Benzene In Gasoline Research Articles

Fabrication, characterization and performance analysis of different Ag/PVA nanocomposite membranes for debenzenation of model pyrolysis gasoline using pervaporation

ABSTRACT According to EURO IV and EURO V, benzene in gasoline should not exceed 1 volume%, to prevent environmental pollution and health risks; hence benzene must be removed from pyrolysis gasoline (octane booster), before blending with gasoline. Polyvinyl alcohol (PVA) based membranes are quite effective for pervaporative separation of hydrocarbon mixtures. The main objective of this work is to fabricate insitu Ag/PVA nanocomposite membranes, using simple solution casting approach, for pervaporative separation of benzene from model pyrolysis gasoline (mixture of benzene/1-octene). Debenzenation of pyrolysis gasoline using PVA-based polymeric membranes was not reported by earlier researchers. The impact of incorporation of nano-Ag in the PVA matrix, on the pervaporative performance of the PVA membrane towards benzene, based on the swelling coefficient, fractional free volume, total flux, separation factor and activation energy, is the novelty of this study. Scanning Electron Microscopy, Transmission Electron Microscopy, mechanical strength, UV-Vis spectroscopy, Fourier Transform Infrared Spectroscopy were used to characterize all the fabricated membranes. The most suitable composite membrane for the intended purpose was identified. The maximum flux and highest separation factor of the said membrane are 4.05 kg/m2/h and 5.51 respectively at 343K operating temperature and 1 mm Hg downstream pressure.

Gasoline-station workers in Brazil: Benzene exposure; Genotoxic and immunotoxic effects

Chronic exposure to benzene is a risk factor for hematological malignancies. Gasoline-station workers are exposed to benzene in gasoline, via both inhalation and dermal contact (attendants and managers) or inhalation (workers in the on-site convenience stores and offices). We have studied the exposure of these workers to benzene and the resulting genotoxic and immunotoxic effects. Levels of urinary trans, trans-muconic acid were higher among gasoline-station workers than among office workers with no known exposure to benzene (comparison group). Among the exposed workers, we observed statistically significant biological effects, including elevated DNA damage (comet assay); higher frequencies of micronuclei and nuclear buds (CBMN assay); lower levels of T-helper lymphocytes and naive Th lymphocytes; lower CD4 / CD8 ratio; and higher levels of NK cells and memory Th lymphocytes. Both groups of exposed workers (inhalation and inhalation + dermal routes) showed similar genotoxic and immunotoxic effects.

ANÁLISIS DEL CONTENIDO DE BENCENO EN LAS GASOLINAS Y ESTIMACIÓN DE EMISIONES DE ESTE COMPUESTO AL AMBIENTE

Use of gasolines has a primordial interest in the ecological area, due to the emissions generated by combustion engines. In order to maintain a good air quality, it is necessary to control several gasoline quality parameters. Mexico City is a metropolis with 4 421 797 vehicles registered in 2014, therefore air quality problems are constantly present. Mexican gasoline quality specifications are regulated by Mexican Official Standard NOM-016-CRE-2016. Benzene, one of the compounds regulated by NOM-016-CRE-2016, is known to be a carcinogenic agent. Moreover, it is considered that the presence of benzene in gasoline can affect population health due to its volatility, which gets it to be in contact with the atmosphere and consequently with the population. In this work, the average amount of benzene present in gasoline commercialized in Mexico City was quantified by ASTM D5769-15. Results showed it was 0.361 % in Magna gasoline, whereas the average amount of benzene present in imported gasoline was 0.55 % and 1.28 % in the gasoline produced locally by PEMEX National Refineries System. This value was higher than imported and commercialized gasoline. In addition, the estimation of benzene emissions by mobile sources was 354.79 t during 2017.

In vitro human skin permeation of benzene in gasoline: Effects of concentration, multiple dosing and skin preparation.

