| Biodiesel, as a renewable and alternative biofuel, has been researched by many researchers from feedstocks and producing technicals as well as other aspects. However, the degree of commercial production is lower. Its main reason is the producing cost is too high. About 75% percent cost comes from feedstocks, therefore there is important significance to have cheap forestry resources as materials to produce biodiesel. Chinese prickly ashseed and shuidonggua oil are cheap and available forest product, and researches of Chinese prickly ashseed biodiesel and shuidonggua biodiesel were seldom reported. In this study, Chinese prickly ashseed oil and shuidonggua oil had high content free fatty acid were used to produce biodiesels by two-steps. Methanol and conc. H2SO4 esterification were adopted to reduce the acid values of Chinese prickly ashseed oil, and Na2CO3 refining were adopted to reduce the acid values of shuidonggua oil. The lower acid value Chinese prickly ashseed and shuidonggua oils were used to produce biodiesels by transesterification with methanol under KOH as catalyst. The optimal conditions of two-steps to produce biodiesel were studied, and the components and contents of the fatty acid methyl esters in the biodiesel were analyzed with GC, and the fuel propertied of Chinese prickly ashseed biodiesel were determined. The results of this study were stated as follows.Under conc.H2SO4 as catalyst, the optimal condition of high acid value Chinese prickly ashseed oil and methanol esterification was: 18:1 molar ratio of alcohol to oil, 2% w/w catalyst of conc. H2SO4 to Chinese prickly ashseed oil, 60℃reaction temperature, 1.5 h reaction time and 600 rpm stirring speed. In this study, the high acid value (about 63 mgKOH·g-1) of Chinese prickly ashseed oil were reduce to less than 2 mgKOH·g-1 in relatively shorter time through one step method.For shuidonggua oil, the refining effect of Na2CO3 was better than that of NaOH. Under the condition of the weight amount of Na2CO310.5% w/w(to shuidonggua oil),17% w/w(water solution) concentration, 75℃reaction temperature, 100 rpm stirring speed and 80℃watering temperature the yield of alkali-refinning shuidonggua oil got the highest over 80%, and the acid value reduced to less than 1 mgKOH·g-1.The optimal reaction condition of producing of biodiesel by transesterification with the lower acid value esterified Chinese prickly ashseed oil and alkali-refined shuidonggua oil was researched respectively. The optimal technicals condition of Chinese prickly ashseed oil transesterifiction to biodiesel was: 6:1 molar ratio of alcohol to oil, 60℃reaction temperature , 0.9 % w/w catalyst of KOH to Chinese prickly ashseed oil, 90 min reaction time and 600 rpm stirring speed , under this condition the contents of fatty acid methyl esters in biodiesel production was 97 %. And the optimal technicals condition of shuidonggua oil transesterifiction to biodiesel was: 5.5:1 molar ratio of alcohol to oil, 40℃reaction temperature, 1.5 % w/w catalyst of KOH to shuidonggua oil, 30 min reaction time and 600 rpm stirring speed, under this condition the contents of fatty acid methyl esters in biodiesel production was over 98 %.Components and contents of fatty acid methyl esters in the biodiesels of Chinese prickly ashseed and shuidonggua oil were determined by GC inner standard method, respectively. The main fatty acid methyl esters in Chinese prickly ashseed biodiesel were Palmitic acid methyl ester , oleic acid methyl ester, linoleic acid methyl ester , linolenic acid methyl ester and Palmitoleic acid methyl ester , among which the contents of oleic acid methyl ester was 35.9 % and linoleic acid methyl ester was 24.8 %. And the main fatty acid methyl esters in shuidonggua biodiesel were Palmitic acid methyl ester , oleic acid methyl ester, linoleic acid methyl ester and Palmitoleic acid methyl ester , among which the contents of linoleic acid methyl ester was over 70 %.Through determination, the fuel properties of Chinese prickly ashseed biodiesel was close to 0# diesel fuel standard.
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