Complex Mixture Of Hydrocarbons Research Articles

APPLICATION OF RANGE EXTENDER BASED ON SOLID OXIDE FUEL CELLS (SOFCS) FOR ELECTRICAL BUSES: EXPERIENCE OF CERES POWER (UNITED KINGDOM) AND WEICHAI POWER (CHINA) COMPANIES

In previous articles on this topic [1-3] we examined the perspectives of application of power plants based on solid oxide fuel cells (SOFCs) as auxiliary power plants as well as range extenders for heavy freight transport [1,2] and cars [3]: we considered experience of USA [1], Europe [2] and Japan [3]. We showed, that such kind of systems give opportunity to obtain electrical power from chemical energy of hydrocarbon fuel oxidation with record-high efficiency (much higher than competitive solutions) in order to supply on-board vehicle systems during stops of main engine, as well as to significantly extend the range of electrical vehicles by means of constant charge of batteries directly during motional and their discharge due to operation of electrical engine. In current manuscript, we examine the world first experience of SOFC power plant application as range extender for electrical buses. Group of Ceres Power (UK) and Weichai Power (China) companies executed a corresponding project. As a result of project execution system prototype with power output of 30 kW was developed and manufactured, tests on bus lines are planned to be executed in nearest future. The system examined in current manuscript is the most powerful in comparison to other systems studied in this set of manuscripts: 30 kW against 1.5 and 9 kW [1], 3 kW [2] as well as 5 kW [3] for systems examined in previous works. Examined system uses compressed natural gas (CNG) as a fuel; this hydrocarbon is very convenient one due to well-developed distribution network, ecological cleanness in comparison with more complex and heavy hydrocarbon mixtures. Application of low-temperature fuel cells (with proton-exchange membrane), which are more simple in manufacture, in automobile transport leads to the demand in development of hydrogen supply networks, which is not developed nowadays at all.

Microscopy techniques applied to submicron characterization of oilfield produced water

Produced water (PW) and formation water are complex mixtures of hydrocarbons and water produced at oil and gas upstream facilities. Submicron oil droplets represent a multitude of issues affecting the performance of downstream advanced water treatment processes, such as micro and ultra-filtration processes. Conventional de-oiling technologies do not efficiently remove submicron oil droplets in PW. An accurate characterization of submicron oil droplets and contaminants is required to improve PW treatment technology. In this study, a methodology for visualization and quantification of submicron oil droplets size distribution (DSD), using optical and electron microscopy techniques, was developed. Various microscopy techniques were evaluated, including epifluorescence microscopy (EpiFM), confocal laser scanning microscopy (CLSM), cryogenic scanning and transmission electron microscopy (cryo-SEM and cryo-TEM, respectively). Synthetic PW was used to improve and standardize the sample preparation and characterization methodology. The improved methodology was then tested with two PW samples from different oilfields in the Middle East region. Two methods were developed for the determination of DSD in oilfield PW samples. The first method is suitable for highly polydisperse PW samples with oil droplets larger than 250 nm. This method is based on using low-temperature agarose to immobilize the samples, avoiding coalescence, and allowing clear visualization of the oil droplets at high magnification in EpiFM. The second method is suitable for concentrated PW samples and oil droplets as small as 20 nm in size. This method is based on cryo-TEM with plunge freezing and without the use of agarose for sample immobilization. The agarose-immobilization technique was also applied for sample preparation in cryo-SEM. Cryo-SEM fixation by high-pressure freezing (HPF) preserved the morphology of oil droplets in synthetic oil-concentrated samples and allowed its visualization in a wide range of sizes from 50 nm up to 20 μm. Cryo-TEM imaging of oilfield PW samples revealed the presence of oil droplets as small as 20 nm in size. However, no quantification of the DSD in the oilfield PW samples was possible due to the low oil concentration. Moreover, a relatively large amount of other submicron particulates/aggregates were observed in PW samples. Cryo-SEM coupled with energy-dispersive X-ray spectroscopy (EDS) provided valuable information on the morphology and elemental composition of the submicron-sized contaminants. These submicron contaminants would not be removed by conventional de-oiling technologies and might cause intrapore blocking in membrane filtration systems downstream. The effect of these submicron contaminants, other than oil droplets present in PW, needs to be addressed to improve the PW treatment technologies.