In vitro human skin benzene permeation was measured from gasoline formulations with benzene concentrations ranging from 0.8 to 10 vol% and from neat benzene. Steady-state fluxes (JSS), permeability coefficients (kp) and lag times (tlag) were calculated from infinite dose exposures. Permeation of benzene from small gasoline doses administered over a two-day period was also studied. The thermodynamic activity of benzene in gasoline at 30 °C was determined and the solution is near-ideal over the range from 0.8 to 100 vol%. JSS through human epidermal membranes were linear (R2=0.92) with concentration over the range from 0.8 to 10 vol%. JSS (μg/cm2/h) from gasoline (0.8 vol% benzene=6.99 mg/ml) through epidermis and full-thickness skin were 9.37±1.41 and 1.82±0.44, respectively. Neat benzene JSS was 566±138. Less than 0.25% of the total applied benzene mass from finite doses (10 μl/cm2) of gasoline was detected in receptor cells, and a small reduction of barrier function was observed from six total doses administered over 2 days. Application of these results to dermal exposure assessment examples demonstrates a range of systemic benzene uptakes that can be expected from occupational and consumer dermal exposures to gasoline, depending on the type and extent of exposure.

Impact of a new gasoline benzene regulation on ambient air pollutants in Anchorage, Alaska

The purpose of this study was to quantify the impact of a new U.S. Environmental Protection Agency (EPA) standard that limits the amount of benzene allowed in gasoline on ambient benzene concentrations. This new standard, together with two companion regulations that limit cold-temperature automotive emissions and the permeability of portable fuel containers, was expected to lower the levels of ambient benzene and other volatile organic compounds (VOCs) nationwide. In this study the impact of the gasoline benzene standard was evaluated in Anchorage, Alaska in a two-phase ambient air monitoring study conducted before and after the new gasoline standard was implemented. Gasoline sold by Anchorage retailers was also evaluated in each phase to determine the content of benzene and other gasoline components. The average benzene content in Anchorage gasoline was reduced by 70%, from 5.05% (w/w) to 1.53% (w/w) following the implementation of the standard. The annual mean ambient benzene concentration fell by 51%, from 0.99 ppbv in Phase 1 to 0.49 ppbv in Phase 2. Analysis suggests the change in gasoline benzene content alone reduced benzene emissions by 46%. The changes in toluene, ethylbenzene, and xylene content in gasoline between Phase 1 and 2 were relatively small and the differences in the mean ambient concentrations of these compounds between phases were modest. Our results suggest that cold winter communities in high latitude and mountainous regions may benefit more from the gasoline benzene standard because of high benzene emissions resulting from vehicle cold start and a tendency to develop atmospheric stagnation conditions in the winter.

Schiff Base Complex Method for the Preparation of Fullerene-Based Ni Nanocatalyst Used in the Hydrogenation of Benzene in Gasoline

A novel Schiff base complex method was used to prepare fullerene based Ni nanocatalyst, which is used in the hydrogenation of benzene. In this method, the functionalized fullerene with primary amine was reacted with ion of nickel and salicylaldehyde. The Schiff-base complex was formed in the presence of metal ion in order to obtain the corresponding metal complex. The nickel(II) complex on C60 shows significantly higher catalytic activity (20%) compared to the nickel bulk. Response surface methodology was also used to examine the cumulative effect of the various parameters namely, pressure, temperature, and time; thus, they were optimized to maximize the hydrogenation of benzene to cyclohexane. The optimized model predicted that the hydrogenation yield should remain maximum (very close to 100%) at reaction temperature of 150°C, reaction time of 180 min, and hydrogen pressure of 22.33 atm.

Determination of oxygenates and benzene in gasoline by various chromatographic techniques

A comparative analysis of gasoline samples has been performed using several chromatographic methods: one-dimensional detailed hydrocarbon analysis (DHA), which allows for determination of the individual component composition of a liquid petroleum product with identification by retention times; two-dimensional gas chromatography 2D-GC with identification by retention times; two-dimensional gas chromatography 2D-GC-MS with identification by retention times and mass spectra of compounds; and determination of the group composition of gasoline by multidimensional gas chromatography using traps and a reactor with a flame-ionization detector. The advantages and disadvantages of each procedure have been shown and application areas for each method have been specified.

