Synthesis of Fatty Acid Methyl Ester from Croton macrostachyus (Bisana) Kernel Oil: Parameter Optimization, Engine Performance, and Emission Characteristics for Croton macrostachyus Kernel Oil Fatty Acid Methyl Ester Blend with Mineral Diesel Fuel

Alternative Methods for Biodiesel Cetane Number Valuation: A Technical Note

Biodiesel is an environmentally beneficial and clean energy source that may replace fossil fuels, which are detrimental to the environment and cannot be replenished. Therefore, the physicochemical parameters of biodiesel must be determined in order to verify its quality. The cetane number is a crucial dimensionless fuel property that gauges the fuel ignition quality in power diesel engines. A higher cetane number results in a shorter ignition delay time, and vice versa. Biodiesel's cetane number may fluctuate due to a variety of fatty acid compositions, including variations in carbon chain length and the degree of unsaturation. The cetane number generally increases with increasing saturation and chain length, while it decreases as chain length is reduced and degrees of unsaturation and branching increase. This is the main reason for why alkanes possess a higher cetane number than alkenes and aromatics. The standard protocols for evaluating the cetane number of biodiesel are ASTM D613 and ISO 5165 test techniques using a monocylindrical cetane engine. However, adhering to these conventional procedures is quite challenging and time-consuming, and the cetane number test result may also be affected by the presence of certain gases and fumes. As a result, many researchers are bothered with cetane number valuation, and occasionally they skip it due to a lack of other options. Consequently, the aim of this paper is to present a set of more straightforward and relevant alternative techniques that can be applied to predict the cetane number of biodiesel when engine-based measurement is not practical. The three techniques with their designed pictographic outlooks conferred in this article include color indicator titration, aniline point, and fatty acid composition-based methods. The reported values of these procedures meet the minimum cut point of the biodiesel cetane number required by ASTM D6751 (≥47) and exhibit minimal variation from the typical standard methods. Nevertheless, the above-mentioned techniques are not applicable to other alternative biofuels except biodiesel products because they have a direct implication on the characteristics of the fatty acid profiles of different oil precursors, such as carbon chain length, degree of saturation or unsaturation, and aromaticity, which make up monoalkyl esters.

Reactive Extraction for Fatty Acid Methyl Ester Production from Castor Seeds Using a Heterogeneous Base Catalyst: Process Parameter Optimization and Characterization

Fatty acid methyl ester (FAME) from oil seeds is conventionally produced via a two/three-process-step method: extraction of oil and subsequent esterification/transesterification to fatty FAME (biodiesel). However, in the present study, we investigated the production of castor kernel oil (CKO) FAME by reactive extraction for extraction and transesterification in a single process using a heterogeneous catalyst. The content of oil that can be extracted was checked by investigating several nonreactive extraction parameters such as solvent type (polar, nonpolar, and mixture), the solvent to kernel ratio, and extraction time. Maximum oil was extracted using methanol as a solvent with a methanol-to-seed ratio of 6.25:1 for 6 h extraction time. The viscosity of CKO obtained by nonreactive extraction was reduced from 288.83 to 19.04 mm²/s by reactive extraction using a 4.09 wt % catalyst concentration (BaO) and a 330.9:1 methanol-to-oil molar ratio for 6 h reaction time at 64 °C. Reactive extraction for transesterification of CKO was performed using BaO, CaO, and ZnO heterogeneous catalysts. BaO results in the increased yield of CKO FAME compared to other catalysts. Central composite design (CCD) using the response surface methodology (RSM) was implemented to design the experimental matrix, process parameter optimization, maximize the yield of CKO FAME, and investigate interaction effects of parameters such as reactive extraction temperature (55-65 °C), catalyst concentration (3-5 wt %), and methanol-to-oil molar ratio (175:1-350:1) on the yield of CKO FAME. A second-order model equation with a p-value < 0.05 and an R ² value near 1.0 was obtained to predict the yield using the input parameters. The maximum yield CKO FAME of 96.13 wt % with 94.4% purity of produced CKO FAME was obtained at a catalyst concentration of 4.09 wt % and a methanol-to-oil molar ratio of 330.9:1 for 6 h with a reaction temperature of 64 °C. Therefore, a comparable conversion of castor seed oil triglyceride (96.13 wt %) was obtained in a single step directly from castor seeds. Furthermore, the rheological behavior investigation of castor kernel oil and castor methyl ester revealed that the dynamic viscosity of both samples was found to be dependent on triglyceride content and temperature.