Optimization using central composite design (CCD) for the biosorption of Cr (VI) ions by Azolla filiculoidus a fresh water macro alga.

The presence of Chromium in aqueous streams arising from the discharge of industrial effluents into water bodies is one of the most important environmental issues because of its toxic nature. In the present study response surface methodological optimization strategy was used for biosorption of Cr(VI) ions by Azolla Filiculoidus. Effect of various operating parameters such as initial pH of solution, initial concentration of solution, biomass dosage and temperature was studied and optimized using response surface methodology. Using central composite design, 30 experiments were carried out for the four test variables. From the statistical analysis of the experimental data the optimum condition for maximum removal of metal ions was achieved at pH-2.9, initial metal concentration-39.04, biomass dosage-0.3 g/L and temperature-33.34 degrees C. At these optimized conditions, the maximum percentage of chromium removal was found to be 89.24. A high R2 value of 0.9906 indicates the fitness of the model to predict the experimental data.