Microwave-assisted Transesterification Research Articles

Kinetics and thermodynamics in microwave-assisted transesterification of palm oil utilizing sulphonated bio-graphene catalysts for biodiesel production

Enhanced reaction performance is what has piqued interest in using graphene-based catalysts in producing biodiesel. However, in-depth analyses were lacking from a kinetic and thermodynamic standpoint. This means that a well-designed experiment is necessary to determine the effect that the graphene catalysts have on the reaction rates and yields. This work addresses the kinetic and thermodynamic aspects of heterogeneously catalyzed transesterification using sulphonated biomass-derived graphene catalysts, i.e., bGO-SO3H and brGO-SO3H. It was accomplished using the pseudo-first order mechanism and the Eyring-Polanyi equation, with all data fitting satisfactorily in both models at the ideal reaction temperature of 353.15 K, resulting in R2 values of 0.9784 (bGO-SO3H) and 0.9884 (brGO-SO3H). The calculated activation energy (Ea) was determined to be 44.45 and 51.73 kJ mol-1 for bGO- and brGO-SO3H, respectively. Additionally, the Gibbs free energy (ΔG) values were determined at −38.09 and −31.81 kJ mol−1 for bGO- and brGO-SO3H, respectively. Meanwhile, the values for ΔH and ΔS were obtained as 41.69 kJ mol−1 and 225.93 J mol−1 K−1, respectively, and 48.96 kJ mol−1 and 228.72 J mol−1 K−1, respectively. These collective outcomes collectively signify the endothermic nature of the reaction and their spontaneity, particularly under elevated temperature conditions.

Utilizing Waste Cooking Oil for Sustainable Biodiesel Production: A Comprehensive Review

The environmental and economic challenges posed by the over-reliance on fossil fuels have driven the search for alternative and sustainable energy sources. Waste cooking oil (WCO) presents a viable feedstock for biodiesel production, offering a dual solution to waste management and renewable energy generation. This comprehensive review examines the current state of biodiesel production from waste cooking oil, exploring the benefits, challenges, and processes involved. Biodiesel derived from WCO has several environmental advantages, including lower greenhouse gas emissions, biodegradability, and enhanced engine lubricity compared to traditional fossil fuels. Moreover, utilizing it for biodiesel addresses waste disposal issues, reducing the contamination of land and water resources. Despite these benefits, several challenges remain, such as the variability in its composition, contamination, and the need for efficient purification and transesterification processes. The review explores various methods for converting WCO into biodiesel, highlighting the key stages of the transesterification process, including the use of catalysts, alcohols, and reaction conditions. Additionally, advanced techniques such as ultrasound-assisted and microwave-assisted transesterification are discussed for their potential to increase efficiency and reduce processing time. This paper also addresses the sustainability aspects of biodiesel production from it, emphasizing its role in promoting a circular economy and reducing waste. The use of its contributes to a closed-loop system, where waste is transformed into a valuable resource. Furthermore, the review explores the economic and social impacts of biodiesel production, noting its potential to create jobs, reduce import dependence, and support local communities. In conclusion, this review underscores the significant potential of waste cooking oil in sustainable biodiesel production. It calls for continued research and technological innovation to optimize processes, enhance efficiency, and overcome existing challenges, thereby contributing to a cleaner and more sustainable energy landscape.

Extraction, purification and in vitro assessment of the antioxidant and anti-inflammatory activity of policosanols from non-psychoactive Cannabis sativa L.

