Purification of docosahexaenoic acid ethyl ester using a silver-ion-immobilized porous hollow-fiber membrane module.
Docosahexaenoic acid ethyl ester (DHA-Et) was purified by adsorption on Ag-ion-immobilized membranes via selective interaction between silver ion and carbon-carbon double bonds of DHA-Et. Silver ions were immobilized onto sulfonic-acid-group-containing porous hollow-fiber membranes at an Ag ion density of 1.4 mol/kg of membrane, and 30 membranes were housed in one module (inner diameter = 18 mm and effective length = 80 mm). The adsorption isotherms of DHA-Et in various organic solvents revealed that DHA-Et was adsorbed on the immobilized Ag ions with a DHA-Et/Ag ion molar binding ratio of 1/5 in methanol, and that acetonitrile was the solvent of choice for the elution of the adsorbed DHA-Et. Permeation of bonito oil ethyl ester solution in methanol through the Ag-ion-immobilized hollow-fiber membrane module demonstrated that the displacement adsorption of other lower unsaturated fatty-acid ethyl esters by DHA-Et proceeded along the membrane thickness. The purity of DHA-Et was improved to 99 wt % by permeating first bonito oil ethyl ester containing 95 wt % DHA-Et and then acetonitrile through the module.
Ozawa
I
I
Department of Materials Technology, Faculty of Engineering, Chiba University, Inage, Japan.
Kim
M
M
Saito
K
K
Sugita
K
K
Baba
T
T
Moriyama
S
S
Sugo
T
T
D000327:Adsorption; D004281:Docosahexaenoic Acids / Q000302:isolation & purification*; D004867:Equipment Design; D005231:Fatty Acids, Unsaturated / Q000302:isolation & purification; D008567:Membranes, Artificial; D010539:Permeability; D012834:Silver / Q000737:chemistry*; D013451:Sulfonic Acids / Q000737:chemistry
D005231:Fatty Acids, Unsaturated; D008567:Membranes, Artificial; D013451:Sulfonic Acids; D004281:Docosahexaenoic Acids; D012834:Silver; C067518:4,7,10,13,16,19-docosahexaenoic acid ethyl ester