High-efficiency degradation of quinclorac via peroxymonosulfate activated by N-doped CoFe2O4/Fe0@CEDTA hybrid catalyst

FeS and Fe3O4 Co-modified biochar to build a highly resistant advanced oxidation process system for quinclorac degradation in irrigation water

Advanced oxidation processes (AOPs), based on sulfate radical (SO4·-) produced by peroxymonosulfate (PMS), can effectively mineralize refractory organic pollutants. However, the coexistence of anions and natural organic matters in actual wastewater prevents the application of AOPs. A simple one-step method was used to prepare FeS/Fe3O4 co-modified biochar materials (FFB) that could activate PMS to degrade quinclorac (QNC) with a removal rate of 100%, even exhibiting optimum degradation of QNC reached 99.31% in irrigation water, demonstrating excellent anti-interference performance for co-existing anions and natural organic matter. Meanwhile, ecotoxicity analysis showed that the toxicity of degradation intermediates was lower than that of QNC. Characterization results demonstrated the even distribution of FeS and Fe3O4 onto biochar, supplying abundant Fe2+ to activate PMS producing reactive oxygen species (ROS), while the generated Fe3+ after reactive continue to be reduced with sulfur species to promote the cycle of Fe2+/Fe3+. The coexistence of ·OH, SO4·-, 1O2, and O2·- in the FFB/PMS-QNC system suggest the possession of two pathway with free radical and non-free radical pathways to degrade QNC. The density functional theory (DFT) was used to analyze the adsorption sites and adsorption energy of PMS, as well as the differential charge density, which further proved the generation of SO4·-, O2·- and 1O2. In addition, the electrochemical test results showed that electron transfer also played an important role in the degradation of QNC. This study provides a feasible approach for the removal of organic pollutants in actual water.

Carbonate-induced enhancement of phenols degradation in CuS/peroxymonosulfate system: A clear correlation between this enhancement and electronic effects of phenols substituents

This study investigated the enhancement effects of dissolved carbonates on the peroxymonosulfate-based advanced oxidation process with CuS as a catalyst. It was found that the added CO₃^2- increased both the catalytic activity and the stability of the catalyst. Under optimized reaction conditions in the presence of CO₃^2-, the degradation removal of 4-methylphenol (4-MP) within 2 min reached 100%, and this was maintained in consecutive multi-cycle experiments. The degradation rate constant of 4-MP was 2.159 min^-1, being 685% greater than that in the absence of CO₃^2- (0.315 min^-1). The comparison of dominated active species and 4-MP degradation pathways in both CO₃^2--free and CO₃^2--containing systems suggested that more CO₃•^-/¹O₂ was produced in the case of CO₃^2-deducing an electron transfer medium, which tending to react with electron-rich moieties. Meanwhile, Characterization by X-ray photoelectron spectroscopic and cyclic voltammetry measurement verified CO₃^2- enabled the effective reduction of Cu²⁺ to Cu⁺. By investigating the degradation of 11 phenolics with different substituents, the dependence of degradation kinetic rate constant of the phenolics on their chemical structures indicated that there was a good linear relationship between the Hammett constants σ_p of the aromatic phenolics and the logarithm of k in the CO₃^2--containing system. This work provides a new strategy for efficient removal of electron-rich moieties under the driving of carbonate being widely present in actual water bodies.

Rice husk biochar mediated red phosphorus for photocatalysis and photothermal removal of E. coli

The current photocatalytic bactericidal materials in the field of food pathogen control are usually consisted of metals that always suffering from poor stability and possible secondary pollution. Besides, the requirement for high energy excitation also inspires the enthusiasm on exploring non-metallic catalysts. Herein, the non-metallic composite of rice shell biochar loaded with red phosphorus (B@RP) was developed for photocatalysis and photothermal removal of bacteria. The B@RP showed effective photocatalysis performance to stimulate the generation of OH and O₂^- free radicals for the elimination of Escherichia coli (E. coli). At the same time, the photothermal effect of B@RP can also increase the permeability of cell membrane, which is conducive to free radicals entering the cell interior. Therefore, the non-metallic composite could achieve complete removal of E. coli within 2 h under illumination. Meanwhile, B@RP had excellent stability and the sterilization efficiency maintained 100% after 9 cycles. Hence, B@RP is expected to be a harmless and efficient bactericidal material for food industry.

Fe3+-cysteine enhanced persulfate fenton-like process for quinclorac degradation: A wide pH tolerance and reaction mechanism

A green, high-efficiency, and wide pH tolerance water remediation process has been urgently acquired for the increasingly exacerbating contaminated water. In this study, a Fe³⁺/persulfate (Fe³⁺/PS) system was employed and enhanced with a green natural ligand cysteine (Cys) for the degradation of quinclorac (QNC). The introduction of Cys into the Fe³⁺/PS system widened the effective pH range to 9 with a superior removal rate for QNC. The mechanism revealed that the Fe³⁺/Cys/PS system can enhance the ability of degrading QNC by accelerating the Fe³⁺/Fe²⁺ redox cycle, maintaining Fe²⁺ concentration and thereby generating more HO^• and SO₄^•-. The impact factors (i.e., pH, concentrations of PS, Fe³⁺ and Cys) were optimized as well. This work provides a promising strategy with high catalytic activity and wide pH tolerance for organic contaminated water remediation.

