FeS2 assisted degradation of atrazine by bentonite-supported nZVI coupling with hydrogen peroxide process in water: Performance and mechanism

Abstract

In this study, bentonite-supported nZVI (B-nZVI) was used as a catalyst to activate H2O2 for atrazine (ATZ) degradation in the presence of FeS2. Results indicated that ATZ degradation by B-nZVI/H2O2 process was significantly enhanced when FeS2 was introduced, and nearly 98% of ATZ was degraded by B-nZVI/FeS2/H2O2 process within 60 min under the optimum conditions. ATZ degradation of B-nZVI/FeS2/H2O2 process was much higher than the sum of B-nZVI and FeS2/H2O2 processes. The presence of HCO3−, PO43− and F− exhibited significant negative effects on the ATZ degradation, whereas both Cu2+ and Ni2+ exhibited positive effects on that. Both citric acid (CA) and ethylenediaminetetraacetic acid (EDTA) with lower concentration enhanced ATZ degradation rate, but significant suppression effects on that with higher concentration. The degradation of ATZ and 2,4-Dichlorophenol (2,4-DCP) could be simultaneously achieved in B-nZVI/FeS2/H2O2 process under certain conditions. High soluble Fe2+ induced an excellent decomposition of H2O2 by B-nZVI and FeS2. OH was dominant radical, and contributed to nearly 86% of the overall ATZ removal. A total of five intermediate products of ATZ were identified, and ATZ degradation was achieved via de-alkylation and hydroxylation processes. An enhanced reaction mechanism for ATZ degradation by B-nZVI/FeS2/H2O2 process was proposed, and B-nZVI/FeS2/H2O2 process exhibited an excellect catalytic performance within four successive runs.