Transesterification of soybean oil by using the synergistic microwave-ultrasonic irradiation

Metabolomic analysis reveals the effect of ultrasonic-microwave pretreatment on flavonoids in tribute Citrus powder

In this study, the ultrasonic-microwave pretreatment was defined as a processing technology in the production of tribute citrus powder, and it could increase the flavonoid compounds in the processing fruit powder. A total of 183 upregulated metabolites and 280 downregulated metabolites were obtained by non-targeted metabolomics, and the differential metabolites was mainly involved in the pathways of flavonoid biosynthesis, flavone and flavonol biosynthesis. A total of 8 flavonoid differential metabolites were obtained including 5 upregulated metabolites (6"-O-acetylglycitin, scutellarin, isosakuranin, rutin, and robinin), and 3 downregulated metabolites (astragalin, luteolin, and (-)-catechin gallate) by flavonoids-targeted metabolomics. The 8 flavonoid differential metabolites participated in the flavonoid biosynthesis pathways, flavone and flavonol biosynthesis pathways, and isoflavonoid biosynthesis pathways. The results provide a reference for further understanding the relationship between food processing and food components, and also lay a basis for the development of food targeted-processing technologies.

A review on recent biodiesel intensification process through cavitation and microwave reactors: Yield, energy, and economic analysis

The use of biodiesel as a reliable and green energy source has grown over the past few years. Biodiesel is sustainable and biodegradable because it is only made from vegetable contents and waste cooking oil. Although biodiesel has many advantages over conventional fuels, there are still a lot of technological issues that need to be addressed during the production process. The yield of biodiesel produced using conventional methods is poor and the process is time-consuming. Process enhancements like cavitation and microwave have thus been developed to address this problem. Starting with a comparison to the conventional biodiesel process, this paper has reviewed the most recent developments in the increase of mixture and transfer of heat in these two reactors. This paper examined biodiesel improvement using microwave and cavitation reactors, including biodiesel yield, by meticulously reviewing and analyzing previous works. The production of biodiesel from various raw materials using a range of catalysts, energy requirements, as well as operating factors, activation energy, and constraints also have been discussed. Additionally, the economic analysis discusses the feasibility and cost-effectiveness of implementing these technologies on a commercial scale. Overall, this review provides valuable insights into the intensification of biodiesel production using cavitation and microwave reactors while considering both the technical and economic aspects.

Progress on Conventional and Advanced Techniques of In Situ Transesterification of Microalgae Lipids for Biodiesel Production

Global warming and the depletion of fossil fuels have spurred many efforts in the quest for finding renewable, alternative sources of fuels, such as biodiesel. Due to its auxiliary functions in areas such as carbon dioxide sequestration and wastewater treatment, the potential of microalgae as a feedstock for biodiesel production has attracted a lot of attention from researchers all over the world. Major improvements have been made from the upstream to the downstream aspects related to microalgae processing. One of the main concerns is the high cost associated with the production of biodiesel from microalgae, which includes drying of the biomass and the subsequent lipid extraction. These two processes can be circumvented by applying direct or in situ transesterification of the wet microalgae biomass, hence substantially reducing the cost. In situ transesterification is considered as a significant improvement to commercially produce biodiesel from microalgae. This review covers the methods used to extract lipids from microalgae and various in situ transesterification methods, focusing on recent developments related to the process. Nevertheless, more studies need to be conducted to further enhance the discussed in situ transesterification methods before implementing them on a commercial scale.

A Comprehensive Review of the Properties, Performance, Combustion, and Emissions of the Diesel Engine Fueled with Different Generations of Biodiesel

Due to the increasing air pollution from diesel engines and the shortage of conventional fossil fuels, many experimental and numerical types of research have been carried out and published in the literature over the past few decades to find a new, sustainable, and alternative fuels. Biodiesel is an appropriate alternate solution for diesel engines because it is renewable, non-toxic, and eco-friendly. According to the European Academies Science Advisory Council, biodiesel evolution is broadly classified into four generations. This paper provides a comprehensive review of the production, properties, combustion, performance, and emission characteristics of diesel engines using different generations of biodiesel as an alternative fuel to replace fossil-based diesel and summarizes the primary feedstocks and properties of different generations of biodiesel compared with diesel. The general impression is that the use of different generations of biodiesel decreased 30% CO, 50% HC, and 70% smoke emissions compared with diesel. Engine performance is slightly decreased by an average of 3.13%, 89.56%, and 11.98% for higher density, viscosity, and cetane, respectively, while having a 7.96% lower heating value compared with diesel. A certain ratio of biodiesel as fuel instead of fossil diesel combined with advanced after-treatment technology is the main trend of future diesel engine development.

