Optimizing the biosorption of Bi3+ ions by Streptomyces rimosus using experimental design and applicability in kinetics and isotherm modeling
Abstract
This investigation seeks to analyze bismuth biosorption onto Streptomyces rimosus in solutions following optimization using a Box–Behnken Design (BBD). Based on an efficient method, three significant parameters including pH, temperature, and initial bismuth (Bi3+) concentration in a batch system were studied using design of experiment (DOE). A central composite second order response surface methodology (RSM) accomplishes the construction of model biosorption (R%) and operating conditions. Using this statistical–mathematical method leads to obtaining a second-order equation for bismuth removal. The regression equation was obtained using Design Expert 7.0 software. The numerical optimization shows a great biosorption percentage (>97%) at pH 8.0, 30 °C, and 30 mg L−1 for bismuth. The quadratic models exhibited higher R2 values, significant p-values, and insignificant lack-of-fit p-values that all confirm their high suitability for predicting the response. Both mathematical and empirical models, due to their high correlation coefficient (R2) of 0.9999, are suitable for predicting the biosorption trend of bismuth in solution. The closeness of the predicted values and experimental values also supports this conclusion. The pseudo-second order kinetic model adequately described the kinetic data. The Langmuir isotherm model described the process of Bi3+ uptake better than the other models. The maximum biosorption capacity of the biosorbent was found to be 38.93 mg g−1 for bismuth biosorption. The possible interactions between biosorbents and bismuth were also evaluated using Fourier transform infrared (FT-IR) spectroscopy analysis.