In the current study, CuFe2O4-NiO nanocomposites were employed as a highly active catalyst for ultrasound-assisted biodiesel production from Moringa oleifera oil (MOO). In this regard, the CuFe2O4-NiO nanocomposite catalysts synthesized via a sono-hydrothermal approach were comprehensively characterized using multiple advanced analytical techniques to elucidate their structural, morphological, and surface features. Central composite design (CCD) demonstrated that the highest biodiesel efficiency employing CuFe2O4 and CuFe2O4-NiO nanocomposite catalysts after 35 min of ultrasonication is 94.23% and 99.15%, respectively. Besides, after seven consecutive reuse cycles, biodiesel yields of 82.53% and 90.61% were achieved, confirming the superior recyclability of the CuFe2O4-NiO nanocomposite catalyst. Kinetic analysis revealed an activation energy of 40.58 kJ mol−1 and a frequency factor of 1.1 × 105 min−1. Fuel blends containing 10, 20, and 30 vol% biodiesel were further tested in a diesel engine. The results indicated reductions in brake thermal efficiency (BTE), exhaust gas temperature (EGT), carbon monoxide (CO), and unburned hydrocarbon (UHC) emissions by 12.45%, 5.1%, 41.17%, and 21.12%, respectively, for B30 compared to diesel fuel. Moreover, energy consumption analysis revealed that the ultrasonic technique required only 0.0312 kWh/kg of biodiesel, which is approximately 10.21 times lower than that of the conventional method. Consequently, a 90.21% reduction in energy demand was achieved without any adverse effect on biodiesel yield. Accordingly, owing to high catalytic activity, excellent reusability, and facile magnetic separation, CuFe2O4-NiO nanocomposites are effective catalysts for the conversion of MMO into high-quality biodiesel via probe ultrasonication.

This study demonstrates a promising strategy for enhancing combustion performance and reducing exhaust emissions in compression-ignition (CI) diesel engines by utilizing biodiesel produced from non-edible Quercus brantii Lindl oil (QBLO) and enriched with nickel oxide (NiO) nanoparticles. The NiO nanoparticles were synthesized via a hydrothermal method and incorporated into a B15 fuel blend (15

Bifunctional nanocatalysts have emerged as a promising class of materials for biodiesel production due to their ability to address key limitations associated with feedstock quality, reaction efficiency, and environmental sustainability. While numerous studies have reported the synthesis and application of such catalysts, existing reviews largely focus on either catalytic performance or material composition, with limited integration of reaction mechanisms, kinetic behavior, and structure-function relationships. To bridge this gap, the present review provides a comprehensive and critical assessment of bifunctional nanocatalysts designed with both acidic and basic active sites within a single nanostructure, enabling the simultaneous promotion of esterification and transesterification reactions. This dual functionality is particularly advantageous for processing low-cost, high free fatty acid (FFA) feedstocks, such as waste and non-edible oils, which are incompatible with conventional base catalysts due to soap formation. This review systematically discusses synthesis strategies, including sol-gel, co-precipitation, hydrothermal, and impregnation methods and elucidates how these approaches influence catalyst morphology, pore architecture, acid-base site distribution, and surface chemistry. A distinctive contribution of this work is the integrated analysis of catalytic mechanisms and reaction kinetics in relation to nanoscale structural features, offering insights into activity, selectivity, and stability trends. Furthermore, the recyclability, structural durability, and techno-environmental implications of bifunctional nanocatalysts are critically evaluated to assess their potential for scalable and sustainable biodiesel production. By correlating catalyst design principles with kinetic performance and future industrial perspectives, this review provides a unified framework to guide the rational development of next-generation bifunctional nanocatalysts aligned with circular economy and green energy objectives.

