Acid Number Value Research Articles

Valuation of Ethanol Grade on the Robustness of Acid Number Determination in Fish Oil

The robustness evaluation of the acid number analysis method in fish oil was carried out to see the effect of the type of ethanol used as a solvent in the titration process. The types of ethanol used in this study were pro analysis grade, pharma and food grade, and technical grade. The acid number values (mgKOH/g) in fish oil with various solvents obtained were 2.3955±0.3211 for pro analysis grade; 2.7932±0.2983 for pharma and food grade; 2.7812±0.3362 for technical grade 1; 2.7031±0.3405 for technical grade 2. The acid number for all types of ethanol has a value that is in accordance with the requirements of SNI 8467: 2018 where the acid number value must be less than 3 mgKOH/g. However, if the measurement uncertainty value is included in the calculation, only the pro analysis grade ethanol solvent has an acid number value that is in accordance with the requirements of SNI. The results of the ANOVA test also showed that there was a significant difference in the variation of ethanol types for determining acid numbers because the calculated F value (13.9004) was greater than the F table (3.0984). Therefore, the solvent that must be used in the method of determining acid numbers in fish oil is pro analysis grade ethanol.

Experimental study of the effect of oil polarity on smart waterflooding in carbonate reservoirs

This study investigates the influence of oil polarity on interfacial tension (IFT), contact angle, oil recovery, and effluent pH in smart water and Low-salinity water injection. The results indicate that the interaction between the hydration shell of ions and the polar components (PCs) of oil is crucial. Increasing oil polarity enhances the potential for interaction with the hydration shell of ions, leading to reduced IFT, altered wettability, and improved oil recovery; which could be boosted by the contribution of a higher number of anions in the smart water bulk through the enhancement of their interaction with the PCs (especially acidic components) of oil. The study demonstrates that increasing the SO42− concentration in seawater increased oil recovery for oils with higher acid component content, as indicated by total acid number values of 0.87, 0.99, and 1.32 mgKOH/g, the tertiary oil recovery factors for these oils were 61.10%, 69.82%, and 87.09%, respectively. The effluent pH results align with the findings of contact angle and oil recovery, confirming the dominant influence of anions on oil recovery. The interaction between the PCs of oil and the hydration shell of ions is thus highlighted as a critical factor in the observed outcomes.

Comparative assessment of beef characteristics from young bulls of different breeds and the influence of storage conditions on meat quality indicators

Comparative assessment results for quality indicators of meat samples obtained from Black Pied, Simmental and Aberdeen Angus young bulls and the influence of different temperature conditions on the quality of vacuum-packed beef during refrigerated storage are presented. The general chemical composition, physicochemical properties, and biological value of the samples based on the content of nonessential and essential amino acids were determined, as well as the protein quality index (PQI) and amino acid score. Analysis of the general chemical composition revealed higher moisture and protein content and the lowest fat content in Black Pied beef compared to other breeds. The amino acid composition of the protein showed a higher content of essential amino acids and the highest PQI value in Simmental beef. According to the calculation results, higher amino acid scores for lysine (149.1% and 129.1%) and tryptophane (200.0% and 240.0%) were noted in meat from Simmental and Aberdeen Angus young bulls, respectively. For the process of storing vacuum-packed meat in a cooled (at a temperature of 2.0 ± 0.5 °C) and superchilled state (minus 2.0 ± 0.5 °C) at a relative air humidity of 85%, a comparative analysis of changes in free amino acids and dynamics of hydrolytic and oxidative spoil- age of meat samples from various breeds was conducted. After 21 days of storage in a superchilled state, the content of free amino acids in Black Pied, Simmental and Aberdeen Angus beef was lower by 13.1% (P > 0.05), 24.1% (P ≤ 0.05) and 17.0% (P ≤ 0.01) compared to storage in a cooled state, respectively. For all studied samples stored in a cooled state, the acid number values were 40% to 41% (P ≤ 0.01) higher than in a superchilled state and peroxide number values were 20% to 23% (P ≤ 0.05) higher than in a superchilled state. It has been established that lowering the storage temperature of vacuum-packed beef helps to better preserve quality and ensure safety for meat from all breeds studied.