Policosanols (PCs) are bioactive compounds extracted from different natural waxes. In this work, the purification, characterization and assessment of the antioxidant and anti-inflammatory activity was carried out on PCs from an innovative source, i.e. a waxy material from supercritical-fluid extraction (SFE) of non-psychoactive Cannabis sativa L. (hemp) inflorescences. Starting from this material, PCs were obtained by microwave-assisted trans-esterification and hydrolysis, followed by preparative liquid chromatography under normal phase conditions. The purified product was characterized using high-performance liquid chromatography (HPLC) with an evaporative light scattering detector (ELSD). In vitro cell-free and cell-based antioxidant and anti-inflammatory assays were then performed to assess their bioactivity.HPLC-ELSED analysis of the purified mixture from hemp wax revealed C26OH and C28OH as the main compounds. In vitro assays indicated an inhibition of intracellular reactive oxygen species (ROS) production, a reduction of nuclear factor kappa B (NF-κB) activation and of the activity of the neutrophil elastase. Immunoblotting assays allowed us to hypothesize the mechanism of action of the compounds of interest, given the higher levels of MAPK-activated protein kinase 2 (MK2) and heme oxygenase-1 (HO-1) protein expression in the PC pretreated HaCaT cells. In conclusion, even if more research is needed to unveil other molecular mechanisms involved in hemp PC activity, the results of this work suggest that these compounds may have potential for use in oxinflammation processes.

Microwave-assisted transesterification of sour cherry kernel oil for biodiesel production: comparison with ultrasonic bath-, ultrasonic probe-, and ohmic-assisted transesterification methods

In this study, sour cherry kernel oil was converted to biodiesel by microwave-assisted transesterification. Evaluations were made of several variables, namely, reaction time (1, 2, 3, 4, and 5 min), microwave power (100, 200, 300, 400, and 500 W), methanol/oil mole ratio (3, 6, 9, 12, and 15), and catalyst (KOH) concentration (0.3%, 0.6%, 0.9%, 1.2%, and 1.5%). The efficiency of fatty acid methyl esters increased in response to lengthier reaction times, greater microwave power, higher methanol/oil mole ratio, and higher catalyst concentrations up to the optimal level. The optimal reaction conditions for microwave-assisted transesterification were 300 W microwave power, 1.2% catalyst concentration, a methanol/oil mole ratio of 1:2, and a reaction time of 4 min. Microwave-assisted transesterification was more effective than ohmic-, magnetic stirrer-, ultrasonic probe-, and ultrasonic bath-assisted transesterification methods. In conclusion, microwave-assisted transesterification can be suggested as a fast, efficient, and economical method compared to other transesterification methods.

A Study of Green Synthesis of Nano-TiO2 Catalyst by Gossypium Leaf Extract and Its Nanocatalysis in the Synthesis of Biofuel from Gossypium Seed Oil

Synthesis of TiO2 nanoparticles by aqueous leaf extract of Gossypium (Gossypiumarboretum) leaves on meta titanic acid [TiO(OH)2]. Rutile tetragonal TiO2 nanoparticles were characterized by XRD, SEM and TEM studies and their particle size was calculated, which was below 100 nm. The Obtained TiO2NPs were used as catalysts in the transesterification of Gossypium seed oil, which enhanced the rate of reaction. Thus, it is a very attractive catalyst for biodiesel production from Gossypium seed oil. The effect of the amount of nano-TiO2 catalyst and microwave heating was studied. In this study, the preparation of both catalyst and biodiesel from the parts of the same Gossypium plant and the feasibility of carrying out the microwave-assisted transesterification (green process) of Gossypium seed oil by using biogenic nanoTiO2 catalyst was explored. They improve the efficiency of transesterification. The used catalyst can be recycled by simple filtration and reused without reduction in its activity. It is a green method (affords nontoxic and noncorrosive medium), clean reaction, simple experimental, isolation procedures, gives high yield and the properties of synthesized biodiesel are in good agreement with that of diesel oil. So, it may be used alone or by blending with diesel.

