Toxicities, kinetics and degradation pathways investigation of ciprofloxacin degradation using iron-mediated H2O2 based advanced oxidation processes

Ciprofloxacin (CIP) is a widespread emerging water pollutant and thus its removal from aquatic environment is vital. The use of Fe3+/H2O2 and Fe2+/H2O2 resulted in 38 and 64% removal of CIP (8.0 ppm), respectively, within 80 min reaction time (pH 5.8, [H2O2](0) = 80 ppm, and [iron](0) = 20 ppm). Low pH, high temperature, high dose of H2O2 and Fe2+, and low OP concentration facilitated removal of CIP. The radical scavenger studies proved in situ generated (OH)-O-center dot to be involved primarily in the removal of CIP. The effect of temperature was used to estimate enthalpy and activation energies of the removal of CIP. At 800 min reaction time, the Fe2+/H2O2 resulted in 54% mineralization of CIP using 16.0 ppm [CIP](0), 320.0 ppm [H2O2](0), and 40.0 ppm [Fe2+](0). The potential degradation pathways of CIP established from the degradation of CIP by (OH)-O-center dot and products evolved was found to be initiated at C-6 through the loss of fluoride ion. The acute and chronic toxicities of CIP and its degradation products were estimated with the final product found to be non-toxic. The results suggest that Fe2+/H2O2-mediated AOPs have high potential for degradation as well as toxicity elimination of CIP and its degradation products. (C) 2018 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.