Physicochemical Characteristics and Technological Properties of Lupinus mutabilis Oil

AbstractThe aim of the presented study is to examine the physicochemical parameters of the lipids present in Lupinus mutabilis seed and to compare the results with the available data for other commonly used vegetable oils. The oil quality indexes, oxidative stability index (OSI), and melting characteristics are examined. Andean lupin oil has remarkably high oxidative stability (OSI = 65 h) comparable to high‐oleic oils counterparts. Quality parameters meet commonly accepted standards, including peroxide value (3.95 meq O2 kg−1) and p‐anisidine value (1.25). The acid number value is 1.85 mg KOH g−1. The iodine value is 110.27 g/100 g, while the enthalpy required to increase the temperature of the sample from −60 to 80 °C is equal to 57.41 kJ kg−1. The beginning of the melting event (Tonset) and the phase transition temperature (Tpeak) values for L. mutabilis seed oil are −29.46 and −22.63 °C, respectively. The presented results indicate the unusually high oxidative stability of the oil obtained from L. mutabilis seeds, which opens up a whole spectrum of application possibilities, e.g., designing blends with other commonly used vegetable oils to enhance their low stability.Practical Applications: The presented results provide insight into physicochemical parameters of the lipid fraction isolated from Lupinus mutabilis seeds. Andean lupin oil has very high oxidative stability, comparable to high‐oleic rapeseed and sunflower oils. Therefore, the identified potential use of the studied oils is, e.g. an additive that can increase the stability of commercial vegetable oils characterized by much lower oxidative stability.

Formulation of Drying and Non Drying Oil Alkyd Resin from Palm Oil (Elaesis guineensis jacq.) and Tuna Fish Oil (Thunnus sp.) toward Acid Number Value and Non Volatile Content as Surface Coating Resin

Resin is a polymer chemical substance that is made up of monomers from carbon and nitrogen. Alkyd resin, a surface coating resin, produced by polycondensation reaction between polybasic and polyhydric alcohols, modified with monobasic acids or their anhydrides, and drying oil at controlled temperatures. Alkyd resin is widely used in the paint and surface coating industries. The advantages of this resin are its strong chemical and thermal resistance, quick drying power, and inexpensive cost. Alkyd resins can be produced from natural oil (palm and tuna fish oil). Oil derived from palm and tuna fish is known as natural oil. Tuna fish oil includes 40.04 % oleic acid. The oleic content is suitable for use in the alcoholysis process in the production of alkyd resins. The major ingredients in this study were tuna fish oil and palm oil. The aim of this research is to determine the influence of a combination of palm oil:tuna fish oil ratio, amount of pthalic anhydride, and temperature of alcoholysis process on the value of acid number and non-volatile content of alkyd resin was investigated using a Completely Randomized Design (CRD).

