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

Abstract

• ZVC/PAA was the first time to be applied for degradation of organic pollutants. • Cu + corroded from ZVC was the key activator for PAA to generate reactive species. • HO • was the dominant reactive species for DCF removal in ZVC/PAA system. • The presence of Cl - , CO 3 2– , Fe 3+ , Cu 2+ and DOM enhanced DCF degradation. • Seven reaction pathways of DCF were proposed based on six detected products. 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 • , CH 3 COO • and CH 3 COOO • , 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, H 2 O 2 and O 2 . 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 - , CO 3 2– , Fe 3+ , Cu 2+ and dissolved organic matter (DOM) promoted DCF degradation in ZVC/PAA system, while SO 4 2- and NO 3 – 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.