Lysine adsorption on cation exchange resin. I. Ion exchange equilibrium and kinetics

Ion exchange equilibria and kinetics are determined for lysine adsorption on the strong acid cation exchanger Dowex HCR-W2. Average ion exchange selectivity coefficients of 5.0 g/cm(3) and 0.75 are obtained for the ion exchange of divalent and monovalent cationic lysine with hydrogen ion, respectively, while values of 1.5 and 1.9 are obtained for the exchange of ammonium and potassium with hydrogen ion. A model based on these binary ion exchange measurements and accounting for the solution equilibria is then developed to predict lysine adsorption over a broad range of conditions. Similarly, resin phase diffusivities are determined by fitting batch binary ion-exchange data with a mass transfer model based on the Nemst-Planck equations. Diffusivities of divalent cationic lysine, monovalent cationic lysine, ammonium ion, and potassium ion are 0.05 x 10(-6), 0.20 x 10(-6), 1.6 x 10(-6), and 1.9 x 10(-6) cm(2)/s, respectively. Finally, a general rate model incorporating ion exchange and solution equilibria is developed to predict batch adsorption and desorption of lysine using these diffusivity values over a broad range of conditions.