Kinetics and Equilibrium Modeling of Sterol Adsorption on Styrene-Divinylbenzene Cation-Exchange Resins

Abstract

The potential of recovering phytosterols from fatty acid methyl esters by an adsorption-desorption process is demonstrated using a strong-acid ion-exchange styrene-divinylbenzene resin (SA-R) as an adsorbent and ethanol as a desorbent. Since the operating cost of the overall process significantly depends on the efficiency of SA-R in the adsorption step, the behavior of SA-R in sterol adsorption is investigated in detail using a model solution of stigmasterol in n-heptane. The results indicate that stigmasterol was associatively and exothermically adsorbed on SA-R. Based on the experimental results, a simple pseudo-second-order model and a modified Langmuir isotherm with their parameters, which well predicted kinetics and adsorption capacity of SA-R, are proposed.