Analysis of parameters and interaction between parameters of the microwave-assisted continuous transesterification process of Jatropha oil using response surface methodology

Optimization of Biodiesel Production Parameters from Cucurbita maxima Waste Oil Using Microwave Assisted via Box-Behnken Design Approach

The production of biodiesel from vegetables or fruits waste oils has high potential as renewable energy. The Cucurbita maxima wastes are massive source of oils, which are believed to indicate the possible sources of renewable energy whose biodiesel can be produced. Hence, the study explores the potential of the Cucurbita maxima wastes, for the production of biodiesel. In this study, the Soxhlet extraction method was used to extract Cucurbita maxima waste oil using an organic solvent. Through Box-Behnken design (BBD), the effects of methanol to oil molar ratio (6–10), catalyst concentration (2–6%), and reaction time (45–75 min) on the transesterification efficiency of methyl esters were investigated. The oil contents of Cucurbita maxima waste was found to be $44.6\pm 0.21$ %. This oil was characterized, and after obtaining the pure characterized oil, biodiesel was produced using microwave assisted by the transesterification process. The optimum conversion efficiency of the Cucurbita maxima waste oil to fatty acid methyl ether was 97.76%, at the optimal parameters, methanol to oil ratio (8.4 : 1), catalyst concentration (3.14%), and reaction time (57.12 min). The results revealed that all parameters have a significant effect on the yield of biodiesel ( $p<0.0001$ ). The physicochemical properties reveal that the Cucurbita maxima waste oil could be applied as a potential source of material for methyl ester production. The fatty acid profile of the oil indicated that it was mainly composed of unsaturated fatty acid, which ensures good flow properties of the fuel. The results of these studies showed the prospective of Cucurbita maxima wastes as a new potential feedstock for biodiesel production.

Biodiesel synthesized from waste cooking oil in a continuous microwave assisted reactor reduced PM and NOx emissions

A synergistic effect of the activated limestone-based catalyst (LBC) and microwave irradiation on the transesterification of waste cooking oil (WCO) was screened using a two-level factorial design and response surface methodology. The catalyst was prepared using a wet-impregnation method and was characterised for its surface element, surface morphology, surface area and porosity. The reaction was performed in a purpose-built continuous microwave assisted reactor (CMAR), while the conversion and yield of biodiesel were measured using a gas chromatography. The results showed that the catalyst loading, methanol to oil molar ratio and the reaction time significantly affect the WCO conversion. The optimum conversion of oil to biodiesel up to 96.65% was achieved at catalyst loading of 5.47 wt%, methanol to oil molar ratio of 12.21:1 and the reaction time of 55.26 min. The application of CMAR in this work reduced the transesterification time by about 77% compared to the reaction time needed for a conventional reactor. The biodiesel produced in this work met the specification of American Society for Testing and Materials (ASTM D6751). Engine test results shows the biodiesel has a lower NOx and particulate matters emissions compared to petrodiesel.

Preparation of solid acid catalysts from waste biomass and their application for microwave-assisted biodiesel production from waste palm oil

Waste utilization is essential and challenging. Utilization of wastes gives environmental, economic, and social benefits. In this study, inexpensive, sulfonated solid acid catalysts were successfully prepared from palm empty fruit bunch (PEFB), coconut meal residue (CMR), and coconut coir husk (CH) waste by a simple protocol. It was found that prepared PEFB-BCS-SO₃H, CMR-BCS-SO₃H, and CH-BCS-SO₃H catalysts have 4.79, 3.75, and 2.80 mmol g^-1 acid density and 739.0, 89.77, and 61.49 m² g^-1 surface areas, respectively. Further, the presence of active functional groups on the surface of the catalysts was confirmed by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Thermal stability of the catalysts was found below 150°C. Results show that biodiesel yield increases with increasing reaction time and methanol loading, when using microwave heating for biodiesel production from waste palm oil (WPO) and prepared catalysts. A maximum biodiesel yield of 95.5% was obtained by PEFB-BCS-SO₃H in 60 minutes using 20:1 methanol:oil (molar ratio) at 70°C. CMR-BCS-SO₃H and CH-BCS-SO₃H obtained 88.7 and 88.5% biodiesel yields in 60 minutes, using 20:1 and 16:1 methanol:oil (molar ratio), at 70 and 110°C, respectively. Even though, the activity of the catalysts decreased during reuse, these are still of interest as the waste biomass of PEFB, CMR, and CH can be used for catalyst preparation and microwave-assisted biodiesel production from WPO.

Successive optimisation of waste cooking oil transesterification in a continuous microwave assisted reactor

The successive optimisation techniques successfully reduce the reaction time by 25.5% and catalyst loading by 32% without significantly affecting the biodiesel conversion.