| Summary: | 碩士 === 臺灣大學 === 生物產業機電工程學研究所 === 98 === Acid value indicates amounts of free fatty acid in wasted fried oil. When the acid value above 1 mg KOH/g, high level of free fatty acid causes soap formation, thus reducing ester yield of biodiesel in the transesterification process for biodiesel production.
In order to reduce the soap formation and increase the ester yield in biodiesel production process, to reduce the acid value of wasted fried oil is preferred. This procedure is termed pre-esterification process. The purpose of this study is to identify the optimal operating condition furing the pre-esterification process using wasted fried oil with three levels of acid value. The four factors and five levels central composite design (CCD) of the response surface methodology (RSM) was employed to evaluate the effects of methanol/oil molar ratio, catalyst amount, reaction temperature and reaction time on the efficiency of pre-esterification and the amount of reduction of the acid value of wasted fried oil.
The results show that the lowest acid value obtained were 0.52 ± 0.02, 0.73 ± 0.02 and 0.83 ± 0.02 mg KOH/g equivalent to 76%, 84% and 85% pre-esterification efficiency when original acid value of wasted fried oil were 2.21, 4.42 and 5.45 mg KOH/g respectively. The R-square of regression models were 0.70、0.63 and 0.61 respectively.
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