Effect of particle size, iron ligands and anions on ciprofloxacin degradation in zero-valent iron process: application to sewage treatment plant effluent

Abstract

BACKGROUND: Ciprofloxacin (CIP) is an antibiotic largely used to treat bacterial infections and found in sewage treatment plant (STP) effluent. Zero valent iron (ZVI, Fe0) technology has great potential for the degradation of residual pharmaceuticals. The effect of some parameters (anaerobic/aerobic, particle size, iron ligands and anions) were evaluated for CIP degradation in distilled water (DW) and finally compared to that obtained in STP effluent. RESULTS: The smaller ZVI particle (200 mesh) resulted in a lower degradation rate than the larger particle (20 mesh) in both anaerobic and aerobic treatment. This is due mainly to the fast generation of Fe2+, hindering the degradation process due to •OH scavenging. A linear increase of CIP degradation rate was observed when the reaction was carried out with increasing EDTA concentrations. The Cl− anions had a positive effect on CIP degradation in the ZVI process. On the other hand, the presence of NO3 − resulted in a decrease of degradation rate, both with 20 and 200 mesh particles. CIP could be degraded in two STP effluents mediated by ZVI (20 mesh). CONCLUSIONS: The ZVI process can be used efficiently for the degradation of CIP in two types of STP effluent (anaerobic treatment or anaerobic/aerobic treatment), revealing a possible applicability of the ZVI process to this type of matrix. © 2017 Society of Chemical Industry.