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

Abstract

KEYWORDSThe adsorption of cobalt ions (Co 2+ ) from aqueous solution onto chitosanhydroxyapatite 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 Co 2+ onto the chitosan-hydroxyapatite are also investigated and the adsorption kinetics is found to follow the pseudo-second-order model with an activation energy (Ea) 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.

Study on removal behavior and separation efficiency of naturally occurring bentonite for sulfate from water by continuous column and batch methods

“…The kinetic equation of the pseudo second-order model is 2 t e 2 e t 1 1 t q q k q (3) where k2 is the rate constant of pseudo-second-order model (g/mg.min), qt and qe are the amounts of sulfate ion sorbed at time t and at equilibrium time (mg/g), respectively [22]. The estimated values of qe and k2 can be gotten from the slope and the intercept of straight-line plots of t/qt vs t. These values are noted in Table 2 and the plots for different temperature of this model were illustrated in Figure 4.…”