Production of biodiesel using Colocynthis citrullus L. oil over green solid heterogeneous catalyst

Abstract

The production and characterization of biodiesel fuel obtained by means of transesterification over green solid heterogeneous catalyst with Colocynthis citrullus L. oil was investigated. The oil was extracted from the Colocynthis citrullus L. using normal hexane by means of soxhlet extractor. The oil obtained was characterized for specific gravity, viscosity, moisture content, free fatty acid (FFA), acid, iodine, peroxide and saponification values, respectively. The biodiesel was synthesized homogeneously using a three-necked round bottom flask at 333 K and the feedstock ratio of catalyst to methanol to oil is 3:10:10. The biodiesel produced was characterized for specific gravity, kinematic viscosity, flash point, American Petroleum Index (API), aniline point and diesel index, respectively. The oil obtained gave a yield of 53% and the values of the various physicochemical properties were specific gravity (0.91 g/cm³), viscosity (36.00 mm²/sec), FFA (1.70 mg KOH/g), acid (3.40 mg KOH/g), iodine (120.00 g/100g), peroxide (8.00 mmol O₂/g) and saponification (191.00 mg KOH/g), respectively. These values were within recommended limits of American Standard for Testing Material (ASTM D6751). The saponification value obtained showed that the oil contained a reasonable proportion of fatty acids. The result revealed that biodiesel produced showed the following properties in the value of viscosity (1.025 mm²/sec), specific gravity (0.83 g/cm³), API (40.00^oC), flash point (65^oC), aniline point (87^oC) and diesel index (66.40) respectively. The result showed that the properties of biodiesel produced were relatively close to the ASTM D6751. This study showed that green solid catalyst (kaolin clay) can be used in the production of quality biodiesel which is an alternative to fossil fuel.

Keywords: Biodiesel, kaolin clay, Colocynthis citrullus L. oil, characterization, heterogeneous catalyst