Biosorptive Performance of Bacillus arsenicus MTCC 4380 Biofilm Supported on Sawdust/MnFe2O4 Composite for the Removal of As(III) and As(V)

Abstract

One of the main environmental concerns of today is the occurrence of arsenic in wastewater. Targeting a solution for this problem, several efforts have been made towards research and application of cost-effective and effortlessly adaptable processes. The ability of a biofilm of Bacillus arsenicus MTCC 4380 supported on sawdust/MnFe2O4 composite to biosorb/bioaccumulate As(III) and As(V) was investigated in batch experiments. Optimum biosorption/bioaccumulation conditions were determined as a function of contact time and temperature. The equilibrium was achieved after about 220 min at 30 °C temperature. Nonlinear regression analysis was done to determine the best-fit kinetic model based on three correlation coefficients and three error functions and also to predict the parameters involved in kinetic models. The results showed that both Brouers–Weron–Sotolongo and Avrami models for both As(III) and As(V) were capable of providing realistic explanation of biosorption/bioaccumulation kinetic. Applicability of mechanistic models showed that the rate controlling step in the biosorption/bioaccumulation of both As(III) and As(V) was film diffusion rather than intraparticle diffusion. The estimated thermodynamic parameters ΔG0, ΔH0, and ΔS0 revealed that biosorption/bioaccumulation of both As(III) and As(V) was feasible, spontaneous, and exothermic under examined conditions. The activation energy (Ea) estimated from Arrhenius equation specified the nature of biosorption/bioaccumulation being ion exchange type. The effect of co-existing ions such as Cu2+, Zn2+, Bi3+, Cd2+, Fe3+, Pb2+, Co2+, Ni2+, Cr6+, and SO42− at different concentrations was inspected.