Equilibrium, Kinetic, and Thermodynamic Studies for Crude Structured-Lipid Deacidification Using Strong-Base Anion Exchange Resin

摘要

This study presents the adsorption behavior of strong base anion exchange D202 resin for the elimination of free fatty acids (FFAs) from 'structure-lipid in nonpolar solvent. The kinetics and thermodynamic behaviors that govern FFAs removal by D202 resin were investigated, and appropriate equilibrium isotherm and kinetics models for the removal in batch experiments were identified. Both the Freundlich and Langmuir adsorption isotherm models were fitted to the experimental results with the best fit obtained by the latter. The adsorption capacity of D202 resin was 235.69 mg.g(-1), as calculated from the nonlinear model of the Langmuir adsorption. The experimental data from the batch adsorption processes were analyzed in terms of the parameters from three adsorption kinetics models, namely, the liquid-film diffusion, the intraparticle, and the chemical-reaction models, to estimate the fit for the adsorption in these systems. The outcomes indicate that the adsorption kinetics between the free fatty acid ions and resin are controlled by liquid-film diffusion as the rate-determining step. In addition, the activation energy (E-a) and the changes in the Gibbs free energy (Delta G), enthalpy (Delta H), and entropy (Delta S) obtained from the thermodynamic studies reveal that the ion exchange adsorption of FFAs on D202 resin is a spontaneous, endothermic, and entropy-driven process.