The aim of this study is the synthesis of ZIF-67@Fe3O4 heterogeneous nanocatalyst by the sol-gel method, to generate biodiesel from waste frying oils (WFO) under ultrasonic irradiation. The physicochemical features of the ZIF-67@Fe3O4 nanocatalyst were characterized using various analytical techniques, including FESEM, CO2-TPD, FTIR, VSM, TEM, XRD, EDX, and BET analyses. Furthermore, the properties of WFO-derived biodiesel were evaluated using 1H NMR, FTIR, and GC-MS techniques. Under optimal conditions: ultrasonic time of 33.7 min, catalyst loading of 2.01 wt%, methanol-to-WFO ratio of 11.1:1 mol/mol, and sonication type B, (power and amplitude of the sonication process were 300 W and 50%, respectively), the highest biodiesel yield achieved was 95.65%, as determined using central composite design (CCD) approach of response surface methodology (RSM). The nanocatalyst demonstrated outstanding catalytic performance, maintaining a biodiesel yield of 87.03% after seven reuse cycles, confirming its suitable stability and recyclability, and highlighting its suitability for industrial-scale applications. Moreover, the reaction follows quasi-first-order kinetics, with a frequency factor of 1.7 & times; 104 and an activation energy (Ea) of 34.75 kJ/mol. As a final assessment, ZIF-67@Fe3O4 nanocatalyst, because of the high biodiesel yield in a short reaction time, considerable stability, and high catalytic activity, can be considered as an appropriate heterogeneous catalyst in the industrial generation of biodiesel.

In this study, MIL-53(Al)-(NH2)@Fe2O3 nanocomposite was successfully synthesized through a controlled hydrothermal route and subsequently applied for biodiesel production from Quercus brantii Lindl oil. Comprehensive physicochemical characterization was carried out using XRD, FTIR, EDX/elemental mapping, BET/BJH, FESEM, CO2-TPD, and TEM analyses to investigate the structural, morphological, and textural properties of both MIL-53(Al)-(NH2) and its Fe2O3-decorated composite. Process optimization using the Box-Behnken design identified the optimal reaction conditions, including a methanol-to-Quercus brantii Lindl oil molar ratio of 11:1, a catalyst loading of 2.5 wt%, and a stirring time of 3  h, achieving a maximum biodiesel yield of 98.16%. Moreover, the nanocatalyst revealed excellent reusability, maintaining a 90.68% conversion efficiency after seven consecutive cycles, confirming its strong structural stability and minimal active-site degradation. FTIR and 1H NMR analyses confirmed the formation of methyl esters. The resulting biodiesel met the ASTM D6751 fuel quality standards. A green chemistry assessment revealed favorable sustainability metrics (E-factor = 0.72, PMI = 1.74, atom economy = 93.8%, TOF = 0.103  h−1), while cost analysis confirmed low production costs of $21.81 for the catalyst and $0.72  kg−1 for biodiesel. Furthermore, sensitivity analysis demonstrated that oil extraction was the dominant cost driver, while catalyst reusability improved the economic viability of large-scale methyl ester production. Accordingly, these findings demonstrate that combining the MIL-53(Al)-(NH2)@Fe2O3 nanocatalyst with Quercus brantii Lindl oil offers a cost-effective and sustainable strategy for biodiesel production.

This study investigated the enhancement of biodiesel yield from sunflower oil via transesterification using a zinc oxide (ZnO) nanocatalyst under ultrasonic irradiation. The properties of the nanocatalyst prepared by the sol-gel method were characterized by XRD, FTIR, SEM, and TEM analyses. The ZnO nanoparticles had an average size of 24 nm with a hexagonal, slightly spherical structure. Response Surface Methodology (RSM) and Central Composite Design (CCD) were applied to evaluate the effect of influential parameters on methyl ester yield. Besides, the accuracy of the suggested model was confirmed by Analysis of Variance (ANOVA). A reasonable accordance between the experimental and predicted data was achieved with R² = 0.9968 and adjusted R² = 0.9938. The optimum process conditions were a methanol/sunflower oil molar ratio of 10.98 mol/mol, an ultrasonic time of 26.28 min, and a nanocatalyst loading of 2.71 wt.%. Under these conditions, the RSM model predicted a maximum biodiesel yield of 90.5%, while the highest experimental yield was 89.57%, confirming the model's accuracy. Moreover, FTIR analysis of the produced biodiesel confirms successful synthesis. The nanocatalyst demonstrated high reusability over seven cycles, maintaining a biodiesel yield above 80% throughout, indicating excellent recyclability. Therefore, this research demonstrated that the combination of ultrasonic radiation and ZnO particles presents a promising approach for biodiesel production, enabling high efficiency within a short reaction time.

