Removal of diclofenac in water using peracetic acid activated by zero valent copper

In this work, the degradation kinetics and mechanism of diclofenac (DCF) using peracetic acid (PAA) activated by zero valent copper (ZVC) were systematically investigated. It was found that PAA could be catalyzed effectively by ZVC to produce HO•, CH3COO• and CH3COOO•, which were responsible for the removal of DCF. Based on the XPS, XRD and FESEM characterization results of ZVC before and after reaction, the corrosion of ZVC was occurred to produce Cu+ under acidic condition, which was the main activator for PAA, H2O2 and O2. The recommended pH for this reaction system was 3.0, and DCF degradation was enhanced gradually with increasing ZVC dose and PAA dose. The existence of Cl-, CO32–, Fe3+, Cu2+ and dissolved organic matter (DOM) promoted DCF degradation in ZVC/PAA system, while SO42- and NO3– had almost no influence on DCF removal. Six intermediates were identified in this system, and the probable degradation mechanism of DCF was thus proposed, including seven transformation pathways, i.e., hydroxylation, amidation, dechlorination-cyclizaiton, dechlorination-hydrogenation, dechlorination-hydroxylation, decarboxylation and formylation. This study provides a new method for PAA activation and DCF removal from the polluted water.