TRANSESTERIFICATION OF TRIGLYCERIDES WITH PROPAN-2-OL CATALYSED BY SULFURIC ACID

Transesterification of sunflower oil triglycerides with propan-2-ol catalyzed by sulfuric acid has been studied. The effect of the homogeneous acid catalyst content and the triglycerides of sunflower oil : propan-2-ol molar ratio on the reagents conversion, selectivity of diisopropyl ether formation, the acid number and the color of reactions products on the iodine scale was determined. It was established that an increase in the sulfuric acid content from 1 wt. % up to 3 wt. % leads to a slight increase in the triglycerides conversion and a significant increase in the propan-2-ol conversion. A further increase in the acid catalyst content causes a decrease in the conversion of both triglycerides and alcohol. Comparison of the obtained results with the data on the reaction products composition allowed us to conclude that a significant increase in the propan-2-ol conversion with an increase in the sulfuric acid content to 3–4 wt. % due to the increase in the diisopropyl ether selectivity formation from 5% by an acid catalyst content of 1 wt. % to almost 65% by a sulfuric acid content of 4 wt. %. It is shown that an increase in the sulfuric acid content in the reaction mixture also leads to a significant increase in the reaction product's color according to the iodine scale - almost 5 times, which also indicates the course of side condensation reactions with the double bonds of higher fatty acids participation, which are part of triglycerides composition. It is established that the reaction product's acid number regularly increases with an increase in the acid catalyst content in the reaction mixture. It is shown that the reaction products acid number value is determined by the amount of acid catalyst used. It is established that the activity of the sulfuric acid in the sunflower oil triglycerides transesterification reaction is slightly lower than the activity of cation exchange resin KU-2-8. The cation exchange resin under the same conditions provides more than 15% higher triglycerides conversion with a lower reaction product's color on the iodine scale value and the absence of a diisopropyl ether formation side reaction. It is concluded that using sulfuric acid as a catalyst for triglyceride transesterification by propan-2-ol is entirely possible.

SYNERGISTIC EFFECT OF WATER AND CO-SOLVENTS ON THE HYDROTHERMAL LIQUEFACTION OF AGRICULTURAL BIOMASS TO PRODUCE HEAVY OIL

Hydrothermal liquefaction was performed on Alberta, Canada's agricultural biomass, corn stover and wheat straw, at an operating temperature of 300°C, initial reactor pressure of 600 psi and zero min retention time. Effects of adding co-solvents (methanol, ethanol, and 2-propanol) on yield and quality of heavy oil has been studied. 2-propanol exhibited to be a promising co-solvent that has improved the quality of heavy oil. Hydrothermal liquefaction of corn stover using a water−2-propanol mixture produced heavy oil having oxygen content of 18.8 wt.%, higher heating value of 32.17 MJ/kg, and total acid number value of 81.74 mg KOH/g oil. Hydrothermal liquefaction of wheat straw using water−2-propanol mixture produced heavy oil showing an oxygen content of 17.99 wt.% and higher heating value of 32.94 MJ/kg.

Research of ostrich fat properties when melting in electrochemically activated medium

In recent decades, there has been a growing scientific interest in various kinds of technologies using electro-activated solutions with high reactivity and representing a powerful toolkit for intensification of production processes. However, theoretical knowledge about the regularities of change in fat properties during melting in an electrolyte is rather fragmentary, scarce and often contradictory. The work is devoted to the study of the main factors influencing the change in physical and chemical properties and yield of fat in the process of melting using catholyte, to substantiate the feasibility of its use and develop an industrial line for obtaining fat. The object of studies was ostrich fat obtained by traditional method – by melting in water and by experimental technology – in catholyte as well as technological regimes of fat extraction. According to the data obtained, the fat melted at pH of catholyte 11, temperature 100 and 75 °С was characterized by low values of acid number – 0,45 mg KOH/g and 0,40 mg KOH/g, respectively. The opposite trend was observed with a successive decrease in the alkalinity of the ECA medium and an increase in the melting temperature of the fat, which led to an increase in the content of secondary oxidation products in the experimental samples. It was found that due to the high reactivity of the EСA medium, the temperature and pH of the catholyte increased, the intermolecular interaction within the fat phase decreased, which increased the mobility of lipid molecules relative to each other. The lowest values of fat viscosity (0,42 and 0,4 kPa?s) were recorded when treating fatty raw materials in catholyte with pH 10.5 and 11 and temperature 100 °С. It is shown that increasing the pH of the catholyte contributes to minimizing the values of peroxide number of ostrich fat, in contrast to the heating temperature. It is established that processing of raw materials in catholyte at 75 °C resulted in the yield of fat 88,4–90,1%, which is almost 1,4 times higher than when melted in water. In the wet method of mellowing in water, denaturation of protein structures and a higher degree of fat extraction can be achieved at a mellowing temperature above 75 °C, in contrast to the proposed method of processing raw materials.

