| This paper has mainly focused on the physicochemical properties,market situation as well as the application of oleic acid and its derivatives.Herein,we reviewed different kinds of extraction methods of oleic acid both at home and abroad.On the basis of a great deal of literature,we proposed a new method to extract oleic acid with high purity by combining solvent crystallization with column chromatography.By using crystallization to improve the purity of generated oleic acid,we studied the effects of the crystallization factors,such as solvent,ratio,temperature and reaction time,on the mass fraction and yield of the oleic acid.The results demonstrated that when the methanol was served as the solvent,solvent ratio was 5,the crystallization temperature was-10?,the crystallization time was 8 h,the separation reached the optimal condition.The mass fraction of oleic acid reached 61.39%and the yield was 75.64%.When applying column chromatography to purify oleic acid,the developing solvent of the thin-layer chromatography was screened primarily which could provide the basis for the selection of eluent.Different components of solvent was used as the developing solvent,and the best volume ratio of n-hexane-ethylacetate-acetic acid(85:15:8)was confirmed by the orthogonal experiment.The precision measurement further confirmed that our method was stable and reliable.In order to further improve the purity,the column chromatography experiment was made on the oleic acid extracted by the solvent crystallization.The effects of the factors,such as the silica gel mesh,silica gel loading height and the sampling amount,on the mass fraction and yield of the oleic acid were investigated.We also studied the recycling uses of chromatography column.The experimental results indicated that when the eluent(n-hexane-ethylacetate-acetic acid)volumn ratio was 85:15:8,the silica gel mesh was 200-300,the silica gel loading height was 40 cm and the sampling amount was 1.1 mL,the separation achieved the optimum state.For cycle 1 experiment,the mass fraction of oleic acid and corresponding yield reached 88.74%and 82.53%,respectively.For cycle 2 experiment,the mass fraction of oleic acid reached 96.91%and the yield was 88.36%.During the repetitive test,the relative standard deviation of mass fraction and yield of the oleic acid both were less than 3%,and the results showed that the chromatography column could be used for many times.The extraction distillation on the eluent waste was simulated by the Aspen Plus software.The effects of the factors,such as overhead distillate ratio,the theoretical plate number,raw material feed stage,extraction agent feed stage,reflux ratio,and solvent ratio,on the mass fraction and yield of the constituent were investigated.And the operating conditions were simulated by orthogonal optimization experiment.The best operating conditions were as follows:in the extractive distillation column,the overhead distillate ratio was 0.72,the theoretical plate number was 29,the raw material feed stage was 19,the extraction agent feed stage was 5,the reflux ratio was 0.2,and the solvent ratio was 1.8;in the solvent recovery column,the theoretical plate number was 19,the raw material feed stage was 10,the reflux ratio was 2,and the overhead distillate ratio was 0.27;in the distillation column,the theoretical plate number was 20,the raw material feed stage was 10,the reflux ratio was 3,and the overhead distillate ratio was 0.17.Under the optimized conditions,the mass fraction and yield of n-hexane reached 99.99%,and the mass fraction and yield of acetate reached 99.84%.The mass fraction and the yield of acetic acid reached 99.75%,90.68%,respectively.In this paper,we proposed a simple method for extracting oleic acid and solvent recovery,and the results might provide a basis for further research of oleic acid. |
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