Thermodynamics and kinetics of the adsorption of CDPC on SH15 resin

Thermodynamics and kinetics of adsorption of cytidine-5'-diphosphate choline (CDPC) by SH15 resin were investigated. The equilibrium isotherms were obtained in a range of temperature, and heat of adsorption (ΔH), Gibbs free energy (ΔG), entropy of adsorption (ΔS) were calculated according to the relationship of the thermodynamic function. The adsorption date fit well into the Langmuir adsorption isotherm, based on the apparent enthalpy changes of adsorption. Thermodynamic parameters depict the exothermic nature of adsorption and the process is spontaneous. On the other hand, the kinetics of adsorption process was studied under different conditions as follows temperature, CDPC concentration, resin particle radium and stirring speed. Moving Boundary Model was applied to describe the kinetics of adsorption process. The results showed that the particle diffusion was the rate-controlling step. The activation energy (E_a), reaction order (n) and adsorption rate constants (k₀) were obtained: E_a=9.73kJ/mol, n=0.47, K₀=0.0744 and the kinetics equation were also obtained.