Effect of tert-butylhydroquinone on biodiesel properties during extreme oxidation conditions

The use of alternative sources for fuel production has been gaining attention in the past years. Thus, the role of biodiesel seems to be crucial, as it can contribute to the sustainable economic growth of developing countries. The main raw materials for biodiesel production are vegetable oils, obtaining fatty acid methyl (or ethyl) esters through transesterification with methanol (or ethanol). The properties of these natural feedstocks can influence the quality of biodiesel. Specifically, its oxidative stability is usually low, not complying with the lower limit established by standards. As a consequence, some properties of biodiesel (especially viscosity and acid number) can vary during storage due to oxidation. In order to avoid these undesirable effects, antioxidant addition, as well as the selection of stable oils, is necessary. Among them, tert-butylhydroquinone (TBHQ) is one of the most popular additives. The aim of this work was to assess the evolution of some properties of biodiesel from different sources (cardoon, waste cooking, rapeseed and high-oleic safflower oil) during extreme oxidation conditions, evaluating the effectiveness of TBHQ addition on quality maintenance. As a result, the most unstable samples (cardoon and waste cooking biodiesel) required higher amounts of TBHQ (750 and 450 ppm, respectively) to comply with the standard (induction point = 8 h), whereas high-oleic safflower did not require any addition (induction point = 8.35 h). During extreme oxidation conditions, all the samples kept their viscosity and acid number values when the right amount of TBHQ was added, assuring their quality parameters during storage.

ANTIOXIDANTS’ EFFECT ON THE STORAGE OF DAIRY PRODUCTS WITH HIGH-FAT CONTENT

The article presents the research results of the antioxidants’ effect of various origins on the storage of dairy products with high-fat content. The quality change of such products was monitored by the oxidation product content. The antioxidants’ effect of natural origin and human-made origin on the change in the peroxide and acid numbers in spreads with food fibers during storage period for 15 and 30 days at a temperature of (20±2) ° C and (0...- 5) °C has been determined. A significant increase in the peroxide number occurs at a temperature of (20±2) °C. It has been established, that after 6 storage days under the given conditions, the indicator for the control sample increases 4 times, while for products with high-fat content with the addition of antioxidants "NovaSOL COF" and "GRINDOX 109" – 1.2 times. On the 12th storage day, the peroxide number in the spread without additives increased by 8.65 times, in the spread with the introduction of the natural flavoring agent "Caraway – elite flavor" – by 7.15, with the antioxidants "NovaSOL COF" and "GRINDOX 109" – by 4.45 and 4 times, respectively. There was a similar trend towards an increase in the acid number for the research samples of products with high-fat content. After 12 storage days, a significant increase in the value of the acid number has been found in the samples of spreads without antioxidants – 13 times, with the introduction of the natural flavoring agent "Caraway – elite flavor" – 7.8 times. Low acid number values are observed in the samples with the addition of the antioxidants "NovaSOL COF" and "GRINDOX 109", in comparison with other spreads. The obtained results are the basis for the development of recommendations for extending the storage life of products with high-fat content.

Purification of Used Cooking Oil by Alkali Neutralization and Bleaching of Bayah Natural Zeolite

Cooking oil that is used repeatedly at high temperatures will reduce the quality of cooking oil. This will trigger the hydrolysis and oxidation processes that will change the characteristics of the oil, such as an increase in free fatty acid levels and peroxide numbers. Purification of used cooking oil can be carried out physically and chemically. The physical purification of oil is carried out by using adsorbents, while chemically purification process is carried out with an alkaline solution. Physically, natural materials such as zeolite can be used, where zeolite is a natural rock or mineral which chemically has a large surface area to be used in the adsorption process. Chemically with alkaline solution you can use sodium hydroxide (NaOH). In this study, used cooking oil is purified by three stages of the process, namely despicing, neutralization and bleaching to comply with the SNI quality standards. The purpose of this study was to determine the optimum operating conditions for the purification of used cooking oil in accordance with the quality standards for cooking oil. based on the results obtained by adding a NaOH concentration of 19% in the neutralization process and a zeolite concentration of 90% can reduce the acid number value of 2.4 mg NaOH/gr, the peroxide number is 7 mekO2/kg, the color degradation of used cooking oil is 51.83%.

