Abstract
Pb2+ removal ability of the immobilized and free filaments of marine cyanobacteria Oscillatoria sp. NTMS01 and Phormidium sp. NTMS02 was studied using batch experiments. Biosorption of lead by immobilized filaments was studied as a function of pH (2, 4, 6, 8, 10), contact time (5-180 min) and initial lead concentration (1, 3, 5, 7 mg/L) and the removal efficiency of free filaments was studied by culturing in the marine medium with the initial concentration (1, 3, 5, 7 mg/L) at pH 7 and incubated for 10 days. The maximum percentage removal was observed at 25 min for immobilized Oscillatoria sp. NTMS01 and 30 min for immobilized Phormidium sp. NTMS02. At 4th and 6th day of incubation, 89% and 77% removal was observed at 1 mg/L of initial lead concentration by free filaments of Oscillatoria sp. NTMS01 and Phormidium sp. NTMS02 respectively and further the removal was decreased with increasing concentration. Chlorophyll-a content was decreased in a dose dependent manner. About 40 and 50% reduction of chlorophyll-a was observed at higher concentration in Oscillatoria sp. NTMS01 and Phormidium sp. NTMS02 respectively. The adsorption capacity of immobilized Oscillatoria sp. NTMS01 was found to be (Q(max)) 217.39 which is comparatively higher than other sorbents. The Pb2+ removal efficiency was performed as described in terms of Langmuir and Freundlich isotherms. These organisms is found to fit better by the Langmuir isotherms.