Towards sustainable biodiesel production by solar intensification of waste cooking oil and engine parameter assessment studies

Renewable energy sources for harnessing biofuels are the viable solution to substitute fossil fuels and reduce production cost. In this study, waste cooking oil was converted into biodiesel via a customized solar reactor. The solar reactor was customized using copper tubes and black surface to trap solar energy for conversion of waste cooking oil into biodiesel. The main experimental parameters studied are temperature (30 to 50 °C), stirring speed (100 to 500 rpm), catalyst loading (0.25 to 1.25 wt%), flow rate (3 to 15 LPH), and methanol to oil ratio (3:1 to 15:1), respectively. The uppermost conversion of 82% was achieved at catalyst load of 0.75 wt%, stirring speed of 300 rpm, flow rate of 3 LPH and methanol/oil ratio of 12:1. Performance of biodiesel blend (D80 + BD20) in CI engine showed a decrease in ignition delay (10.5 deg. CA) and brake thermal efficiency (32.7%) at maximum load (100%). Smoke emission was also decreased with an increase in biodiesel blend at lower brake power, but an increase in brake power increased the smoke emission.

Prospects and Challenges of Microwave-Combined Technology for Biodiesel and Biolubricant Production through a Transesterification: A Review

Biodiesels and biolubricants are synthetic esters produced mainly via a transesterification of other esters from bio-based resources, such as plant-based oils or animal fats. Microwave heating has been used to enhance transesterification reaction by converting an electrical energy into a radiation, becoming part of the internal energy acquired by reactant molecules. This method leads to major energy savings and reduces the reaction time by at least 60% compared to a conventional heating via conduction and convection. However, the application of microwave heating technology alone still suffers from non-homogeneous electromagnetic field distribution, thermally unstable rising temperatures, and insufficient depth of microwave penetration, which reduces the mass transfer efficiency. The strategy of integrating multiple technologies for biodiesel and biolubricant production has gained a great deal of interest in applied chemistry. This review presents an advanced transesterification process that combines microwave heating with other technologies, namely an acoustic cavitation, a vacuum, ionic solvent, and a supercritical/subcritical approach to solve the limitations of the stand-alone microwave-assisted transesterification. The combined technologies allow for the improvement in the overall product yield and energy efficiency. This review provides insights into the broader prospects of microwave heating in the production of bio-based products.

Dispersive Liquid-Liquid Microextraction Combined with Microwave Demulsification for Determination of FAME Residuals in Biodiesel Wastewater

Biodiesel consists of various fatty acid methyl esters (FAMEs) that are mainly produced through transesterification of plant oil or animal fat. It is essential for biodiesel to be purified utmostly to meet its product standard before being traded, while the universal purification method has been water washing. However, water washing inevitably causes the residual of FAMEs in wastewater, which represents a loss of industrial profits. For the purpose of determination and monitoring of the FAME profile in wastewater, there is a necessity to develop a fast and reliable approach with small volume of sample in need. Hence, in this study, a combination of dispersive liquid-liquid microextraction (DLLME) and microwave demulsification is applied for the enrichment of residual FAMEs in water, followed by qualitative and quantitative analyses using gas chromatography-mass spectrometry. The results indicate that the optimal extractant in DLLME approach is toluene. And the optimal parameters are 20 mL of water sample, 80 μL of toluene as the extractant, 60 s of ultrasonic irradiation duration, 200 W of microwave power and 2 min of microwave irradiation duration. The standard curves and linear equations obtained with these conditions are used for the quantitative analysis of biodiesel wastewater, which reveals that there was 50.35 mg·L-1 of the total FAME residuals in wastewater. To the best of our knowledge, it is for the first time that the combined technique of DLLME and microwave demulsification is applied in determination of residual FAMEs in water samples. The proposed method corresponds to small volumes of sample and extractant and short analytical period. It also has the potential to be extended to the analysis of other water pollutants.

In-situ reactive extraction of castor seeds for biodiesel production using the coordinated ultrasound - microwave irradiation: Process optimization and kinetic modeling

The present study demonstrates innovative and industrially viable in-situ biodiesel production process using coordinated ultrasound-microwave reactor. Reactive extraction process has been carried out by mixing grinded castor seeds with methanol in the presence of base catalyst (KOH). Response surface methodology coupled with central composite design has been applied for process optimization to achieve maximum yield. The result shows that maximum biodiesel yield of 93.5 ± 0.76% was obtained under favorable conditions of: molar ratio (350:1), catalyst (w/w) (1.74%), reaction temperature (43 °C) and reaction time (30 min). Regression equation obtained for the model having (R²), and (R²_adj) equal to 0.9737 and 0.9507 respectively shows goodness of fit. First time reaction kinetics as well as oil extraction kinetics studies have been performed on coordinated ultrasound-microwave reactor. Assuming pseudo first order reaction activation energy was found to be 28.27 kJ·mol^-1 and activation energy for oil extraction was observed to be 9.11 kJ mol^-1. Estimated activation energy for the reaction kinetics and extraction kinetics was reduced by 27%, reaction rate constants were eight to ten times higher and diffusion coefficient was found to be two times higher in case of hybrid system as compared to conventional mechanical stirring technique. Estimated thermo-physical properties of biodiesel were found in agreement with ASTM and DIN standards in comparison to gasoline diesel.