Utilization of Dairy Waste Scum Oil for Microwave-Assisted Biodiesel Production over KOH-Waste Eggshell based Calcium Oxide Catalyst

The sustainability can be maintained by utilizing the available waste as feedstock and catalysts such as dairy and eggshell waste respectively for biodiesel production. In this study, the calcium oxide (CaO) synthesized from calcined eggshell was doped with potassium hydroxide (KOH-ECaO) via wet impregnation method and analyzed the catalyst performance on biodiesel production from dairy waste scum oil (DWSO) via microwave-assisted transesterification. The catalyst was characterized by X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy equipped with Energy Dispersive X-ray (SEM-EDX), Brunauer-Emmett-Teller (BET) and Thermogravimetric analysis (TGA). The fatty acid methyl ester (FAME) contents were deduced by Gas Chromatography-Mass Spectrometry (GC-MS). The KOH-ECaO catalyst shows good potential based on the characterization analysis such as high pore size (25.5 nm) which is supported by SEM pattern analysis. The highest biodiesel production (75%) was obtained at optimum reaction parameters conditions. The optimized conditions were discovered to be 3 wt.% of catalyst, 16:1 of methanol to oil molar ratio, reaction temperature of 65°C and 15 minutes of reaction time as microwave provided faster reaction for the transesterification. These innovative results showed that KOH-ECaO could enhance the biodiesel production from DWSO which encourage the usage of waste for wealth product.

Fatty acid methyl ester production from rainbow trout waste oil using microwave-assisted transesterification

The desirable oil content of Rainbow Trout waste makes it a valuable resource for the industrial-scale production of biodiesel. Limited research has been conducted regarding the utilization of microwave-assisted transesterification (MAT) as a cost-effective method for biodiesel production from this accessible resource. In this study, MAT was optimized in terms of reaction time (1–5 min), microwave power level (100–500 W), methanol/oil molar ratio (3−15), and catalyst concentration (0.3–1.5%). The optimal condition was reaction time of 4 min, microwave power 300 W, molar ratio of 12, and catalyst concentration of 1.2%, ensuring utmost efficiency and purity. In addition, MAT was compared to ohmic-, ultrasonic probe-, ultrasonic bath-, and magnetic stirrer-assisted transesterification techniques, assessing physicochemical properties, energy consumption, and thermal properties of produced methyl esters. The microwave, ohmic, and ultrasonic probe showed superior efficiency, briefest reaction time, and minimal pouring and cloudy values, respectively. Additionally, these techniques consumed only 5.3, 5.7, and 6.7 Wh/g, respectively, signifying the lowest energy usage. Conversely, magnetic stirrer and ultrasonic bath showed less desirable performance. Overall, MAT can be suggested as a novel and effective technique for enhancing efficiency, reducing reaction time, and decreasing energy consumption in the production of marine waste oil methyl esters.

Microwave-assisted transesterification of Litchi chinensis seed oil using extracted KOH from potato waste for sustainable development

The fast depletion of conventional fuel supplies has forced the world to find suitable substitutes to overcome the expected energy crisis. Fossil fuels also contribute to global warming because of their harmful emissions. Biofuels are sustainable and environment friendly. Biodiesel can be sourced from both edible and non-edible oils to replace fossil fuels. To avoid a shortage of food supply, it is preferred to produce biodiesel from non-edible oils. In this research, Litchi chinensis seed oil (LSO) is used as a feedstock to synthesize biodiesel employing transesterification using a microwave oven. The catalyst, potassium hydroxide (KOH), used in this research was extracted from potato waste. Sun-dried potato waste was converted into ash. The produced ash is then dissolved in distilled water, leading to a 34% yield of KOH. The transesterification achieves a 92.9% conversion rate under the conditions: 30% microwave power utilization, a catalyst loading of 15% (W/W), a stirring speed of 700 RPM, and a methanol concentration of 70% (V/V) with an 8-min reaction time. Response surface methodology (RSM), in comparison with artificial neural networks (ANNs), has been utilized for the optimization of biodiesel yield, giving efficient results with errors of 0.003% for RSM and 0.005% for ANN. Consequently, the study reports optimized biodiesel yields of 92.9% (experimental), 93.27% (RSM), and 92.40% (ANN). Physicochemical properties such as kinematic viscosity (4.4 mm2/s) at 40°C, density (875 kg/m3) at 15°C, cetane number (53.2), calorific value (38.8 MJ/kg), flash point (175°C), oxidative stability (6.1 h), and cold flow properties were determined with respect to the ASTM and EN standards. The findings reveal that biofuels primarily support Sustainable Development Goals (SDGs) 7 and 13, with the prime focus on “affordable and clean energy” and “climate action,” respectively.