A heterogeneous catalyst was synthesized via the pyrolysis of agricultural waste, employing KOH-activated biochar derived from peanut shells. This catalyst offers an innovative and cost-effective solution for converting waste cooking oil (WCO) into biodiesel. Its structural and chemical properties were characterized through various techniques, including XRD, FT-IR, EDS/mapping, TEM, SEM, and BET analysis. To identify the optimal reaction parameters, response surface methodology (RSM) was applied. Under the optimized conditions a WCOto-methanol molar ratio of 1:12, catalyst loading of 4.75 wt%, reaction duration of 4 h, and a constant temperature of 65 degrees C, a maximum biodiesel yield of 94% was achieved. The catalyst demonstrated good recyclability, maintaining an efficiency of 78.65% after seven consecutive cycles. Engine performance analysis revealed that, under full load conditions, increasing the biodiesel content in the fuel blend from 0 to 30 vol% resulted in a 27.27% rise in brake specific fuel consumption. Consequently, brake thermal efficiency decreased by 12.45%, and exhaust gas temperature dropped by 29.14%. Under maximum load conditions, the use of B30 fuel resulted in emission reductions of 38% in carbon monoxide and 14.02% in unburned hydrocarbons. These results demonstrate that biodiesel fuel blends produced with KOH-activated peanut shell biochar contribute to carbon emission reduction. Moreover, elevated levels of CO2 and NOx emissions were observed, reaching 30.42 and 32.90%, respectively. This research introduces a sustainable and environmentally feasible method for producing biodiesel, which enhances catalyst performance and reduces carbon emissions.

Calcium aluminate supported by KOH was synthesized via urea-nitrate combustion method where sorbitol was utilized as an auxiliary fuel. Sorbitol, a polyol with high oxygen and carbon content, promotes combustion temperature and released gaseous from the combustion medium which can directly influence on textural properties and crystallinity. The synthesized catalysts were utilized for microwave-assisted biodiesel production. The inclusion of sorbitol enhanced surface area (12.9 m2/g), pore volume (0.119 cc/g), mean pore diameter (8.8 nm) and crystallinity of the catalyst, resulting in improved catalytic activity. The optimal catalyst with the highest activity in microwave-assisted biodiesel production from canola oil was obtained at urea-sorbitol ratio of 1:0.25. The optimization of transesterification conditions was performed using Response Surface Methodology (RSM) via optimal catalyst where the maximum yield of 94.9 %, with an experimental yield of 93.8 %, was achieved. The reusability of the catalyst was evaluated at the optimum transesterification conditions of 450 W of microwave power, methanol/oil molar ratio of 14.3, catalyst amount of 4.5 wt% and 51 min of reaction time, showing only a 14 % reduction in biodiesel yield after six cycles. These results highlight the potential of sorbitolassisted synthesis for sustainable catalyst development and the ability of K/Ca-Al mixed metal oxides, as effective catalyst, for biodiesel production.

Alkaline batteries are widely used in contemporary society. However, their black powder, which contains metals, categorizes them as hazardous waste, posing environmental risks if not disposed of correctly. Similarly, waste cooking oil (WCO), frequently produced in homes and restaurants, is often discarded into the environment as waste. In this study, the spent black powder from alkaline batteries was effectively utilized as a catalyst for biodiesel generation from WCO. This catalyst, containing carbonaceous materials, MnO2, ZnO, and K, facilitated both esterification and transesterification processes. It featured a Brunauer-Emmett-Teller (BET) value of 31.87 m2/g. Response Surface Methodology with Central Composite Design (RSM-CCD) was used to evaluate the influence of key variables on production efficiency. The highest biodiesel yield (99.23%) was attained with a methanol-to-oil ratio of 16:1, a temperature of 70 degrees C, a catalyst mass of 3 wt%, and a production time of 160 min. The regeneration process revealed that n-hexane effectively removes glycerol and biodiesel residues from the catalyst. Additionally, the catalyst demonstrated strong reusability for up to five cycles, with a significant decline in catalytic activity observed after the fifth cycle. The process demonstrated an activation energy of 22.046 kJ/ mol and a pre-exponential factor of 62.878 min-1. It was characterized as endothermic (Delta H: 19.274 kJ/mol) and non-spontaneous (Delta G: 94.666 kJ/mol). The economic assessment in this study showed that the production cost of 1 kg of biodiesel using a catalyst derived from waste batteries is $0.579, demonstrating its cost-effectiveness compared to alternative methods for large-scale applications. Fourier Transform Infrared Spectroscopy (FTIR), 13C-NMR, and 1H-NMR analyses validated the catalyst's effectiveness in converting WCO to biodiesel. Therefore, it is suggested that this catalyst be tested at an industrial scale.

