This study investigated biosorption of Cr(VI) and Co(II) ions by fresh water dead algal biomass Cosmarium panamense from aqueous solution. Batch experiments were conducted to determine the biosorption behavior of the biomass and it was observed that the adsorption capacity for Cr(VI) and Co(II) ions by the biomass are initial metal ion concentration, biosorbent dose, shaking time, pH and temperature dependent. The maximum adsorption capacities for Cr(VI) and Co(II) ions are 109.9mgCr/g and 16.69mgCo/g of the biomass respectively at initial concentration of 20ppm and pH of 2.05 for Cr(VI) and 4.05 for Co. The equilibrium data of Cr(VI) sorption was well described by Freundlich isotherm while that of Co2+ sorption fitted well in Langmuir isotherm model and isotherms were used to determine thermodynamic parameters of the metal ions sorption process viz free energy change, enthalpy change and entropy change and the nature of the sorption process were found to be endothermic and spontaneous in nature. Uptake kinetics of the selected heavy metals ion follow pseudo - second order model. Effect of biosorption on various properties of the algal biomass, as adsorbent, was explored in the characterization of the adsorbent were, chemical composition by EDAX , Simultaneous Thermal Analysis by TGA – DSC, Surface morphology by SEM images and surface functionality by FTIR, of the algal biomass before and after biosorption were investigated.
