. The photocatalytic property of GBT or the Ag3PO4/Gd2BiTaO7 heterojunction photocatalyst (AGHP) was reported. The structural properties of GBT and AGHP were characterized by an X-ray diffractometer, scanning electron microscope–X-ray energy dispersive spectra, an X-ray photoelectron spectrograph, a synchrotron-based ultraviolet photoelectron spectroscope, a Fourier transform infrared spectrometer, an UV-Vis diffuse reflectance spectrophotometer and an electron paramagnetic resonance spectrometer. The results displayed that GBT was well crystallized with a stable cubic crystal system and space group Fd3m. The lattice parameter or band gap energy of GBT was found to be a = 10.740051 Å or 2.35 eV, respectively. After visible light irradiation of 30 min, the removal rate of bisphenol A (BPA) reached 99.52%, 95.53% or 37.00% with AGHP as the photocatalyst, with Ag3PO4 and potassium persulfate (AP-PS) as photocatalysts or with N-doped TiO2 (NT) as a photocatalyst, respectively. According to the experimental data, it could be found that the removal rate of BPA with AGHP as a photocatalyst was 2.69 times higher than that with NT as a photocatalyst. AGHP showed higher photocatalytic activity for photocatalytic degradation of BPA under visible light irradiation compared with GBT or AP-PS or NT. The removal rate of total organic carbon (TOC) was 96.21%, 88.10% or 30.55% with AGHP as a photocatalyst, with AP-PS as photocatalysts or with NT as a photocatalyst after visible light irradiation of 30 min. The above results indicated that AGHP possessed the maximal mineralization percentage ratio during the process of degrading BPA compared with GBT or AP-PS or NT. The results indicated that the main oxidation radical was •OH during the process of degrading BPA. The photocatalytic degradation of BPA with AGHP as a photocatalyst conformed to the first-order reaction kinetics. This study provided inspiration for obtaining visible light-responsive heterojunction photocatalysts with high catalytic activity and efficient removal technologies for organic pollutants and toxic pollutants, and as a result, the potential practical applications of visible light-responsive heterojunction photocatalysts were widened. The subsequent research of thin-film plating of the heterojunction catalysts and the construction of complete photoluminescent thin-film catalytic reaction systems, which utilized visible light irradiation, could provide new technologies and perspectives for the pharmaceutical wastewater treatment industry.