Removal of Heavy Metals from Aqueous Solutions by Immobilized Bacteria using biochar and lignosulfonate into Chitosan: A Study on Cadmium and Lead

Abstract

This study aimed to isolate cadmium (Cd) and lead (Pb) resistant bacteria from the soil around the steel industry and to remove both metals from aqueous solution by coupling the bacteria with modified chitosan. A combination of corn biochar, and lignosulfonate with chitosan was used to immobilize the bacteria. Six bacterial isolates were identified and half-maximal effective concentration (EC50) values for cadmium (Cd) and lead (Pb) were determined. FTIR analysis of Pb- and Cd- exposed bacteria revealed the functional groups involved in metal sorption. Immobilized bacteria in biochar-chitosan and lignosulfonate-chitosan beads could efficiently remove metals. The best fit of adsorption isotherms for Cd and Pb was obtained using the Freundlich isotherm model. The maximum adsorption capacity at an initial concentration of 200 mg L− 1 of Cd and Pb was 52.72 mg g− 1 and 58.68 mg g− 1, respectively, by immobilized bacteria using biochar in chitosan (CbB). The adsorption capacity of the beads for both metals increased with increasing contact time. The Intraparticle diffusion model indicated the best fit to explain the kinetic data for Pb and Cd. The maximum removal of Pb and Cd by CbB were 99.7% and 99.4%, respectively, after 240 min.