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 radionudides on microorganisms efficiently and quickly. (C) 2016 Elsevier B.V. All rights reserved.