Study on the Quantitative Fatty Acids Correlation of Fried Vegetable Oil for Biodiesel with Heating Value

Quantitative analysis of palmitic acid (C16:0), oleic acid (C18:1) and linoleic acid (C18:2) in the fried vegetable oil cooked for 0, 15, 45 min and cooked oil sample was determined by Gas Chromatography–Flame Ionization Detector (GC-FID). As the results, the concentrations of C16:0, C18:1 and C18:2 showed in a range of 28-39, 40-54 and 4-13% v/v, respectively. After that, each of all samples was transesterified with methanol at the ratio of 3:1 and 0.40% KOH as a catalyst at 60 °C for 8 hrs and cooled down to room temperature for 16 hrs to afford biodiesel. The percentage yields of the cooked oil for 0, 15, 45 min and the cooked oil samples were found to be 91.08, 89.28, 87.32 and 80.19% wt/wt, respectively. Heating value of the biodiesel, which was prepared from the cooked oil, was determined using bomb calorimeter to be in the range of 38,993–39,480 kJ.kg-1, whereas from diesel displayed at value of 45,979 kJ.kg-1.