Gasoline Hydrocarbons Research Articles

Bioremediation of diesel contamination at an underground storage tank site: a spatial analysis of the microbial community.

The present study reports on a real case of contamination due to the chronic leakage of diesel fuel from an underground tank at a dismissed service station. Speciation of the microbial community according to both lateral and vertical gradients from the origin of the contaminant release was analyzed by means of the PCR-DGGE technique. Moreover, the effects of a landfarming treatment on both the microbial community structure and the abatement of contamination were analyzed. The concentration of total petrol hydrocarbons (TPHs) decreased along the horizontal gradient (from 7042.2 ± 521.9 to 112.2 ± 24.3 mg kg(-1)), while increased downwards from the position of the tank (from 502.6 ± 43.7 to 4972.5 ± 275.3 mg kg(-1)). PCR-DGGE analyses and further statistical treatment of the data indicated a correlation between structure of the bacterial communities and amount of diesel fuel contamination. On the other hand, level of contamination, soil texture and depth were shown to affect the fungal community. Chloroflexi and Ascomycota were the most abundant microbes ascertained through culture-independent procedures. Landfarming promoted 91.6 % reduction of TPHs in 75 days. Furthermore, PCR-DGGE analyses evidenced that both bacterial and fungal communities of the treated soil were restored to the pristine conditions of uncontaminated topsoil. The present study demonstrated that bacterial and fungal communities were affected differently by soil factors such as level of hydrocarbon contamination as well as soil depth and texture. This report shows that a well-planned landfarming treatment can drive the restoration of the soil in terms of both abatement of the contaminants and resilience of the microbial community structure.

RECYCLING AND PYROLYSIS OF WASTE PLASTICS

Plastic has achieved such an extensive market due to fact that it is lightweight, cheap, flexible and reusable. But now it is regarded as a serious hazard. All recommendation for and against plastics finally land up on the reality that plastics are slow to degrade. By the end of the 20th century, plastics are found as persistent polluters of many environmental niches, from Mount Everest to the bottom of the sea. There are numerous ways by which plastic pollution can be controlled. Pyrolysis is referred to as polymer cracking and its main advantages are that it can deal with plastic waste .This paper provides an overview of the science and technology of pyrolysis of waste plastics. The major advantage of the pyrolysis technology is its ability to handle unsorted, unwashed plastic. The production of gasoline, kerosene and diesel from waste plastics is an emerging technological solution to the vast amount of plastics that cannot be economically recovered by conventional mechanical recycling. The disposal and decomposition of plastics has been an issue which has caused a number of research works to be carried out in this regard. Currently, the paper reviews the production of Petroleum-based fuel viz. gasoline, kerosene and diesel from recycling of waste plastics is an emerging technological solution to the vast amount of plastic wastes that cannot be economically recovered by conventional mechanical recycling operations. This involves the use of pyrolysis which permits recovery of valuable gasoline and diesel-range hydrocarbons from waste plastics that are otherwise land filled.

Comet assay based DNA evaluation of fuel filling stations and automobile workshops workers from Khyber Pakhtunkhwa province, Pakistan.

BackgroundFuel filling stations workers and automobile workshops mechanics are consistently exposed to gasoline hydrocarbons during their occupation, this may cause DNA damage. Objective of this study was to evaluate the level of DNA damage in subjects occupationally exposed to these hydrocarbons.MethodsComet assay was performed on blood lymphocytes of exposed subjects to assess the probable DNA damage. 100 cells per individual were scored and graded by comet tail length. Exposed group consisted of 98 subjects (age 25.4 ± 7.2 years), of which 68 were CNG/Petrol filling men and 30 were automobile workshop workers, selected randomly from different service stations and automobile workshops of populated and adjacent cities of Peshawar, Mardan and Nowshera of Khyber Pakhtunkhwa province, while control group included 92 subjects (age 26.7 ± 11.8 years) were also from the same areas.ResultsSignificantly high level of DNA damage was found in the subjects exposed to gasoline hydrocarbons as compared to control subjects (173.2 ± 50.1 and 61.0 ± 25.0, P = 0.001, respectively). Period of exposure and use of tobacco also showed considerable effects (P < 0.05) on DNA damage, while effect of age and daily working hours on total comet score (TCS) were non-significant (P > 0.05).ConclusionsThe results of our study concluded that petroleum hydrocarbons have the potential to cause DNA damage in the exposed subjects. The study also suggested that protective strategies should be implemented by the concerned authorities to minimize exposure to fuel hydrocarbons.

