Biosorption of copper(II) and cadmium(II) by Bacillus cereus sys1 isolated from oil-contaminated site

Abstract

Biosorption of copper(II) and cadmium(II) was studied using Bacillus cereus sys1 cells. The biosorption capacity of the cells has been studied as a function of pH, initial metal concentration, cell concentration and contact time. Batch studies showed that the B. cereus sys1 cells could adsorb up to 90% of both metals. For copper, total contact time of 90 min was required with 100 ppm initial metal concentration at pH 5 using 10 mg/ml cells, whereas 180 min was required for 30 ppm cadmium at pH 7. The study demonstrated correlation with Langmuir model with different concentrations of both Cu(II) and Cd(II). The adsorption capacity was found to be 225 mg/g for copper and 34.67 mg/g for cadmium. As per the Freundlich isotherm, value of 1/n, which shows the strength of adsorption, was found to be 0.5114 for copper and 0.2492 for cadmium indicating a normal and favourable adsorption intensity. The surface adsorption of metals was confirmed using SEM with EDS. It revealed that the cells treated with oil could adsorb 7.55% copper as compared to untreated cells which showed 7.29% adsorption. Similarly, for cadmium oil-treated cells showed 9.44% adsorption compared to 2.63% of untreated cells. This indicated that the cells grown in the presence of oil have a better capacity for metal ion adsorption.