Bimetallic oxychloride as an efficient oxone activator: Radical and non-radical oxidation of non-steroidal anti-inflammatory drugs

A novel iron-cobalt mixed oxychloride (CoFeOCl) nanosheet, with a plane size in the ranges of 0.2-1.0 mu m and a thickness of 30-40 nm, was manufactured firstly and employed as catalyst for peroxymonosulfate (PMS) activation. The CoFeOCl/PMS system exhibits excellent catalytic activity for non-steroidal anti-inflammatory drugs removal at buffered pH 5.5-8.5 with extremely low catalyst dosage (0.03 g/L). The mechanism of PMS activation by CoFeOCl indicated that center dot OH and O-1(2) played a key role at pH 5.5-7.0 and pH 8.5 respectively, and O-2(-center dot) was involved for all pHs. The cycle of Co2+-Co3+ and Fe2+-Fe3+ were answerable to center dot OH and O-1(2) generation. Furthermore, CoFeOCl/PMS pre-oxidation before chlorination engendered in a reduce in the concentration of total disinfection by-products (DBPs) at pH 8.5. A feasible reaction pathway of DBPs formation was examined with density functional theory (DFT) calculation. The findings provide a new routine for effective PMS activation.