Adsorptive behavior of free and immobilized Chlorella pyrenoidosa for decolorization

Abstract

In the present work, the potential adsorptive behavior of algal cells (Chlorella pyrenoidosa) for decolorization of dye industry wastewater has been studied in the form of free algal cells (FAC) and immobilized algal cells (IAC). Effect of concentrations of real dye industry wastewater (50 and 100%), temperatures (30, 40, 50, and 60 °C) at controlled pH, and equal amount of algal cells (2 g mL−1) have been studied. Adsorption isotherms (Langmuir and Freundlich) with kinetic and thermodynamic equations were applied to experimental data; 52–87% of decolorization was noticed with both algal cells and concentrations at room temperature. But, maximum (98%) decolorization was obtained at 50 °C with immobilized form of algal cell. Results were analyzed by Langmuir and Freundlich equations at different temperatures and were found to be more significant (R2 = 0.99) with Langmuir isotherm for adsorption with IAC. The pseudo-second-order kinetic model was also found significant (R2 = 0.90) to explain the kinetics of adsorption more efficiently. Endothermic nature reaction has been in adsorption process and thermodynamic parameters (ΔG, ΔH, and ΔS) also have been calculated. It has been concluded from the results that adsorption of the dye in wastewater that follows a pseudo-second-order kinetics provides a low-cost approach solution for treatment.