INCIDENCES OF BITUMEN CONTAMINATION OF WATER SOURCES IN SOME COMMUNITIES OF ONDO STATE, NIGERIA

Bitumen was discovered in some communities: Agbabu, Ilubinrin, Lodasa and Boridele in Ondo State, Nigeria around 1900 but was found inadequate for commercial exploitation. This report is on the levels of presence of bitumen in the areas and its effects on the available water sources and to make recommendations. Samples of water taken from 3 selected streams and 2 wells per location were subjected to physico-chemical analyses in line with America Public Health Association (APHA). Questionnaire were administered to sixty (60) people from bitumen-affected areas which covered sources of water, water pre-treatment measures, availability of water treatment facilities and effects of bitumen deposits on water bodies. Results obtained shown that most water users sourced water from groundwater recorded 73.33% followed by 16.67% for surface water and 9% for rain water harvesting. There might be population using a combination of the two or more sources of water. About 90% of the respondents knew that direct use of such water was harmful for drinking, washing, bathing and cooking. Water quality impairment such as colour and high level of salt are common in the water. This practice could have health implication on them if continued unabated. Pollution index for toxic metals (Pb,As and Hg ) and Total Petroleum Hydrocarbons(TPH) values determined were relatively high suggesting pollutant are related to the bitumen deposits in the region. For example Ilubinrin well (0.5 mg/L), and Lodasa well (0.3 mg/L) while others were at non detection level. For TPH, there were variations in the tested water samples, Lodasa well recorded the highest value of 1480 mg/L, Agbabu stream 900, Ilubinrin stream and well 240 mg/L and 120 mg/L, respectively, Agbabu well 110 mg/L, and the least at Lodasa stream 80 mg/L. This could be attributed to seasonal rain that control streamflow of water bodies in the bitumen-rich area. The study indicated that bitumen, being a complex mixture of hydrocarbons and associated metals was responsible to the pollution level in the water bodies reported

Optimization of the gas collection and treatment system of the Beregovoye gas condensate field

At present, the experience of exploitation of various fields shows that a lot of associated water and gas is extracted during the oil production process. A liquid is extracted from wells, which is a complex mixture of various hydrocarbons in various aggregate states, various impurities and water. The water extracted from the reservoir negatively affects the equipment, causing its abrasion. At the same time, the period of major repairs is being shortened. The object of the current research is a gas condensate field. The purpose of this work is to increase the efficiency of the gas dehydration process by improving mass-transfer, as well as to analyze the gas collection and treatment system. At the same time, the analysis of the arrangement of technological schemes of equipment for gas treatment and absorption is carried out.

On the distillation of waste tire pyrolysis oil: A structural characterization of the derived fractions

Tire pyrolysis oil (TPO) is a complex mixture of hydrocarbons spanning a wide boiling point range. Due to its complexity, direct implementation of TPO to combustion applications has been challenging. Distillation is a simple method for grouping similar compounds, based on their volatility, thereby facilitating further upgrading and use. In this work, TPO was distilled at atmospheric pressure into different fractions (light, low-middle, high-middle, and heavy), and the structural characteristics of each fraction were explored. Therefore, advanced analytical techniques such as GC–MS, APPI FT-ICR MS and 1H and 13C NMR were utilized. For the light fraction, the GC–MS revealed a significant presence of benzene, toluene, and xylene, as well as limonene. From the APPI FT-ICR MS results, the low-middle, high-middle, and heavy fractions were classified into a number of molecular classes. Among these, pure hydrocarbons (HC), hydrocarbons containing one sulfur atom (S1), hydrocarbons containing two oxygen atoms (O2), etc. Here, HC and S1 were found to be the most abundant molecular classes in all fractions. Finally, a structural analysis of the functional groups present in each TPO fraction was conducted by 1H and 13C NMR. Average molecular parameters (AMPs), such as the number of aromatic, naphthenic, and olefinic carbons/hydrogens, were determined. In addition, derived AMPs, such as the aromaticity factor (fa), C/H paraffinic, C/H aromatic, etc., were calculated. Fractionation by distillation resulted in concentration of both the sulfur and aromatic compounds in the heaviest fraction. In this manner, effective application and upgrading strategies could be individually designed for each fraction.

