Biodiesel production through thermally induced transesterification from waste cooking oil using calcium phosphate catalyst

Heterogenous catalysts for transesterification from snail, crustacean and mollusc shells

RSM optimization of biodiesel production from Spirogyra as environmentally friendly and the fastest growing algae using phycosynthesized CuZnO green catalyst

A green and sustainable biodiesel production from Chlorella vulgaris microalgae using functionalized carbon nanotube heterogenous catalysts derived from rice husk and mixed fruit waste

Developing robust and efficient heterogeneous catalysts remains a key challenge in catalytic organic transformations. In this work, a lacunary polyoxometalate-based catalyst (LPOM) was synthesized and subsequently functionalized with 3-(aminopropyl)trimethoxysilane (APTMS) and then 1,3-propanesultone (1,3-PS) to achieve LPOM/APTMS/1,3-PS. Comprehensive characterization using various physicochemical techniques confirmed the successful modification of the lacunary POM framework with desired functional groups. The catalytic behavior of the prepared material was assessed through two representative transformations: the ring-opening of styrene oxide and the esterification of oleic acid with methanol toward biodiesel synthesis. The catalyst demonstrated remarkable efficiency, delivering 99% conversion of styrene oxide within 10 min and 98% oleic acid conversion within 2 h. Moreover, it maintained excellent structural integrity and catalytic efficiency over four consecutive cycles. These findings demonstrate the potential of LPOM/APTMS/1,3-PS as a stable, highly efficient, and environmentally benign catalyst for sustainable organic transformations and biofuel synthesis.

The need to find sustainable energy sources has taken the center stage in the light of the growing energy global requirements. The renewable energy sources have also taken much interest in biofuels, as they promise to add renewable and environmentally benign sources of energy. The feedstock used in biodiesel is usually a wide range of inexpensive feedstock. In the current research, a new synthesis method using a feedstock with a green microalga, namely, Nannochloropsis sp. is defined. According to the authors, bio-diesel blends based on this microalgal source would help in producing less toxic fuels, increase the functionality, and at the same time, minimize emissions. The present paper examines production of biodiesel using Nannochloropsis sp. a microalga with high calorific value thus qualifying as a feedstock. After one hour of ultrasonication at 500Hz frequency, the recovery of bio-oil was around 720mL. Afterwards, the resulting bio-oil was undergone to a single-pot transesterification with sodium hydroxide as the catalyst in methanol to extract the bio-oil with an extraction efficiency of 92%. Nuclear magnetic resonance spectroscopy, gas chromatography-mass spectrometry, and Fourier-transform infrared spectroscopy were used to determine physicochemical properties of the resultant biodiesel ensuring it was suitable as a fuel. The combustion stability of the resulting B20 + 7.5H2 blend was better than that of the diesel fuel, with peak in-cylinder pressure of 47bar and a net heat release rate of 20.51J/°CA compared to 46.5bar and 19.98J/°CA for diesel. The emission analysis showed that B20 resulted in a decrease in smoke (from 62 to 44.8%) and an increase in CO (from 0.012 to 0.3%) and hydrogen supplementation (2.5-7.5 L m-1) further improved combustion. Notably, B20 + 7.5H2 reduced CO₂ (from 9.3 to 8.5%), while NOx remained within 1763-1694ppm. These results demonstrate that hydrogen-enriched algae biodiesel blends can improve engine efficiency and reduce harmful emissions, providing a viable, cleaner alternative for diesel engines.

The microalga Chlorella vulgaris was cultured under the aerial-phase conditions with or without nitrogen to investigate the effects on lipid production. Under the three culture conditions (liquid conditions without nitrogen; aerial-phase conditions with and without nitrogen), oxygen production decreased during the culture period, indicating that photosynthetic activity was suppressed. The carbohydrate content was lower in the algal cells cultured under aerial-phase conditions than under non-aerial conditions, suggesting that carbohydrate biosynthesis was suppressed and that accumulated carbohydrates were used for lipid biosynthesis. The dry cell weight under aerial-phase conditions with or without a nitrogen source increased 2.9- and 2.4-fold over 14 days, respectively, while lipid content increased 5.1- and 5.9-fold. C. vulgaris underwent cell division and produced biomass and lipids under both nutrient-depleted and nitrogen-supplemented conditions. Aerial-phase cultivation with nitrogen could simultaneously achieve growth and lipid accumulation, supporting the potential for sustainable biodiesel production using C. vulgaris under the aerial-phase conditions.

