Biosorption of Hexavalent Chromium by Shewanella putrefaciens MTCC 8104: Response Surface Methodology Optimization and Mechanistic Insights

Hexavalent chromium (Cr(VI)) is a widespread contaminant that poses an imminent danger to the well-being of humans. Recently, there has been a growing interest in using microbes to adsorb heavy metals. Nevertheless, research is limited on the process of biosorption of Cr(VI) by Shewanella putrefaciens MTCC 8104, a bacterium known for its ability to reduce metals. This article used single-factor experiments to examine the impact of hexavalent chromium on S. putrefaciens MTCC 8104. Additionally, response surface methodology (RSM) based on the Box–Behnken design (BBD) was employed to analyze the biosorption behavior of S. putrefaciens MTCC 8104 towards Cr(VI). The coefficient of determination (R² = 6.35 for Cr(VI)) and probability value (p < 0.05) indicate relevance in the regression model. The model matched experimental data with S. putrefaciens MTCC 8104, achieving 86.50% Cr(VI) removal efficiency at 20 h contact time, pH 9, and biomass dosage of 12 g/L. Further experiments confirmed this result. A 3D response graph and ANOVA analysis revealed substantial impacts of temperature and the pH. The results of the experiments promoter that S. putrefaciens (MTTC 8104) might be a viable bacterial strain for recovery of Cr(VI) in polluted water.