Magnetic nanocatalysts NiFe2O4/SiO2 and NiFe2O4 were synthesized using the sol-gel technique. It's used to generate biodiesel from waste frying oil (WFO) through transesterification. Multiple methods were used to characterize the nanocatalysts, including XRD, BET-BJH, SEM, EDX, VSM, FTIR, and TEM. The spherical shape of the magnetic NiFe2O4/SiO2 nanocatalyst was evident, with an average nanoparticle diameter of 51.6. The impact of different characteristics was explored using response surface methodology and Box-Behnken design (RSMBBD). The optimal parameters for biodiesel production were achieved with reaction times of 204 min for NiFe2O4 and 228 min for NiFe2O4/SiO2, catalyst concentrations of 2.07 and 2.04 %, and methanol/WFO ratios of 11.5 and 11.58, respectively. Under optimal conditions, the maximum biodiesel production for NiFe2O4 and NiFe2O4/SiO2 nanocatalysts was 95.16 and 97.23 %, respectively. The catalyst's reusability over seven cycles showed an 88.56 % decrease in biodiesel production, indicating the NiFe2O4/SiO2 nanocatalyst's stability. Additionally, the kinetics and thermodynamics of the transesterification process revealed that the reaction is characterized as endothermic and non-spontaneous. 1H NMR and FT-IR spectra confirmed the transesterification process that converts WFO into biodiesel. Incorporating Waste Frying Oil Methyl Ester (WFOME) and NiFe2O4/ SiO2 into diesel at various engine loads generated significant improvements in engine performance and reductions in emissions.

This research surveys biodiesel synthesis from used edible oil (UEO) using biochar/MnO–NiO nanocomposite, highlighting its efficiency and sustainability as a heterogeneous catalyst. The physical and chemical features of the manganese and nickel oxide nanocatalysts immobilized on biochar were thoroughly characterized through FTIR, BET, XRD, EDX, TEM, and FESEM analyses. The findings confirmed the successful deposition of manganese and nickel oxide nanoparticles onto the biochar surface. Moreover, the specific surface area of the biochar/MnO–NiO nanocatalyst was determined to be 25.436 m2/g, while EDX analysis validated the elemental composition, confirming the presence of carbon, manganese, nickel, and oxygen in the synthesized catalyst. The impacts of critical procedure variables on the transesterification process were investigated. Response surface methodology was applied to analyze and optimize the process. Among the variables studied, the methanol/UEO molar ratio was identified as the most influential variable affecting transesterification efficiency. Optimal conditions for maximum biodiesel yield were determined to be a methanol/UEO molar ratio of 14, a reaction time of 150 min, and a catalyst concentration of 2.5 wt.

