Removal of Pb²⁺ from aqueous system by live Oscillatoria laete-virens (Crouan and Crouan) Gomont isolated from industrial effluents.

Cyanobacteria have been found to be potential biosorbents of metal ions from waste water. The Pb²⁺ removal capacity of growing cells of indigenous cyanobacterium Oscillatoria laete-virens (Crouan and Crouan) Gomont was studied under batch experiments and it was found capable of removing Pb²⁺ of lower concentrations (below 100 mg L⁻¹). The effects of different concentrations of Pb²⁺, on the growth rate of alga were also evaluated. The research parameters include the pH of the solution, contact time, initial concentration of Pb²⁺, and culture density. Of the parameters studied, the pH of the solution was found to be the most crucial. The removal of Pb²⁺ peaked at an initial pH of 5. The data obtained from the equilibrium experiments were found well fitting with the Langmuir isotherm with a maximum sorptive capacity (q(max)) of 20.36 mg g⁻¹, indicating a good biosorbtive potential of growing cells. This was confirmed using scanning electron microscope and energy dispersive X-ray analysis, which showed the adsorption of lead on the surface of the cell. The species could tolerate a concentration as high as 60 mg L⁻¹ of Pb²⁺. It was observed that the removal obeyed the pseudo-second-order kinetics. The percentage removal was found to decrease with increasing metal concentration, from 10 to 100 mg L⁻¹. FTIR analysis indicates the involvement of amino, carboxylic and amide groups in the sorption process. Among the desorbing agents evaluated, an efficient recovery of 90.2 % was achieved by HCl, in 24 h. Thus Oscillatoria laete-virens (Crouan and Crouan) Gomont seems to be a promising metal biosorbent for the treatment of Pb²⁺, in waste waters.