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 CIP concentration facilitated removal of CIP. The radical scavenger studies proved in situ generated [rad]OH 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 [rad]OH and products evolved was found to be initiated at C₆ 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.