BIOSORPTION OF SOME TOXIC METALS FROM AQUEOUS SOLUTION USING NON-LIVING ALGAL CELLS OF CHLORELLA VULGARIS

Dead cells of Chlorella vulgaris were used experimentally to remove cadmium (Cd2+), copper (Cu2+) and lead (Pb2+) ions from aqueous solution under various conditions of pH, biosorbent dosage and contact time. C. vulgaris was isolated from Lake Manzala (Egypt) and then cultivated outdoors, in growth media, maintaining pH of nearly 7.5. After cultivation, the cells were harvested by coagulation and prepared to make an experiment with different variants of pH, contact time and adsorbent dose. The adsorption specific characteristics of C. vulgaris were examined using Fourier Transformation Infrared Spectroscopy (FTR) and Scanning Electron Microscopy (SEM). The FTIR and SEM data showed vibration frequency changes for the peaks corresponding to the surface functional groups and morphological changes of C. vulgaris, respectively, after its exposure to metal ion solution. The maximum removal efficiency for copper and lead at ambient room temperature was recorded at pH 5 and 20-minute contact time, while the contact time of 120 minutes at pH 6 created the most suitable conditions for cadmium biosorption. On the other hand, 2 g dm(-3) of C. vulgaris under optimum conditions was sufficient to remove 95.5%, 97.7% and 99.4% of Cd2+, Cu2+ and Pb2+, respectively, from a mixed solution of 50 mg dm(-3) of each metal ion. The removal trend was in order of Pb2+ > Cu2+ > Cd2+. The results suggested that the biomass of C. vulgaris is an extremely efficient and environmentally friendly biosorbent for the removal of Cd2+, Cu2+ and Pb2+ from aqueous solutions, which may be applied on a large, industrial scale.