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[Display omitted] • The silver-copper mixed-oxide Ag 2 Cu 2 O 3 was successfully prepared. • The catalyst showed high performance for PNP degradation via PMS activation. • The synergistic effect between Cu and Ag in the catalyst was clarified. • A possible mechanism for PNP degradation was proposed. Recently, the development of efficient mixed metal oxide catalysts for organic pollutants degradation via peroxymonosulfate (PMS) activation is a hot topic in the area of wastewater treatment. In this work, the silver-copper mixed-oxide, Ag 2 Cu 2 O 3 (ACO) was reported for the first time as a highly active catalyst for removing organic pollutants in the presence of PMS. ACO was successfully synthesized from Ag+ and Cu2+ ions at 60 °C, and its structure was strongly influenced by the temperature. The catalyst could almost completely remove p -nitrophenol and other pollutants with 0.65 mM PMS after 20 min, and also exhibited satisfactory stability and recyclability. The system efficiency was shown to vary with the concentration of PMS and catalyst, as well as solution pH. Scavenger experiment and EPR analysis indicated that radicals produced by the oxidation of Ag(I) and Cu(I) with PMS could promote degradation reaction. The synergistic effect between Cu and Ag in the bimetallic catalyst was demonstrated to contribute to the high performance: Cu(II)-O-Ag(I) bonds promote the conversion of Cu(II) species to Cu(I) through reaction with PMS, and facilitate the oxidation of Cu(I) and Ag(I) by PMS to generate active radicals. The study provides a feasible strategy to design efficient and stable bimetal oxide catalysts for PMS activation. [ABSTRACT FROM AUTHOR]

In this study, the photogeneration of OH and 1O 2 and the degradation mechanism of organic pollutants in biochar suspension under the simulated solar light irradiations were investigated. Biochar derived from rice husk with 550 °C of charring temperature (R550) was selected to degrade benzoic acid. It was found that 10 g/L of R550 could degrade 78.7% of benzoic acid within 360 min at pH 3, and the degradation efficiency was promoted to 95.2% as ultraviolet (UV) presented. By checking the production of p-hydroxybenzoic acid, UV accelerated the production of OH, which was confirmed by the enhanced degradation efficiency of 59.2% caused by the evaluated OH as UV appeared. The furfuryl alcohol loss in the R550 suspension under light irradiations testified to the production of 1O 2 , which contributed to 9.3% of benzoic acid degradation. Oxidization treatment using gradient concentrations of H 2 O 2 was employed to enhance the ageing process of biochar. As the ageing processed, the biochar possessed a declined performance towards OH production from O 2 activation and the radical degradation of organic pollutants. As a contrast, the evaluated content of 1O 2 and enhanced non-radical degradation of organic pollutants was reached as UV presented. The further study indicated that phenolic hydroxyl groups on biochar facilitated the production of OH via the electron transfer, and quinone like structures (C=O) on biochar boosted the generation of 1O 2 via the energy transfer. Moreover, upon eliminating the BA degradation, persistent free radicals were formed on biochar, which was enhanced owing to the presence of UV. Unlabelled Image • Degradation of organic contaminants by biochar was enhanced by UV. • UV triggered the production of OH and 1O 2 from biochar suspension. • Quinone-type structures on biochar induced the production of 1O 2. • The ageing favored the production of 1O 2 under light irradiations. • The ageing retarded OH formation and radical degradation of organic contaminants. [ABSTRACT FROM AUTHOR]

Silver-based materials have emerged as excellent catalysts for peroxymonosulfate (PMS) activation in wastewater pollutants degradation. However, the mechanism of pure silver oxides towards PMS activation remains insufficient. In this work, Ag 2 O and AgO were selected as typical silver oxides to detect the catalytic performance. AgO/PMS possessed higher activity for p-nitrophenol and other pollutants degradation than Ag 2 O/PMS. The stability experiment and structure changes characterized from XRD, FTIR, and XPS, as well as quenching research, demonstrated that SO 4 •− was the main free radical produced from the oxidation of Ag(I) to Ag(II) and reduction of Ag(II) to Ag(I) by PMS; meanwhile, the high valence Ag(II) could directly oxidize the pollutants, which was also contributable to the degradation. Compared with Ag 2 O, AgO exhibited better efficiency and recyclability. These results provide key mechanistic insights into silver oxides towards PMS activation. [Display omitted] • Silver based oxides Ag 2 O and AgO was used for PMS activation. • The two catalysts showed similar performance for PNP degradation. • The reusability and stability of AgO was much better than that of Ag 2 O. • SO 4 •− radicals were produced from the oxidation of Ag(I) by PMS. • The high active Ag(II) species contributed to the degradation process. [ABSTRACT FROM AUTHOR]

[Display omitted] • Mullite YMn 2 O 5 with abundance surface labile oxygen species was prepared. • The catalyst shows high activity for BPA degradation via PMS activation. • The degradation rate is linearly dependent on the ratio of labile oxygen species. • Direct electron transfer process plays a significant role in BPA degradation. • Possible degradation pathway of BPA was proposed. The development of efficient and eco-friendly Mn-based catalysts for peroxymonosulfate (PMS) activation and revealing the mechanism are highly desired for pollutants removal in wastewater. In this study, a ternary mullite oxide YMn 2 O 5 (YMO) was synthesized for bisphenol A (BPA) degradation in the presence of PMS for the first time. Combined with XPS, EPR and TG, abundant surface labile oxygen species (O lab) with a ratio of 39.7% were identified in the mullite materials, which was higher than that for α-, β-, γ- and δ-MnO 2. YMO also exhibited higher interfacial conductivity and stronger interactions among the catalyst, PMS and BPA than other MnO 2. Superior performance in BPA degradation was observed with YMO, and O lab was suggested as the main active sites, for the normalized first-order rate constant was linearly dependent on the ratio of the oxygen species. Chemical quenching experiments, EPR and open circuit potential suggested that the degradation of BPA was mainly caused by the direct electron transfer process through the reactive O lab -PMS complexes. The influence of YMO concentration, PMS concentration, solution pH, different anions and reaction temperature was thoroughly studied. Moreover, the intermediates were identified and the possible degradation pathways were proposed. This work demonstrated that mullite oxide YMO with enriched O lab species can be used as eco-friendly catalysts for efficient PMS activation to remove recalcitrant organic compounds in wastewater. [ABSTRACT FROM AUTHOR]