Biosorption of Cd(II)/Pb(II) from aqueous solution by biosurfactant-producing bacteria: isotherm kinetic characteristic and mechanism studies.

The potentiality of biosurfactant-producing bacterium Pseudomonas sp. LKS06 to remove Cd(II) and Pb(II) ions from aqueous solution was investigated in this study. The maximum biosorption capacity of Pseudomonas sp. LKS06 biomass for Cd(II) and Pb(II) was found to be 27.5 and 77.8 mg g(-1), respectively, at the optimum pH of 6.0. The process can be better explained by Langmuir-Freundlich dual isotherm model (R(2)>0.981) while the kinetic data was best described by using the pseudo-second-order kinetic model (R(2)>0.999). Both metal ions were successfully recovered from the bacterial biomass using 0.1M HNO3 with 90% recovery and the biomass shows high stability in the experiment of regeneration. Scanning electron microscopic analysis demonstrates a conspicuous surface morphology change of the Cd(II)/Pb(II)-adsorbed biomass. The results of zeta potential measurement and Fourier transform infrared spectroscopy suggested the involvement of amine, carboxyl, phosphate and hydroxyl groups during the biosorption process. Based on the results, it can be concluded that the biomass of Pseudomonas sp. LKS06 can be evaluated as an alternative biosorbent to remove Cd(II) and Pb(II) ions from industrial wastewater.