Deacidification of vegetable oil by extraction with solvent recovery

Deacidification of a vegetable oil by extraction and regeneration of the solvent by means of adsorption was studied. This novel approach to solvent regeneration is posed as an alternative to distillation in systems with high solvent-to-feed ratios in which evaporation of large solvent amounts is economically unattractive. An example was chosen of deacidification of sunflower oil by extraction with methanol and regeneration of the alcohol by adsorption over activated carbon. The example has application for the biodiesel and technical oils industries. The results showed that high temperatures of extraction increased the acid–methanol partition coefficient but also the mutual solubility of oil and methanol. One extraction stage with a solvent-to feed ratio of 20 (vol:vol) reduced the oil acidity to acceptable values. Regeneration of the extract by adsorption over activated carbon was found to be efficient. For regenerating the bed, elution with a hot solvent was studied. Adsorbent regeneration was completed to a high degree, with elution temperature being the most important variable. For exploring the influence of process variables on the performance of extraction-adsorption, simulation was used. Necessary parameters for mass transfer and adsorption were fitted from breakthrough tests with the aid of a linear driving force model. Simulation results confirmed the viability of the proposed process as an alternative for solvent regeneration of extraction units.