Search Results (281)

The transesterification process of vegetable oil applied in biodiesel synthesis is catalytic. Industrial production uses chemical catalysts that are difficult to separate from the product, regenerate, and reuse, which is why there is a search for new catalysts that are of natural origin or obtained from various types of waste. Calcium oxide is widely used as a heterogeneous catalyst, and can be obtained from calcium carbonate. The article reviews the possibilities of using eggshells as a catalyst for biodiesel synthesis: the optimal calcination conditions, the efficiency of the obtained catalyst, the optimal transesterification conditions, and the influence of various factors on biodiesel yield. It also discusses the possibilities and conditions for regenerating the catalyst and reusing it. Another food industry waste containing calcium compounds is animal bones, from which an effective biodiesel synthesis catalyst can be obtained. Before use, the bones are also crushed and calcined. The article presents the conditions for catalyst preparation and catalytic activity, and the possibilities for its enhancement by incorporating other elements, as well as the dependence of ester yields on transesterification conditions. The process of catalyst regeneration and reuse is discussed. Full article

Macauba is a versatile palm and has been explored in various sectors due to its ability to produce oils, proteins, energy, and biofuels. This paper presents the extraction, refining, and characterization of the macauba kernel oil, the synthesis of biodiesel, and an evaluation of the density and viscosity of its blends with mineral diesel, ranging from B15 to B20. Conversion was determined using the integral areas of the ¹H NMR spectrum for the FAME methyl ester (3.62, -CH₃) and FAME carbonyl (2.26, -COOCH₂). Predictions of the key inputs required for the extraction and degumming of the macauba kernel oil, as well as for the biodiesel production, are also presented. These results provide valuable insights into diesel-biodiesel blends exceeding 14% (vol.) of biodiesel, thereby contributing to the expansion of the biofuels industry. Full article

Biodiesel, as one of the alternatives to fossil fuels, faces significant challenges in large-scale industrial production due to its high production costs. In addition to raw material costs, catalyst costs are also a critical factor that cannot be overlooked. This review summarizes various methods for preparing biodiesel catalysts from solid waste. These methods not only enhance the utilization rate of waste but also reduce the production costs and environmental impact of biodiesel. Finally, the limitations of waste-based catalysts and future research directions are discussed. Research indicates that solid waste can serve as a catalyst carrier or active material for biodiesel production. Methods such as high-temperature calcination, impregnation, and coprecipitation facilitate structural modifications to the catalyst and the formation of active sites. The doping of metal ions not only alters the catalyst’s acid-base properties but also forms stable metal bonds with functional groups on the carrier, thereby maintaining catalyst stability. The application of microwave-assisted and ultrasound-assisted methods reduces reaction parameters, making biodiesel production more economical and sustainable. Overall, this study provides a scientific basis for the reuse of solid waste and ecological protection, emphasizes the development potential of waste-based catalysts in biodiesel production, and offers unique insights for innovation in this field, thereby accelerating the commercialization of biodiesel. Full article

The food industry consumes large amounts of water across various processes, and generates wastewater characterized by parameters like biochemical oxygen demand, chemical oxygen demand, pH, suspended solids, and nutrients. To meet environmental standards and enable reuse or valorization, treatment methods such as physicochemical, biological, and membrane-based processes are applied. This review focuses on the valorization of food industry wastewater in the biotechnological production of high-value products, with an emphasis on starch-rich wastewater, wineries and confectionery industry wastewater, and with a focus on new technologies for reduces environmental burden but also supports circular economy principles. Starch-rich wastewaters, particularly those generated by the potato processing industry, offer considerable potential for biotechnological valorization due to their high content of soluble starch, proteins, organic acids, minerals, and lipids. These effluents can be efficiently converted by various fungi (e.g., Aspergillus, Trichoderma) and yeasts (e.g., Rhodotorula, Candida) into value-added products such as lipids for biodiesel, organic acids, microbial proteins, carotenoids, and biofungicides. Similarly, winery wastewaters, characterized by elevated concentrations of sugars and polyphenols, have been successfully utilized as medium for microbial cultivation and product synthesis. Microorganisms belonging to the genera Aspergillus, Trichoderma, Chlorella, Klebsiella, and Xanthomonas have demonstrated the ability to transform these effluents into biofuels, microbial biomass, biopolymers, and proteins, contributing to sustainable bioprocess development. Additionally, wastewater from the confectionery industry, rich in sugars, proteins, and lipids, serves as a favorable fermentation medium for the production of xanthan gum, bioethanol, biopesticides, and bioplastics (e.g., PHA and PHB). Microorganisms of the genera Xanthomonas, Bacillus, Zymomonas, and Cupriavidus are commonly employed in these processes. Although there are still certain regulatory issues, research gaps, and the need for more detailed economic analysis and kinetics of such production, we can conclude that this type of biotechnological production on waste streams has great potential, contributing to environmental sustainability and advancing the principles of the circular economy. Full article

