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 Cd2+ and degradation of HCIP. The adsorption isotherms results exhibited that the adsorption capacity of the Fe@C for Cd2+ and HCIP was 367.95 and 262.76 mg/g, respectively. The TOC removal efficiency reached 33.64 % after degradation for 4 h. The adsorption mechanisms of Cd2+ were precipitation adsorption and complex formation 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 adsorption of Cd2+ was enhanced because of the existence of HCIP. The degradation of HCIP was promoted visibly due to the complexation of Cd2+ and HCIP. 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.