Physicochemical Properties of Purified Biodiesel Based on Oil Recovered from Catfish (Ictalurus punctatus) Viscera

Abstract

The effects of neutralization, transesterification, and adsorption on the physicochemical properties of fatty acid methyl esters (FAME) obtained from crude catfish oil (CO) were investigated. CO was recovered from catfish viscera and subjected to: neutralization (NCO) with 20 (g/100 g) NaOH solution, transesterification (BIO) with methyl alcohol (1:6 molar ratio, oil: alcohol) and 1 (g/100 g) (w/w) NaOH, and purification by adsorption (PBIO) with activated earth (10 g/100 g of BIO). CO, NCO, BIO, and PBIO were evaluated for FAME, free fatty acids (FFA), peroxide value (PV), cloud and flash points, free and total glycerin, rheological properties, and minerals. Catfish viscera had a lipid content of 28.5 g/100 g (wet basis), of which 20.9 g were recovered as CO (73.33% yield). Furthermore, 84.67 g of NCO, 77.53 g of BIO, and/or 60.22 g of PBIO were produced from 100 g of CO processed. NCO had significantly (P < 0.05) lower FFA, density, cloud point, flash point, and diacylglycerols content than CO. Meanwhile, PBIO had significantly (P < 0.05) lower PV and cloud points when compared to BIO. CO, NCO, BIO, and PBIO behaved as Newtonian fluids at 25 °C. BIO and PBIO adhere to the american society for testing and materials (ASTM) biodiesel standards for FAME, moisture, density, cloud point, free and total glycerin, Na, P, and S. This study demonstrated the feasibility of converting high‐viscosity CO into low‐viscosity PBIO with promising physicochemical attributes. PBIO has the potential to serve as a viable alternative biofuel.