Dynamic Processes in Capillary Fringes

CSA NewsVolume 60, Issue 6 p. 23-23 News & PerspectiveOpen Access Dynamic Processes in Capillary Fringes First published: 09 June 2015 https://doi.org/10.2134/csa2015-60-6-8AboutSectionsPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL The May 2015 issue of Vadose Zone Journal features a special section on processes in capillary fringes, with a focus on the complex interaction of biological, chemical, and physical processes in this environemnt. Capillary fringes are highly dynamic and periodically changing zones at the interface between the water-saturated aquifer and the unsaturated zone. As a consequence, we observe steep gradients in terms of hydraulic state variables, biogeochemical conditions, and thus, biological activity (Berkowitz et al., 2004). With fluctuations of the groundwater table, this reactive zone moves dynamically along the vertical direction, further complicating our understanding of specific processes that occur in both space and time. This special compartment is not only an interesting and challenging subject of research, it is also highly relevant for mass fluxes with terrestrial systems (Silliman et al., 2002; Haberer et al., 2011) and especially the biodegradation of contaminants (Lahvis et al., 1999; Dobson et al., 2007). To gain a comprehensive understanding of the mass transfer and transformation in the CF, the close interactions of physical, chemical, and biological processes call for an interdisciplinary approach. This was the motivation to establish the interdisciplinary research group DyCap, funded by the Deutsche Forschungsgemeinschaft for a period of 6 years. The aim was to explore the basic physical, (hydro-)geological, chemical, and microbiological processes in CFs and their interaction, while collaborating closely with an interdisciplinary team of researchers. This special issue contains some of the latest results of DyCap, together with other actual research related to the dynamics of capillary fringes. This special issue presents examples of complex processes within capillary fringes. The contributions demonstrate the intensive coupling of biological, chemical, and physical processes relevant for a profound understanding of mass fluxes and turnover within this hot spot at the surface of the groundwater table. We hope these papers and increased knowledge will inspire future research on dynamic capillary fringes. References Berkowitz, B., Silliman, S.E., and Dunn, A.M. 2004. Impact of the capillary fringe on local flow, chemical migration, and microbiology. Vadose Zone J. 3: 534– 548. https://doi.org/10.2113/3.2.534 Dobson, R., Schroth, M.H., and Zeyer, J. 2007. Effect of water-table fluctuation on dissolution and biodegradation of a multi-component, light nonaqueous-phase liquid. J. Contam. Hydrol. 94: 235– 248. https://doi.org/10.1016/j.jconhyd.2007.07.007 Haberer, C.M., Rolle, M., Liu, S., Cirpka, O.A., and Grathwohl, P. 2011. A high-resolution non-invasive approach to quantify oxygen transport across the capillary fringe and within the underlying groundwater. J. Contam. Hydrol. 122: 26– 39. https://doi.org/10.1016/j.jconhyd.2010.10.006 Lahvis, M.A., Baehr, A.L., and Baker, R.J. 1999. Quantification of aerobic biodegradation and volatilization rates of gasoline hydrocarbons near the water table under natural attenuation conditions. Water Resour. Res. 35: 753– 765. https://doi.org/10.1029/1998WR900087 Silliman, S.E., Berkowitz, B., Šimůnek, J., and Genuchten, M.T. 2002. Fluid flow and solute migration within the capillary fringe. Ground Water 40: 76– 84. https://doi.org/10.1111/j.1745-6584.2002.tb02493.x Volume60, Issue6June 2015Pages 23-23 ReferencesRelatedInformation

