Exploring the potential of nano-zerovalent copper modified biochar for the removal of ciprofloxacin from water

Ciprofloxacin (CIP), an emerging water contaminant is of great concern due to its high-level presence in aquatic environments. A novel biochar (BC) coupled with nano-zerovalent copper (nZVCu/(BC) was prepared to provide an environmental-friendly solution for the remediation of CIP-contaminated water. Results showed 88% removal efficiency and 138.89 mg/g adsorption capacity of CIP by nZVCu/BC versus 38% removal efficiency and 62.89 mg/g adsorption capacity by BC using 10 mg/L of [CIP]₀ and 500 mg/L of each [BC]₀ and [nZVCu/BC]₀. The characterization analysis showed enhanced characteristics of nZVCu/BC over BC. The nZVCu/BC was found to remove CIP through adsorption due to interaction between functional groups of the prepared solid materials and additionally through ·OH formed from nZVCu/BC reactions in aqueous solutions. Resulting oxidation products from CIP degradation and use of tert-butyl alcohol as the ·OH scavenger confirmed ·OH formation from nZVCu/BC reactions. Use of different [CIP]₀, [nZVCu/BC]₀, pH and competing species influenced CIP removal. Analysis of R² values and comparison of calculated and experimental values showed Freundlich adsorption isotherm and pseudo-first-order kinetic models best fitting CIP removal. Ecotoxicities of CIP and its DPs as well as mineralization efficiency of CIP were estimated. The good performance of nZVCu/BC in removal of CIP at seventh cycle of treatment, low leaching of copper ions and formation of non-toxic acetate suggests greater recovery, reusability, stability, and potential of the prepared composite material for remediation of CIP-contaminated water.