Comparative life cycle cost analysis of bio-valorized magnetite nanocatalyst for biodiesel production: Modeling, optimization, kinetics and thermodynamic study

An active, high surface area, recyclable, magnetic, basic, iron oxide-based nanocatalyst was developed from banana leaves waste and used for microwave-assisted transesterification of soybean oil to biodiesel. According to the Hammett indicator, the catalyst has a high total basicity of 15 < H < 18.4. After optimization through the response surface methodology, the reaction allows 96.5 % biodiesel yield in the presence of 24:1 methanol to soybean oil molar ratio, 6 wt% BLW@Fe3O4, 0.5 h at 65 °C. The magnetic nature of the catalyst improves reusability for up to 6 cycles. Thermodynamic analyses showed that transesterification of soybean oil to biodiesel is an endothermic reaction. Moreover, the catalyst has the potential to reduce biodiesel production costs by utilizing abundant biomass waste materials. The calculated cost for 1 kg of catalyst is $1.14, while the biodiesel's cost per kg produced in this work is merely $1.05, showing high commercial viability.

Maximizing biodiesel yield of a non-edible chinaberry seed oil via microwave assisted transesterification process using response surface methodology and artificial neural network techniques

In this study, the non-edible Chinaberry Seed Oil (CBO) is converted into biodiesel using microwave assisted transesterification. The objective of this effort is to maximize the biodiesel yield by optimizing the operating parameters, such as catalyst concentration, methanol-oil ratio, reaction speed, and reaction time. The designed setup provides a controlled and effective approach for turning CBO into biodiesel, resulting in encouraging yields and reduced reaction times. The experimental findings reveal the optimal parameters for the highest biodiesel yield (95 %) are a catalyst concentration of 1.5 w/w, a methanol-oil ratio of 6:1 v/v, a reaction speed of 400 RPM, and a reaction period of 3 min. The interaction of the several operating parameters on biodiesel yield has been investigated using two methodologies: Response Surface Methodology (RSM) and Artificial Neural Network (ANN). RSM provides better modeling of parameter interaction, while ANN exhibits lower comparative error when predicting biodiesel yield based on the reaction parameters. The percentage improvement in prediction of biodiesel yield by ANN is found to be 12 % as compared to RSM. This study emphasizes the merits of both the approaches for biodiesel yield optimization. Furthermore, the scaling up this microwave-assisted transesterification system for industrial biodiesel production has been proposes with focus on its economic viability and environmental effects.

Advancing biodiesel production from Pyrus glabra seed oil: Kinetic study and RSM optimization via microwave-assisted transesterification with biocompatible hydroxyapatite catalyst

In this study, a biocompatible hydroxyapatite (HAp) catalyst was synthesized using the chemical precipitation method to create biodiesel (FAME). The HAp was characterized for its structure (FT-IR and XRD), particle size, morphology (SEM and TEM), and surface area (BET). The obtained results indicated that HAp had a spherical shape ranging in size from 28.36 to 51.40 nm, a specific surface area of 21.90 m2/g, and a pore diameter of 15.36 nm. The aforementioned catalyst was employed in the transesterification of Pyrus glabra seed oil, with the assistance of microwaves, and the optimization of the biodiesel production process was achieved using RSM-CCD. The impact of the reaction parameters, including catalyst weight (0.5–1.5 wt%), temperature (60–80 °C), and time (10–30 min), was analyzed. The highest biodiesel yield of 89.21% was achieved in 30 min using a 0.5 wt% catalyst at 80 °C. Microwave-produced FAME was evaluated with FT-IR and GC-MS analysis. GC-MS results revealed 78.02% unsaturated and 13.16% saturated FAME content. The FTIR spectrum validated the presence of methyl and ester groups in the produced biodiesel. Both the FTIR and GC-MS results illustrated that the produced biodiesel had good quality. Transesterification of Pyrus glabra seed Oil followed first-order kinetics with an activation energy of 23.20 kJ/mol and an Arrhenius constant of 2.43 × 104 min−1. The catalyst remained active over six recycling cycles without notable decline. The optimal properties of Pyrus glabra biodiesel, meeting ASTM standards, highlight its potential as a catalyst for large-scale production, aligning with the Sustainable Development Goals (SDGs).