UV-C irradiation was evaluated as a strategy to enhance the dual-use potential of green microalgae Desmodesmus quadricauda and Scenedesmus dimorphus for functional food and biodiesel applications. Cultures were exposed to UV-C for 0-3h and cultivated for 14 days. Biomass production increased significantly, reaching maxima at 3h in D. quadricauda (1.63 ± 0.10g L-1) and at 1h in S. dimorphus (1.27 ± 0.05g L-1). UV-C irradiation markedly enhanced carotenoid content and increased protein levels by 1.2-1.3-fold, suggesting improved nutritional value. Lipid content and productivity peaked at 1h in both species, with 1.4-1.9-fold increases relative to controls. Fatty acid composition was modified under UV-C treatment, including increased oleic acid levels and the detection of docosahexaenoic acid (DHA), supporting potential functional food applications. Biodiesel properties, calculated from fatty acid methyl ester profiles, showed cetane numbers exceeding EN 14,214 minimum requirements, however, the cold-flow properties (CP and CFPP) of both species failed to meet the standard specifications. Overall, UV-C irradiation modulated biomass accumulation and metabolite composition, enhancing lipid productivity and altering fatty acid profiles, although further optimization is required to fully meet biodiesel fuel standards.

An alternative strategy to mitigate the ecological and economic challenges posed by invasive fish species is to transform these organisms into valuable resources, generating economic benefits while simultaneously addressing ecosystem-related concerns. However, while the search for sustainable feedstocks continues, the specific potential of highly resilient invasive fish species for high-yield biodiesel production has not yet been evaluated. The aim of this study was to address this research gap by producing high-yield biodiesel using the invasive fish Carassius gibelio as an oil source. In this context, lipase immobilized MnFe2O4- polyhydroxymethyl methacrylate magnetic nanogels were prepared and the production system conditions (lipase amount, methanol/oil molar ratio, and temperature) were optimized. Optimal conditions were obtained using a 4000 U lipase amount, a 5:1 methanol/oil molar ratio and a temperature of 55°C. A 97.45% biodiesel yield was achieved with this system prepared under optimum conditions, and this prepared biocatalysis system was able to produce biodiesel with at least 50% yield 13 times. This study is the first to use the highly invasive C. gibelio as a sustainable raw material for biodiesel production. It introduces a novel biocatalytic approach by integrating invasive fish species utilization with a reusable MnFe2O4-pHEMA nanogel system, achieving both high efficiency and operational stability.

This work studied the production of biodiesel from waste cooking oil using an ultrasonic reactor and the testing of biodiesel fuel performance in a diesel engine on a light truck. The process for biodiesel production consisted of several steps, including waste cooking oil filtration, esterification, ultrasonic-assisted transesterification, biodiesel separation using the decantation process, washing, and drying. The main transesterification reaction was conducted using methanol with a molar ratio to the oil of 6:1 and a KOH catalyst of 1%. The reaction was accomplished at 60℃ in 30 minutes. Biodiesel produced was tested to reveal its main characteristics, i.e., flash point, density, viscosity, FAME content, and caloric values. Biodiesel was then mixed with commercial diesel fuel at various ratios (B40, B45, B50, B55, B60, and B65) and tested to evaluate their performance as fuel in a diesel engine on a light truck. A chassis dynamometer was used to measure vehicle torque and power in light trucks that resulted from biodiesel fuel, which was mixed with fossil diesel fuel at a range of ratios. The test revealed that the biodiesel fuels met the standards of fuel characteristics, and the performance in a diesel engine was comparable to that of a diesel engine powered by diesel oil.

A KCr/calcium oxide (CaO) bifunctional catalyst was synthesized from CaO from eggshells and impregnated with K2Cr2O7 (KCr). The catalysts were assessed in a transesterification reaction between waste cooking oil and ethanol (EtOH) for the biodiesel production. The properties of the KCr/CaO catalyst were investigated by using scanning electron microscopy, X-ray diffraction, ATR/FTIR, TGA, and FESEM-EDS. The results show that Cr2O7 2- can be reduced by trace elements (Mg, Si, and C) in CaO and converted to Cr2O3, which facilitates catalytic activity. The reactions were optimized using a Box-Behnken design and response surface methodology (RSM), and the results were analyzed by analysis of variance. According to the RSM, the consequences showed that an EtOH-to-WCO molar ratio of 12, KCr/CaO of 4.0% w/w, and 180 min produced an 89.32% biodiesel yield. Reaction catalysts and time were key factors influencing the biodiesel synthesis. The biodiesel under these conditions was found to be substantially consistent with the parameters given in ASTM D6751 and EN 14214.

High-yield microbial lipid synthesis through organic waste co-fermentation guided by reverse carbon and nitrogen regulation: Optical photothermal infrared and transcriptomic insights.

Enhanced lignin-to-lipid bioconversion via glucose-assisted co-metabolism in newly isolated bacteria.

