Hydroxyl and sulfate radical-based degradation of ciprofloxacin using UV-C and/or Fe2+-catalyzed peroxymonosulfate: Effects of process parameters and toxicity evaluation

Ciprofloxacin (CIP) is a valuable antibiotic and discharged in huge quantities in aquatic environment. Different (OH)-O-center dot and SO4 center dot--based advanced oxidation technologies (AOTs), e.g., Fe2+/PMS, UV-C/PMS, and UV-C/Fe2+/PMS are developed for treatment of CIP. The removal of CIP by Fe2+/PMS, UV-C/PMS and UV-C/Fe2+/PMS was 63, 77, and 87 %, respectively, under identical conditions which showed better performance of UV-C/Fe2+/PMS. The UV-C/Fe2+/PMS also caused high removal of total organic carbon of CIP. This high performance of UV-C/Fe2+/PMS-based AOTs possibly looked due to dual activation of PMS by UV-C and Fe2+. The removal of CIP by the three AOTs was found due to (OH)-O-center dot and SO4 center dot- and the later showed high reactivities with CIP, i.e., 2.45 x 10(9) and 2.35 x 10(9) M-1 s(-1), respectively. The study of factors affecting the reactivities and/or yield of (OH)-O-center dot and SO4 center dot- diminished CIP degradation efficiency. The change in pH of solution and temperature and doses of Fe2+, PMS, and CIP exhibited significant impacts on the removal of CIP. The addition of inorganic ions showed strong inhibiting effects of NO2-, CO32-, and HCO3- while Cu2+ showed facilitating role. Analysis of degradation of CIP by GC-MS was used to develop proposed pathways. Acute and chronic toxicities of CIP and its products were measured by ECOSAR program and showed the resulting products to be non-toxic.