PREPARATION AND CHARACTERIZATION OF METHYL ESTER FROM HIGH FREE FATTY ACID OIL BY TWO STEP CHEMICAL PROCESS

摘要

The present work proposes preparation and characterization of methyl ester (ME) from Nile tilapia (Oreochromis niloticus) oil used as an ingredient in animal feeds via two-step chemical process (acid esterification followed by alkaline transesterification). Experimental results indicated that the optimum condition for esterification process was at reaction temperature of 50°C, methanol to oil molar ratio of 12:1, catalyst (sulfuric acid, H_2SO_4) amount of 2%, and reaction time of 120 minutes, resulting in the reduction of free factty acid (FFA) content from 6.6% to 0.30%. It was found from the transesterification process that an increase in reaction temperature tended to decrease viscosity of the ME obtained. Higher methanol to oil molar ratio, greater amount of catalyst (potassium hydroxide, KOH) and longer reaction time led to less yield and lower kinematic viscosity of the product.