Preparation And Application Research Of Novel Tocopherol Molecularly Imprinted Materials

Tocopherol,as a common fat soluble vitamin,is listed as a daily routine nutrient by FAO and WHO.It is worth noting that tocopherol can not be synthesized in human body,so we need to find its source to meet the basic needs of human beings.As a by-product in the refining process of vegetable oil,the deodorized distillate of vegetable oil is rich in tocopherol,which is listed as one of the main raw materials for the separation and extraction of tocopherols.At present,the common separation methods of tocopherol from deodorized distillate of vegetable oil mainly include:molecular distillation,column chromatography,etc.But these methods have the problems of high energy consumption and low yield.Therefore,molecularly imprinted polymers of tocopherol were prepared by the combination of molecularly imprinted technology and ionic liquid.The feasibility of the separation method was verified by saponification pretreatment of camellia oil deodorization distillate and one-step adsorption desorption experiment of the imprinted materials.The main results are as follows:（1）Selection and preparation of functional monomersThe adsorption of tocopherols by methacryloyloxyethyl trimethyl ammonium chloride（DMC）and two conventional monomers,acrylamide and methacrylic acid,was studied by UV scanning and imprinting experiments.The results showed that the adsorption capacity of the imprinted polymer prepared with DMC as the functional monomer forα-tocopherol was as high as 81.7 mg/g,and its adsorption effect was much better than that of the other two functional monomers studied in the same period.At the same time,the preparation method of the functional monomer DMC was explored.Through one-step esterification of choline chloride and methacrylic acid,triethylamine was selected as the acid adsorber,acryloyl chloride as the polymerization inhibitor and toluene as the water carrying agent to synthesize DMC.After the optimization of the process,the optimum conditions were:30℃,the ratio of choline chloride to methacrylic acid 1:17,180 min,and the conversion of DMC was 60.4%by testing with UV scanning.The results of Fourier infrared spectroscopy（FT-IR）and polymer activity analysis showed that DMC synthesized by this one-step method has practical application value compared with DMC purchased from the market.（2）Preparation ofα-tocopherol molecularly imprinted polymer Based on the above experimental results,DMC was selected as functional monomer,α-tocopherol as template molecule,glycol dimethacrylate as cross-linking agent,azodiisobutyronitrile as initiator,Si O₂as substrate,ethanol as solvent bulk polymerization to prepareα-tocopherol molecularly imprinted material（MIP）and non imprinted material（NIP）.After the optimization of single factor experiment,the reaction conditions were obtained as follows:65℃,8 h.Meanwhile,the results of SEM characterization of the prepared molecularly imprinted materials showed that compared with NIP,the MIP forms larger pores,which explains why the adsorption effect of MIP is higher than that of NIP.Because of the coating on the surface of Si O₂,a large contact area was formed,which provided favorable conditions for the attachment of tocopherol to some extent.The results of FT-IR testing showed that the MIP was attractive to tocopherol.The results of kinetic and thermodynamic adsorption experiments on MIP inα-tocopherol solution showed that the optimal adsorption condition is 9 h and the solvent concentration is 1.5 mg/m L.The results of pseudo second-order kinetics and Langmuir equation analysis showed that the adsorption ofα-tocopherol by the material belongs to chemical adsorption,and the adsorption process is relatively uniform.（3）Application ofα-tocopherol molecularly imprinted polymerThe results of the adsorption experiments of MIP and four kinds of tocopherols showed that the imprinted material has a strong adsorption effect on four kinds of tocopherols,and there is no significant difference in the adsorption effect.The tocopherols in the deodorized distillate of camellia oil was separated and purified by the pre-treatment of saponification and one-step adsorption desorption of MIP,The results showed that the purity of tocopherols were increased to about 85%,and the recovery of tocopherols were up to 98.7%.The results of repeated using experiments showed that the adsorption capacity of the imprinting material is gradually reduced,and its best reuse times are 3 times.