In this study, NiFe2O4@g-C3N4 nanocatalyst was synthesized using ultrasonication and pyrolysis techniques and subsequently applied as a highly efficient and reusable catalyst for biodiesel production from waste cooking oil (WCO). Comprehensive structural analyses such as X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Brunauer–Emmett–Teller (BET), energy-dispersive X-ray spectroscopy (EDX), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Raman spectroscopy, carbon dioxide temperature-programmed desorption (CO2-TPD), and vibrating sample magnetometry (VSM) confirmed that the NiFe2O4@g-C3N4 nanocatalyst possesses a high specific surface area coupled with notable magnetic features, facilitating its effectiveness in catalysis and ease of separation post-reaction. Under optimized conditions of 2.85 wt% catalyst dosage, 11.72:1 methanol-to-oil molar ratio, 61.17 °C reaction temperature, and 24 kHz ultrasound frequency (250 W), the NiFe2O4@g-C3N4 nanocatalyst achieved a maximum biodiesel yield of 98.83% within 31.02 min. Additionally, the catalyst demonstrated remarkable stability and reusability, maintaining a biodiesel yield of over 90% even after seven consecutive reuse cycles. The reaction kinetics revealed that the process follows a pseudo-first-order model. Kinetic and thermodynamic evaluations of the transesterification process revealed that the reaction is endothermic, with an enthalpy change (ΔH°) of 98.5 kJ/mol. The activation energy of 101.2 kJ/mol indicated that the NiFe2O4@g-C3N4 nanocatalyst possesses sufficient energy to drive the transesterification reaction efficiently. These results highlight the incorporation of g-C₃N₄ nanoparticles to reinforce NiFe₂O₄, which enhances its surface area, magnetic recoverability, and structural stability attributes that significantly improve catalytic activity and reusability in biodiesel production.

This study focused on generating biodiesel from waste cooking oil (WCO) employing an αFe₂O₃/CuO nanocatalyst synthesized via a co-precipitation method. Several characterization techniques, including FTIR, XRD, SEM-EDX, BET, and TEM analyses, were applied to scrutinize the features of the fabricated nanocatalyst. The results confirmed the successful incorporation of CuO into the αFe₂O₃ structure. BET analysis further revealed that the addition of CuO nanoparticles significantly enhanced the catalyst’s surface properties, increasing the number of active sites available for transesterification reactions. Besides, the αFe₂O₃/CuO nanocatalyst exhibited a specific surface area of 334 m²/g, highlighting its high surface availability for catalytic activity. The process was statistically optimized using response surface methodology (RSM) with a Box-Behnken design (BBD) to assess the influence of critical reaction parameters. Vital parameters evaluated included temperature (50–70 °C), methanol/WCO molar ratio (8–14 mol/mol), and catalyst loading (1–3 wt%). Moreover, ANOVA results indicated that the methanol/WCO molar proportion had the most remarkable effect on biodiesel production efficiency, with an F-value of 337.11. Under optimal conditions reaction time of 3 h, methanol/WCO molar ratio of 11, αFe₂O₃/CuO dosage of 2 wt%, and temperature of 60 °C a highest biodiesel yield of 94.27% was achieved. Additionally, the reusability assessment of the αFe₂O₃/CuO nanocatalyst demonstrated notable stability, with only a 12% reduction in efficiency observed over seven cycles. This research demonstrates that αFe₂O₃/CuO nanocatalysts, owing to their unique properties, have the potential to serve as highly effective heterogeneous catalysts for transesterification.

In this research, the photocatalytic removal of Methylene Blue (MB) dye was investigated using ZSM-5@ZnO nanoflowers. Facile synthesis of ZSM-5@ZnO nanoparticles was performed using a sol-gel procedure. Moreover, crystal structure, functional groups, and morphology of the synthesized nanoparticles were confirmed by applying X-Ray Diffraction (XRD) analysis, Fourier Transform InfraRed (FT-IR), Energy Dispersive X-ray (EDX), Brunauer-Emmett-Teller (BET), and Scanning Electron Microscope (SEM) approaches. Experiments on the initial concentration of MB, catalyst dosage, pH of the medium, light source power, amount of H2O2, and kinetic studies were carried out to achieve the maximum amount of MB removal. The highest removal rate of MB dye was achieved under optimum circumstances, i.e., dye concentration of 5 mg/L, pH of 9, 0.2 ml of H2O2, 50 mg of ZSM-5@ZnO nanocatalyst dosage, and 120 min under 50 W light-emitting diode (LED) lamp irradiation. Regarding the mentioned conditions, the maximum dye removal rate was 94.09%. The Kinetic study also expresses that the removal process follows the first-order model with the equation y=0.024x, R2=0.985, and AARD = 4.269%. Besides, the optimal time for the photocatalytic removal process is 120 min. Notably, the reusability of the nanocatalyst during 5 cycles was promising, and only 4.59% of dye removal efficiency decreased.

