Microwave-facilitated biodiesel production through rGO-based multifunctional metal oxide nanocatalysts to improve engine characteristics

Abstract

In this study, an improved bifunctional rGO/CaO/NiO (rCN) nanocomposite was designed and used to synthesize biodiesel (BD) from waste edible oil (WEO) via a microwave-aided method. Detailed structural characterisation of the catalyst indicated a large precise surface area and excellent surface characteristics. Response surface methodology (RSM) based 3⁴ factorial central composite design (CCD) was used to otimize the biodiesel production parameters. The optimal reaction conditions, which included a molar ratio of 11.1:1, microwave treatment for 7.5 min, a catalyst dosage of 3 wt%, and an agitation alacrity of 700 rpm, resulted in a significant BD yield of 97.46 %. The catalyst has shown outstanding stability and performed well by proving its reusability till seventh sets to produce high yield of BD. The kinetic analysis showed that the conversion of WEO to BD had 30.91 kJ/mol of reaction initiation energy and an exponential influence of 2.3 × 10⁴ min⁻¹ . It was discovered that the physical characteristics of the biodiesel obtained from WEO met ASTM D6751 requirements. Further, the model of the engine is DIESEL 3LD510 an make is Lombardini is used to test the performance and emissions of biodiesel blends (B0, B10, B20 and B30) in various loading. At maximum load, the B10, B20, and B30 blends showed a decrease in BSFC by 2.19 %, 5.43 % and 9.21 % respectively, while BTE improved by 1.91 %, 2.52 % and 4.1 % compared to the B0. Additionally, the inclusion of biodiesel in the B30 mixture led to a reduction in CO, HC, and NOₓ releases by 40.02 %, 36.11 %, and 5.68 %, respectively, relative to the base fuel B0. Overall, the rCN nanocatalyst stands out as an excellent option for the production of high yield of BD due to its shorter time of response and unparalleled reusability.