Uranium biosorption by autolyzed residues of baker yeast: characterization and optimization

Biosorption is a good choice for removal of pollutants from water. In this study, hull cell of thermally autolyzed baker yeast, was used as a low-cost biosorbent against U(VI) pollution. The changes of biomass properties due to autolysis were analyzed using SEM, FTIR and BET techniques. Uranium (VI) biosorption capacity was evaluated and the effective parameters were examined by Placket Burman Design and the levels of significant factors (including pH, biomass concentration, initial U(VI) concentration) were further optimized using Response Surface Methodology. Based on the results obtained from the proposed quadratic model, maximum U uptake (84 mg/g) was occurred under optimum conditions including: 2.0 g biomass/L, pH value of 4.5 and 300 mg/L of initial U(VI) concentration. Furthermore, the experimental data were fitted to pseudo-first-order kinetic model (R 2 = 0.991) and Freundlich isotherm model (R 2 = 0.965). Uranium is desorbed in the presence of diluted solutions of sulfuric acid (about 70%) indicated the potential of the metal recovery.