Cobalt-gadolinium modified biochar as an adsorbent for antibiotics in single and binary systems

Abstract

In this work, fresh biochar modified with cobalt (Co) and rare earth element gadolinium (Gd) was prepared for ciprofloxacin (CIP) and tetracycline (TC) removal in single- and binary-solute systems. Co- and Gd-modified biochar (MBC), possessing a sponge-like structure, was found to be efficient in CIP and TC removal in both systems. The BET surface area and pore volume of MBC were 370.3737 m2/g and 0.1991 cm3/g, respectively. Both TC and CIP sorption kinetic data in regard to MBC were fitted with a pseudo-second-order model. Adsorption of CIP onto MBC was consistent with the Langmuir model, while TC adsorption was consistent with the Freundlich model. The adsorption capacity of MBC was 44.44 mg/g for CIP and 119.05 mg/g for TC. Although the adsorption capacity decreased in the competitive system, it still reached 31.15 and 117.65 mg/g, respectively. Therefore, MBC might yield a great promise to treat complex antibiotic wastewater.