Chloride ion with ferric ion in boosting zero-valent copper activated peroxydisulfate for efficiently removing tetracycline

Abstract

The Cu0-stimulated PDS system, which produces reactive oxygen species (ROS) to decompose environmental pollutants, has been widely studied. Although Cu+ is produced in the Cu0-stimulated PDS system, its susceptibility to disproportionate and easy oxidized by O2 must be considered. To improve the utilization of Cu+, Cl− and Fe3+ were considered for strengthening the Cu0-stimulated PDS process. With the addition of Cl− and Fe3+ in the Cu0-stimulated PDS system (Cl−/Fe3+/Cu0/PDS system), the decomposition of tetracycline was greatly increased within 8 min. In the Cl−/Fe3+/Cu0/PDS system, Cl− limited the disproportionation reaction of Cu+ by promoting Cu0 and Cu2+ reaction with Cl− and increased Cu+ utilization rate. Fe3+ promoted the recycling of Fe2+/Fe3+ and contributed to reducing the invalid oxidation of Cu+ by O2. Sulfate radical, reactive chlorine species and hydroxyl radical were generated in the Cl−/Fe3+/Cu0/PDS system. NO3− and SO42− had no influence on decomposing tetracycline in the Cl−/Fe3+/Cu0/PDS system, but humic acid inhibited tetracycline decomposition. Moreover, the Cl−/Fe3+/Cu0/PDS system had great performance on the experimental water samples with the removal rate of tetracycline was higher than 80%. Furthermore, when the final solution pH was adjusted to 8.0, only 0.88 mg/L total dissolved copper remained after precipitation and filtering.