Biosorption and bioaccumulation behavior of uranium on Bacillus sp. dwc-2: Investigation by Box-Behenken design method

In this paper, the effect of contact time, biomass dosage, pH, initial uranium concentration on biosorption of uranium by Bacillus sp. dwc-2 were optimized using response surface methodology (RSM). The results revealed that the empirical models were adequately fitted to the experimental data (p < 0.0001). Evaluation of responses by analysis of variance (ANOVA) indicated high coefficient determination value and satisfactory second-order regression. Under optimum condition, response was found to be 86.86% uptake of uranium ions, and was also validated experimentally with very close compatibility. Furthermore, TEM-EDX microscopy showed the cellular localization of uranium needle shaped precipitates. Besides, XPS characterization confirmed the role of several functional groups and chemical-state alterations on Bacillus sp.dwc-2 biomass, which were responsible for the removal of uranium. Results from this study should be useful in exploring the biosorption behavior and mechanism of radionuclides on microorganisms efficiently and quickly.