Microwave-assisted Sustainable Production of Biodiesel: A Comprehensive Review

Abstract: Limited crude petroleum and growing awareness of fossil fuel depletion have enabled the development of alternative fuels and new energy sources. Biodiesel, also known as fatty acid methyl esters (FAME), has received a lot of attention due to its biodegradability, renewability, cost effective and nontoxicity. The purity of biodiesel production and uniform heating are the major hurdles for large scale biodiesel production. Recent microwave energy-based heating method has proved the potential for cleaner chemical production, short time duration, uniform heating, and purity over conventional heating method. The goal of this review is to discuss the biodiesel production using microwave-assisted heating. The different feedstocks used for biodiesel production, effects of mi-crowave irradiation, factors affecting the rate of microwave-assisted transesterification to produce biodiesel were comprehensively discussed. Microwave irradiation has been compared to other tech-nologies aiming to enhance the efficiency of overall process. The primary knowledge gaps in bio-diesel production can be identified based on this research, ensuring the biodiesel industry's long-term sustainability.

Integrated global optimization and process modelling for biodiesel production from non-edible silk-cotton seed oil by microwave-assisted transesterification with heterogeneous calcium oxide catalyst

Second generation feedstock like non-edible seed oil, used cooking oil, and animal fats for biodiesel production has huge potential, yet these feedstocks have been underutilised. In this current study, non-edible Ceiba pentandra seed oil (CPSO) was used to produce biodiesel. Ceiba pentandra seed yielded an oil content of 18.6% after extraction. CPSO had 6.87% free fatty acid, 0.911 specific gravity, 98.9 g I2/100 g oil iodine value, 1.47 refractive index, 189.14 mg KOH/g oil saponification, 13.67% acid value, and 3.29 meq O2/kg oil peroxide value. CPSO was characterized using Fourier transform infrared spectroscopy (FT-IR) and gas chromatography-mass spectrometry (GC-MS) analysis. The free fatty acid value of CPSO was reduced to 0.83% using the esterification process at 60°C for 60 min with a 3:1 methanol to oil volumetric ratio, 5% sulfuric acid. The microwave-assisted transesterification process (MATP) was carried out by CPSO and methanol as reactants and calcium oxide (CaO) as a catalyst. CaO was characterised using FT-IR, scanning electron microscope, energy dispersive X-ray analysis, and Brunauer–Emmett–Teller analysis. To optimise the process variable of the MATP, response surface methodology was used, followed by an artificial neural network coupled with a genetic algorithm. At 270 W and 114 s reaction time, 0.3 wt.% CaO, and 18:1 alcohol to oil molar ratio, 97.4% biodiesel yield was obtained. FT-IR, GC-MS, 1H &13C Nuclear magnetic resonance, Heteronuclear single quantum coherence spectroscopy, and Heteronuclear multiple-bond correlation were used to characterise the biodiesel. In conclusion, CPSO has the potential to produce a large quantity of quality biodiesel by the application of the CaO catalyst.

Optimization and Comparison of Biodiesel Production Process by Electric Heating and Microwave-Assisted Heating Transesterification for Waste Cooking Oil via One-Way Experiments and ANOVA

Base-catalyzed transesterification of waste cooking oils (WCOs) into biodiesel is a widely used renewable fuel production technology. The traditional heating method for this process is electric heating (EH), while microwave-assisted heating (MW) has also received extensive attention in recent years. This study compares the two reaction processes in detail by one-way experiments and ANOVA. Catalyst content, reaction temperature (average temperature), and alcohol–oil molar ratio are key factors for these two transesterification processes. The maximum FAME yield of both EH and MW processes appeared at 1.0% catalyst concentration, with the reaction temperature around 60°C, while the MW process called for more methanol. It is speculated that the acid value of WCOs may be closely related to the time required for transesterification as well. The MW process can improve the transesterification efficiency, which is shown in kinetics as much larger than the reaction constant of the EH process and about one-tenth of the activation energy.