Biodiesel, a renewable and environmentally friendly alternative to fossil fuels, has attracted significant attention due to its potential to reduce greenhouse gas emissions. However, high production costs and complex processing remain challenges. Heterogeneous catalysts have shown promise in overcoming these barriers by offering benefits, such as easy separation, reusability, low-cost raw materials, and the ability to reduce reaction times and energy consumption. This review evaluates key classes of heterogeneous catalysts, such as metal oxides, ion exchange resins, and zeolites, and their performance in transesterification and esterification processes. It highlights the importance of catalyst preparation methods, textural properties, including surface area, pore volume, and pore size, activation techniques, and critical operational parameters, like the methanol-to-oil ratio, temperature, time, catalyst loading, and reusability. The analysis reveals that catalysts supported on high surface area materials often achieve higher biodiesel yields, while metal oxides derived from natural sources provide cost-effective and sustainable options. Challenges, such as catalyst deactivation, sensitivity to feedstock composition, and variability in performance, are discussed. Overall, the findings underscore the potential of heterogeneous catalysts to enhance biodiesel production efficiency, although further optimization and standardized evaluation protocols are necessary for their broader industrial application. Full article

Current biodiesel production is costly, in part due to the catalysts added during transesterification and later washed out. We have previously shown that intact rapeseed shells can be ball-milled with an alcohol to produce biodiesel without an added catalyst. Here, we report on the activation and identity of the complexing agent within the shells of rapeseeds and sunflower seeds. Lignin, present in the cell walls of plant matter, complexes with iron and manganese within metallic media, such as in a ball mill, and acts as a catalyst support in a transesterification reaction with oil and methanol. When ball-milled with methanol, rapeseed and sunflower seeds produce up to 90% biodiesel, similar to yields produced by industrial methods. However, this new method for producing biodiesel is a greener alternative, as it requires fewer organic solvents, may reduce the time and energy required for synthesis, and may reduce the effort required for product purification. Full article

Biodiesel synthesis, particularly through transesterification, is a mature technology in constant evolution and update. These innovative changes should be validated from different points of view: economic, social, and, especially, environmental perspectives. In this sense, life cycle assessment (LCA) is the perfect procedure to verify the sustainability of these advances. This brief review covered the present status and future prospects of life cycle assessment (LCA) applied to biodiesel production. For this purpose, the current energy scenario, along with the foundations of biodiesel production and LCA, has been explained, including current research about the specific application of LCA to biodiesel from various perspectives. As a result, LCA was proven to be a versatile tool that can be easily adapted to biodiesel production, which includes continuous innovative works that should be validated from an environmental perspective. However, the counterpart is the heterogeneity found in LCA studies in general, especially concerning functional units (from 1 MJ to 1 t of biodiesel, for instance) and boundary system selection, mainly due to the wide range of possibilities in biodiesel processing. This fact makes the comparison between works (and general recommendations) difficult, requiring additional research. Nevertheless, further studies will cover the existing gaps in LCA, contributing to completing the outlook on its application to biodiesel. Nevertheless, biodiesel production, compared to diesel, normally presents better environmental impacts in categories like global warming and ozone depletion potential. Full article

