r Ghanei - Chemical Engineering Department, Engineering Faculty, IAU-Farahan branch, Farahan, Iran
a Heydarinasab - Chemical Engineering Department, Engineering Faculty, IAU-Farahan branch, Farahan, Iran
g.r Moradi - Chemical Engineering Department, Engineering Faculty, IAU-Farahan branch, Farahan, Iran

In recent decade, since the fossil fuel sources are diminished, many researchers have proposed to use a pure, non-toxic and biodegradable fuel which is called biodiesel, instead of traditional diesel fuel. Waste Frying Oil (WFO) as valueless material which disposed to environment can be used aspromising feedstock to produce biodiesel in Iran. In this study double step biodiesel production from waste frying oil were performed and the product was evaluated as diesel fuel. First, esterification and transesterification of WFO were carried out at 65°C, MeOH to oil molar ratio of6:1, 2 wt% of HCl as catalyst under vigorous mixing for 6 h. Yield of the reaction was 29.4%methyl ester and free fatty acid content of 0.918%.In second step, transesterification of acidprocessed WFO was done at 65°C , MeOH to oil molar ratio of 6:1, 1 wt% of KOH as catalyst under vigorous mixing for 2 h. Yield of the reaction was 93.1% methyl ester. Final produced biodiesel was very clear and had good characteristics as diesel fuel

Biodiesel, Waste frying oil, acid pretreatment, transesterification, esterification