Homogeneous Catalysis of High Free Fatty Acid ...

The waste cooking oil (WCO) is a promising feed stock for the synthesis of biodiesel. In this study, the WCO used for biodiesel production has a very high acid value (>13 mg KOH/g) so a simple base transesterification process was not suitable, which resulted in soap formation. Here we reported a two step process for biodiesel production from WCO, acid catalyzed esterification followed by base catalyzed transesterification. In the first step, the acid value of WCO was reduced below 1 mg KOH/g by homogeneous acid catalysis and in the second step, acid catalyzed WCO was transformed to biodiesel in the presence of NaOH as homogeneous base catalyst. GC/MS analysis was done to determine the chemical composition of WCO biodiesel. Five FAMEs, methyl dodecanoate (C12:0), methyl tetradecanoate (C14:0), methyl hexadecanoate (C16:0), methyl octadecanoate (C18:0) and methyl 9-octadecenoate (C18:1) were identified. The synthesized FAMEs were confirmed by FTIR and NMR (1H and 13C). The 1H NMR was also used to determine the percentage conversion of triglyceride to methyl esters which was 97.89%. The prepared biodiesel was investigated for fuel properties using ASTM standards methods.