Motor Gasoline's Hydrocarbons Vibration Bands in the Mid-Infrared Region Under Exposure to a Static Magnetic Field

Fourier transform infrared spectroscopy was used to investigate motor gasoline's vibration bands in the mid-infrared region under exposure up to 2 hr to 150 mT uniform magnetic field. No change in symmetric and asymmetric stretching of methyl and methylene vibrations was observed up to 2 hr exposure. In contrast, the band around 1465 cm−1, assigned to methylene scissoring vibration, was observed to decrease significantly after 1 and 2 hr of exposure, showing that static magnetic field changes methylene bending vibration in gasoline's hydrocarbons. Furthermore, methyl symmetrical deformation band at 1378 cm−1 and C–C vibrations at 1610 and 1522 cm−1 decreased in intensity after exposure. These results lead to the conclusion that exposure to a low-intensity uniform magnetic field can change the structure of motor gasoline, thereby declustering hydrocarbon molecules and improving the combustion process.

Biofiltration of gasoline and diesel aliphatic hydrocarbons

The ability of a biofilm to switch between the mixtures of mostly aromatic and aliphatic hydrocarbons was investigated to assess biofiltration efficiency and potential substrate interactions. A switch from gasoline, which consisted of both aliphatic and aromatic hydrocarbons, to a mixture of volatile diesel n-alkanes resulted in a significant increase in biofiltration efficiency, despite the lack of readily biodegradable aromatic hydrocarbons in the diesel mixture. This improved biofilter performance was shown to be the result of the presence of larger size (C9-C12) linear alkanes in diesel, which turned out to be more degradable than their shorter-chain (C6-C8) homologues in gasoline. The evidence obtained from both biofiltration-based and independent microbiological tests indicated that the rate was limited by biochemical reactions, with the inhibition of shorter chain alkane biodegradation by their larger size homologues as corroborated by a significant substrate specialization along the biofilter bed. These observations were explained by the lack of specific enzymes designed for the oxidation of short-chain alkanes as opposed to their longer carbon chain homologues.Implications: Biological removal of petroleum hydrocarbons from contaminated air has not become a widely used technology due to its low efficiency. This paper presents the analysis of this problem using bench-scale experiments and provides several reasons for the low biodegradation efficiency of gasoline. The results reported suggest that gasoline removal efficiency strongly depends on the substrate composition, with aromatic hydrocarbons being removed preferentially. The study also opens up a new perspective for the efficient biofiltration of diesel hydrocarbons as opposed to gasoline, as higher molecular weight n-alkanes of diesel were removed readily. By contrast, low-molecular-weight n-alkanes of gasoline turned out to be poor substrates for biofiltration, and the biological reasons for this phenomenon were suggested.

Reclamation of petrol oil contaminated soil by rhamnolipids producing PGPR strains for growing Withania somnifera a medicinal shrub.

Soil contaminated by hydrocarbons, cannot be used for agricultural intents due to their toxic effect to the plants. Surfactants producing by plant growth promotory rhizobacteria (PGPR) can effectively rig the problem of petroleum hydrocarbon contamination and growth promotion on such contaminated soils. In the present study three Pseudomonas strains isolated from contaminated soil identified by 16S rRNA analysis were ascertained for PGPR as well as biosurfactants property. Biosurfactants produced by the strains were further characterized and essayed for rhamnolipids. Inoculation of the strains in petrol hydrocarbon contaminated soil and its interaction with Withania somnifera in presence of petrol oil hydrocarbons depict that the strains helped in growth promotion of Withania somnifera in petrol oil contaminated soil while rhamnolipids helped in lowering the toxicity of petrol oil. The study was found to be beneficial as the growth and antioxidant activity of Withania sominfera was enhanced. Hence the present study signifies that rhamnolipids producing PGPR strains could be a better measure for reclamation of petrol contaminated sites for growing medicinal plants.

