BIOSORPTION OF Pb(II) BY Bacillus cereus M16 IMMOBI- LIZED IN CALCIUM ALGINATE GEL

Biosorption is an alternative to traditional physicochemical means for removing toxic metals from ground and wastewaters. Biosorption of Pb(II) ion from solution was studied using Bacillus cereus M116 immobilized in calcium alginate gel in batch mode, and optimum conditions were determined. The experimental results showed that the immobilized bacterial strain was effective in removing Pb(II) ion from solution. The uptake of metal was very fast initially, and equilibrium was attained within 270 min. It was found that the overall adsorption process was best described by pseudo second-order kinetics. Intra-particle diffusion was not the only rate determining step. The sorption data conformed well to the Freundlich isotherm model. Adsorption increased with an increase in pH in the pH range 3.6 – 6.0, beyond which the adsorption could not be carried out due to precipitation of metal. The highest value of lead uptake was 99%, with 5.4% biomass in 500 mg of adsorbent using 50-ml solution containing 50 mgL-1 Pb(II) ion in a 250-ml Erlenmeyer fl ask at 300 C and 120 rpm.