Effect of experimental data accuracy on stochastic reconstruction of complex hydrocarbon mixture

Stochastic reconstruction (SR) is one of the most usable molecular reconstruction approaches applicable to heavy petroleum cuts, using statistical distribution to describe the structure attribute of molecules in a mixture. Suitable values for distribution parameters are estimated during an optimization process on the base of mixture characterization data. This study focuses on searching the connection between the parameter of structure attribute distributions and different types of experimental data, used for hydrocarbon mixture characterization.An algorithm has been introduced that allows to determine which types of analytical data affect the distribution of structure attributes based on testing statistical hypotheses. The core idea is looking for a significant correlation between calculated properties and distribution parameters, and then comparing the magnitude of parameter impact with measurement precision. It was shown that different types of analytical data can affect different parameters of the reconstructed composition: distillation curve data is the main source of information about distributions variance, while elemental analysis and PNA helps determine mean values for various structure attributes; information concerning the number of branches in molecules are strongly connected with 13C NMR data.

Weathered Railroad Diesel Removed from a Loamy Sand Soil by Means of Mono-rhamnolipids

ABSTRACT The extensive use of diesel as fuel has contributed to the current problem of soil contamination, and the aged diesel is a highly toxic pollutant for the soil microbial flora. The objective of the present work was to determine the ability of mono-rhamnolipid surfactants to solubilize weathered diesel absorbed for decades in a loamy sand soil. The mono-rhamnolipids were produced by P. aeruginosa ATCC 9027, using glycerol as the carbon source. The mono-rhamnolipid characterization revealed that 90% of congeners contained saturated fatty acids of short chains. At its CMC (70.3 mg/L), the mixture of mono-rhamnolipids decreased the surface tension of deionized water (30.3 mNm−1) and emulsified complex mixtures of petroleum hydrocarbons (73%). A 0.5% mono-rhamnolipid solution allowed solubilizing the following hydrocarbon fractions identified in the weathered diesel: aliphatics (66 ± 3%), polycyclic aromatic hydrocarbons (PAHs) (23.16 ± 11%), and asphaltenes (41.4 ± 6%). Within the group of PAHs, four PAHs derivatives, well known to be highly carcinogenic and mutagenic to humans, were identified: neutral, methylated, nitrated, and oxydated. The PAHs and the first three derivatives were removed in an average of 20%. However, regarding the oxy-PAHs, the increment of their concentration allowed assuming the biodegradation of the PAHs during the desorption process. Results show that hydrocarbon desorption with mono-rhamnolipid solutions of high content of saturated fatty acids offers an effective and viable alternative for soil bioremediation because of the low concentration of surfactants required (0.2–0.5%), the short treatment times (≈72 h) and above all, because mono-rhamnolipids are biodegradable compounds friendly to the environment.

Chemical Profiling Provides Insights into the Metabolic Machinery of Hydrocarbon-Degrading Deep-Sea Microbes.

Marine microbes are known to degrade hydrocarbons; however, microbes inhabiting deep-sea sediments remain largely unexplored. Previous studies into the classical pathways of marine microbial metabolism reveal diverse chemistries; however, metabolic profiling of marine microbes cultured with hydrocarbons is limited. In this study, taxonomic (amplicon sequencing) profiles of two environmental deep-sea sediments (>1,200 m deep) were obtained, along with taxonomic and metabolomic (mass spectrometry-based metabolomics) profiles of microbes harbored in deep-sea sediments cultured with hydrocarbons as the sole energy source. Samples were collected from the Gulf of México (GM) and cultured for 28 days using simple (toluene, benzene, hexadecane, and naphthalene) and complex (petroleum API 40) hydrocarbon mixtures as the sole energy sources. The sediment samples harbored diverse microbial communities predominantly classified into Woeseiaceae and Kiloniellaceae families, whereas Pseudomonadaceae and Enterobacteriaceae families prevailed after sediments were cultured with hydrocarbons. Chemical profiling of microbial metabolomes revealed diverse chemical groups belonging primarily to the lipids and lipid-like molecules superclass, as well as the organoheterocyclic compound superclass (ClassyFire annotation). Metabolomic data and prediction of functional profiles indicated an increase in aromatic and alkane degradation in samples cultured with hydrocarbons. Previously unreported metabolites, identified as intermediates in the degradation of hydrocarbons, were annotated as hydroxylated polyunsaturated fatty acids and carboxylated benzene derivatives. In summary, this study used mass spectrometry-based metabolomics coupled to chemoinformatics to demonstrate how microbes from deep-sea sediments could be cultured in the presence of hydrocarbons. This study also highlights how this experimental approach can be used to increase the understanding of hydrocarbon degradation by deep-sea sediment microbes.IMPORTANCE High-throughput technologies and emerging informatics tools have significantly advanced knowledge of hydrocarbon metabolism by marine microbes. However, research into microbes inhabiting deep-sea sediments (>1,000 m) is limited compared to those found in shallow waters. In this study, a nontargeted and nonclassical approach was used to examine the diversity of bacterial taxa and the metabolic profiles of hydrocarbon-degrading deep-sea microbes. In conclusion, this study used metabolomics and chemoinformatics to demonstrate that microbes from deep-sea sediment origin thrive in the presence of toxic and difficult-to-metabolize hydrocarbons. Notably, this study provides evidence of previously unreported metabolites and the global chemical repertoire associated with the metabolism of hydrocarbons by deep-sea microbes.