Express method for total content assessment of aromatic hydrocarbons and oxygen in finished gasolines by refractometry and densimetry

This paper presents routine refracto-densimetric indicators which may be used to identify unbalanced automobile gasoline and falsifications (surrogates). These criteria are supposed to reduce considerably the amount of testing via standard chromatographic and spectroscopic methods. Refracto-densimetric method for controlling the limiting weight content of oxygen is based on substantial difference between specific refractions of oxygenates and hydrocarbon gasoline components. Application of the refractive intercept which is additive in the volume fractions of components and constant for different homologous series of hydrocarbons allowed to establish its maximum value, the excess of which identifies a gasoline with a high content of aromatic hydrocarbons. In addition, the excess of refractive intercept of certain limit value can also indicate the possible presence of conjugated diolefins in gasoline and bicyclic arenes.

Long term aging of LLDPE based multi-layer film by exposure to light hydrocarbons

This study focuses on the stability of a polymeric Linear Low Density Polyethylene/Polyamide/Linear Low Density Polyethylene multi-layered container during long-term aging by exposure to light hydrocarbons in aviation gasoline. The containers examined and tested for this work were stored and used for different service periods, the longest of which is 10 years. During the containers' service periods, the inner LLDPE layer is exposed to avgas (aviation gasoline), and the outer LLDPE layer – to air. The aging process caused by the film interaction with avgas was examined by a variety of methods. Pb line-scan and IR spectroscopy show no evidence for the presence of small organic carbohydrate molecules originating from the avgas in the LLDPE. The viscoelastic and thermo-mechanical properties of the material were not significantly changed after 10 years. Nevertheless, DSC-OIT analysis shows a remarkable rise in oxidation rate as samples get older, presumably, as a result of antioxidants leaching out or being used up. The SEM results show the polymer to be much more prone to cracking, indicating a rise in crystallinity, as further substantiated by the results from DSC 1st heating cycle enthalpy evaluation. The 2nd DSC heating cycle results, which show no differences between samples, indicate the difference seen in the 1st heating cycle is affected by intermolecular rearrangements. Macro-mechanical properties show a remarkable stability for at least a decade, negating the aging phenomena discussed. Polyamide, as the load baring layer in the film, is probably responsible for the dampening seen in these results. In years to come, apparent oxidation will begin – most prominently in the outer layer – but probably would not compromise the structural strength of the bag, as both polyethylene layers are not the main load bearing layers.

Enhanced bioremediation of oily sludge using co‐culture of specific bacterial and yeast strains

AbstractBACKGROUNDConsiderable volumes of petrochemical oily sludge can be generated from oil production and processing activities. Total petroleum hydrocarbons (TPH) contained in oily sludge are detrimental to human health and the environment. Thus, oily sludge is classified as a priority environmental pollutant by the US Environmental Protection Agency and it must be treated properly before discharge into the environment.RESULTSIn this study, a functional microbial consortium consisting of Bacillus subtilis, Bacillus megaterium, Achromobacter xylosoxidans, Pseudomonas fluorescens, Candida tropicalis and Rhodotorula dairenensis, isolated from petroleum‐contaminated soil, was applied for bioremediation of petrochemical oily sludge in a shake flask and oily sludge microcosm study. These strains utilized the oily sludge as sole source of carbon and energy. The oily sludge contained 21.5% (w/w, dry weight basis) of total petrol hydrocarbons (TPH). Results showed that the microbial consortium exhibited an excellent oily sludge degradation capacity, reducing 92.5% of aliphatics, 79.3% of aromatics, 48.6% of NSO‐containing compounds, 31.8% of asphaltenes and 80.6% of TPH, by the end of the 1‐year microcosm experiment. In contrast, biodegradation rates of these fractions were 83.3%, 17.5%, 8.4%, 4.7% and 56.1%, respectively, in the non‐inoculated treatment. These strains survived well and adapted to the oil sludge environment throughout the incubation period. Dehydrogenase and polyphenoloxidase activity of the oily sludge was remarkably promoted by inoculation of the microbial consortium.CONCLUSIONThe results indicated that the microbial consortium has the potential to be used in bioremediation of petrochemical oily sludge polluted environments. © 2014 Society of Chemical Industry

