Removal of Organic Acids from Wine by Adsorption on Weakly Basic Ion Exchangers: Equilibria for Single and Binary Systems

In order to remove or reduce the organic acids from wine and liqueur, we investigated their adsorption on weakly basic resins. CC-S, WA-10, and WA-30, which were made from chitosan, acryl, and styrene, respectively, appeared technically feasible. The concentration of the fixed amino group in CC-S, WA-10, and WA-30 is 3.31, 2.37, and 2.81 kmol/m3, respectively. These resins adsorbed citric acid and malic acid from wine selectively. The equilibrium isotherms for single component systems of citric acid or malic acid were little affected by the initial concentration (C 0 = 0.01, 0.02, and 0.03 kmol/m3) and by ethanol. The equilibrium data were correlated by the Langmuir equation. The equilibrium data were correlated by the Langmuir equation. The equilibrium isotherms for the binary system of citric and malic acids were affected by the initial concentration (C A0 = 0.02, C B0 = 0.03 kmol/m3; C A0 = 0.014, C B0 = 0.004 kmol/m3). The equilibrium data were correlated reasonably well by the Markham-Benton equation. The equilibrium constants for citric acid were much larger than those for malic acid. By using these constants, the equilibrium data for adsorption of citric and malic acids from wine could be adequately correlated by the Markham-Benton equation.