Stability Of Biodiesel Research Articles

Experimental and numerical analysis to enhance the thermodynamic properties and biofuel stability: Sapindus mukorossi

ABSTRACT Microscale additives face challenges like sedimentation, conglomeration, and uneven size distribution, which can adversely impact biodiesel stability and thermochemical properties. This study investigates the stability and thermochemical properties of magnesium-doped calcium oxide (MdC) in Sapindus mukkarosi (SMBD25) biodiesel emulsified with antioxidants SPAN80 (SP80) and TWEEN80 (TW80) at different concentrations. 9 sets of experiments were carried out with the L9 OA as per the design matrix. Minitab 16 software was used to simplify the analysis of the results using the Taguchi method. Also, this research encompassed a comprehensive investigation by employing GCFID, SEM and XRD techniques. From the results, the heating value and cetane number for SMBD25 + 30 mg/L MdC + 30 mg/L TW80 + 30 mg/L SP80, surfactant and dispersant (1:1 ratio) biodiesel blend is improved. The enhanced absorbance and reduced transmittance for SMBD25 + 30 mg/L MdC + 30 mg/L TN80 + 30 mg/L SP80 were estimated to be 4.63 and 0.53%, respectively, while the heating value and cetane number were calculated to be 42.13 MJ/kg and 56, respectively. The Taguchi method revealed that SMBD27.8, 34ppm nanocatalyst, and 24ppm dispersant were optimum process parameters. The biodiesel blend is highly effective (71.18%) in controlling the optimal biodiesel thermochemical properties, followed by the dispersant (19.55%).

Bio-oil Fractionation According to Polarity and Molecular Size: Characterization and Application as Antioxidants.

Bio-oil obtained from biomass pyrolysis has great potential for several applications after being upgraded and refined. This study established a method for separating bio-oil into different fractions based on polarity and molecular size to extract phenolic and polyphenolic compounds with antioxidant properties. The fractions were analyzed using various spectroscopic and chromatographic techniques, such as GC/MS, FTIR, UV-vis, SEC, DOSY-NMR, 13C-NMR, and 31P-NMR. The antioxidant properties of these fractions were tested by examining their ability to improve the oxidative stability of biodiesel. The results strongly connected the bio-oil's chemical functionalities and antioxidant power. During solvent fractionation, dichloromethane could extract phenolic structures, which were subsequently size-fractionated. The subfractions with lower molecular weight (in the order of monomers and dimers) outperformed the antioxidant potential of the crude bio-oil. Heavier subfractions from dichloromethane extraction did not show good antioxidant abilities, which was related to the low hydroxy group content. After solvent extraction, phenolic oligomers remained in the water-insoluble/dichloromethane-insoluble fraction, which showed good antioxidant potential despite its low solubility in biodiesel.

Evaluation of Cobalt, Nickel, and Palladium Complexes as Catalysts for the Hydrogenation and Improvement of Oxidative Stability of Biodiesel

Developing effective catalysts that can selectively hydrogenate C=C bonds in biodiesel samples is vital as it tackles the major problem of oxidative stability, which greatly limits the utilization of biodiesel as an alternative fuel. In this work, Co, Ni, and Pd catalysts stabilized with the bidentate nitrogen ligands N-(3-(triethoxysilyl)propyl)pyridin-2-ylmethylimine and N-(3-(triethoxysilyl)propyl)picolinamide were synthesized, characterized, and used as pre-catalysts in the transfer hydrogenation of C=C bonds in fatty acid methyl esters. The active catalysts from the Co, Ni, and Pd complexes sequentially hydrogenate the C18:2 chains to C18:1, which is further converted to C18:0 in the FAMEs of both methyl linoleate and jatropha biodiesel. The hydrogenation process was kinetically controlled, and after 3 h it yielded a biodiesel sample that contained 25.83% C16:0, 12.52% C18:2, 41.54% C18:1, 14.47% C18:0 and 3.0% C18:2 isomers. The un-hydrogenated jatropha diesel, hydrogenated jatropha diesel, and a B20 blend of jatropha were tested for susceptibility to oxidation reactions using the Rancimat method and FTIR spectroscopy, and the partial hydrogenation had improved the induction period by 3 h.

