Simultaneous removal of Cr(VI) and triclosan from aqueous solutions through Fe3O4 magnetic nanoscale-activated persulfate oxidation

Abstract

Triclosan (TCS) and Cr(VI), which are dangerous to human and ecological health, are frequently detected in surface waters. As a proposed solution, in this study, Cr(VI) and TCS were removed through an Fe3O4-activated persulfate (PS) oxidation process. At first, several influence factors on TCS degradation were investigated such as initial pH value, PS dose, temperature, Fe3O4 dosage and Cr(VI) concentration. 87.5% degradation of 5 mg L−1 TCS and 99.5% removal of 1 mg L−1 Cr(VI) were achieved within 120 min by using 2 g L−1 of Fe3O4 and 1 mM PS at 30 °C with a pH of 7. The degradation of TCS follows the pseudo-first-order kinetics under the given experimental conditions. Acid conditions were beneficial to TCS removal. TCS oxidation remained feasible at circumneutral pH. Moreover, CO32−, HPO42−, less than 10 mM of chloride ions and humic acid slightly inhibited the removal of Cr(VI) and TCS. Radical scavenger experiments indicated that sulfate radicals are the primary radical species responsible for TCS degradation. Then, three possible degradation pathways were proposed, including the breakage of ether bond, dechlorination and hydroxylation. This study indicates that the Fe3O4-activated PS oxidation process could be used as a novel treatment technique for the simultaneous removal of heavy metal and organic pollutants.