Biosorption of Cd2+ from aqueous solution by a NaOH-treated bacterial dead Streptomyces rimosus biomass

The cadmium biosorption capacity of a Streptomyces rimosus biomass treated with NaOH (0.1 M) was studied in the batch mode. After pretreatment of biomass at the ambient temperature, optimum conditions of biosorption were found to be: a biomass particle size between 50 and 160 μm, an average saturation contact time of 1 h, a biomass concentration and a stirring speed in the range of 2.5–3 g L−1 and 200–250 rpm, respectively. The external mass transfer was found to be the controlling step in the overall sorption process. The equilibrium data could be fitted by Langmuir isotherm equation. Under these optimal conditions, a biosorption capacity of 63.3 mg Cd2+/g biomass was obtained.