Quantification of styrene-butadiene rubber swelling as a function of the toluene content in gasoline: A new method to detect adulterations of fuels (original) (raw)
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Influence of solvent addition on the physicochemical properties of Brazilian gasoline
Fuel, 2008
The influence of several solvents (anhydrous ethanol, white spirit, alkylbenzene AB9, diesel) on the physicochemical parameters of gasoline was studied according to ASTM international standard methods. The parameters investigated (distillation curves, density, Reid vapor pressure) showed differentiated behavior, depending on the class of the solvent (oxygenated, light and heavy aliphatic, aromatic) and the quantity added to the gasoline. The azeotropic mixtures formed by ethanol and hydrocarbons showed a strong influence on the behavior of the distillation curves and the location of the point of a sudden change in temperature was shown to be a possible way to detect adulterations and determine the quantity of solvent added to the gasoline.
Estimation of resistance of engine rubber sealants to influence of mixed diesel fuel
Voprosy Khimii i Khimicheskoi Tekhnologii, 2021
The sorption-diffusion properties of rubbers in contact with fuels containing methyl esters of fatty acids derived from non-food raw materials have been studied. The hypothesis was advanced according to which there is a dependence of oil resistance of rubbers on their solubility parameter of butadiene-nitrile rubber. The properties of standard oil-resistant rubbers based on butadiene nitrile rubbers of SKN-18 and SKN-40 brands were compared with those of SKN-18-based rubber and Byprene 110 chloroprene-based rubber, to each of them 30% of the plasticized polyvinyl chloride was added. It was found that the contact with the fuel composition, which consists of 70% diesel fuel and 30% methyl esters of fatty acids made from technical sunflower oil, has the strongest destructive effect on all experimental samples of rubber except for rubber-based rubber of SKN-40 brand. It was determined that SKN-40-based rubber, which is characterized by the maximum solubility parameter, is the most stabl...
Static and Dynamic Studies of Gasoline in View of its Octane Number and its Toxic Effect
JOURNAL OF ADVANCES IN CHEMISTRY
Gasoline come primarily from petroleum cuts, it is the preferred liquid fuel in our lives. Two gasoline samples of octane numbers 91 and 95 from Saudi Arabia petrol stations were studied. This study was achieved at three different temperatures 20oC, 30oC and 50oC representing the change in temperatures of the different seasons of the year. Both the evaporated gases of light aromatic hydrocarbons (BTEX) of gasoline samples inside the tank were subjected to analyze qualitatively and quantitatively via capillary gas chromatography. The detailed hydrocarbon composition and the octane number of the studied gasoline samples were determined using detailed hydrocarbon analyzer. The idea of research is indicating the impact of light aromatic compounds in gasoline on the toxic effect of human and environment on the one hand, and on octane number of gasoline on the other hand. Although the value of octane number will be reduced but this will have a positive impact on the environment as a way t...
SAE International Journal of Fuels and Lubricants, 2014
The compatibility of elastomeric materials used in fuel storage and dispensing applications was determined for test fuels representing neat gasoline and gasoline blends containing 10 and 17 vol.% ethanol, and 16 and 24 vol.% isobutanol. The actual test fuel chemistries were based on the aggressive formulations described in SAE J1681 for oxygenated gasoline. Elastomer specimens of fluorocarbon, fluorosilicone, acrylonitrile rubber (NBR), polyurethane, neoprene, styrene butadiene rubber (SBR) and silicone were exposed to the test fuels for 4 weeks at 60°C. After measuring the wetted volume and hardness, the specimens were dried for 20 hours at 60°C and then remeasured for volume and hardness. Dynamic mechanical analysis (DMA) was also performed to determine the glass transition temperature (T g). Comparison to the original values showed that all elastomer materials experienced volume expansion and softening when wetted by the test fuels. The fluorocarbons underwent the least amount of swelling (<25 %) while the SBR and silicone samples exhibited the highest level of expansion (>100%). The level of swelling for each elastomer was higher for the test fuels containing the alcohol additions. In general, ethanol produced slightly higher swell than the oxygen equivalent level of isobutanol. When dried, the fluorocarbon specimens were slightly swollen (relative to the baseline values) due to fuel retention. The NBRs and neoprene exhibited shrinkage and embrittlement associated with the extraction of plasticizers. SBR also experienced shrinkage (after drying) but its hardness returned to the baseline value. The dried volumes (and hardness values) of the silicone, SBR and fluorosilicone rubbers closely matched their original values, but the polyurethane specimen showed degradation with exposure to the test fuels containing ethanol or isobutanol. The DMA results showed that the test fuels effectively decreased T g for the fluorocarbons, but increased T g for the NBR materials. The T g values other elastomers were not affected by the test fuels.
