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

The Cu 0 -stimulated PDS system, which produces reactive oxygen species (ROS) to decompose environmental pollutants, has been widely studied. Although Cu + is produced in the Cu 0 -stimulated PDS system, its susceptibility to disproportionate and easy oxidized by O 2 must be considered. To improve the utilization of Cu + , Cl − and Fe 3+ were considered for strengthening the Cu 0 -stimulated PDS process. With the addition of Cl − and Fe 3+ in the Cu 0 -stimulated PDS system (Cl − /Fe 3+ /Cu 0 /PDS system), the decomposition of tetracycline was greatly increased within 8 min. In the Cl − /Fe 3+ /Cu 0 /PDS system, Cl − limited the disproportionation reaction of Cu + by promoting Cu 0 and Cu 2+ reaction with Cl − and increased Cu + utilization rate. Fe 3+ promoted the recycling of Fe 2+ /Fe 3+ and contributed to reducing the invalid oxidation of Cu + by O 2 . Sulfate radical, reactive chlorine species and hydroxyl radical were generated in the Cl − /Fe 3+ /Cu 0 /PDS system. NO 3 − and SO 4 2− had no influence on decomposing tetracycline in the Cl − /Fe 3+ /Cu 0 /PDS system, but humic acid inhibited tetracycline decomposition. Moreover, the Cl − /Fe 3+ /Cu 0 /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.