Biodiesel production from mixed non-edible oils, castor seed oil and waste fish oil

Abstract

Biodiesel production from non-edible oils is one of the effective approach to reduce cost of production, and solve part of the obstacles facing the availability of the traditional raw materials. The present investigation explores biodiesel production from mixed non-edible oils, castor seed oil (CSO) and waste fish oil (WFO). Different blends of WFO and CSO (10:90–50:50% WFO:CSO w/w) were implemented and evaluated in order to select the optimal blend that possesses properties closer to those of conventional raw oils that were used for biodiesel production. The equivalent blend (50:50% WFO:CSO w/w) was found to be the optimal blend; thus, it was transesterified with methanol to produce fatty acid methyl ester. Effect of the operating and processing variables, such as the type and the concentration of the catalyst, methanol to oil molar ratio, reaction temperature, reaction time, and the rate of stirring were thoroughly investigated. The results revealed that the optimal conditions for synthesis of biodiesel were 0.50wt% KOH, 8:1 methanol to oil molar ratio, 32°C reaction temperature, 30min of reaction, and 600rpm rate of stirring. Under these conditions, biodiesel with a yield of 95.20±2.5% w/w was obtained. 1HNMR spectroscopy was used to assure the conversion of the oils blend to biodiesel. Based on 1HNMR spectroscopy results, conversion of mixed CSO and WFO into biodiesel was 97.74%. The fuel properties of the resulting biodiesel were within the acceptable limits prescribed by ASTM D 6751. Furthermore, biodiesel from the said blend, have low viscosity and density comparing to those of CSO biodiesel. In conclusion, the proposed oils blend may be a profitable feedstock source, and easy way to improve biodiesel properties that synthesized from CSO.