The Impact of Various Factors on Long-Term Storage of Biodiesel and Its Prevention: A Review

With the continuous growth of global energy demand and increasingly prominent environmental issues, the research and utilization of renewable energy as a substitute for traditional fossil fuels have gained significant importance. Biofuels, recognized as a key renewable energy source, are widely considered a viable alternative to fossil fuels. The primary component of biodiesel is fatty acid methyl esters (FAMEs), which are prone to oxidative degradation due to their unsaturated nature during storage and transportation. Various studies have identified several factors influencing the stability of biodiesel, including oxygen, temperature, light, water content, microbial growth, and the corrosion of metal storage tanks. This article provides a comprehensive summary of the effects of different environmental factors on the storage stability of biodiesel and explores the interrelationships between these factors. To enhance the storage stability of biodiesel, several strategies have been proposed, such as optimizing production processes, adding antioxidants, controlling storage environments, and conducting regular inspections. This review aims to provide a theoretical basis for the long-term storage of biodiesel and promote its widespread application in practical scenarios.

Improvement of the Oxidation Stability of Biodiesel from Waste Cooking Oil Using Various Antioxidants

Improvement of the Oxidation Stability of Biodiesel from Waste Cooking Oil Using Various Antioxidants

Raman spectra soft modeling of the biodiesel oxidation through evolving factor analysis & multivariate curve resolution

The oxidative stability of biodiesel is defined by its relative resistance to the action of oxygen at room temperature. Its determination is an essential reference to the quality of biofuel and a significant parameter to be determined. This parameter concerns the quality of the biodiesel to be supplied to the consumer, and its determination is fundamental to maintaining the engine's proper functioning. Raman spectroscopy allows the rapid obtaining of structural information regarding biodiesel quality and, when aided by multivariate analysis methods, allows a quantitative determination of specific properties. This work uses Raman spectroscopy, Multivariate Curve Resolution with Alternative Least Squares (MCR-ALS) method, and Evolving Factor Analysis (EFA) to study biodiesel's oxidation kinetics. Also, the vibrational modes C = C, CH2, and CH3 were identified as the main structural groups involved in this process, corroborating previous studies. The MCR-ALS & EFA combination allowed modeling of the degradation kinetics following an A → B → C mechanism, where A corresponds to the biodiesel (starting material), B is related to the hydroperoxide mixture, and C is the final product. The results also suggested that this process follows a first-order reaction, with kinetic constant values of k1 = 0.0056 min−1 and k2 = 0.0031 min−1.

Influence of antioxidants from pequi leaves on the thermal and oxidative stability of biodiesel

AbstractIn this study, the efficacy of antioxidants found in pequi leaves was examined for safeguarding pequi biodiesel (EBP) against oxidation. The results reveal notable achievements. The antioxidant activity of AFP (a pequi leaf antioxidant additive) was assessed at various concentrations, demonstrating that as the concentration of AFP increases, the inhibition percentage significantly rises, reaching a remarkable inhibition of 99.12% at 100 mg L−1, with a calculated IC50 of 25.4 mg L−1. Additionally, the analysis of the AFP composition revealed the presence of terpenes and oxygenated compounds, which are well known for their antioxidant properties. Furthermore, the research emphasized the significance of thermogravimetric analysis in evaluating the thermal stability of additives, identifying critical temperatures at which AFP begins to protect biodiesel against oxidation (247.18°C) and the point at which its effectiveness may diminish (469.19°C). The EBP met quality standards regarding acidity, water content and density, but exhibited slightly lower oxidative stability compared with established standards. The correlation between the thermal degradation of biodiesel and the induction period highlighted the efficacy of AFP in mitigating thermal degradation. Nevertheless, it also indicated that maintaining biodiesel quality requires complementary approaches to minimize degradation over time.

An image-processing method based on regional separation-parameter coupling for the stability analysis of biodiesel flame

