Evaluation of soy oil lutein isotherms obtained with selected adsorbents in hexane miscellas

Bleaching of soy oil hexane/miscellas by adsorption of the lutein was examined. Quantitative differences in the adsorption behavior between a bleaching clay, alkaline rice hull ash and acid rice hull ash were measured by comparing the constants,K andn, of Freundlich isotherms. All the isotherms were dose-dependent withK being inversely related andn directly related, to adsorbent mass. Overall, the bleaching clay performed better than the ashes. Alkaline ash had a largerK value than acid ash, but then value of acid ash was greater. Equations of lutein adsorption were derived based on initial concentrations on lutein and the amount adsorbed per gram. Logarithmic plots produced constants,K ⁱ and ni which were the intercept and slope, respectively. As adsorbent dose increased,K ⁱ decreased andn ⁱ increased for each adsorbent studied. These findings may have applications in the processing of dilute miscellas where low temperature, low viscosity oil refining is desired.