SEPARATION OF POLYUNSATURATED FATTY-ACIDS WITH SILVER-NITRATE USING AHOLLOW-FIBER MEMBRANE EXTRACTOR

Solvent extraction of ethyl esters of polyunsaturated fatty acid such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) was perf ormed with an aqueous silver nitrate solution using a microporous hydr ophobic hollow-fiber membrane extractor, The mixture of four kinds eth yl esters of fatty acids involved in fish oil was employed as a model solution of fish oil. Also studied was the extraction equilibria of th ese fatty acids at various conditions. It was demonstrated from the ex perimental results that EPA and DHA ethyl esters could be satisfactori ly separated from ethyl esters of lower fatty acids such as oleic and palmitic acids. In addition, the effects of silver and ester concentra tions in aqueous and organic feed solutions on the apparent permeabili ties of fatty acids ethyl esters were investigated in extraction and s tripping stages, respectively. It was concluded that the permeation ra te was controlled by the diffusion across the membrane and the laminar boundary layer in the inner and outer sides of the hollow fiber.