Column leaching tests on soils containing less investigated organic pollutants

Column tests are a common tool to investigate the leaching behavior of contaminated soil and waste materials. In contrast to inorganic analytes, fewer studies with organic contaminants are available based on column tests. This paper is aimed at the question if soil materials contaminated with organic pollutants can be reliably investigated by column tests. Soils contaminated with TPH (total petrol hydrocarbons), PFC (perfluorinated surfactants) and the biocide tebuconazole were used for column percolation tests. Differences in the leaching behavior are mainly driven by partitioning behavior between organic carbon and water, which can be estimated from log KOW values and size and shape of molecules. PFC show higher release (10–50% for individual compounds) than pesticides (3.7–5.3%) and TPH (<1%) at liquid to solid ratio of 4l/kg. All eluate concentrations are low with maximum concentrations of 50μg/l for PFC and 1–2mg/l for pesticides and TPH. Despite this, the observed standard deviations are quite small suggesting good repeatability. In general the observed concentration trends are similar to that from lysimeter studies found in the literature and thus, it can be concluded that laboratory column experiments are a reliable tool for organic compounds with various physico-chemical properties.

Physicochemical and catalytic characteristics of La-H-ZSM-5 zeolite in converting dimethyl ether to the mixtures of gasoline hydrocarbons: Effect of ion exchange conditions

The effect of the manner and conditions of introducing lanthanum cations into NH4-ZSM-5 zeolite on the properties of catalysts for the conversion of dimethyl ether into the mixtures of gasoline hydrocarbons is studied. The physicochemical properties of synthesized catalysts are studied by means of temperature-programmed ammonia desorption, the adsorption of benzene, atomic absorption spectroscopy, differential scanning calorimetry, and thermogravimetry. It is shown that the degree to which lanthanum cations are replaced by ammonium cations both depends on the conditions of ion exchange in the zeolite and affects its acidity spectrum and the selectivity of the formation of paraffin hydrocarbons with isostructure. It is concluded that an increase in the amount of introduced lanthanum leads to an increase in the content of iso-paraffins from 69 to 76 wt % and a decrease in the content of aromatic hydrocarbons from 10.5 to 5.5 wt % and that of durene from 1.5 to 0.2 wt % in the products.

Restoration of Petrol Contaminated Soil by PGPR Consortium Producing Rhamnolipids and Enhancement of Growth and Antioxidant activity of Withania somnifera

Oil spills may considerably damage the soil quality. Increased contamination of agricultural soil by different hydrocarbons due to increased extraction and refinement of hydrocarbon are a serious environmental hazard due to their persistence in nature for a long time. Scope of bioremediation strategies is limited due to poor hydrocarbon accessibility and their low solubility which can be overcome by use of rhamnolipids, a class of biosurfactants. In the present study, pseudomonas strains (RK 4 and RK 3) isolated from contaminated soil identified by 16S rRNA were ascertained for PGPR as well as biosurfactants (rhamnolipids) property and checked for the compatibility to form consortium. Inoculating the strains and consortium of both the strain in petrol hydrocarbon contaminated soil and its interaction with Withania somnifera in presence of petrol oil reveals that rhamnolipids property of the strains helped in lowering the impediment effect of petrol engine oil hydrocarbons and the growth promotory activities enhanced the growth and antioxidant activity of Withania somnifera. Consortium of the both the strains showed positive results as compared to the individual strain and the interaction were found to be beneficial. The selected consortium of the strain could be further used for restoration of hydrocarbon contaminated soils for growing Withania sominfera.