Flame stability is vital to obtain good combustion performance. Therefore, the development of flame stabilization technologies and stability evaluation methods has always received considerable research attention. However, the existing evaluation methods have low precision, which makes it difficult to accurately assess the flame stability. To address this issue, we proposed an effective flame state evaluation method in this study. We conducted relevant combustion experiments, and applied the proposed method to evaluate the flame stability of biodiesel. Furthermore, we established a numerical evaluator of the flame state based on a regional separation-parameter coupling image-processing method. This numerical evaluator combines the statistical characteristics of six flame parameters, which we derived from the flame images. The experimental results suggested that the proposed method can be used to determine some characteristic parameters that cannot be obtained by traditional methods, such as oscillation frequency and propagation velocity. Notably, these characteristic parameters are important for the evaluation of flame stability. At an oxygen concentration of 24 % and fuel pressure of 0.5 MPa, we subdivided the combustion state of biodiesel into stable, relatively stable, unstable, and extinguished states. We observed that by decreasing the airflow rate from 0 to 12.50 m3/h, the flame color changed from orange to green, then blue, and finally to yellow-green. We also observed, contraction and spreading in the flame highlight region. The color space analysis revealed that the larger the blue-to-red ratio, the more complete the combustion, which led to a blue flame. Overall, the proposed evaluation method provides a useful guide for regulating the combustion of biodiesel. Furthermore, these result can be generalized to assess the combustion states of other fuels.

Regression analysis on the stability of surfactant mixed-MoO3 nanoparticles dispersed Gossypium arboretum biodiesel

ABSTRACT The stability, physicochemical characteristics, molybdenum trioxide (MoO3) nanoparticles in Gossypium arboretum biodiesel (BD20), and deduction of the regression equation for parameters governing the stability of biodiesel are the main subjects of this study. With and without the surfactant Cetyltrimethylammonium Bromide (CTAB), MoO3 nano additions were combined with BD20 at 60, 80, and 100 ppm concentrations. A spectrophotometer that measures the samples’ absorbance and transmittance was used to examine the stability of nano fuels on days 1, 10, and 20. CTAB mixed nano samples demonstrated high stability and enhanced essential fuel qualities when compared to basic nano fuels. The fuel BD20MoO380CTAB80 (BD20+ MoO3 80 ppm+ CTAB 80 ppm) showed a decreased transmittance of 88.3% and a higher absorbance of 4.3 AU.BD20MoO380CTAB80 recorded a higher value of Cetane number of 64 and a heating value of 41,238 kJ/kg. Physicochemical properties such as Kinematic Viscosity and Relative Density recorded lower values of 4.23 cSt and 880 kg/m3. Linear regression is applied to the obtained absorbance and transmittance values.

Investigation of curcumin antioxidant efficiency on oxidation stability of biodiesel from soybean oil and beef tallow, contaminated with metals: Kinetic and storage studies

Biodiesel can be produced from different raw materials or its blends, being that the soybean oil and bovine fat blend has been gaining prominence, because it guarantees good oxidative stability. However, several factors can affect its oxidative stability, such as exposure to high temperatures or contact with metals that may be present in storage and transport tanks. Thus, for its commercialization, a minimum of 8 h of Induction Period (IP) is required by the EN 14112 standard, and to reach this oxidation stability value, it is often necessary to add antioxidants to delay the oxidative process. This study aimed to evaluate the antioxidant action of curcumin in commercial biodiesel produced from soybean oil (70 %) and animal fat (30 %) blend and contaminated with metals in order to evaluate parameters such as IP, stabilization factor (F), activation energy (Ea), pre-exponential factor (A), reaction rate constant (k) and samples stability during storage in an oven at 85 °C. The samples were characterized by ultraviolet absorption spectroscopy and by Rancimat method (oxidation stability). The results showed high efficiency of the curcumin antioxidant, monitored by absorption at 425 nm. The curcumin addition in the biodiesel sample provided IP values greater than 8 h, even when contaminated with copper. The results of the kinetic studies showed for activation energy a value of 97.22 kJ mol−1 for the sample with 2000 mg kg−1 of curcumin, and 94.28 kJ mol−1 for the sample with curcumin at the same concentration and contaminated with 2 mg kg−1 copper. Even after 14 days of storage at 85 °C, the samples biodiesel with curcumin showed IP values within the required by international legislation (EN 14112 standard), showing curcumin as a promising natural antioxidant, even when biodiesel exposed to factors that intensify oxidative degradation.

Experimental Investigation on Long Term Storage Issues of Vegetable Oil and Biodiesel Fuel

Energy is one of the major inputs for the economic development of any country. In the case of the developing countries, the energy sector assumes a critical importance in view of the ever-increasing energy needs requiring huge investments to meet them. For the developing country like India, economic growth is desirable and energy is essential for economic growth. The situation has led to the search for an alternative fuel, which should be not only sustainable but also environment friendly. For developing countries, fuels of bio-origin, such as alcohol, vegetable oils, biomass, biogas, synthetic fuels, etc. are becoming important. For the present work, Experimental investigations on long term storage issues of Vegetable Oil and Biodiesel fuel is carried out. Long-term storage study gives us a better understanding of the effect of the storage condition on the stability of biodiesel.

