Biosorption of Cd(II) and Cu(II) ions using Lysinibacillus fusiformis KMNTT-10: equilibrium and kinetic studies

Abstract

The biosorption of Cd(II) and Cu(II) ions from aqueous solutions on the biomass of Lysinibacillus fusiformis KMNTT-10 was investigated by batch method as functions of pH, contact time, biomass dose and initial metal concentrations. The experimental results showed the optimum pH for adsorption of Cd(II) and Cu(II) ions was 6.0, while the contact time was 2 h at room temperature (27 ± 2°C). The experimental data were successfully evaluated by isotherm and kinetic models. The maximum adsorption capacities (Q_max) for Cd(II) and Cu(II) ions obtained from the Langmuir equation were 53.19 and 46.29 mg g⁻¹, respectively. The adsorption kinetics for tested metals followed the pseudo-second-order model than the pseudo-first-order model. Scanning electron microscopic analysis showed deformation and surface damage in the Cd(II) and Cu(II) adsorbed cells. Energy-dispersive X-ray scanning results confirmed the adsorption of Cd(II) and Cu(II) onto biomass. Fourier transform-infrared spectroscopy analysis indicated that functional groups (amino, carboxyl, hydroxyl and carbonyl groups) on the cell surface were responsible for metal binding.

Keywords:

• Biosorption
• Heavy metals
• Isotherms
• SEM–EDX analysis
• Functional groups

Acknowledgements

Authors are thankful to the authorities of Bharathidasan University for the infrastructure facilities and acknowledge the University Grant Commission (UGC), Government of India for providing the financial support in carrying out this work (reference no. F. No. 36-55/2008 (SR) dated: 24-03-2009).