Adsorption behaviour of cadmium by Bacillus cereus M116: some physical and biochemical studies

Abstract

Adsorption behaviour of cadmium from its aqueous solution by growing and non-growing cells of a mutant strain of Bacillus cereus M116 has been studied to explore the possibility of the biomass to address environmental pollution due to this toxic metal. The results establish that about 75% and 88% of the cadmium can be removed by growing and non-growing cells of the selected strain respectively from its aqueous solution at pH 6.8 ± 0.2, temperature 30 ± 1°C and 120 rpm shaking speed. For growing cells, inoculum size 2% and medium volume 50 mL is found to be optimum. The adsorption rate of cadmium on the biomass is very fast initially and attains equilibrium within 60 min following pseudo second-order rate model (R2 = 0.99). The equilibrium adsorption isotherm can be best described by Langmuir–Freundlich dual model (R2 = 0.99) indicating that both physisorption and chemisorption take place simultaneously. Cadmium can be desorbed from the loaded biomass using mineral acids (0.1 M).