Biosorption of copper(II) from aqueous solution by Bacillus subtilis cells immobilized into chitosan beads

The ability of Bacillus subtilis immobilized into chitosan beads (BICB) to remove Cu(II) from aqueous solution was studied. The effects of pH, biosorbent dosage, temperature, initial Cu(II) concentration and contact time on removal of Cu(II) were studied using batch adsorption experiments. The results show that the Cu(II) absorption strongly depends on pH and the optimum pH is 6. Compared with chitosan beads (CB), the BICB has higher efficiency and capacity on Cu(II) removal. The Langmuir isotherm model (R-2=0.994) is proved to fit the equilibrium data best. The maximum adsorption capacity determined from Langmuir model is 100.70 mg/g. The kinetic data fit well with the pseudo-second-order model and the correlation coefficient is greater than 0.999. The biosorbents are successfully regenerated using 0.1 mol/L NaOH solution.