Light Naphtha Isomerization Process: A Review

The isomerization process is gaining importance in the present refining context due to limitations on gasoline benzene, aromatics, and olefin contents. The isomerization process upgrades the octane number of light naphtha fractions and also simultaneously reduces benzene content by saturation of the benzene fraction. Isomerization complements catalytic reforming process in upgrading the octane number of refinery naphtha streams. Isomerization is a simple and cost-effective process for octane enhancement compared with other octane-improving processes. Isomerate product contains very low sulfur and benzene, making it ideal blending component in refinery gasoline pool. Due to the significance of isomerization to the modern refining industry, it becomes essential to review the process with respect to catalysts, catalyst poisons, reactions, thermodynamics, and process developments. The present research thrust in this field along with future scope of work is also discussed briefly. The isomerization process is compared with another well-known refinery process called the catalytic reforming process.

Rapid detection of gasoline by a portable Raman spectrometer and chemometrics

Identification of the gasoline purity is important for quality control and detection of gasoline adulteration. Principal component analysis and Raman spectroscopy were used to authenticate gasoline adulterated with methyl tert‐butyl ether (MTBE) and benzene. Gasoline could be clearly distinguished from gasoline adulterated with MTBE and benzene by a plot of the first principal component (x‐axis) against the second principal component (y‐axis). And the radial basis function neural network was used for quantitative prediction of the volume percentages of MTBE and benzene in gasoline based on Raman Spectra. The correlation coefficient (r) and mean absolute percentage error between predictive values and spiked values were 0.9907 and 0.9934 and 15.73 and 8.19%, respectively. Moreover, the Raman spectra of the samples were obtained with a portable Raman spectrometer. Therefore, the method is simple, effective, fast, does not require sample pre‐processing, and is promising for rapid gasoline detection. Copyright © 2012 John Wiley & Sons, Ltd.

Fast-HRGC method for quantitative determination of benzene in gasoline

Gasoline is a very complex mixture of hundreds different components and, from a toxicological point of view, benzene is the most hazardous one. Some of the methods recommended present many drawbacks, such as time-consuming. Thus, the need to develop fast methods for routine analysis of benzene is fundamental to the quality control of gasoline. Therefore, the present work compared two different capillary columns to develop a new method for routine analysis of benzene in gasoline by HRGC–FID. The quantitative analysis was carried out using external standard from 0.1%, 0.5%, 1.0%, 1.5% to 2.0% (v/v) of benzene in ethanol and in spiked gasoline. The results show that, using Fast-HRGC, it is possible to separate benzene and other 245 compounds found in gasoline in analysis time of 8min with high accuracy.

Benzene exposure: An overview of monitoring methods and their findings

Benzene has been measured throughout the environment and is commonly emitted in several industrial and transportation settings leading to widespread environmental and occupational exposures. Inhalation is the most common exposure route but benzene rapidly penetrates the skin and can contaminant water and food resulting in dermal and ingestion exposures. While less toxic solvents have been substituted for benzene, it still is a component of petroleum products, including gasoline, and is a trace impurity in industrial products resulting in continued sub to low ppm occupational exposures, though higher exposures exist in small, uncontrolled workshops in developing countries. Emissions from gasoline/petrochemical industry are its main sources to the ambient air, but a person's total inhalation exposure can be elevated from emissions from cigarettes, consumer products and gasoline powered engines/tools stored in garages attached to homes. Air samples are collected in canisters or on adsorbent with subsequent quantification by gas chromatography. Ambient air concentrations vary from sub-ppb range, low ppb, and tens of ppb in rural/suburban, urban, and source impacted areas, respectively. Short-term environmental exposures of ppm occur during vehicle fueling. Indoor air concentrations of tens of ppb occur in microenvironments containing indoor sources. Occupational and environmental exposures have declined where regulations limit benzene in gasoline (<1%) and cigarette smoking has been banned from public and work places. Similar controls should be implemented worldwide to reduce benzene exposure. Biomarkers of benzene used to estimate exposure and risk include: benzene in breath, blood and urine; its urinary metabolites: phenol, t, t-muconic acid ( t, tMA) and S-phenylmercapturic acid ( sPMA); and blood protein adducts. The biomarker studies suggest benzene environmental exposures are in the sub to low ppb range though non-benzene sources for urinary metabolites, differences in metabolic rates compared to occupational or animal doses, and the presence of polymorphisms need to be considered when evaluating risks from environmental exposures to individuals or potentially susceptible populations.