Physico-chemical Analysis of beeswax procured from Mumbai market, Western Ghats (Natural Habitat)

Beeswax is the substance that is obtained from the structure of a honey comb. The bees secrete wax to build the honey combs to store honey. It has rich hydrophobic property, the beeswax is in fact present within cosmetics and body products. Also, beeswax is used in food industry. Beeswax is a complex mixture of hydrocarbons, free fatty acid, esters of fatty acid. Beeswax plays an important role in Ayurvedic medicine, the traditional medicine name with Madhushistha (Beewax). The Madhushistha is used for the care of wound from abrasion or even from burns with topical application. Some references in Ayurvedic granth highlight the use of Madhushistha in combination with other herbal and mineral mixture, like Sikta Taila, Mruddaharshringa, Jatyadi Taila, etc. Beeswax is mainly of two types, natural beeswax and processed beeswax. Natural beeswax is clarified further heating in water with petroleum waxes. Because of high demand and shortage in market, adulteration of beeswax with cheaper materials are common like animal fat, plant oil and petroleum spirits (Paraffin wax). Hence authenticity of beeswax is major concern and that can be determined by using physico-chemical parameters such as- organoleptic test, solubility, Melting point, Spacific gravity, Refractive index, Acid value, Ester value, Saponification value, volatile matter. With this justification the present study is expected to determine the quality status of four different beeswax samples procured from Mumbai market, western ghats (Natural habitat). The physico-chemical analysis revealed that volatile matter is detected in market sample (2) whereas market sample (1) shows higher melting point as compare to beeswax collected from the Natural habitat. Market sample (1,2) of beeswax shows slight adulteration hence natural habitat samples (1,2) of beeswax should be used in medicine preparation.

Modeling of interfacial tension in binary mixtures of CH4, CO2, and N2 - alkanes using gene expression programming and equation of state

Interfacial tension (IFT) plays a key role in enhanced oil recovery (EOR) processes that involve the injection of light hydrocarbon and non-hydrocarbon gases into oil reservoirs. Crude oil is a complex mixture of different hydrocarbons, its phase behavior is unknown in presence of miscible gas under reservoir conditions; therefore, most of the IFT measurement experiments are done using a certain fluid, such as n-alkanes. CO2 is a common gas used for EOR purposes. Since N2 and CH4 impurities in the injected CO2 stream substantially influence the IFTs and the MMP of the system, several experimental studies conducted on (N2 + n-alkane) and (CH4 + n-alkane) systems over a wide range of temperature and pressure to provide a comprehensive IFT database. Accurate prediction of this property under the thermodynamic conditions encountered in petroleum reservoirs is of paramount importance for achieving the highest amount of oil recovery. In this study, two different models are developed for prediction of IFT in binary mixtures containing (CO2 + n-alkane), (N2 + n-alkane), and (CH4 + n-alkane). These models include the thermodynamic-based model of Weinaug and Katz 1943 [1] combined with PR-EoS, and the mathematical-based model of Gene Expression Programming (GEP). A preprocessing based on Z-score method is applied on the assembled dataset to remove the outliers and duplicates from the data. The GEP and EoS models were able to predict accurate IFT results in all three systems with the EOS providing slightly inferior results in systems containing N2 gas. For some experimental observations the EoS model failed to provide any IFT results. In addition, to have a better understanding of the performance of the developed models, they were compared for IFT values less and greater than or equal to 1 mN/m for all the systems. The average squared coefficient of determination (R2) for the GEP model in CH4, CO2, and N2 – alkanes systems were 0.92, 0.94, and 0.91, and for EoS model were 0.94, 0.87, and 0.66, respectively. The findings of this study can help for a better understanding of interfacial tension under the thermodynamic conditions encountered in petroleum reservoirs is of paramount importance for achieving the highest amount of oil recovery.

