Enhancing Jatropha oil biodiesel by using Citrus Limetta peels as a biocatalyst: A sustainable way to reduce emissions and enhance the efficiency of CI engine

Abstract

Biodiesel has become one of the promising alternative fuel resources for petro-diesel. Biodiesel is obtained by mixing oil and alcohol through transesterification reaction. A catalyst (base or acid) is typically added to accelerate the transesterification reaction and yield the maximum biodiesel production. The use of the traditional catalyst has problems like catalyst separation, soap formation, high reaction time, more energy consumption and environmental pollution. Literature shows that the addition of a catalyst from organic sources can overcome these problems. Biocatalysts were produced from different bio-waste like animal bones, plant leaves, fruit and vegetable peels, but there is no work found on the effects of Citrus Limetta peel waste for the biodiesel production. In this work, the feasibility of using Citrus Limetta peel ashes as an eco-friendly biocatalyst was investigated for the biodiesel production from Jatropha oil. The biocatalyst was obtained from Citrus Limetta peel waste after drying, pulverizing and calcination. XRD, SEM and EDX were used for the characterization of the biocatalyst. The biodiesel was tested for conformance with Euro standards. Then, three biodiesel blends (JT90, JT80 and JT70 with 10, 20 and 30 % biodiesel) were tested for determining the engine performance and emission characteristics in a Kirloskar 4-stroke CI diesel engine. SEM and EDX indicated a substantial concentration of potassium (26.8 %) and calcium (71.59 %) in the biocatalyst. The maximum biodiesel yield was achieved with 2 wt% biocatalyst, 15:1 Jatropha-to-methanol molar ratio, 60 °C reaction temperature and 1 h reaction time. Engine performance study showed that the JT80 blend demonstrated a BTE improvement of 1.2 % with a significant BSFC reduction of 11 % when subjected to full load conditions, surpassing that of pure diesel. Emissions study revealed that the JT80 blend demonstrated a substantial decrease in emissions compared to pure diesel. Specifically, there was a noteworthy 10.3 % reduction of carbon monoxide (CO), 14 % of carbon dioxide (CO2), 11 % of unburnt hydrocarbon (HC) and 3 % of nitrogen oxides (NOX), but with an increase of 2 % in smoke emissions.

Keywords

• Biocatalyst
• Transesterification process
• Jatropha oil
• Biodiesel
• Emission
• And performance