Research on the effect of the effective microorganisms, silver solution and colloidal nanosilver addition on the engine oil acid number (TAN)

In the article, acid number as a parameter characterizing engine oil were characterized. The next part of the article discusses the phenomenon of aging and degradation of engine oil. The factors that influence on this phenomenon have also been analyzed. In the further part of the article, the methodology of testing the used oil samples with the addition of effective microorganisms and silver solution was described. In the main part of the article the measuring test stand and acid number value for fresh and used oil compared to oils with the addition of microorganisms and a solution of silver and colloidal silver was shown. Next the analysis of the influence of these additives on the acid number value was made. The article was completed conclusions.

Oxidative stability performance of new azophenol derivatives as antioxidants in working fluids for high-temperature solar applications

In solar applications, the oxidation stability of heat transfer fluidsreducesthe thermal energy storage cost. In this work, the effect of new two azophenols, namely -2-sec-butyl-4-((3-chlorophenyl) diazenyl) phenol and 2-sec-butyl-4-((3-nitrophenyl) diazenyl)phenol, was studied to produce an oil that has good characteristics and is compatible with metals such asstainless steel, carbon steel, aluminum, and copper, which are generally used to manufacture pipes, heat exchangers, receivers, and storage tanks. The prepared compounds were characterized using spectroscopy analysis. The prepared compounds were added to a heat transfer fluid under operating conditions in the presence of iron and copper as catalysts. At different time intervals, the samples were tested by measuring the total acid number value. The results of this measurement show that compound II performed better than compound I. Additionally, the quantum chemical parameters were calculated. The theoretical calculations were compatible with the experimental results.

Oxidation Studies on Mineral Insulating Oil Using an Accelerated Method with Continuous Online Monitoring

In this study, an alternative method was applied to evaluate the accelerated oxidation of mineral insulating oils using continuous real time monitoring, with smaller samples and lower experimental times than the standard ASTM D2440 method. Using this method, the influence of temperature and presence of a metal catalyst on the oxidation behavior was evaluated. The activities of commercial metal passivators and antioxidants were also studied at different conditions. The addition of the metal passivators (BTA: 1,2,3-benzotriazole, and Irgamet-39: n-(1,2,3-benzotriazol-1-methyl)-n-alkylamine) at low concentrations (8 mg/kg) increased the induction period (IP) of doped samples. Furthermore synergetic effects on retarding the oxidation reactions when using both metal passivators and two commercial antioxidants (DBPC, 2,6-di-tert-butyl-p-cresol, and Irganox L115, 2,2'-thiodiethylen-bis(3,5-di-tert-butyl-4 hydroxyphenyl-proprionate) were observed, increasing the IP values by up to 25 times when compared to a fresh oil sample. Experimental IP values from this newly proposed technique (up to 10 h) may be used to estimate the Total Acid Number values obtained when using the ASTM D2440 method (164 h).

Biodiesel Dry Purification Using Unconventional Bioadsorbents

The dry washing method is an alternative to replace water washing, thereby reducing the negative impacts of contamination. However, commercial adsorbents come from industrial processes that, due to their composition, may not be such a sustainable resource in the global biodiesel production process. In this study, the use of organic residues, such as sawdust, coconut fiber, nutshell, rice husk, and water hyacinth fiber, were proposed as bioadsorbents for the purification of biodiesel from waste cooking oil. Quality parameters such as the acid number, water content, and free and total glycerin content were evaluated and compared with those after purification with commercial adsorbents (Magnesol and Amberlite BD10DRY). Promising results were obtained using sawdust in the purification process, achieving a reduction in the acid number value of 31.3% respect to the unpurified biodiesel. Indeed, the reduction with sawdust was more efficient than with Amberlite BD10DRY (that increased the acid number). In addition, sawdust reduced free glycerin by 54.8%, again more efficient than Amberlite BD10DRY. The total glycerin values were similar between commercial adsorbents and sawdust. Water content after purification with sawdust was similar to the obtained with Amberlite BD10DRY and better than with Magnesol (399, 417, and 663 mg/kg respectively). These results show that sawdust can be used as an alternative bioadsorbent in a dry purification method for biodiesel, generating less environmental impact.