The present study aimed at preparing an efficient nanocomposite composing activated carbon (C), ZnO and NiO as a highly reactive photocatalyst for degradation of reactive red 120 (RR120) wastewater under LED light irradiation. The combination of ZnO and NiO motivates charge recombination from one photocatalyst to the other, thus suppressing charge recombination which is a big target in photocatalytic process. On the other hand, the dispersion of photocatalyst particles over activated carbon matrix leads to the efficient light absorption and promoting photocatalytic activity. The photocatalysts were prepared hydrothermally and characterized by XRD, FTIR, SEM, EDS, BET and UV–vis DRS analyses. The C/ZnO–NiO photocatalyst demonstrated a flower-like morphology with mesoporous features. To obtain the best photocatalytic dye degradation, a step-by-step study was carried out to find out the optimum values of ZnO/NiO molar ratio, photocatalyst amount, carbon mesh size, solution pH, initial RR120 concentration, H2O2 and power of LED lamp. The maximum photocatalytic RR120 degradation of 94.88

In this scientific study, Fe3O4@UiO-66-NH2 nanoparticles were prepared and applied as an efficient and magnetic nanocomposite to synthesize biodiesel from restaurant waste oil via microwave irradiation. Various techniques were employed to describe the nanocomposite structure, such as FTIR, BET, SEM, XRD, CO2-TPD, TEM, EDX/Mapping, and VSM. The greatest biodiesel efficiency via Fe3O4@UiO-66-NH2 under optimal circumstances including methanol to waste oil proportion of 11.38:1, time of 8.84 min, nanocatalyst amount of 3.27%, and stirring speed of 723.38 rpm) was 98.72%, which is a substantial performance. Besides, the Fe3O4@UiO-66-NH2 nanocatalyst was applied in seven reutilizing processes with a remarkable output, hence after the 7th round, its methyl ester purity was more than 90%, confirming the high reusability of the Fe3O4@UiO-66-NH2 nanocatalyst. In addition, kinetic and thermodynamic examinations of transesterification of waste oil applying Fe3O4@UiO-66-NH2 nanocatalyst were executed, and the outputs demonstrated that the reaction is endothermic. Moreover, different proportions of biodiesel and diesel at various torques were experimented on the compression-ignition engine performance (i.e. EGT, BTE, and BSFC) also the emission of harmful pollutants (i.e., CO2, CO, UHC, and NOx). The outputs indicated that adding biodiesel and Fe3O4@UiO-66-NH2 nanocatalyst to diesel has favorable impacts on the diesel engine characteristics.

In this study, a novel Co3O4 decorated with rGO nanocatalyst was utilized in synergy with microwave heating as a novel approach for the generation of biodiesel. In this process, 98.04 % biodiesel yield was achieved by adopting response surface methodology algorithm under MEOH/oil molar ratio of 12.75:1, Co3O4@rGO loading of 1.53 wt%, microwave time of 7.17 min, and stirring speed of 512 rpm. The catalyst can be reused for seven times with biodiesel yields beyond 85 %. Co3O4@rGO was used as a nano-additive in the diesel engine to investigate the emission and performance of biodiesel blended with diesel. The Co3O4@rGO nanoparticles were dispersed into the B20 fuel with concentrations of 50 and 100 ppm. The outcomes discovered that the brake thermal efficiency of B20Co3O4@rGO50 is 1.22 % greater than B20, and the brake specific fuel consumption is declined by 5.05 %. The emissions from the diesel engine i.e. CO (29.88 %) and UHC (16.38 %) were significantly lowered compared to B20. The emission of NOx for B20Co3O4@rGO100 is 7.4 % lower than B20 and greater than conventional petrodiesel. Owing to its remarkable stability, excellent biodiesel yield, effective utilization in diesel engine, and high catalytic activity, the Co3O4@rGO is strongly proposed for industrial biodiesel generation utilizing microwave radiation.