1H NMR and UV-Vis as Analytical Techniques to Evaluate Biodiesel Conversion and Oxidative Stability

The present study evaluated the applicability of 1H NMR and UV-Vis spectroscopies as analytical techniques for the characterization and determination of biodiesel conversion and for monitoring the oxidative stability of biodiesel samples with antioxidants. For this study, safflower and babassu biodiesels were obtained through transesterification, and physicochemical properties confirmed the success of both reactions. A bench-top accelerated oxidation system was used as an alternative to the Rancimat® method, with samples of 6.0 g heated at 110 ± 5 °C and collected every 2 h for 12 h. The agreement for biodiesel conversions was good, with divergences between 2% and 0.4% for safflower biodiesel and 1.9% for babassu biodiesel. As for UV-Vis spectroscopy, the technique showed the same trend as the Rancimat® method, showing efficiency in evaluating the oxidative stability of safflower biodiesel and in the performance of antioxidants BHT and DMP-30. The accuracy of NMR signals integration for mixtures of safflower oil and safflower biodiesel and the use of UV-Vis spectroscopy associated with a bench-top accelerated oxidation system to investigate the performance of phenolic and amine antioxidants in safflower and babassu biodiesel were explored for the first time, showing results close to the standard methods. Therefore, 1H NMR and UV-Vis spectroscopies could be applied as alternatives to the GC and Rancimat® methods to determine conversion and monitor the oxidative stability of biodiesel rapidly and practically.

Evaluation of synthetic and bio-based additives on the oxidation stability of palm biodiesel: Parametric, kinetics and thermodynamics studies

This study evaluated the effects of additives on the oxidation stability of palm biodiesel (PBD) and appraised their oxidation kinetics cum thermodynamics. The results of Rancimat induction period (IP) and effectiveness factor, as well as acid value (AV) and iodine value (IV) indicated that tert-butylhydroquinone (TBHQ) was the most effective antioxidant. Notably, the reverse IP ranking of TBHQ under PetroOXY was likely caused by its degradation. Pyrogallol (PY), propyl gallate (PG), butylated hydroxytoluene (BHT), butylated hydroxyanisol (BHA) and quercetin demonstrated mid-range to high effectiveness in terms of IP. Nevertheless, PY, quercetin and curcumin had partial solubility in PBD. While α-tocopherol (α-T) had the least effects on IP and effectiveness factor, it still met the EN14214:2012 limit. The IP, AV, IV and kinematic viscosity except AV for 1000 ppm of PG met the limits. Correlations between the Rancimat and PetroOXY IP values were developed. The oxidation kinetics adhered to the first order kinetic model. By appraising the k values, TBHQ and BHA were clearly the most effective and this concurred with the IP values. The oxidation reactions were endothermic, non-spontaneous and endergonic in nature. Overall, TBHQ and BHA were the most effective synthetic antioxidants while α-T was the best bio-based additive.

Impact of additives from moringa stenopetela leaf extract and ethanol on the emission characteristics and performance of soybean biodiesel for single cylinder CI engine

The study investigates the effect of ethanol and Moringa antioxidant on the performance and emission characteristics of a Soybean biodiesel blend (B15, B20, and B25) using a direct injection, four-stroke, naturally aspirated, water-cooled single-cylinder diesel engine equipped with SCADA software. The effect of reaction parameters on FAEE yield such as, time, catalyst concentration, molar ratio of alcohol to oil, and blending quality, was optimized using the one factor at a time experimental technique. The maximum yield of 97.8% biodiesel was produced at the ideal catalyst concentration, blending quality, alcohol to oil molar ratio, and time of 1 h, are 1%, 12:1, and 500 rpm, respectively. The Rancimat method was used to assess the oxidative stability of pure biodiesel after the natural antioxidant (extracted from Moringa leaf) was added at concentrations of 1500, 2500, 3500, and 4500 ppm. The addition of antioxidants to biodiesel significantly increased its induction time from 4.52 to 19.98 h. Brake-thermal efficiency increased by 4.4% whereas brake-specific fuel consumptions decreased by 4.6% for B15E2M (15% SB+2E + M) when compared to B15. Emission characteristics of B25E2M showed higher reduction of CO, HC and NOx by 20.27%, 8% and 7% as compared to the B25 respectively. The physicochemical qualities, performance, and emission characteristics of B15 blends with additive are generally comparable to those of diesel fuel. In conclusion, both additives significantly improved the combustion performance of soybean biodiesel blend.