The increasing global demand for sustainable and renewable energy has intensified interest in microbial lipases as efficient biocatalysts for biodiesel production. A lipase-producing bacterium isolated from waste-oil-contaminated environments was identified as Stenotrophomonas maltophilia strain HO5 through 16S ribosomal RNA gene sequencing. The strain exhibited a maximum lipase production of 28 U mL⁻¹. The purified monomeric enzyme (approximately 55kDa) showed a Michaelis constant (Km) of 1.728 mM and a maximum reaction velocity (Vmax) of 80 U mL⁻¹, indicating high catalytic efficiency. The enzyme retained 112.05% residual activity in the presence of ferric ions and 113.10% activity in methanol, while ethylenediaminetetraacetic acid caused strong inhibition (> 80%), suggesting partial metal ion dependence. The enzyme efficiently catalyzed the conversion of non-edible wild olive oil and taramira oil into biodiesel, confirmed by Fourier transform infrared spectroscopy through characteristic ester carbonyl stretching peaks. Gas chromatography-mass spectrometry analysis revealed fatty acid methyl esters ranging from C8 to C24. Wild olive oil biodiesel was dominated by methyl oleate (48.53%), followed by methyl linoleate (21.64%) and methyl palmitate (14.85%), whereas taramira oil biodiesel contained higher proportions of methyl linoleate (32.81%), methyl oleate (22.37%), and methyl erucate (18.72%). The predominance of unsaturated methyl esters confirms efficient enzymatic transesterification and highlights the catalytic robustness and industrial potential of this lipase for sustainable biodiesel production.

While electro-technological studies on algae typically focus on direct current, electric field, and high-voltage electric field applications, this study investigates the effects of various alternating current electric waveforms on the biomass production, macromolecular, and carotenoid composition of the microalgae species Chlorella vulgaris. The findings reveal that the applied waveforms significantly enhanced the growth performance of C. vulgaris compared to the control group. OD680 values increased by 40% in the Pulse-10 group, 33% in the Pulse-90 group, 26% in the Sine, 24% in the Square group and group 19% in the Triangle group. Chlorophyll-a content also increased similarly, with the highest increase of 54% observed in the Pulse-10 group. Furthermore, macromolecule and total carotenoid production was supported and increased compared to the control group. In conclusion, these findings contribute to innovative electro-technological applications that enhance the commercial potential of C. vulgaris for use in fields such as food, feed, cosmetics, and biodiesel production.

This study presents a combined experimental and life cycle assessment of the production of biodiesel from Datura stramonium (DS) seed oil, using a one-pot sulfonated corn-cob solid acid catalyst. The catalyst, synthesized through simultaneous hydrothermal carbonization and sulfonation using sulfuric acid (H₂SO₄), was characterized by Fourier Transform Infrared Spectroscopy (FTIR), showing -SO₃H functionalization; X-ray Diffraction (XRD), indicating an amorphous carbon structure; and Brunauer-Emmett-Teller (BET) surface analysis showed 1.53 m2/g surface area, while the catalyst acidity was determined by titration, yielding 1.79 mmol/g. The esterification/transesterification process was optimized to achieve a conversion of 91.35% at 8.75 wt% catalyst loading, 63.2°C, and 4.8h(h) reaction time. A cradle-to-gate life cycle assessment (LCA) was performed according to ISO 14040/14044 with Ecoinvent 3.11 APOS system model integrated in OpenLCA 2.5 and the ReCiPe 2016 (H) method for 18 midpoint impact categories. The major environmental hotspots were associated with electricity and solvent consumptions for catalyst sulfonation, oil extraction, and esterification. The measured climate change potential for 17 experimental runs was in the range of 15.40kg CO₂-eq (minimum impact) to 84.75kg CO₂-eq (maximum impact), while terrestrial acidification was in the range of 0.129kg SO₂-eq to 0.239kg SO₂-eq.In the optimised condition, 15.70kg CO₂-eq and 0.1306kg SO₂-eq were obtained, which showed that a proper balance exists between high conversion and low environmental burden, thus confirming the use of corn cob derived acid catalysts for sustainable biodiesel production towards the circular bioeconomy.

Optimization of mutant strains of Rhizopus oligosporus lipases for sustainable biodiesel production and other eco-friendly industrial applications using non-edible oils as substrates

CFD simulation of methanol and soybean oil mixing in SMX static mixers: the effect of length-to-diameter ratio

This study investigates the process performance and energy efficiency of a solar-assisted electrolysis-based biodiesel production using first, second and third-generation feedstocks. Palm oil, pongamia pinnata (karanja) oil and Waste cooking oil (WCO) were examined to evaluate electrolysis behavior, biodiesel yield, and overall process efficiency. Biodiesel production was carried out at room temperature using graphite electrodes, resulting in yields of 93.66%, 94.80% and 96% for palm, karanja and waste cooking oil, respectively. Integration of solar energy into the electrolysis process demonstrated notable improvements in process energy efficiency. Compared to the conventional process, solar-assisted electrolysis reduced energy consumption by 61.89% and electricity cost per unit by 59%, while processing costs decreased by 85.38% and carbon emissions by 97.31%. Relative to grid-powered electrolysis, cost and carbon emission reductions of 51.77% and 92.82%, respectively, were achieved. Application-based evaluation done by engine testing of biodiesel fuels. Diesel recorded the highest brake thermal efficiency, followed by B30 karanja blend. WCO biodiesel exhibited the lowest carbon monoxide (CO) as well as hydrocarbons (HC) emissions and the highest NOx emissions. Overall, karanja and WCO biodiesel showed sustainability advantages, confirming that solar-assisted electrolysis offers an energy-efficient process route with clear mechanical and environmental advantages.

Influence of organic loading rate on bioflocculant production derived from waste glycerin pitch and mixed microbial culture in single-step system.