Oleochemicals, which are obtained from vegetable and animal fats and oils, have become indispensable in the food, cosmetics, pharmaceutical and biofuel industries. Traditionally, they are synthesized using chemical catalysts, a process that is often associated with high energy requirements and a considerable environmental impact. Biocatalysis, using enzymes such as lipases, has emerged as a transformative alternative that offers high specificity, environmental friendliness and cost-efficiency. This review comprehensively examines the current state of biocatalysis for oleochemical synthesis, highlighting key reactions such as esterification and transesterification and their integration into industrial processes. A bibliometric analysis uncovers global trends and collaborations, while case studies illustrate cost efficiency and scalability. The article outlines recommendations and future research directions to advance biocatalytic processes. This review is intended to be an important resource for researchers and industries transitioning to sustainable oleochemical production. Full article

This study investigates the synthesis of biodiesel from three vegetable oils with significantly different chemical compositions. Based on the properties of these biodiesel samples, a method was proposed to estimate the density of petrodiesel–biodiesel blends using an artificial neural network (ANN). The ANN employed in this research consisted of 10 neurons. The experimental data showed a high correlation, indicating effective training and precise estimations in relation to the provided training data. The accuracy of the estimations was evaluated by comparing the blending densities determined through the method presented in this study with the mean of three estimations generated by the neural network. The deviation between the determined and estimated values ranged from 4.1 to 25.2 kg/m³, which is attributable to the limited size of the training database. Most errors fell between −7.1% and 3.8%, with the lowest error being observed for petrodiesel–Brassica carinata biodiesel blends. Excellent correlations for both training and validation data were obtained (R = 0.99 and R = 0.98) for blends incorporating palm and Brassica carinata biodiesel. The estimation method using neural networks proposed in this paper can be effectively adapted for other mixtures and to estimate additional blending properties, accommodating each user’s needs. Full article

Agricultural waste poses significant environmental, economic, and social challenges globally, with estimates indicating that 10–50% of agricultural products are discarded annually as waste. This review explores strategies for managing agricultural waste to mitigate its adverse impacts and promote sustainable development. Agricultural residues, such as those from sugarcane, rice, and wheat, contribute to pollution when improperly disposed of through burning or burying, contaminating soil, water, and air. However, these residues also represent untapped resources for bioenergy production, composting, mulching, and the creation of value-added products like biochar, bioplastics, single-cell protein and biobased building blocks. The paper highlights various solutions, including integrating agricultural waste into livestock feed formulations to reduce competition for human food crops, producing biofuels like ethanol and biodiesel from lignocellulosic materials, and adopting circular economy practices to upcycle waste into high-value products. Technologies such as anaerobic digestion for biogas production and gasification for synthesis gas offer renewable energy alternatives and ample feedstocks for gas fermentation while addressing waste management issues. Composting and vermicomposting enhance soil fertility, while mulching improves moisture retention and reduces erosion. Moreover, the review emphasizes the importance of policy frameworks, public-private partnerships, and farmer education in promoting effective waste management practices. By implementing these strategies, agricultural waste can be transformed into a resource, contributing to food security, environmental conservation, and economic growth. Full article

Biodiesel is obtained by transesterification of triglycerides using catalysts. The possibilities of using a natural catalyst—dolomite in the synthesis of biodiesel are explored in this article. The conditions for preparing dolomite are presented, with considerable emphasis placed on the dependence of the structural changes and activity of dolomite on the calcination conditions. The optimal conditions for the transesterification of triglycerides with methanol are discussed, along with the possibilities for dolomite regeneration and reuse. It has been established that the calcination temperature of dolomite ranges from 800 to 900 °C, and using it can produce biodiesel that meets standard requirements, but this requires a large excess of alcohol in the transesterification reaction medium. The main issues related to the use of dolomite are linked to increasing catalytic activity and the possibilities of regenerating and reusing it. Researchers have recently focused on this by studying the possibilities of modifying dolomite using physical and chemical processes. The findings are contradictory and further studies are necessary, the possibilities for reuse have also been insufficiently explored. It is appropriate to analyze the economic indicators of dolomite preparation, modification, and regeneration in comparison with the preparation of other catalysts, so that the use of this catalyst aligns with the principles of sustainable synthesis. Full article