Enhancing biodiesel stability and performance: synthesis and extraction of macauba biodiesel for sustainable engine applications

The demand for sustainable fuels has driven research on biodiesel blends’ combustion characteristics and emissions. The study evaluates the performance of macauba and soybean biodiesel blends by analyzing torque, power, and fuel consumption indicators. The effects of leaf extract additives on engine performance are also assessed. Comparing macauba and soybean blends show similar load, brake power, and engine speed trends on response variables. However, slight variations in coefficients and significance levels indicate unique combustion and emission profiles for each blend. Understanding these distinctions is crucial for optimizing engine performance and emission control strategies. Parameters analyzed include brake-specific fuel consumption (BSFC), brake thermal efficiency (BTE), exhaust gas temperature (EGT), carbon monoxide (CO) emissions, hydrocarbon (HC) emissions, oxides of nitrogen (NOx) emissions, smoke opacity, cylinder pressure, heat release rate, and ignition delay. Blends 80% Soy Methyl and 20% Macauba Methyl Biodiesel (BSM20) demonstrates 5–10% superior fuel efficiency, 8–12% higher energy conversion capability, 3–5% lower exhaust temperatures, 10–15% reduced emissions, and 5–8% enhanced efficiency versus other blends and Diesel. It also shows 10–20% lower hydrocarbon and CO emissions, 15–25% reduced NOx, 20–30% lower particulate matter, and more efficient energy release during combustion. Optimizing heat release rate and ignition delay is crucial; BSM20 shows a 10–15% shorter ignition delay. Understanding blend distinctions is key for optimizing performance and emissions. BSM20 blend demonstrates superior fuel efficiency, energy conversion capability, lower exhaust gas temperatures, reduced emissions, and enhanced engine efficiency compared to other blends and Diesel. It also shows lower hydrocarbon, CO, and NOx emissions, reduced particulate matter emissions, and more efficient energy release during combustion. Optimizing heat release rate and ignition delay is crucial for cleaner combustion and improved engine performance.

Enhancing oxidative stability of biodiesel using fruit peel waste extracts blend: Comparison of predictive modelling via RSM and ANN techniques

This work harnessed the potentials of banana, mango, and palm fruit peels as green sources of natural antioxidants whose liquid extracts were recovered via supercritical fluid extraction (SFE) to improve biodiesel's low oxidative stability (OS). Response surface methodology (RSM) and artificial neural network (ANN) models were explored and compared in predicting the OS of the extracts' stabilized biodiesel. The induction period (IP) for the freshly synthesized (Y1) and 8-weeks stored (Y2) extracts-blended biodiesel was determined using Rancimat analyzer. Optimization of the biodiesel's IP was carried out using central composite design (CCD) for the chosen process variables namely extracts' dosage ratio, mixing speed, and reaction time against the response variable (IP). Accordingly, the optimal conditions that accounted for the maximum IP value of 17.59 h for Y1 were a dosage ratio of 1.24, a mixing speed of 496.66 rpm, and a reaction time of 64.99 min. Whereas, a corresponding dosage ratio of 0.94, a mixing speed of 430.27 rpm, and a reaction time of 46.71 min produced the highest IP (12.82 h) value for the response Y2. The predictive capability of both models was manifested based on the results and found to be within an acceptable range. However, the ANN presented lower percentage errors and a high correlation coefficient (R2) corresponding to 0.9710 and 0.9462 for Y1 and Y2 respectively, demonstrating the model's superior predicting ability compared to 0.9428 and 0.8091 for the same responses presented by RSM. Finally, the limitation of the traditional RSM chemometric approach can be overcome by utilizing the ANN line of optimization which proved to be more accurate in the prediction ability.

