ENHANCEMENT OF BIOSORPTION OF LEAD AND CADMIUM IONS FROM AQUEOUS SOLUTION BY MICROORGANISMS

摘要

The microorganisms Rhodococcus opacus and Rhodococcus ruber were used for the investigation of biosorption parameters for the removal of lead and cadmium ions from aqueous solutions, both biosorbents were activated with NaOH 0.1M to enhance the biosorption capacity. The isotherms and kinetics of biosorption were studied in batch system under optimum operating conditions. Experimental equilibrium data were analyzed using Langmuir and Freundlich isotherm models, with a maximum capacity of 33.33 mg.g~(-1), 43.86 mg.g~(-1) and 56.49 mg.g~(-1) for lead biosorption by Rhodococcus opacus (RO), Rhodococcus opacus treated (RONa) and Rhodococcus ruber treated (RRNa) and 14.59 mg.g~(-1) for cadmium biosorption by Rhodococcus opacus treated with NaOH 0.1M (RONa). The biosorption showed a pH dependent profile showing that the optimum pH value for cadmium biosorption was 7 for RR and RO, 6 for RONa and RRNa, and for lead biosorption was 4, 7, 5 and 6 for RR, RRNa, RO and RONa respectively. The relatively fast biosorption follows the pseudo-second-order kinetic model. The possible ion-biosorbent interactions were evaluated by the FTIR analysis. Results of this work showed that those microorganisms could be used as an effective and eco-friendly biosorbentforthe removal of lead and cadmium.