Study On The Process Of Producing Biodiesel With Chinese Prickly Ash Seed Oil

As the renewable substitute energy, biodiesel was becoming more of a concern. Currently, biodiesel industry in China was still at an initial stage, and was facing the difficult problem of material supplying. So it was significant to produce biodiesel with cheap forestry resources. Chinese prickly ash seeds were the co-product collected after planting zanthoxylum, which were rich sources and cheap and easy to get. To produce biodiesel with Chinese prickly ash seed oil had broad prospects. The process of producing biodiesel by alkali-catalyzed method with Chinese prickly ash seed oil was studied in this paper. The conclusions were showed as follows:1. At first, the extraction methods of prickly ash seed oil were researched and the results were showed as follows:Among the extraction rate of three different solvents, hexane was the highest, the second was petroleum ether and ether was the lowest. Economically, petroleum ether was the suitable solvent.Through single factor tests and orthogonal experiments, the optimum extraction process was achieved: the extraction solvent was petroleum ether, liquid to solid ration was 13:1, extraction time was 2h, temperature was 60℃and extracting for 2 times. Under this condition, the extraction rate was 91.52%.Through the comparision of different extration methods, the extration rate of ultrasonic extration was the highest, the second was solvent extration and cold soaking was the lowest. Taking the consideration of the cost of production, the solvent extration method was suitable for industrial production.2. Second, the paper studied the process of pretreatment of Chinese prickly ash seed oil.The process was degumming, deacidification by solvent extration and esterification. After deacidification by solvent extration, the acid value of oil decreased from 67.16 mgKOH/g to 33.57 mgKOH/g. Then through esterification, the acid value of oil decreased under 2 mgKOH·g^-1 .By the response surface analysis, the second-order polynomial equation of deacidification by esterification was as follows:Y=2.1928-1.6356X₁-1.0235X₂-0.3469X₃-0.2635X₄+0.6479X₁²+0.2954X₂² +0.0566X₃²+0.6279X₄²+0.2284X₁X₂+0.0572X₁X₃+0.8984X₁X₄ -0.0159X₂X₃-0.1572X₂X₄-0.1434X₃X₄The optimun esterification process was: H2SO4 concentration was 2.1%, methanol:oil(molar ratio) was 21:1, the time was 1.75h and the temperature was 58℃. Under this condition, the experimental acid value was 1.92 mgKOH·g^-1, while the predicted was 1.87 KOH·g-1 and the prediction error percentage was 2.67%.3. Further, the process of producing biodiesel by alkali-catalyzed method, on the base of single factor tests and the response surface analysis, the second-order polynomial equation of deacidification by esterification was as follows:Y=90.61+5.8829X₁+3.6487X₂+0.9513X₃-1.2609X₄-1.9939X₁²-0.5211X₂² +0.3314X₃²-1.6574X₄²-1.0119X₁X₂+0.0406X₁X₃-3.1419X₁X₄ 0.2881X₂X₃+0.4606X₂X₄+0.5656X₃X₄The optimun transterification process was: KOH concentration was 1.07%, methanol:oil(molar ratio) was 6.4:1, the time was 93min and the temperature was 59℃. Under this condition, the experimental content of FAME was 95.98% and the prediction error percentage was 0.83%.5. Through amplification tests, 1000g Chinese prickly ash seed oil could abtain 934.62g biodiesel.4. Through the preliminary study of subsequent treatments of biodiesel, the ideal subsequent treatment was first acid pickling and then washing by salt water. Under this process, the residual content of glycerol in biodiesel reached the criteria of biodiesel.