Process optimization of biodiesel production from waste beef tallow using ethanol as co-solvent

Abstract

This present study deals with production of biodiesel from waste beef tallow using co-solvent based transesterification. Waste tallow was dry rendered from discarded fleshing and processing wastes; whose maximum fat content was estimated to be 48.35 ± 0.87%, collectively. Following this, biodiesel was produced from rendered tallow using methanol as primary solvent; and ethanol as co-solvent in presence of potassium hydroxide as base catalyst. Ideal range for reaction parameters were decided based on reaction parameters optimized for methanol based and ethanol based transesterification separately. Accordingly, the optimal reaction conditions for methanol-ethanol based transesterification are as follows: (1) oil to alcohol molar ratio: 1:6; (2) methanol to ethanol molar ratio: 3/3; (3) catalyst concentration: 0.55% KOH; (4) reaction temperature: 70 °C; (5) reaction time: 35 min and produced a maximum yield of 97.2 ± 1.08%. Apart from production optimization, the resultant biodiesel/tallow methyl ethyl ester (TMEE) was evaluated for its thermal & physicochemical properties as per ASTM D6751 standards. Interestingly, the fuel properties of TMEE were found to be superior than compared to tallow methyl esters and was accounted by presence of ethyl esters in them.