Equilibrium, Kinetics, and Thermodynamics of Soybean Oil Deacidification Using a Strong Anion Exchange Resin

Abstract

This study investigated the adsorption kinetics, isotherms, and thermodynamic parameters of the removal of free fatty acids from soybean oil using the strong anion exchange resin Amberlyst A26 OH. The presence and type of organic solvents used in the solution and in the resin, due to its pretreatment, affected the reduction of acidity and the adsorption rate as well as its catalytic activity. Adsorption of free fatty acids was further studied in two systems involving the resin drying step and the adsorbate dissolved in either vegetable oil alone or vegetable oil with hexane. The fitting of pseudo-first-order and pseudo-second-order models showed high coefficients of determination. Langmuir, Freundlich, and Temkin isotherms could describe the equilibrium data. The adsorption in this study is a spontaneous and endothermic process. The reported results highlight that Amberlyst A26 OH has good adsorption capacity for the free fatty acids contained in vegetable oils.