MOFs-derived CuO-Fe3O4@C with abundant oxygen vacancies and strong Cu-Fe interaction for deep mineralization of bisphenol A

A novel CuO-Fe₃O₄ encapsulated in the carbon framework with abundant oxygen vacancies (CuO-Fe₃O₄@C) was successfully prepared by thermal conversion of Cu(OAc)₂/Fe-metal organic framework. The as-prepared catalyst exhibited excellent peroxymonosulfate (PMS) activation performance, good recyclability and fast magnetic separation. Under optimal conditions, the added BPA (60 mg/L) could be completely removed by CuO-Fe₃O₄@C/PMS system within 15 min with the degradation rate constant (k) of 0.32 min^-1, being 10.3 and 246.2 times that in CuO/PMS (0.031min^-1) and Fe₃O₄/PMS (0.0013 min^-1) system. A deep mineralization rate of BPA (＞80%) was achieved within 60 min. The results demonstrated the synergistic effect of bimetallic clusters, oxygen vacancies and carbon framework was a key benefit for the exposure of more active sites, the electron donor capacity and the mass transfer of substrates, thereby promoting the decomposition of BPA. Capture experiments and EPR indicated that ¹O₂ was the predominant reactive oxygen species (ROSs). The degradation routes of BPA and the activation mechanism of PMS were proposed. This study offers an opportunity to develop promising MOFs-derived hybrid catalysts with tailored structures and properties for the practical application of SR-AOPs.

Treatment of Water Contaminated with Non-Steroidal Anti-Inflammatory Drugs Using Peroxymonosulfate Activated by Calcined Melamine@magnetite Nanoparticles Encapsulated into a Polymeric Matrix

In the present study, calcined melamine (CM) and magnetite nanoparticles (MNPs) were encapsulated in a calcium alginate (CA) matrix to effectively activate peroxymonosulfate (PMS) and generate free radical species for the degradation of ibuprofen (IBP) drug. According to the Langmuir isotherm model, the adsorption capacities of the as-prepared microcapsules and their components were insignificant. The CM/MNPs/CA/PMS process caused the maximum degradation of IBP (62.4%) in 30 min, with a synergy factor of 5.24. Increasing the PMS concentration from 1 to 2 mM improved the degradation efficiency from 62.4 to 68.0%, respectively, while an increase to 3 mM caused a negligible effect on the reactor effectiveness. The process performance was enhanced by ultrasound (77.6% in 30 min), UV irradiation (91.6% in 30 min), and electrochemical process (100% in 20 min). The roles of O•H and SO4•- in the decomposition of IBP by the CM/MNPs/CA/PMS process were 28.0 and 25.4%, respectively. No more than 8% reduction in the degradation efficiency of IBP was observed after four experimental runs, accompanied by negligible leachate of microcapsule components. The bio-assessment results showed a notable reduction in the bio-toxicity during the treatment process based on the specific oxygen uptake rate (SOUR).

Nanohybrid catalysts with porous structures for environmental remediation through photocatalytic degradation of emerging pollutants

Water supplies have been seriously challenged by new emerging pollutants, which are difficult to remove by traditional wastewater treatment. Thus, new technologies such as catalytic advanced oxidation processes have merged as suitable solutions; however, the drawbacks of typical catalysts limit their application. To overcome this issue, new materials with enhanced textural properties have been developed, showing that their porosity and chemical nature influence their potential as a catalyst. Herein, the recent progress in highly porous catalysts and their suitable deployment to effectively nano-remediate the polluted environmental matrices are reviewed in detail. First, following a brief introduction, several environmental pollutants of emerging concerns from different sectors, including pharmaceutical residues, endocrine-disrupting chemicals (EDCs), pesticides, and hazardous dyes are also introduced with relevant examples. To effectively tackle the sustainable remediation of emerging pollutants, this work also focuses on the multifunctional features of nanohybrid porous materials that act as catalysts constructs to degrade emerging pollutants. The influence of surface reactive centers, stability, bandgap energies, light absorption capacities, and pollutants adsorption capacities are also discussed. Successful examples of the employment of nanohybrid porous catalysts for the degradation of pharmaceutical pollutants, EDCs, pesticides, and hazardous dyes are summarized. Finally, some challenges faced by nanohybrid porous materials to achieve their potential application as advanced catalysts for environmental remediation have been identified and presented herein.