Biodiesel is a sustainable biofuel, which is synthesized from sources of oil utilizing an appropriate catalyst. Therefore, catalysts not only play a key role in biodiesel generation with high yield, but are also effective in reducing the cost of biodiesel synthesis. Metal-organic frameworks (MOFs) and covalent organic frameworks (COFs) have emerged as promising catalysts for biodiesel generation owing to their unique properties. These include extraordinary specific surface area, significant stability, high reactivity, regular structure, and high active sites. Accordingly, these catalysts offer significant advantages over traditional catalysts, driving increased attention and research in their application for biodiesel generation. The main objective of this review article was to deeply investigate MOFs and COFs catalysts, their features, and their potential in biodiesel production. Besides, the biodiesel generation mechanism using these catalysts was fully studied. Further, their cost analysis and environmental impact were examined in detail. The characteristics of biodiesel generation employing MOFs and COFs catalysts were studied in terms of kinetic and thermodynamic parameters. According to previous investigations, MOFs catalysts have been utilized more than COFs. Moreover, MOFs catalysts have shown extraordinary reusability as well as considerable biodiesel yields, so they are strongly recommended in the industrial generation of biodiesel. To the best of our knowledge, this is the first study that deals deeply with the biodiesel generation process employing MOFs and COFs structured heterogeneous catalysts.

Annona reticulata plant components such as leaves and seeds are successfully employed as low-cost and environmentally-safe sustainable materials for the synthesis of cerium oxide nanoparticles and biodiesel production. The synthesized CeO2 NPs worked well as a catalyst to convert A. reticulata oil into biodiesel. At a methanol to oil molar ratio of 8.97:1, a catalyst (CeO2 NPs) loading of 2.97 wt. %, and reaction time of 56.4 minutes, the maximum 96.8 % biodiesel yield was attained. A pseudo-first-order reaction with activation energy (Ea) of 49.77 kJ/mol and a frequency factor (A) of 1.8 x 105 min-1 is consistent with the Annona reticulata methyl ester (ARME) production. The performance and emission characteristics of diesel engines were found to be significantly impacted by the use of CeO2 NPs. While the BSFC of ARME20CeO250 and ARME20CeO2100 decreased by 2.04% and 5.10%, respectively, the BTE of ARME20CeO250 and ARME20CeO2100 increased by 1.8% and 2.41%, in contrast to ARME20 at maximum load. When CeO2 nano-additive (100 ppm) is added to the ARME20 blend, the CO, HC, and NOx are reduced by 42%, 35.59%, and 5.94%, respectively, in comparison to the ARME20 fuel. Thus, the A. reticulata plant may be seen as an eco-friendly source from its leaves extract, and the oil extracted from its seeds may be used as a feedstock for the effective production of biodiesel.

This study surveys the valorization of dairy waste scum oils (DWSO) to synthesis biodiesel using a novel rice husk ash-supported CuO nanocatalyst. The rice husk ash-supported CuO nanocatalyst was synthesized through a facile impregnation method and characterized by BET, XRD, FTIR, EDX, CO2/TPD, TEM, and FESEM to confirm its structural and morphological features. Transesterification of DWSO was conducted under optimized conditions, achieving a maximum biodiesel yield of 97.42 % at temperature of 62.36 degrees C, methanol/DWSO proportion of 11:12, and nanocatalyst loading of 2.76 wt% within 2.85 h. Kinetic studies revealed that the transesterification reaction follows a pseudo-first-order model with an activation energy of 100.34 kJ/mol. Thermodynamic analysis indicated that the reaction is endothermic (Delta H = 100.26 kJ/mol) and non-spontaneous (Delta G = -11043.6 kJ/mol) at the studied temperature range, suggesting the requirement of external heat to drive the process. Reusability tests demonstrated that the rice husk ash-supported CuO nanocatalyst retains over 86 % of its initial activity after seven cycles, highlighting its potential for practical applications. This study highlights the dual benefits of utilizing agro-industrial waste for both feedstock and catalyst support, promoting a cleaner and economically viable approach for biodiesel generation.