Enhanced production of biodiesel using nanomaterials: A detailed review on the mechanism and influencing factors

The deterioration of fossil fuel supplies, combined with growing environmental concerns about fossil fuel extraction and consumption, has prompted worldwide communities to focus on renewable energy. Biodiesel production from various biomass feedstock is identified as an environmentally friendly and sustainable alternative. The application of nanomaterials as catalysts in the synthesis of biodiesel has enhanced the yield due to the selectivity. This review article is focused on the applications of potential nanoparticles in biodiesel production and their mechanism of action. The effect of operating variables, namely nanomaterial type, concentration, temperature, methanol to oil ratio, and water content on biodiesel production have been summarized. Under microwave-assisted transesterification, both sodium hydroxide and strontium oxide catalysts, produced highest yield (99%). For calcium oxide nanocatalyst, the highest biodiesel conversion obtained was 98.2% through microwave-assisted transesterification method of waste cooking oil. The optimal conditions for such a high conversion yield were methanol to oil ratio, reaction temperature, time, and catalyst loading of, 1:8, 65 °C, 76 mins, and 4 wt% respectively. The maximum biodiesel conversion yield achieved using KOH nanocatalyst was 96.44% in a microwave-assisted transesterification of waste cotton-seed cooking oil, at optimum conditions of 9.6 min, 0.65 wt% catalyst loading, and 7:1 methanol: oil ratio, respectively. Future perspectives on nanocatalysis for biodiesel production are explained.

Phosphomolybdic acid/chitosan as acid solid catalyst using for biodiesel production from pomegranate seed oil via microwave heating system: RSM optimization and kinetic study

In this research, a green solid catalyst of phosphomolybdic acid (HPA) prated on Chitosan was synthesized to produce biodiesel. The prepared catalyst was characterized using Fourier Transform Infrared spectroscopy (FTIR), Field Emission Scanning Electron Microscope (FESEM), Energy Dispersive X-Ray (EDX), X-ray diffraction (XRD), and XRF analyses. The catalyst was applied in microwave-assisted trans-esterification of Pomegranate oil, and the biodiesel production process was optimized by response surface methodology based on central composite design (RSM-CCD). The effect of influential reaction parameters, including time (33–142 min), catalyst weight (0.15–5.6 wt%), and methanol to oil molar ratio (3.3:1–17:1), were investigated. The maximum biodiesel yield of 95% was obtained in a short time (74 min) using the catalyst weight of 1.25 wt% and methanol to oil molar ratio of 6:1 at the temperature of 65 °C. The catalyst was reused six times without any significant reduction in catalyst activity. The H NMR spectroscopy was employed to compare Pomegranate oil and biodiesel. The kinetic results of transesterification via microwave-assistant have good agreement with first-order kinetics as well as the activation energy and Arrhenius constant are 50 kJ/min and 16.47 × 107 min−1, respectively. As a result, Pomegranate biodiesel has high quality. The physicochemical properties of Pomegranate biodiesel under the optimal condition agreed with the ASTM standard. In conclusion, phosphomolybdic acid/Chitosan as a catalyst has a high potential for biodiesel production on a large scale.

Parametric study and optimization of microwave assisted biodiesel synthesis from Argemone Mexicana oil using response surface methodology

Biodiesel production from nonedible feedstock is a viable alternative to fulfill the energy need and to reduce the emission from constraint fuel. Argemone Mexicana is a weed that grows in the arid zone and contains a high amount of non-edible oil makes it an ideal feedstock for biodiesel synthesis. The motive of the present study is to explore the transesterification of Argemone Mexicana oil using a microwave heat source and a Parametric study, following by optimization of biodiesel yield using response surface methodology employing central composite design. The quadratic model with a high value of R2 99, R2adj 97.60 revealed good agreement with the actual AOME yield. The optimized operating parameters such as temperature, catalyst amount, time, and methanol to oil molar ratio were found to be 58.8 °C, 1.03 wt%, 3.56 min, and 9.54:01 respectively. The predicted yield of 99.28 wt% was in close agreement with an actual yield of 99.03%. The study reveals that catalyst amount, temperature, time, and methanol to oil molar ratio have a significant effect on microwave-assisted transesterification of Argemone oil. Argemone oil methyl esters (AOME) exhibit property close to ASTM standards and it has the potential as an alternative to diesel.