2012
Due to dependence on the use of gasoline, traders see an opportunity to increase their profit by adding solvents such as ethanol, kerosene, turpentine and diesel. Attenuated total reflectance with Fourier transform infrared spectroscopy (ATR-FTIR) is a fast and nondestructive technique and requires little sample. In this work, the applicability of ATR-FTIR for detection of adulteration of Brazilian gasolines using liquid-liquid aqueous separation and chemometric tools was evaluated. Gasolines from 15 gas stations from the cities of Tietê, Ibaté and São Carlos (State of São Paulo) were acquired. Three data sets were generated: pure gasolines, polar phase and aqueous phase. The partition procedure aids in the identification of possible adulterants, since ethanol, present in Brazilian gasoline, presents strong peaks in the IR spectra. By IR spectra analysis methanol was found in the polar fraction of a sample, a novelty in the "gasoline tampering procedure". The same partition procedure was applied on samples spiked with methanol (MTH), ethanol (ETH), turpentine spirit (TUS) and toluene (TOL) from 0 to 25% yielding twelve datasets. It was found that identification of adulterated gasolines can be performed using spectra without partition but the quality of PCA separation is increased when pure, nonpolar and polar fraction spectra are concatenated, due the increase of chemical information. PLS models presented standard errors of cross-validation of 1.36%, 4.10%, 1.92% and 2.34% for MTH, ETH, TUS and TOL, respectively. The tampered sample presented 8.93% of methanol, using the developed model.
Fuel, 2012
Ethanol has become one of the main components for reformulated fuels because it is able to comply with environmental regulations. Biofuels have great advantages due to their physical and chemical characteristics, raw materials and production costs. However, they also have some disadvantages, mainly in terms of their compatibility with existing materials. Some components that are normally compatible with gasoline can be degraded by the presence of ethanol in fuel. The aim of this study was to evaluate the physical and chemical behavior of different polymeric materials typically used in autoparts, exposed in a mixture of gasoline and ethanol. To evaluate the resistance to degradation of the polymer samples, a continuous immersion test was performed according to SAE 1748. The effects of the 20% ethanol À80% gasoline mixture (E20) were examined by comparing changes in gain/loss of mass and by measuring the ShoreD hardness of the material at the end of exposure. The characterization of polymers was carried out before and after exposure by using the techniques of differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and Fourier Transform Infrared Spectroscopy (FTIR). In general, polymeric materials submerged in gasoline showed negligible changes in mass. Samples of POM, HDPE, PA6/6 and PA6 exposed to E20 showed mass increases below 10%. The chemical structure and mechanical properties (hardness) of the evaluated polymers were not significantly affected by the E20 blend with the exception of PA66. Since significant changes were observed in the thermal properties of this polymer, it can be concluded that it was at the limit of compatibility.
Journal of Chromatography A, 2003
The primary standard test method used for the determination of gasoline diluent in used engine oils is method D 3525-93 of the American Society for Testing and Materials (ASTM), which involves direct injection of used oil onto a packed GC column and flame ionization detection. Recently, we have utilized a new headspace sampling method: headspace solvent microextraction (HSM), for GC and GC-MS analysis of gasoline diluent in used engine oils. High resolution capillary columns can be used without the necessity for the use of inlet cryogenic cooling or expensive sampling interfaces. This analytical method, which we generically refer to as headspace microdrop analysis yields results comparable to those obtained using the ASTM method, with the added benefit that it allows the quantification of individual volatile diluent components, including benzene, toluene, ethylbenzene and the xylenes. (J.M. Kokosa). mass of the sample used.
The criminal act of fuel (gasoline) adulteration still remains a global worry due to its environmental, health and economic effect. Current methods for the detection of fuel adulteration have not been effective in most developing countries due to the associated cost of implementation. Therefore, there is the need for a fast, reliable and cheaper approach for screening of adulterants in fuel. This study combined FTIR analyses with Chemometric (multivariate) techniques for qualitative and quantitative determination of four possible adulterants: kerosene, diesel, naphtha and premix in gasoline. Synthetic admixtures prepared by mixing the gasoline with varying proportions of the adulterants were obtained and used for the model calibration. Soft Independent Modeling Class Analogy (SIMCA) classification and Partial Least Square (PLS) regression methods were the Chemometric techniques employed. The SIMCA classification model developed predicted the type of adulterant present at an error rate of 6.25% for Kerosene and naphtha, and 12.5% for premix. However, no prediction error was recorded for classifying samples contaminated with diesel. The PLS regression model was able to predict the concentrations of adulterant with prediction errors lower than 5% for all adulterants ABOUT THE AUTHORS
Journal of Chemometrics, 2011
Samples of commercial gasoline, from the National Program of Fuel Quality Monitoring of the National Petroleum Agency, were collected from gas stations located in the Midwestern state of Sao Paulo, Brazil, and analyzed by several physicochemical standard methods established by ANP Resolution no. 309. Also, important information related to tampering was analyzed with the marker solvent. Statistical analysis and exploratory chemometric were employed to discriminate the presence of markers of solvents in commercial gasoline. The results showed that statistical and chemometric parameters such as atmospheric distillation temperatures T10 and T90, RON, benzene and saturated and aromatic hydrocarbons satisfactorily describe the presence of marker solvent, usually with a probability exceeding 70%. Furthermore, after optimizing the SIMCA algorithm, sensitivity in the training set with cross-validation leave-one-out (83.8%) and the set of prediction (77.1%) were revealed. The proposed method will become indispensable and recommended for discriminating samples of fuels for commercial applications in routine monitoring programs and quality control.