Multiloop PI Controller Tuning for Maximum Gasoline Yield in an Industrial Catalytic Cracking Unit

Any control or optimization study of the FCC unit requires a process model which captures the major effects and interactions taking place in the unit. In this paper, the Dynamic behavior of the Simulated model (includes four lump Yield model to describe cracking kinetics) for the entire catalytic cracking unit of Petroleum Industry is analysed where the reactor riser is treated as an adiabatic plug flow reactor. A suitable controller is designed for this complex Industrial Process for the control of Reactor and Regenerator Temperature. The plugged Yield model is helpful in estimating the weight fraction of gasoline and other hydrocarbon products which is highly influenced by the variations in Reactor and Regenerator Temperature.

Effect of gasoline composition on oxidative desulfurization using a phosphotungstic acid/activated carbon catalyst with hydrogen peroxide

This work is concerned with the question of why oxidative desulfurization (ODS) catalyst that show good catalytic performance for ODS of model gasoline thiophenic compounds is not effective for real gasoline. For the first time, the effects of gasoline composition on ODS using a phosphotungstic acid/activated carbon (HPW/AC) catalyst with H2O2 were investigated. ODS of thiophene, one of the most difficult thiophenic compounds to be oxidized, was studied in a model fuel system, where a high thiophene conversion rate of 90% could be reached in 2h at 90°C. However, when applying the ODS to a real gasoline, the ODS conversion rate decreased to only 32%, suggesting a strong inhibiting effect of gasoline composition on ODS. The ODS studies in different model fuels suggested that the inhibiting effect can be ascribed to the competitive adsorption and oxidation with the presence of the alkenes and alkylated aromatic hydrocarbons in real gasoline. The active pi-electrons in alkenes and alkyl groups in alkylated aromatic hydrocarbons may react with polyoxoperoxo species or peroxo-metallate complexes formed by phosphotungstic acid–H2O2 interaction. Additionally, it was indicated that the ODS selectivity followed the order of benzothiophene>trimethylthiophene>dimethylthiophene∼methylthiophene>thiophene, suggesting the partial charge on the electron-rich sulfur atom may play a decisive role for its oxidation reactivity. To mitigate the inhibiting effect of gasoline composition on ODS, we propose (a) implementation of selective separation–oxidation processes; (b) choice of suitable selective oxidants; (c) optimization of selective ODS reaction temperature, etc. to improve ODS selectivity for real gasoline desulfurization applications.

Quality assessment of automotive fuel and oil-improving environmental sustainability

Ethanol as a radical scavenger being non-lead additive to fuel can act as quality improver as well as range extender, which abates the COx emission and helps to improve air quality. Its limited concentration in blended fuels is beneficial, whereas, higher percentage of ethanol damage automotive fuel lines. Thus, a sensor system has been designed for evaluating the quality of ethanol blended gasoline by utilizing molecular imprinting technique in combination with transducers such as quartz crystal microbalances (QCMs). Moreover, a low cost miniaturized device based on interdigital transducers (IDTs) has also been developed for characterizing ethanol/gasoline mixtures. Acrylic acid and sodium p-styrene sulfonate polyelectrolytes as sensitive layers on IDT enable us to detect different percentages of polar ethanol in non-polar gasoline hydrocarbons by resistive measurements. Another step in improving environmental situation is achieved by characterizing the lubricating oil to determine an optimal time of oil change. Mass-sensitive devices are also tuned by utilizing molecular imprinting approach to analyze the octane number of fuel by differentiating the isomers iso-octane and n-octane.

Can Handling E85 Motor Fuel Cause Positive Breath Alcohol Test Results?

Hand-held breath alcohol analyzers are widely used by police in traffic stops of drivers suspected of driving while intoxicated (DWI). E85 is a motor fuel consisting of 85% ethanol and 15% gasoline or other hydrocarbons, and is available at nearly 2,600 stations in the USA. We sought to determine whether handling E85 fuel could produce measurable breath alcohol results using a hand-held analyzer and to see if this would be a plausible explanation for a positive breath alcohol test. Five healthy adult subjects dispensed or transferred 8 US gallons of E85 fuel in each of four scenarios. We measured breath alcohol concentration in g/210 L of exhaled breath using the BACTrack S50 at 0, 2, 4, 6, 8, 10, 15 and 20 min after each fuel-handling scenario. Most of the subjects had no detectable breath alcohol after handling E85 motor fuel. Transient elevations (0.02-0.04 g/210 L) in breath alcohol measurement occurred up to 6 min after handling E85 in a minority of subjects. We conclude that it is unlikely that handling E85 motor fuel would result in erroneous prosecution for DWI.

