Biosorption and Elution of Cr(VI): A Detoxification Strategy

Abstract

Biosorption of Cr(VI) from solution was studied using pH-conditioned biomass of Bacillus coagulans. Effect of several environmental factors on metal uptake was characterised. Biosorption of Cr(VI) was found to be influenced by the pH of the solution. As the pH of metal solution decreased, a rise in the biosorption could be noticed, which peaked at pH 2.5 and declined on further pH decrease. Equilibrium metal sorption was found to fit the Langmuir adsorption model, and the ‘best fit’ parameter for Cr(VI) biosorption at pH 2.5 and 28° C was determined to be Qmax = 62.11 mg/g and b = 0.071 L/mg. The metal biosorption process was not affected by contact time and the system attained equilibrium in 60 min. Increase in incubation temperature resulted in a marginal increase in biosorption of Cr(VI). Biosorption of Cr(VI) was not affected by presence of heavy metals, except for lead, which resulted in a maximum of 11.81 % decrease in the presence of 200 mg lead/L solution. A 1.0 M H2SO4 solution could elute chromium loaded on B. coagulans biomass and regenerate biomass for another cycle of Cr(VI) biosorption.