Research On Purification Of Tocopherol By Ion Exchange Technology

This work studies the possibility of separating tocopherol from the molecular distillation products by ion exchange technology.Firstly, the batch adsorption of tocopherol by a strong base anion exchange resin was studied. The strong base gel resin was selected as the ion exchanger, and ethanol was selected as the solvent of ion exchange. The effects of contact time,the presence of fatty acids and temperature on the adsorption of tocopherol was studied. Experimental results indicated that the whole process needed about 7h to achieve equilibrium and was controlled by intraparticle diffusion. Fatty acid had higher affinity than tocopherol and its the presence significantly affectedthe adsorption of tocopherol. Adsorption of tocopherol by resins is an exothermicm process, and with the increase of temperature, tocopherol adsorption is significantly decreased. The adsorption isothermal is a broken line, suggesting the special phenomenon may be caused by the competitive adsorption of fatty acids. Under the experimental conditions, the maximum adsorption capacity of tocopherol is 506.1 mg/g dry resin.The adsorption of tocopherol in the fixed-bed was described by equilibrium theory, predicting the sequence of tocopherol effluents the occurence of overshoots. The results indicated that the sequence was related to the acidity of the components, and the penetration followed the order ofδ-tocopherol>β+γ- tocopherol>α- tocopherol, contrarying to the acidic order of these three components. The extent of overshoot from big to small isδ-tocopherol>β+γ- tocopherol>α- tocopherol.In this study, the purity of 85% tocopherol could be obtained by passing strong base ion exchange resin column, and the yield of tocopherol is about 90%, resin process load is about 100mg/ml. Moreover, if the pure solvent was used to desorb he pigments before the desorption, the color of the product will be improved significantly. On the basis of results in the present study if can be concluded that if the replacement chromatography is used,certain degree separation of tocopherol homolog could be obtained. Therefore, it is possible to separateδ- fromβ+γ- andα- tocopherol, and the purify of 90%β+γ-tocopherol as well as 80%δ-tocopherol could be obtain.