STUDIES ON PRODUCTION AND UTILISATION OF BIODIESEL FROM MIXED OILS

Abstract

To meet the rising demand for liquid fossil fuels while minimizing environmental impacts, biodiesel serves as a viable alternative. Biodiesel is eco-friendly, biodegradable, non-toxic, and carbon-neutral. However, challenges arise from the limited availability and subpar quality of feedstocks, such as oils and fats used in its production. Use of mixed oils as a biodiesel feedstock is a solution that combines different oils before biodiesel production, improves fuel qualities and reduces reliance on a single oil while avoiding additives. The fatty acid composition of oil affects biodiesel quality, with variations among different oils. Manipulating the fatty acid profile through oil blending improves properties like density, viscosity, calorific value, flash point, oxidation stability, and cetane number. This cost-effective approach enables custom-designed biodiesel production with desired characteristics. This thesis focuses on the enhancement of biodiesel fuel quality through the use of an optimal oil mixture. Four oils, namely Karanja, Jatropha, Palm, and Waste cooking oil (WCO), were selected and blended in various combinations for their binary mixture (Karnaja-Palm, Karanja-WCO, Jatropha-Palm and Jatropha-WCO). A simplex lattice mixture design model was developed to analyze the biodiesel properties, including kinematic viscosity, density, cetane number, and oxidation stability. The optimization process identified the optimal ratio for the Karanja:Palm oil mixture as 51.6:48.4% v/v. The biodiesel from this optimal mixture exhibited KV of 3.854 mm2/s, density of 860 kg/m3, CN of 56.189, and OS of 9.565 hours. Notably, the OS of the biodiesel from the optimal mixture showed a 21.47% improvement, while CN increased by 4.2% compared to Karanja biodiesel. Jatropha biodiesel did not meet the biodiesel quality standards (EN 14214/IS 15607). However, when mixed with Palm oil at an optimal ratio of 34.8:65.2% v/v (Jatropha:Palm), the biodiesel from this optimal mixture posed a KV of 3.822 mm2/s, density of 869.95 kg/m3, CN of 55.69, and OS of 8.16 hours. Thus, the Jatropha and Palm oils mixture improved the biodiesel's OS by 46.9% and CN by 11.28%, satisfying the biodiesel standards. Unfortunately, no suitable optimum ratio for mixture of Waste cooking oil with Jatropha or Karanja was found to produce biodiesel that meets the biodiesel standards. In the laboratory, biodiesel was synthesized using Karanja oil, Jatropha oil, Palm oil, and an optimal mixed oil (Karanja:Palm, 51.6:48.4(%v/v) and Jatropha:Palm, 34.8:65.2(%v/v)). The purpose was to investigate the impact of oil mixing on the fuel properties of biodiesel. The transesterification method, commonly used by researchers, was employed to produce biodiesel from Karanja oil, Jatropha oil, and Palm oil. However, the production process for optimal mixed oil biodiesel was optimized by adjusting the reaction time, reaction temperature, catalyst quantity, and oil-to-alcohol ratio to achieve the highest possible biodiesel yield. To optimize the biodiesel production process, a Response Surface Methodology (RSM) based on Box-Behnken experimental design was employed with Design-Expert 13.0.1.0 software. The optimized operating parameters for the Karanja-Palm oil mixture were determined as follows: methanol-to-oil ratio of 10.8:1, reaction time of 105 minutes, reaction temperature of 64 °C, and catalyst concentration of 0.5 w/v%. These parameters resulted in a biodiesel yield of 97.84%. For the Jatropha-Palm oil mixture, the optimized parameters were a methanol-to-oil ratio of 9.7:1, reaction time of 130.5 minutes, reaction temperature of 61.5 °C, and catalyst concentration of 0.53 w/v%, yielding a biodiesel with a maximum yield of 95.84%. The RSM model exhibited high accuracy, as indicated by the analysis of variance (ANOVA) with a p-value <0.05 and an R2 value of 99.99%. The physicochemical properties of the optimized mixed oil biodiesel met the standards specified by ASTM D6751, EN14214, and IS 15607.