Investigation on Yield, Fuel Properties, Ageing and Low Temperature Flow of Fish Oil Esters

Sustainable energy derived from waste resources helps to mitigate the greenhouse gas emissions generated from fossil fuels. In this study, a solid heterogeneous catalyst was synthesized by using eggshell and copper oxide [CaCu(OCH3)2]. Using this catalyst, biodiesel fuels were produced from waste sardine fish oil using either methanol, ethanol, or iso-propanol. To reduce the fatty acid content, esterification of the fish oil was performed before the transesterification. Three biodiesel samples were produced, namely, fish oil methyl ester (FOME), fish oil ethyl ester (FOEE), and fish oil propyl ester (FOPE). Experimental analysis studies were carried out under various operating conditions such as alcohol-to-oil ratio (v/v), catalyst concentration, reaction time and reaction temperature. The results indicate that the optimal operating condition were a 16:1 alcohol: oil ratio, using 3% catalyst (w/w %), a 90 min reaction time; and reaction temperatures of 65°C, 80°C, 85°C for methanol, ethanol, and isopropanol, respectively. The quality of prepared biodiesel samples revealed that both FOEE and FOPE have better physio-chemical properties than FOME. Ethanol and iso-propanol increased the low-temperature flow properties such as cloud point and pour points. In addition, stability studies performed over 10 months revealed that FOME is less stable than to FOEE and FOPE. These results will aid in strategies aimed at improving the use of polyunsaturated fish oils for biodiesel production.