BIODIESEL PROCUCTION BY USED VEGETABLE OIL AND APPLICATION OF BY-PRODUCT BASED GLYCEROL TO PRODUCE BIOETHANOL AND POLYHYDROXYBUTYRATE

Abstract

This study aimed to produce biodiesel from used vegetable oil. Moreover, glycerol (the by-product) from biodiesel process was also utilized for bioethanol and polyhydroxyalkanoate production. The experiment was divided into 2 steps. First, the production of biodiesel from used vegetable oil and methanol by transesterification reaction using potassium hydroxide as catalyst. The condition for biodiesel production containing 6:1 oil to methanol ratio, 1% catalyst, 250 rpm at 60 ºC for 1 h. Under these condition, 90.92±0.06% of biodiesel with 96.5±0.01% methyl ester was obtained. In addition, the acid value, free fatty acid, saponification value, molecular weight (Potentiometric Titration), pour point and cloud point of biodiesel were 0.45±0.02 mg KOH/g oil, 0.21±0.02%, 153.3±0.15 352±0.15 g/mol, 18 ºC and 16 ºC, respectively. The characteristic of biodiesel was met the standard of Department of Energy Business (Thailand). Afterward, the glycerol by-product was isolated from biodiesel and utilized as carbon source for bioethanol and polyhydroxyalkanoate production using C. necator TISTR 1095 and S. cerevisiae under batch fermentation (150 rpm, 37 ºC). The result found that the NB supplemented with 10% glycerol yield highest bioethanol at 1.94% after 48 h cultivation. While, the highest polyhydroxyalkanoate (3.98 g/L) obtained from NB supplemented with 10% glycerol and 4% palm fiber after 84 h cultivation