Activated biochar supported iron-copper oxide bimetallic catalyst for degradation of ciprofloxacin via photo-assisted electro-Fenton process: A mild pH condition

Abstract

Iron-copper oxide impregnated NaOH-activated biochar (FeCu/ABC) was successfully fabricated through simple pyrolysis of activated biochar, followed by the impregnation method. The catalytic activity of the bimetallic catalyst was investigated for ciprofloxacin (CIP) degradation through a heterogeneous photo-electro-Fenton process at natural pH. The characterization analyses verified the structural suitability of as-synthesized FeCu/ABC to act as a catalyst for treating CIP. The effects of operating parameters such as Cu/Fe mass ratio, initial pH, catalyst dosage, electrical current and initial concentration of CIP were carefully studied. Complete removal of CIP concentrations of up to 45 mg/L was obtained after 2 h of reaction at Cu/Fe mass ratio of 1:1, pH 5.8, catalyst dosage of 1 g/L, and electrical current of 400 mA. CIP decay followed pseudo-first-order reaction kinetics. The synthesized heterogeneous catalyst exhibited a remarkable catalytic activity at natural pH (92 % mineralization of CIP after 8 h under the optimum conditions). The prepared catalyst possessed great stability and structural integrity for 5 consecutive runs. Furthermore, from a practical point of view, the catalyst exhibited an acceptable performance by oxidizing CIP dissolved in various water matrices such as tap water, river water, and a real sample of wastewater. The possible CIP degradation pathways were also proposed based on the identification of different oxidation by-products.