On the use of ionic liquid capillary columns for analysis of aromatic hydrocarbons in low-boiling petrochemical products by one-dimensional and comprehensive two-dimensional gas chromatography

One-dimensional and comprehensive two-dimensional flow modulated gas chromatography with simultaneous flame ionization and mass spectrometric detection were applied for the identification and quantification of benzene, toluene, ethyl benzene and xylenes (BTEX) as well as of all C9–C11 aromatic hydrocarbons in the low-boiling petroleum products gasoline, reformate and fluid catalytic cracking (FCC) samples. GC×GC experiments were performed on two reversed phase polarity column sets namely SLB-IL100 (25m×250μm i.d.×0.2μm df)+HP-5MS (5m×250μm i.d.×0.25μm df) and SLB-IL111 (30m×250μm i.d.×0.2μm df)+HP-5MS (5m×250μm i.d.×0.25μm df). The one-dimensional GC experiments were carried out on the same ionic liquid columns. The most powerful method is GC×GC on the SLB-111+HP-5MS column combination. Quantitative analysis of individual aromatic hydrocarbons (C6–C11) present in gasoline, reformate and fluid catalytic cracking (FCC) samples was performed by GC×GC-FID using the internal normalization method. Mass spectra obtained by GC×GC-qMSD were used for identification of the aromatic hydrocarbons in these samples.

Isobaric vapor–liquid equilibrium for systems containing sulfur compounds

Isobaric vapor–liquid equilibrium (VLE) data for the binary systems of thiophenic compounds with three hydrocarbons in gasoline (2,3-dimethyl-1-butene, 2,3-dimethyl-2-butene and n-heptane) were measured in dilute solutions at 101.33kPa with a modified Rose–Williams still. General Coulomb meter was used to analyze the compositions of the samples from the vapor–liquid equilibrium systems. The VLE data was compared with the calculated value by the Wilson model with the interaction parameters regressed over the entire concentration range. Results found that neither the activity coefficient model nor the Henry's model could describe the VLE behavior of the trace component in the dilute solution accurately. Thus a concept of multi-scale phase equilibrium was proposed.

Public health impacts of secondary particulate formation from aromatic hydrocarbons in gasoline

BackgroundAromatic hydrocarbons emitted from gasoline-powered vehicles contribute to the formation of secondary organic aerosol (SOA), which increases the atmospheric mass concentration of fine particles (PM2.5). Here we estimate the public health burden associated with exposures to the subset of PM2.5 that originates from vehicle emissions of aromatics under business as usual conditions.MethodsThe PM2.5 contribution from gasoline aromatics is estimated using the Community Multiscale Air Quality (CMAQ) modeling system and the results are compared to ambient measurements from the literature. Marginal PM2.5 annualized concentration changes are used to calculate premature mortalities using concentration-response functions, with a value of mortality reduction approach used to monetize the social cost of mortality impacts. Morbidity impacts are qualitatively discussed.ResultsModeled aromatic SOA concentrations from CMAQ fall short of ambient measurements by approximately a factor of two nationwide, with strong regional differences. After accounting for this model bias, the estimated public health impacts from exposure to PM2.5 originating from aromatic hydrocarbons in gasoline lead to a central estimate of approximately 3800 predicted premature mortalities nationwide, with estimates ranging from 1800 to over 4700 depending on the specific concentration-response function used. These impacts are associated with total social costs of $28.2B, and range from $13.6B to $34.9B in 2006$.ConclusionsThese preliminary quantitative estimates indicate particulates from vehicular emissions of aromatic hydrocarbons demonstrate a nontrivial public health burden. The results provide a baseline from which to evaluate potential public health impacts of changes in gasoline composition.