Adsorption of U(VI) by Bacillus mucilaginosus

The uranium contamination is a major environmental problem. Biosorption is a potentially important pathway for immobilization of uranyl cations (UO2 (2+)). This study investigated the potentiality of utilization of Bacillus mucilaginosus as a biosorbent for U(VI) removal from aqueous solutions. Batch experiments were conducted to examine U(VI) adsorption to B. mucilaginosus when pH, sorption time, reaction temperature, biosorbent dosage, initial U(VI) concentration were independently changed. The Freundlich and Langmuir adsorption models were used for the mathematical description of the adsorption equilibrium. The accumulation process was highly pH dependent within the pH range between 2.0-7.0. An initial solution pH of 5.5 was most favorable for U(VI) removal. Temperature over the range 25-45 A degrees C had no effect on the U(VI) biosorption. The U(VI) uptake was rapid within the first 30 min and equilibrium was reached at 1 h. The U(VI) removal efficiency increased concomitantly with increasing biomass dosage, while the biosorption capacity decreased. The biomass had an observed maximum U(VI) biosorption capacity of 172 mg/g dry weight of biomass. The biosorption process could be well defined by Langmuir isotherms. The adsorption kinetics data were fitted very well by the pseudo first-order rate model. The X-ray photoelectron spectroscopy analysis confirmed that uranium in the solution was immobilized onto the biomass during the course of biosorption. The present results suggest that B. mucilaginosus can be used as a biosorbent for an efficient removal of U(VI) from aqueous solution.