Highly efficient peroxymonosulfate catalyst prepared from electrolytic manganese residues coupled with Camellia oleifera shell biochar for ethylparaben degradation.

Pharmaceuticals and personal care products (PPCPs) contamination can be effectively remediated using sulfate radical-based advanced oxidation processes (SR-AOPs). In this work, a novel composite catalyst (EMR-BC) was successfully prepared using Camellia oleifera shell (COS) biochar (BC) coupled with electrolytic manganese residue (EMR), and the as-obtained catalyst was used to activate peroxymonosulfate (PMS) for the degradation of ethylparaben (EtP). EMR-BC showed superior catalytic performance comparing to EMR and BC, with an EtP remove rate of 97.5 % within 120 min. The •OH, SO•, O and O• were the dominant reactive oxygen species (ROS) during EtP degradation. Reactions between the Fe/Fe and Mn/Mn/Mn redox pairs in EMR and the existence of functional groups in BC improved the efficiency of electron transfer, and thus promoted the production of ROS in EMR-BC/PMS system. Electrochemical tests indicated that the direct-electron pathway was also involved in EtP degradation. After three recycling tests, an 87.9 % EtP removal efficiency was still achieved. Moreover, EMR-BC catalyst showed a good adaptability to actual water environment and a broad application to the removal of other pollutants. Finally, the intermediates generated during the degradation process were determined, and the plausible decomposition pathway of EtP was proposed. The developed system expanded the horizon for the high-value utilization of EMR and COS and the treatment of PPCPs in wastewater.