Catalytic Oligomerization of ethylene over nano-sized HZSM-5

The nano-sized HZSM-5 zeolites with different Si/Al ratios were pretreated, characterized, and tested in ethylene oligomerization performed in a fixed-bed reactor under relatively mild conditions. The effects of catalyst acidity and reaction temperature on the activity, selectivity and stability were investigated, and a possible reaction route of ethylene over acidic sites of nano-sized HZSM-5 catalyst was proposed. In comparison with micro-sized HZSM-5 zeolite, nano-sized HZSM-5 zeolites exhibited higher activity and better resistance to deactivation. Under optimal conditions (T = 275–300 °C, P = 3.0 MPa, WHSV = 1.0 h−1), The average ethylene conversion was 62.5% over the nano-sized HZSM-5 with an Si/Al ratio of 80, while the selectivity to C4+ olefins and α-olefins was 64.3% and 13.3%, respectively. Furthermore, the products of ethylene oligomerization were a complex hydrocarbon mixture due to the acid-catalyzed secondary reactions, for which the distribution of even and odd numbered carbon atoms formed a continuous volcanic shape mainly centered on C6–C10. Furthermore, these tests demonstrate that the activity and selectivity of ethylene oligomerization depend on the operating conditions and the acidity of the catalysts. These results indicate that the Brønsted acid sites may be mainly responsible for secondary reactions and deactivation of the catalyst, whereas the Lewis acid sites may be more advantageous for ethylene oligomerization.

Unresolved complex mixtures of petroleum hydrocarbons in the environment: An overview of ecological effects and remediation approaches

Unresolved complex mixtures (UCMs) of hydrocarbons are the pollutants of serious concern commonly occurring in most of the environments contaminated with petroleum hydrocarbons. UCMs constitute a relatively unidentified group of compounds compared to the well-resolved hydrocarbons that could easily be identified by the modern chromatographic methods. UCMs that accumulate in the environment cause several toxicological effects of ecological significance, and indirectly affect the human health. Despite decades-long efforts to provide adequate information in this area of research, the fate and environmental impacts of UCMs of petroleum hydrocarbons are poorly understood. Techniques for extraction and analysis of UCMs in the environment are very important in their identification and quantification. Also, remediation of toxic UCMs of petroleum hydrocarbons is all the more essential. In fact, UCMs are often neglected in the risk assessments due to lack of proper identification methods and toxicity data. This critical review presents an overview of our current knowledge on the environmental occurrence, sources, separation, and identification methods for UCMs. The ecological toxicity of UCMs toward the biota and the strategies for remediation of the environments contaminated with UCMs have also been discussed in detail.

Characterization of Hydrocarbon Groups in Complex Mixtures Using Gas Chromatography with Unit-Mass Resolution Electron Ionization Mass Spectrometry

Complex mixtures of hydrocarbons are ubiquitous as petroleum fuels and, consequently, environmental contaminants. Because they contain thousands of individual components with similar molecular structures, detailed chemical characterization of hydrocarbon mixtures relies on advanced analytical techniques that are not accessible to many researchers. Many analyses of hydrocarbon mixtures instead characterize them as "unresolved complex mixtures", with quantification limited to a small number of resolvable components and/or total observed mass within specified volatility ranges. This work develops a new analytical approach to characterize the hydrocarbon component of petroleum and environmental mixtures by "hydrocarbon group" (defined by carbon number, degree of unsaturation and, in certain cases, degree of branching) using gas chromatography coupled to a unit-mass-resolution electron ionization quadrupole mass spectrometer (GC/EI-MS), a standard and widely available instrument. Average mass spectra of hydrocarbons from a widely used spectral library are combined with chromatographic signal representing the molecular ion of each hydrocarbon group to recreate the magnitude and mass spectra of the chromatogram. Characterization of hydrocarbons in diesel fuel by this approach is in good agreement with state-of-the-art techniques relying on high-resolution and fast-response mass spectrometers. Application of this approach to subsurface soil gas samples from remediated sites of underground storage tank spills demonstrates that composition of hydrocarbons in environmental samples varies significantly and that the total signal of samples from contaminated sites may contain a substantial fraction of oxygenated components.

