Degradation of chloramphenicol by persulfate activated by Fe2+ and zerovalent iron

This study evaluated the removal of chloramphenicol (CAP) by persulfate (PS) activated by Fe2+ and zerovalent iron (ZVI). Results showed that the Fe2+-PS system ineffectively degraded CAP. However, CAP oxidation accelerated as the number of Fe2+ portions added increased. Comparing with Fe2+, up to 96.1% of CAP was degraded when ZVI was employed as an alternative source of Fe2+. The ZVI-PS system was effective in a broader initial pH range from 3 to 10, and low pH promoted CAP degradation. In addition, the results of scavenging tests suggested that HO center dot, SO4- and O-2(center dot-) contributed to the overall degradation performance, but HO center dot predominated at all pH levels used. The rate of CAP removal slightly increased upon the addition of 1 mM Cl-, but adding Cl- at concentrations higher than 1 mM apparently inhibited CAP degradation. HCO3-, NO3-, NO2-, H2PO4-, HPO42-, and HA significantly inhibited CAP decomposition. Up to 92.8%, 94.7%, and 75.7% of CAP were removed from the filtrate, permeate, and retentate phases of wastewater, respectively. This result indicated that the ZVI-PS system can significantly remove CAP from wastewater and even concentrated wastewater. The intermediate products during oxidation were identified, and the degradation pathways of CAP were tentatively proposed. (C) 2015 Elsevier B.V. All rights reserved.