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[Display omitted] • The catalyst with Co/Mg molar ratio of 1/200 rapidly activated PMS to remove CQP. • CoO nanoparticles were wrapped by MgO in catalyst, limiting cobalt ion leaching. • MgO accelerated the formation of Co-OH complex and redox cycle of Co2+- Co3+- Co2+. • Activation mechanism of PMS by the catalyst was analyzed in depth. Cobalt oxide could be used to activate peroxymonosulfate (PMS) for removal of contaminants, while its use was restricted due to low catalytic activity by limited active sites and the risk of cobalt ion leaching. This study investigated chloroquine phosphate (CQP) degradation by Co-Mg mixed metal oxides with highly dispersed minute quantities of CoO nanoparticles to activate PMS. It was demonstrated that the Co/Mg optimal molar ratio of catalyst was 1/200, and by characterization of catalysts and their effects on degradation of CQP, CoO nanoparticles could be widely dispersed and wrapped by MgO support. In the catalyst/PMS system, degradation of CQP could accelerate with the increase of catalyst dosage, PMS concentration and temperature and the addition of C l - , H P O 4 2 - and H 2 P O 4 - , but decrease with the addition of Mg2+, N O 3 - , H C O 3 - and nature organic matter (NOM). By quenching experiments of active radicals, it was illustrated that S O 4 · - and O 2 · - made more significant contributions than H O · in this system for CQP degradation. The activation mechanism of PMS by the catalyst with good repeatability and stability was explained that MgO could effectively adsorb hydroxy groups, promoting the formation of Co-OH complex and accelerating the redox cycle of Co2+- Co3+- Co2+ in the catalyst. The strong interaction between CoO and MgO prevented cobalt ion leaching and enhanced catalyst activity over the wide pH range (5–10). And proposed intermediates and degradation pathways of CQP were analyzed. [ABSTRACT FROM AUTHOR]

[Display omitted] • The catalyst with optimized Cu/Mg molar ratio rapidly activated PMS to remove TAP. • MgO wrapped CuO nanoparticles in the catalyst and limited copper ion leaching. • MgO promoted the formation of Cu-OH complex and redox cycle of Cu+-Cu2+-Cu+. • Activation mechanism of PMS and degradation pathways of TAP were proposed. Copper-base catalysts with high load content of CuO were commonly utilized to activate peroxymonosulfate (PMS) for removal of contaminants but limited catalytic efficiency and increased risk of copper ion leaching restricted their use. In this paper, Cu-Mg mixed metal oxides with highly dispersed minute quantities of CuO were successfully prepared by one-pot synthesis for efficiently activating PMS to remove thiamphenicol (TAP), which was economical and environmentally friendly. The catalytic activities of catalysts with different molar ratios of Cu and Mg for PMS and their characteristics were evaluated, illustrating the optimal molar ratio of Cu and Mg (1:15, named CuMg-MMO) in the catalyst. For the CuMg-MMO catalyst, MgO widely dispersed and wrapped CuO nanoparticles, minimized the copper ion leaching and promoted the generation of Cu-OH complex and non-radical species. In the CuMg-MMO/PMS system, the influence factors for TAP degradation were analyzed, including different systems, catalyst dosages, PMS concentrations, temperatures, initial pH values, TAP concentrations, anions (N O 3 - , H C O 3 - , C l - , H P O 4 2 - and H 2 P O 4 -) and natural organic matter (NOM) concentrations. Under the optimal conditions (i.e., [catalyst]: 75 mg/L, [PMS]: 0.3 mM, temperature: 30 °C and initial pH: 6.5), TAP removal efficiency obtained by this system was 99.9%. S O 4 · - , · O 2 - and 1O 2 played more important roles than H O · in TAP degradation. Four successive repeated experiments indicated that CuMg-MMO possessed good reusability and stability. PMS decomposition, mineralization of TAP, the activation mechanism of PMS and possible degradation pathways of TAP were analyzed. [ABSTRACT FROM AUTHOR]