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A novel carbon catalyst was created based on plant metallurgy strategy for organic pollutants removal. Plants rich in CeO2 NPs in water were used as carbon precursors and pyrolyzed with urea to obtain Ce/N co-doped carbon catalysts, which were used in the degradation of sulfamethoxazole (SMX) by active peroxymonosulfate (PMS). The results showed that the Ce/N @BC/PMS system achieved to 94.5% degradation of SMX in 40 min at a rate constant of 0.0602 cm-1. The activation center of PMS is widely dispersed Ce oxide nanocrystals, and CeO2 NPs promote the formation of oxygen centered PFR with enhanced catalytic ability and longer half-life. In addition, N-doping facilitates the transfer of π-electrons within the sp2 carbon of biochar, increasing active sites and thus improving PMS activation efficiency. The degradation process was contributed to by both radical and non-radical activation mechanisms including 1O2 and direct electron transfer, with O2•- serving as 1O2's precursor. Through the DFT calculations, LC-MS and toxicological analyses, the degradation pathway of pollutants and the toxicity changes throughout the entire degradation process were further revealed, indicating that the degradation of SMX could effectively reduce ecological toxicity.

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In this study, we developed a novel self-catalytic oxidation system involving peroxymonosulfate (PMS) and permanganate (KMnO4), named as CUPP, to efficiently mineralize sulfamethoxazole (SMX) in groundwater. It was found that amorphous MnO2 derived from the in situ reduction of KMnO4 can directly adsorb HSO5-, a complex hydroxyl group, mediate the internal disproportionation reaction of HSO5- with the manganese complex, and effectively activate PMS, thereby promoting the oxidation of SMX and its degradation intermediates through sulfonate radiation. Furthermore, by using electron spin resonance (EPR), HPLC/MS full scan, and response surface methodology, the coexistence of HO˙, SO4-˙, O2-˙, 1O2, and active chlorine (Cl2, HOCl) in the CUPP system was confirmed. A total of 24 intermediate products were detected, and four possible degradation pathways were identified for SMX. In addition, it was found that the CUPP system has a strong impact resistance to pH variations, groundwater anions, and natural organic matter stress. Undoubtedly, the CUPP system presents an innovative approach for the degradation of various emerging organic pollutants in groundwater.

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Lead (Pb) contamination arising from the production of lead-acid batteries is getting more severe, and research on its treatment technology reflects the increasing concern worldwide. Vermiculite is a mineral with a layered structure, containing hydrated magnesium aluminosilicate and has high porosity and large specific surface area. Vermiculite has the ability of improving soil permeability and water retention performance. However, in recent studies, vermiculite is shown to be less effective than other stabilizing agents in immobilizing heavy metal Pb. Nano-iron-based materials have been widely used to adsorb heavy metals in wastewater. Therefore, vermiculite has been modified with two nano-iron-based materials-nanoscale zero-valent iron (nZVI) and nano-Fe3O4 (nFe3O4) to improve its immobilization effect for the heavy metal lead. SEM and XRD analysis confirmed that nZVI and nFe3O4 were successfully loaded on the raw vermiculite. XPS analysis was applied to further understand the composition of VC@nZVI and VC@nFe3O4. The stability and mobility of nano-iron-based materials were improved after being loaded on raw vermiculite, and the Pb immobilization effect of modified vermiculite on Pb-contaminated soil was evaluated. Adding nZVI-modified vermiculite (VC@nZVI) and nFe3O4-modified vermiculite (VC@nFe3O4) increased the immobilization effect and decreased the bioavailability of Pb. Compared with raw vermiculite, adding VC@nZVI and VC@nFe3O4 increased the amount of exchangeable Pb by 30.8% and 6.17%. After leaching ten times in soil column leaching experiments, the total concentration of Pb in the leachate of the soil with VC@nZVI and VC@nFe3O4 were reduced by 40.67% and 11.47%, compared with raw vermiculite. These results prove that the modification with nano-iron-based materials enhances the immobilization effect of vermiculite, in which the effect of VC@nZVI is significantly better than VC@nFe3O4. Vermiculite was modified with nano-iron-based materials, resulting in a better fixing effect of the modified curing agent. This study provides a new approach for the remediation of Pb-contaminated soil, but further research is needed for soil recovery and utilization of nanomaterials.

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Natural siderite (FeCO3), simulated synthetic siderite and nZVI/FeCO3 composite were used as green and easily available iron-based catalysts in peroxydisulfate activation for remediating 2-chlorophenol as the target contaminant and this technique can effectively degrade organic pollutants in the soil. The key reaction parameters such as catalysts dosage, oxidant concentration and pH, were investigated to evaluate the catalytic performance of different materials in catalytic systems. The buffering property of natural soil conduced satisfactory degradation performance in a wide pH range (3-10). Both the main non-radical of 1O2 and free radicals of SO4·- and OH· were evidenced by quenching experiment and electron paramagnetic resonance. The reduction of nZVI on FFC surface not only has the advantage for electronic transfer to promote the circulation of Fe(III) to Fe(II), but also can directly dechlorinate. Furthermore, the intermediates were comprehensively analyzed by GC-MS and a potential removal mechanism of three oxidant system for 2-CP soil degradation was obtained. Briefly, this research provides a new perspective for organic contaminate soil treatment using natural siderite or simulated synthetic siderite as efficient and environmental catalytic material.

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