TECHNOLOGICAL, ANTIOXIDANT, ANTIMICROBIAL AND SENSORY PROFILES OF SELECTED KINDS OF GRAPE OILS

The aim of this study was to determine technological (fat content, acid number, peroxide value, oxidation stability, fatty acid profiles), antioxidant (DPPH method), antimicrobial activity (antibacterial and antifungal) and sensory profiles of 4 kinds of Slovak grape seed oils (commercial, oil from white grape variety, oil from blue grape variety and oil made from grape after alcoholic fermentation). The fat content ranged from 95.86 % (blue grape variety oil) to 98.23 % (commercial oil). The values of acid number ranged from 0.15 mg KOH. g-1 (blue grape variety oil) to 0.90 mg KOH. g-1 (commercial oil) and of peroxide number from 2.75 mmol O2. kg-1 (blue grape variety oil) to 8.91 mmol O2. kg-1 (commercial oil). Values of antioxidant activity (DPPH method) ranged from 47.61 mg TEAC. l-1 (commercial oil) to 75.30 mg TEAC. l-1 (blue grape variety oil) and oxidation stability from 2.75 h (commercial oil) to 8.91 h (blue grape variety oil). The predominant acid in all samples was essential omega-6 fatty acid linoleic acid, which can decrease the cholesterol levels and it is necessary for the activity of cell membranes. Its content differed from 69.43± 0.00 % in commercial oil to 72.75± 0.04 % in blue grape variety oil. Grape oils inhibited microscopic fungi (Candida albicans), gramnegative G- (Yersinia enterocolitica, Salmonella enterica subs. enterica) and grampositive G+ (Bacillus cereus, Staphylococcus aureus subs. aureus) bacteria. Sensory analysis of tested oils was evaluated good, with the best results in commercial oil, especially consistency and overall appearance. The results of this work characterize and accentuate the qualities of edible grape oils, as a nutritionally valuable food for the nutrition of the human organism.

PROGNOSTICATION OF STORAGE TERMS FOR PASTEURIZED SAUSAGES WITH ACTIVE PACKAGE ELEMENTS

The work is devoted to optimization modeling of an influence of pasteurization with oxygen absorbers on spoilage processes of lipids of boiled sausage products. According to the results, the influence on changes of peroxide and acid numbers of lipids of small sausages, pasteurized at presence of an oxygen absorber, has been mathematically prognosticated. At mathematical modeling, mathematic packages MathCad and «Data analysis» (ЕТ) MSExcel were used. The experiment was planned according to the plan of full factorial experiment. The dependence as to the influence of the recipe composition of sausage products at their storage on peroxide and acid number values has been revealed. The conducted modeling allows to state the adequacy of obtained regressive equations. The obtained empirical dependencies allow to prognosticate a storage term of boiled sausages products, pasteurized with elements of active package at using protecting barrier multi-layer polymeric materials. The optimization modeling was conducted by structuring a mathematical model as an analytic expression that reflects the connection of factor signs with a parametric index. The obtained response functions are adequate and have a high correspondence to real experimental data. Storage terms were substantiated for small sausages, which recipe included beef, pork, poultry meat and also food emulsions, based on animal proteins. The process of repeated pasteurization was conducted at temperature 85–90 °С during 15–20 minutes

Refining and Physicochemical Test of Tengkawang oil Shorea stenoptera Origin Sintang District West Kalimantan