Determination of benzene in gasoline using direct injection-mass spectrometry

A high-speed determination of benzene in gasoline samples using a non-separative method based on direct injection into the mass spectrometer is proposed. The results obtained are very similar to those provided with fast GC–MS. The calibration set was made up of gasoline samples in which the benzene was determined chromatographically and samples of gasoline subjected to a process of evaporation – until the complete disappearance of the original benzene – to which known concentrations of this compound had been added. A PLS1 multivariate calibration model was constructed. Cross-validation was used to select the optimum number of PLS components. The prediction capacity of the model was checked with an additional group of gasoline samples that had not been used either in the construction or in the validation of the model. With the direct injection method proposed here it was possible to analyse 24 samples over a period of 1 h. The direct injection method is rapid, simple and – in view of the results – highly suitable for the determination of benzene in gasoline samples.

PBPK modeling of complex hydrocarbon mixtures: gasoline

Petroleum hydrocarbon mixtures such as gasoline, diesel fuel, aviation fuel, and asphalt liquids typically contain hundreds of compounds. These compounds include aliphatic and aromatic hydrocarbons within a specific molecular weight range and sometimes lesser amounts of additives, and often exhibit qualitatively similar pharmacokinetic (PK) and pharmacodynamic properties. However, there are some components that exhibit specific biological effects, such as methyl t-butyl ether and benzene in gasoline. One of the potential pharmacokinetic interactions of many components in such mixtures is inhibition of the metabolism of other components. Due to the complexity of the mixtures, a quantitative description of the pharmacokinetics of each component, particularly in the context of differing blends of these mixtures, has not been available. We describe here a physiologically-based pharmacokinetic (PBPK) modeling approach to describe the PKs of whole gasoline. The approach simplifies the problem by isolating specific components for which a description is desired and treating the remaining components as a single lumped chemical. In this manner, the effect of the non-isolated components (i.e. inhibition) can be taken into account. The gasoline model was based on PK data for the single chemicals, for simple mixtures of the isolated chemicals, and for the isolated and lumped chemicals during gas uptake PK experiments in rats exposed to whole gasoline. While some sacrifice in model accuracy must be made when a chemical lumping approach is used, our lumped PK model still permitted a good representation of the PKs of five isolated chemicals ( n-hexane, benzene, toluene, ethylbenzene, and o-xylene) during exposure to various levels of two different blends of gasoline. The approach may be applicable to other hydrocarbon mixtures when appropriate PK data are available for model development.

Sister chromatid exchanges and micronuclei in peripheral lymphocytes of shoe factory workers exposed to solvents.

We examined sister chromatid exchanges (SCEs) and micronuclei (MN; cytokinesis-block method) in cultured peripheral lymphocytes from 52 female workers of two shoe factories and from 36 unexposed age- and sex-matched referents. The factory workers showed an elevated level of urinary hippuric acid, a biomarker of toluene exposure, and workplace air contained high concentrations of various organic solvents such as toluene, gasoline, acetone, and (in one of the plants only) ethylacetate and methylenediphenyl diisocyanate. The shoe factory workers showed a statistically significant higher frequency of micronucleated binucleate lymphocytes in comparison with the referents. This finding agreed with three preliminary MN determinations (each comprising 27-32 shoe workers and 16-20 controls) performed in one of the plants 2-5 years earlier. The shoe factory workers also had a lower average level of blood hemoglobin than the referents. In contrast, no difference was found between the groups in SCE analysis. Smokers showed significantly higher mean frequencies of SCEs per cell and high frequency cells (HFC) than nonsmokers. Aging was associated with increased MN rates and reduced cell proliferation. Polymorphism of the glutathione S-transferase M1 gene (GSTM1) did not affect the individual level of SCEs; but in smoking shoe workers an effect of the occupational exposure on the frequency of micronucleated cells could be seen only in GSTM1 null subjects. The low prevalence of the glutathione S-transferase T1 (GSTT1) null genotype precluded the evaluation of the influence of GSTT1 polymorphism. Our results show that the shoe factory workers have experienced genotoxic exposure, which is manifest as an increase in the frequency of MN, but not of SCEs, in peripheral lymphocytes. The exposures responsible for the MN induction could not be identified with certainty, but exposure to benzene in gasoline and methylenediphenyl diisocyanate may explain some of the findings.

