Bioremediation potential of Chlorella: spectroscopic, kinetics, and SEM studies

A dead dried alga, Chlorella sp., was used for the uptake of Cr+3, Cr2O7(-2), Cu+2, and Ni+2 from the aqueous solutions of these metal ions. The equilibrium data were fitted using the Langmuir and Freundlich isotherm model and the maximum uptakes for Cr+3, Cr2O7(-2), Ni+2, and Cu+2 were 98, 104, 108, and 183 mg/g, respectively. The Freundlich model, in comparison to the Langmuir model, better represented the sorption process. The kinetics of metal ions uptake by Chlorella sp. was best described by a pseudo-second order rate equation. Infrared spectroscopic data were employed to identify the site(s) of bonding in Chlorella sp. A scanning electron microscopic (SEM) study of pure dead Chlorella sp. and the species treated with different metal ions provided an idea of the extent of metal uptake by this species. The dead Chlorella sp took up maximum Cu(II). The size of the cell of the metal-treated Chlorella sp. obtained from SEM data is in agreement with the extent of metal uptake.