30F-2 |
A kinetics study: selective adsorption of free fatty acids from crude catfish oil onto chitosan, activated carbon and/or activated earth |
S. SATHIVEL and W. Prinyawiwatkul. Department of Food Science, Louisiana State University Agricultural Center, Baton Rouge, LA 70803-4200 Free fatty acids, phospholipids, and peroxide derivatives in fish oils must be removed during refining process. Activated earth and carbon were reported to be effective adsorbents for removal of free fatty acids from oils. Adsorption thermodynamic and kinetics are important aspects for evaluating adsorption as a unit operation, selecting an appropriate adsorbent, and predicting the performance of adsorption systems. The objectives were to determine an appropriate model (among Freundlich, Langmuir, and Redlich-Peterson isotherm models) for selective adsorption of free fatty acids (FFAs) from crude catfish oil onto chitosan, activated carbon and/or activated earth and to identify the best adsorbent for FFAs removal. Batch adsorption of FFAs was investigated in triplicate. 20, 40, 60, and 80%w/w of crude catfish oil/n-hexane miscella were prepared. Each adsorbent (0.8g) was added to each 25-ml miscella and sealed, and the mixture was stirred for 1-hour at 25°C. The adsorbent was then removed from the oil-hexane miscella by centrifugation. The miscella phase was analyzed for FFAs. The adsorption affinity parameters for FFAs were determined. The Freundlich and Langmuir models adequately described the relationship between adsorption capacity of chitosan and FFAs concentration, while the Redlich-Peterson model was appropriate for the activated earth. The n value (index of adsorption efficiency) of the Freundlich model for chitosan was lowest (0.827); the n value of less than 1.0 indicated good adsorption efficiency. The Kf value of the Freundlich model for chitosan, activated carbon, and activated earth was 2.26, 1.73, and 1.56, respectively. The Kf value increased with increased total adsorption capacity of an adsorbent to bind FFAs. Chitosan is an effective adsorbent for removing FFAs from crude catfish oils. The information from this study will be useful for a process design for removal of FFAs at a larger scale operation. Use of chitosan as an adsorbent may eliminate the neutralization step.
Session 30F, Food Engineering: Transport processes and kinetics
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