(412f) Multicomponent Aqueous Phase Adsorption Equilibria of Organic Acids on Ion-Exchange Resin

Thermal separation of valuable organic acids from biomass fermentation broth requires high investment cost and high energy consumption. Adsorptive separation is advantageous due to its high efficiency, high selectivity, and reduced energy requirement as compared to thermal separation. To investigate adsorptive separation of organic acids from fermentation broth, systematic aqueous phase adsorption equilibrium measurements are carried out with the unary, binary, and ternary systems of acetic acid, butyric acid, and lactic acid on a commercial ion-exchange resin IRN-78 at wide range of solution concentrations (1 – 50 g/L), pH (3 – 7), and temperatures (298.15 – 328.15 K). Furthermore, thermodynamic modeling of the adsorption equilibrium data is performed with a newly developed generalized Brunauer-Emmett-Teller (gBET) isotherm for aqueous phase adsorption equilibrium. Taking into account competitive adsorption of adsorbates and solution chemistry of organic acids in aqueous solution of different pH and temperatures, the model precisely captures the unary, binary, and ternary aqueous phase adsorption equilibria experimental data. The gBET isotherm representations are also compared against those with conventional Overloading model and Ideal Dilute Solution Theory. The gBET isotherm provides a sound thermodynamic foundation for multicomponent aqueous phase adsorption equilibria of organic acids and outperformed the estimations from conventional models. The experimental and modeling efforts shall support the subsequent process simulation, development, and design of adsorptive separation pilot plant units for organic acid separation to facilitate the scale-up of biorefineries.