Benzene in gasoline and crude oil: occupational and environmental implications.

A review of studies, published in peer-reviewed journals and articles available as technical reports of various organizations, regarding benzene in gasoline and crude oil was performed. The summarized data will be useful for retrospective exposure assessments in epidemiological studies. It shows that in the past, benzene in gasoline has been quite high, but now, there is a distinct trend in North America and Europe to reduce benzene in gasoline to a level of about 1%. The reduction of benzene in gasoline results not only in the lowering of occupational exposure for workers, but it also has far greater influence in decreasing the environmental benzene exposure for the general public.

Benzene in Gasoline and Crude Oil: Occupational and Environmental Implications

Benzene in Gasoline and Crude Oil: Occupational and Environmental Implications

Cadmium, carcinogen, co-carcinogen and anti carcinogen.

As a stress agent, inducing apoptosis and blocking it, Cd can have both helpful and harmful effects. The atmosphere is a thin envelope which makes the worid a global village. Cd is the most toxic metal in air. As both the first and second messenger of the stress response, it is synergistically toxic with all other stressors, including many other carcinogens. Elimination of Pb and its replacement with added benzene in gasoline appears to have increased the toxicity of atmospheric Cd. With scientific understanding of the molecular basis of Cd's role in carcinogenesis and anti-carcinogenesis, primary cancer prevention can be practiced by reducing Cd and chemical air pollution and educating the public on smoke cessation, healthy eating habits and stress reduction. Using the existing information on Cd and its effects, determinations could be made on established cancers so that individualized treatment protocols can be developed to improve patient care.

Population risk assessment of ambient benzene and evaluation of benzene regulation in gasoline in Japan

The aggregate population cancer risk due to ambient benzene was evaluated for the entire Japanese population. This was done using data of ambient NOx levels measured at as many as 2000 air pollution monitoring stations nationwide and the regression equation between the levels of benzene and NOx obtained by continuous monitoring. The population-weighted exposure levels for the roadside population and general-environment population were calculated to be 2.1 ppb and 1.0 ppb, respectively. Eighty-four percent of the entire population was exposed to a lifetime cancer risk level of 1 × 10−5 or greater, and the annual number of cancer deaths was estimated to be 29.6 cases at the 1997 benzene level. Due to the regulation which established the upper limit of benzene content in gasoline to be 1 vol. % by January 2000, the total emission of benzene was estimated to be reduced by 27%, compared to 1993. The annual number of cancer deaths was expected to be reduced by 8.8 cases through the regulation of benzene in gasoline. Japanese petroleum companies have estimated the annual cost of the reduction of the benzene content in gasoline to be 25.6 billion yen. The cost per life saved by the regulation of benzene in gasoline is estimated to be 2.9 billion yen. The method implemented in this study to predict population risk is useful for identifying potential risk management options and evaluating their effectiveness before making decisions.

Supported and Coated Nickel Catalysts: Are they Suitable for the Partial Gas Phase Hydrogenation of Benzene to Cyclohexene?

Due to the reduction of benzene in gasoline, uses for the surplus benzene are being sought. The gas phase hydrogenation of benzene to cyclohexene over various nickel catalysts. The authors report on the selectivities to cyclohexene under suitable reaction conditions in the absence and presence of methanol as a reaction modifier.

A New GC-MS Experiment for the Undergraduate Instrumental Analysis Laboratory in Environmental Chemistry: Methyl-t-butyl Ether and Benzene in Gasoline

With the recent ACS approval of an option in environmental chemistry at the undergraduate level, there is a need for new experiments that illustrate fundamental principles of instrumental analysis in the context of environmental chemistry. We describe an experiment that utilizes combined gas chromatography-mass spectrometry (GC-MS) in the qualitative and quantitative analysis of methyl tert-butyl ether (MTBE) and benzene in gasoline. This is particularly appropriate, given the increased use of oxygenates in reformulated gasolines in the United States. In addition to illustrating the fundamentals of GC and MS, this experiment demonstrates (i) the use of internal standards to improve precision; (ii) the application of the method of standard additions; and (iii) the importance of techniques such as selected ion extraction/monitoring in the identification and measurement of specific highly volatile organic compounds in complex environmental mixtures.