The oil from Tengkawang fruit (Shorea stenoptera) has been processed by indigenous people in West Kalimantan as cooking oil and margarine. This research examined the degumming process, neutralization and bleaching of Tengkawang oil to reduce the high acid and peroxide numbers resulted from traditional processes. The oil produced at each stage of the refining process were tested for their physicochemical properties by calculating the acid, iodine and peroxide numbers. Respectively, the values of acid number (mg NaOH/100 g sample), iodine number (g I2/100 g sample), and peroxide number (mg equivalent O2/kg sample) for initial Tengkawang fat were 10.14; 32.49 and 10.98; for Tengkawang fat after degumming were 10.25; 28.81 and 10.88); for Tengkawang fat after neutralization were 6.09; 30.52 and 5.57; and for Tengkawang fat after bleaching were 6.14; 31.39 and 5.55. The acid number of Tengkawang oil after neutralization process with variation of volume 5, 7.5 and 10 % were 7.83; 6.14 and 3.12 mg NaOH/100 g sample, respectively. The refining process increased the quality of physicochemical properties of Tengkawang oil to fall into industrial grade.

EXTRACTION OF NAPHTHENIC ACIDS FROM ACIDIC PETROLEUM CRUDE OIL UTILIZING 2-METHYLIMIDAZOLE WITH THE AID OF Ca/Al2O3 AND Ce/Al2O3 CATALYSTS

Naphthenic acids (NAs) is one of the major sources of corrosion in oil pipelines and distillation units in crude oil refineries. Removing NA compounds from crude oils is regarded as one of the most crucial processes in heavy oil upgrading. Catalytic deacidification method had been developed in order to reduce the total acid number values in crude oil. Crude oil from Petronas Penapisan Melaka had been chosen to be studied with original total acid number (TAN) of 2.43 mg KOH/g. The parameters used were different catalyst calcination temperatures, catalyst loading, reagent concentration, reaction times and reaction temperature. Acid removal agent of 2-methylimidazole in ethanol and monometallic calcium and cerium doped with alumina were used as a catalyst. The results showed that with the aid of catalyst, the TAN can be reduced to lower than 1 mg KOH/g. Catalyst of Ca/Al2O3 calcined at 900oC gave a better reduction than Ce/Al2O3 with 83.54% of TAN reduction (2.43 to 0.4) for Ca/Al2O3 catalyst and 71.19% (2.43 to 0.7) for Ce/Al2O3 catalyst. The best catalyst underwent several characterization methods such as X-Ray Diffraction Spectroscopy (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetry Analysis (TGA-DTA) for its physicochemical properties. It can be concluded that catalytic deacidification method was effective in extracting NAs from the crude oil thus lowered the TAN value to less than 1 mg KOH/g.
 Keywords: Naphthenic acids; Crude oil; Catalysts

ASSESSMENT OF ANTIOXIDANT ACTION OF CURCUMIN DURING STORAGE OF COMMERCIAL BIODIESEL PRODUCED FROM SOYBEAN OIL AND BEEF TALLOW

Biodiesel has emerged as an alternative source to fossil fuels. In Brazil, to assign a good quality to biodiesel, regarding oxidation stability, it is necessary that the biodiesel shows a minimum of 8 h of induction period (IP), determined at a temperature of 110 ºC by the Rancimat method, in accordance with Resolution No. 45/2014 of ANP. As, in most cases, the biodiesel produced does not meet the established standards of oxidation stability, it is necessary to add antioxidants, which slow down the oxidative process. Thus, this paper proposes a study on the action of curcumin, a natural antioxidant, on commercial biodiesel produced from blending 80% soybean oil and 20% beef tallow. In this study, samples were stored for 180 days at 43 ºC, according to ASTM D4625 recommendations. It was possible to observe that curcumin ensured greater oxidation stability to biodiesel and lower acid number values during the period of storage. Kinetic studies showed that samples with the addition of curcumin showed the highest value of activation energy for the oxidative degradation process, demonstrating that adding this natural antioxidant makes biodiesel more resistant to oxidation.