Response surface methodological approach for optimizing removal of Cr (VI) from aqueous solution using immobilized cyanobacterium

The potential use of alginate immobilized algal beads for the removal of chromium from aqueous solution has been investigated under optimized conditions in this study using a novel cyanobacterium, Lyngbya putealis isolated from metal contaminated soil. Batch mode experiments were performed to determine the adsorption equilibrium and kinetic behaviour of chromium in aqueous solution allowing the computation of kinetic parameters and maximum metal adsorption capacity. Influences of other parameters like initial metal ion concentration (10–100 mg/L), pH (2–6) and temperature (25–45 °C) on chromium adsorption were also examined, using Box–Behnken design. Very high regression coefficient between the variables and the response (R2 = 0.9984) indicates excellent evaluation of experimental data by second-order polynomial regression model. The response surface method indicated that 50–60 mg/L initial chromium concentration, 2–3 pH and a temperature of 45 °C were optimal for biosorption of chromium by immobilized L. putealis, when 82% of the metal is removed from the solution.