The transesterification process for biodiesel production is constrained by high thermal input, prolonged residence time, and intensive mechanical agitation. This study investigates process intensification via hydrodynamic cavitation using a custom-built Shockwave Power Reactor (SPR), enabling continuous biodiesel synthesis from soybean and used cooking oils. A statistically designed experimental matrix was applied to evaluate the reactor’s transient–stable thermal regime and the influence of operational parameters: rotor speed (1700–3415 rpm), volumetric flow rate (60–105 mL/min), methanol-to-oil molar ratio (6:1 to 12:1), and alkali catalyst type (NaOH or KOH). For benchmarking, conventional alkaline transesterification was optimized. The FAME yields from the SPR system exceeded 96.5% and complied with EN14103 standards. Specific energy analysis showed that cavitation-enhanced transesterification reduced energy consumption and peak temperature compared to traditional methods. The SPR’s capacity to induce high shear and localized turbulence under controlled cavitation offers a promising pathway for low-energy, scalable biodiesel production. Full article

This work reviews the use of biodiesel synthesis experiments in science education, emphasising their potential for explicit nature of science (NOS) teaching. Through a literature review and experimental insights, it highlights how transesterification of waste cooking oil (WCO) with a basic catalyst can serve as an educational tool. While biodiesel reaction conditions are well-documented, this study presents them in a pedagogical context. Simple viscosity and density measurements illustrate empirical analysis, while a design of experiments (DoE) approach using a Hadamard matrix introduces systematic optimisation and scientific reasoning. By integrating biodiesel synthesis with explicit NOS instruction, this work provides educators with a framework to foster critical thinking and a deeper understanding of scientific inquiry. Additionally, this approach aligns with green chemistry principles and resource efficiency, reinforcing the broader relevance of sustainable chemistry. Full article

With conventional fuels dwindling and emissions rising, there is a necessity to develop and assess innovative substitute fuel for compression ignition (CI) engines. This study investigates the potential of magnesium oxide (MgO) nanoparticles as a sustainable additive to enhance the performance and reduce emissions of used cooking oil (UCO) biodiesel–diesel blends in CI engines. MgO nanoparticles were biosynthesized using Citrus aurantium peel extract, offering an environmentally friendly production method. A single-cylinder CI engine was used to test the performance of diesel fuel (B0), a 20% biodiesel blend (B20), and B20 blends with 30 ppm (B20M30) and 60 ppm (B20M60) MgO nanoparticles. Engine performance parameters (brake thermal efficiency (BTE), brake-specific fuel consumption (BSFC), and exhaust gas temperature (EGT)) and emission characteristics (CO, NO_x, unburnt hydrocarbons (HCs), and smoke opacity) were measured. The B20M60 blend showed a 2.38% reduction in BSFC and a 3.38% increase in BTE compared to B20, with significant reductions in unburnt HC, CO, and smoke opacity. However, NO_x emissions increased by 6.57%. The green synthesis method enhances sustainability, offering a promising pathway for cleaner and more efficient CI engine operation using UCO biodiesel, demonstrating the effectiveness of MgO nanoparticles. Full article

The high demand for sustainable biodiesel feedstocks has led to the exploration of innovative strategies to enhance lipid productivity in microalgae. This study introduces a push–pull strategy to optimize lipid accumulation in Nannochloropsis oculata. The benzyl amino purine (BAP) and naphthalene acetic acid (NAA) stimulation, acting as the ‘push’ component, significantly boost growth and nutrient stress tolerance. Meanwhile, the ‘pull’ component, nitrogen (N) deficiency, triggers lipid biosynthesis. A Box–Behnken design was employed to optimize the factors named BAP fraction (0–1), total phytohormone (PH) BAP/NAA mix dose (0–20 ppm), and N-concentration (0–50%). The combined BAP/NAA treatment significantly increased biomass (15% higher than the control) and mitigated N-stress with higher doses (20 ppm). Lipid yield surged from 12.4% to 38.87% under optimized conditions (23.25% N, 39.5 ppm NAA, and BAP fraction 0). The push–pull strategy contributed to boosting lipid synthesis and balancing biomass production. N-limitation and total PH dosage were the determining factors in this strategy. This work demonstrates the potential of the push–pull strategy in increasing lipid accumulation, offering a promising and optimistic solution for biodiesel production at scale from microalgae. By reducing dependence on fossil fuels, N. oculata emerges as a reliable feedstock for oil extraction and biodiesel. Full article