Production of Rubberseed Biodiesel and Palm Biodiesel using Ultrasonic Instrument and Characteristics of Its Blending

Abstract

Biodiesel is one of known alternative fuel, obtained by oil processing, for example from rubberseed oil and palm oil. Conventionally, biodiesel obtained by reacted oil with methanol for 1 hour at temperature of 65 oC with mechanical stirring, using homogenous catalyst such as NaOH. Homogeneous catalysts dissolve fully in the glycerol layer and partially in the biodiesel layer during the triglyceride transesterification process. Heterogeneous (solid) catalysts, such as CaO, can prevent contamination, making product separation much easier. Moreover, the reaction time of conventional methods can be shortened by applying ultrasonic energy. This research consists of several stages, aimed to obtain biodiesel yield from transesterification using homogenous and heterogenous catalyst, to produce rubberseed biodiesel and palm biodiesel by applying ultrasonic energy, and then obtain the characteristics of palm biodiesel, rubberseed biodiesel, and mix of both. The result showed that the transesterification process using heterogenous catalyst need longer time and give the lower biodiesel yield than the transesterification using homogenous catalyst. Ultrasonic transesterification of palm oil gives a greater yield then the conventional stirring methods, which ultrasonic transesterification yield range between 96.52% to 98.03% and the acid number range from 0.50 mg KOH/g sample to 0.63 mg KOH/g sample. Ultrasonic esterification succeeded in reducing acid value of rubber seed oil in a shorter time, which is smaller than acid value by 30 minute conventional esterification. Ultrasonic transesterification only succeeded to form biodiesel from rubberseed oil that has gone through the 30 minutes ultrasonic esterification (78.84% yield) and through an 1 hour conventional esterification (91.55% yield). Rubberseed biodiesel, palm methyl ester, and a blended of both meets the SNI-04-7182-2006 on the characteristics of acid value, density, viscosity, and cloud point. The iodine number of rubberseed biodiesel was still above the standard, but blending palm methyl ester to rubberseed biodiesel can reduce the iodine number of blended biodiesel to meet the standards. Production cost analysis at biodiesel blended (25% palm methyl ester ini rubberseed biodiesel) resulted : ultrasonic methods still more expensive than conventional methods.