Improving biodiesel yield from pre-esterified inedible olive oil using microwave-assisted transesterification method

In the present research, biodiesel production from olive oils with different initial free fatty acid concentrations (2.5, 5.0, and 10.0%) was evaluated. A two-stage acid-catalyzed esterification and alkaline-catalyzed transesterification (ACT) process using the microwave heating method was compared with the traditional heating method. Free fatty acid was reduced to less than 2.0% in the first stage. Although no significant difference was observed between microwave and traditional esterification methods in terms of fatty acid reduction, the microwave treatment significantly decreased reaction time by 92.5%. Comparing microwave ACT results with those of the traditional heating method showed that the microwave can significantly increase methyl ester yield and purity, and simultaneously decrease reaction time. Physical constants of methyl esters were also improved using the microwave heating method. Therefore, the microwave heating method can be regarded as an efficient method instead of the two-stage method for biodiesel production. This method is capable of using inedible olive oil with high concentrations of free fatty acids.

Magnetic silica particles functionalized with guanidine derivatives for microwave-assisted transesterification of waste oil

This study aimed to develop a facile synthesis procedure for heterogeneous catalysts based on organic guanidine derivatives superbases chemically grafted on silica-coated Fe3O4 magnetic nanoparticles. Thus, the three organosilanes that were obtained by reacting the selected carbodiimides (N,N′-dicyclohexylcarbodiimide (DCC), N,N′-diisopropylcarbodiimide (DIC), respectively 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) with 3-aminopropyltriethoxysilane (APTES) were used in a one-pot synthesis stage for the generation of a catalytic active protective shell through the simultaneous hydrolysis/condensation reaction with tetraethyl orthosilicate (TEOS). The catalysts were characterized by FTIR, TGA, SEM, BET and XRD analysis confirming the successful covalent attachment of the organic derivatives in the silica shell. The second aim was to highlight the capacity of microwaves (MW) to intensify the transesterification process and to evaluate the activity, stability, and reusability characteristics of the catalysts. Thus, in MW-assisted transesterification reactions, all catalysts displayed FAME yields of over 80% even after 5 reactions/activation cycles. Additionally, the influence of FFA content on the catalytic activity was investigated. As a result, in the case of Fe3O4@SiO2-EDG, a higher tolerance towards the FFA content can be noticed with a FAME yield of over 90% (for a 5% (weight) vs oil catalyst content) and 5% weight FFA content.

Continuous Biodiesel Production from Waste Soybean Oil Using a Nano-Fe3O4 Microwave Catalysis

In this study, we conducted an efficient microwave-assisted transesterification process combining homogeneous and heterogeneous catalytic phases to produce biodiesel from waste soybean oil. A cylindrical quartz reactor packed with nanoparticles of Fe3O4 as a co-catalyst was applied to improve the reaction. The process was carried out with a methanol-to-oil molar ratio of 6:1, power of 560 W, and residence time of 30 s. The specifications of the biodiesel produced in this study were compared with two standards, i.e., ASTM D6751 and EN 14214. We found that the continuous conversion of waste soybean oil to methyl ester was approximately 95%. The biodiesel showed a higher flash point and a higher carbon residue content than that of both standards, and the viscosity (5.356 mm2/s) and density (898.1 kg/m3) were both at a high level. Compared to a conventional heating plate, the energy consumption was significantly reduced by nearly 93%. It is expected that these findings will provide useful information for green and sustainable processes for the regeneration and reuse of oil.