Binary Effect of Tertiary Butylhydroquinone and Butylated Hydroxytoluene Additives with The Addition of Glycerol Monostearate to Improve Oxidative Stability of Palm Oil-Based Biodiesel

Biodiesel is a renewable and environmentally friendly alternative to conventional diesel fuel. However, like any fuel, biodiesel is subject to oxidation, which can negatively impact its quality and performance when kept for long-term. The addition of binary antioxidants such as TBHQ:BHT had been proven to improve oxidation stability of biodiesel. Combining surfactant such as GMS into single antioxidant had been proven to solve its insolubility issue. However, the implementation of mixing binary antioxidants and surfactant has not been done yet. Therefore, this research analyzed the effect of single antioxidant, binary antioxidants, and binary antioxidants with GMS (100 ppm) addition into biodiesel and biodiesel blend B35. The effect was observed within 8 weeks storage period. The result showed that B35 did not have any significant impact. While in pure biodiesel samples, B100-bi and B100-bi+GMS had a slight difference in the results of oxidative parameters. B100-bi showed the best result in induction period and kinematic viscosity. Rancimat test showed 170 hours for B100-bi and 168 hours for B100-bi+GMS. While B100-bi+GMS indicated as the best additives in term of acid number, iodine value, and dispersion test. Hence, the addition of surfactant into binary antioxidants showed similar performance with B100-bi but with slightly better solubility.

Evaluation of the effects of oxygen enrichment on combustion stability of biodiesel through a PSO-EMD-RBF model: An experimental study

<abstract> <p>In this study, we processed the flame images of biodiesel combustion in industrial furnaces, classified and evaluated flame states using digital image processing techniques, and proposed a combustion stability index (CSI) using the particle swarm optimization (PSO) algorithm. In order to more accurately predict the combustion stability under different oxygen concentrations, we proposed a method that combines the Multi-Input Radial basis function neural network (RBF-NN) with empirical mode decomposition (EMD). Initially, the EMD method was employed to decompose the original time series of CSI. Subsequently, a decomposition model incorporating initial parameters and CSI was established using the radial basis function. The results of the computations indicate that the EMD-RBF-NN model significantly outperforms existing models in enhancing the accuracy of CSI.</p> </abstract>

Antioxidant properties of some plant extracts and effect of their addition on the oxidation stability of biodiesel

The extracts from the leaves of Deschampsia antarctica É. Desv., Camelina sativa (L.) Crantz, and Camellia japonica L. plants, as well as from defatted Camelina sativa and Silybum marianum seedcakes were investigated as potential additives for improvement of biodiesel stability against oxidation. Composition of the extracts was studied by means of HPLC, and antioxidant properties were evaluated using the Folin-Ciocalteu assay and the DPPH test. The oxidation of biodiesel was monitored during the accelerated procedure at 43C, with the changes in the acid number of biodiesel samples being the criteria of this process. In spite of significant distinctions in the content of various phenolic compounds, all the extracts were found to possess high antioxidant activity and decelerate biodiesel oxidation by 9-26%. The data did not reveal a directly proportional relationship between the antioxidants content in the extract, on the one hand, and the enhancement in biodiesel stability, on the other hand; various extracts had different influence on the behaviour of biodiesel from rape and Camelina seed oils. The results obtained are consistent with the assumption that there is no universal stabilizer for different types of biodiesel and indicate the prospects on searching for novel antioxidants of natural origin to inhibit oxidative processes.

Survey on Antioxidants Used as Additives to Improve Biodiesel’s Stability to Degradation through Oxidation

A major problem that limits the use of biodiesel is maintaining the fuel at the specified standards for a longer period. Biodiesel oxidizes much more easily than diesel, and the final oxidation products change its physical and chemical properties and cause the formation of insoluble gums that can block fuel filters and the supply pipes. This instability of biodiesel is a major problem and has not yet been satisfactorily resolved. Recently, the use of biodiesel has increased quite a lot, but the problem related to oxidation could become a significant impediment. A promising and cost-effective approach to improving biodiesel’s stability is to add appropriate antioxidants. Antioxidants work better or less effectively in different biodiesel fuels, and there is no one-size-fits-all inhibitor for every type of biodiesel fuel. To establish a suitable antioxidant for a certain type of biodiesel, it is necessary to know the chemistry of the antioxidants and factors that influence their effectiveness against biodiesel oxidation. Most studies on the use of antioxidants to improve the oxidative stability of biodiesel have been conducted independently. This study presents an analysis of these studies and mentions factors that must be taken into account for the choice of antioxidants so that the storage stability of biodiesel fuels can be improved.