Simultaneous Removal of Cd and Ciprofloxacin Hydrochloride by Zvi/Biochar Composite in Water: Compound Effects and Removal Mechanism

Abstract

The combined pollution of heavy metals and antibiotics in wastewater does great harm to the ecological environment in recent years. In this work, ZVI/biochar (Fe@C) was prepared by a simple green method and was used to remove Cd2+ and ciprofloxacin hydrochloride (HCIP) from aqueous solution. The material has shown splendid efficiency in the simultaneous adsorption of Cd and degradation of HCIP. The physicochemical properties like chemical composition and surface morphology of the Fe@C were characterized. The effects of pH, initial solution concentration and material dosage on the co-removal were investigated, and the kinetics and isotherm fitting were carried out. The results exhibited that the adsorption capacity of the Fe@C for Cd2+ was 356.96 mg/g, and the removal efficiency of HCIP was 72.65%. The adsorption of HCIP was promoted visibly due to the existence of Cd2+. In addition, the mechanism of co-removal was discussed. The adsorption mechanisms of Cd2+ were precipitation adsorption and coordination complexes with oxygen-containing functional groups, while the HCIP were cation bridging, electrostatic interactions, π-π interaction and hydrogen bonding interaction, and Cd2+ could act as a bridge. The quenching experiments and electron paramagnetic resonance analysis showed that the superoxide free radical (O2·-) rather than SO4·- and ·OH was the main species leading to HCIP degradation. This work provides a simple, green and low-cost way for the preparation of environmental remediation materials, and can effectively achieve co-removal of Cd2+ and HCIP, which has potential application prospects.

Keywords: simultaneous removal, combined pollution, composite material, Adsorption, advanced oxidation, catalytic