Biosorption of cadmium by Brevundimonas sp ZF12 strain, a novel biosorbent isolated from hot-spring waters in high background radiation areas

The aim of this study is to screen cadmium biosorbing bacterial strains isolated from soils and hot-springs containing high concentrations of radium (Ra-226) in Ramsar using a batch system. Brevundimonas sp. ZE12 strain isolated from the water with high 226Ra content caused 50% removal of cadmium at a concentration level of 250 ppm. The biosorption equilibrium data are fitted well by the Langmuir adsorption isotherm and kinetic studies indicated that the biosorption follows pseudo second-order model. The effect of different physico-chemical parameters like biomass concentration, pH, cadmium concentration, temperature and contact time on cadmium sorption was also investigated using FTIR, SEM and XRD analytical techniques. A high desorption efficiency (above 90%) was obtained using a pH range of 2.0-4.0. Reusability of the biomass was examined under consecutive biosorption-desorption cycles repeated thrice. In conclusion, Brevundimonas sp. ZF12 is proposed as an excellent cadmium biosorbent that may have important applications in Cd removal from wastewaters. (C) 2011 Elsevier B.V. All rights reserved.