Study of the adsorption of Co(II) on the chitosan-hydroxyapatite

Abstract

The adsorption of cobalt ions (Co²⁺) from aqueous solution onto chitosan-hydroxyapatite composite is investigated in this study. The effects of adsorption time, initial concentration, temperature, and pH are studied in details. Kinetics and thermodynamics of the adsorption of Co²⁺ onto the chitosan-hydroxyapatite are also investigated and the adsorption kinetics is found to follow the pseudo-second-order model with an activation energy (E_a) of 10.73 kJ/mol. Thermodynamic studies indicates that the adsorption follows the Langmuir adsorption equation. The value of entropy change (∆S^ө) and enthalpy change (∆H^ө) are found to be 83.50 and 18.09 kJ/mol, respectively. The Gibbs free energy change (∆G^ө) is found to be negative at all fives temperatures, demonstrating that the adsorption process is spontaneous and endothermic.