Abstract

Abrus precatorius seed oil is not edible and possesses lethal toxicological properties; hence, alternative use as low cost feedstock for biodiesel production was investigated. The n-hexane extracted oil was characterized for its chemical and physical properties, and subsequently transesterified using 1% sodium hydroxide at 60°C to produce biodiesel. The biodiesel produced had acceptable quality following characterization of its fuel properties. The relative density was found to be 0.889 with kinematic viscosity of 3.34 mm²/s within limits of Thailand biodiesel fuel standard. The acid value was 0.281 mg KOH/g, iodine value 52.43 mgI₂/g, peroxide value 3.45 mEq/kg, saponification value 227.8 mg KOH/g and 2.87% free fatty acid content. The flash point and the cetane number were 137°C and 58.3, respectively while the heat of combustion was 38.28 MJ/Kg. The low temperature operability properties of A. precatorius seed biodiesel determined by parameters such as cloud point, pour point and cold-filter plugging point were - 2, 1 and - 4°C, respectively. The sulfated ash value and refractive index were found to be 0.09% and 1.457, respectively. GC analysis of the fatty acid methyl esters profile revealed 50.86 and 49.1%, saturated and unsaturated fatty acid methyl esters (FAME), respectively. A percentage FAME yield of 86.1%; with higher content of methyl palmitoleate (31.94%) and a lowest value for methyldecanoate (1.27%) was obtained. Although a n-hexane oil yield was low (2.52% w/w), the results show that Abrus seed oil derived biodiesel has commercially acceptable fuel properties and may be suitable as fuel for internal combustion engine.

Key words: Biodiesel, Abrus precatorius, oil, non-edible oil, fatty acid methyl ester.