Bioreactors for the remediation of hydrocarbon-polluted water of the Bitzal River, a place of environmental emergency due to the death of manatees

The objectives of this research are: identify the hydrocarbons in water from the Bitzal River, Tabasco; select a carbon source that serves as a representative substrate of the determined compounds; and finally, design an experimental proposal for bioreactors that are capable of consuming compounds formed by complex mixtures and, therefore be effective in the elimination of specific hydrocarbons. We identified 16 compounds that belong to different hydrocarbon fractions. Pentacene (24.3 ± 0.09 mg L−1), n-nonane (2.11 ± 0.96 mg L−1) and benzo [a] pyrene (1.39 ± 0.57 mg L−1) were the compounds with the highest concentrations in water. Two culture media, mineral medium and seawater were used. Diesel and Mayan crude oil were used for each culture medium, with a total of four bioreactors. Diesel represented light- and medium-fraction hydrocarbons, while Mayan crude oil represented the heavy fraction as well as the recalcitrant and polycyclic aromatic hydrocarbons (PAH). The maximum growth of suspended solids for diesel in mineral medium reached 2.95 g L−1, and diesel was completely consumed in 8 days. In seawater, suspended solids for diesel reached 2.70 g L−1, and diesel was consumed in 12 days. For Mayan crude oil in mineral medium, suspended solids increased from 0.8 to 2.41 g L−1, and Mayan crude oil was completely consumed in 12 days. Using seawater, Mayan crude oil also degraded in 12 days, and suspended solids growth reached 2.11 g L−1. Compounds that simulate complex mixtures of hydrocarbons from light to heavy fractions could be degraded, and the use of bioreactors is an alternative method of hydrocarbon pollution remediation in the Bitzal River.

Abstract A02: A case for re-examination of the contribution of nitro-PAHs to combustion-product carcinogenesis

Abstract One of the most studied compounds in all of cancer research is the environmental carcinogen benzo[a]pyrene (BaP). There is little doubt that BaP and its PAH congeners are the principal carcinogens in products like coal tar pitch, a category 1 IARC carcinogen. However, their concentrations in other complex hydrocarbon mixtures, like uncracked petroleum oils, are too low to account for their overall carcinogenic potency (that is, discounting contributory factors like tumor promotion and cumulative mutagenic insult). Nonetheless, the potent carcinogenicity of BaP and other four- and five-ring PACs has made reducing the release of these compounds into the environment from their principal endogenous source, petroleum, a major goal of health and safety regulation. Similar efforts to minimize the levels of the same PAHs pyrosynthesized and released into the atmosphere by the combustion of carbon fuels, have, however, faced a far greater challenge, given the immensity of that release on a daily basis. Moreover, the regulatory focus on parent, largely unsubstituted, PAHs has led to a de-emphasis on other potential contributors to the carcinogenicity of complex hydrocarbon mixtures, which in the case of the combustion products studied here, include their nitro-PAH derivatives. There are valid reasons for this de-emphasis. But there are also grounds to believe that a re-examination of the nitro-PAH role in combustion product carcinogenesis is warranted. Among them are the demonstration by Rosenkranz et al. (Science 1980;209:1039-43) that one such compound, 1,8-dinitropyrene (DNP), induces over one million mutations per microgram in the Ames Test, and the Iwagawa et al. report (Carcinogenesis 1989;10:1285-90) that its isomer 1,6-DNP, when injected directly into the lungs of rats, exhibited three times the carcinogenic potency of BaP similarly introduced. The present report demonstrates that extracts of soot or ash from a variety of sources, including wood, liquified petroleum gas, and the burnt ends of cigarettes, contain an extremely potent Ames Test mutagen that, when fractionated by HPLC, coelutes with authentic DNP. These results would seem to be inconsistent with the known low activities in lung tissue of the nitroreductase required for DNP’s activation to its ultimate carcinogenic form. But one possible explanation for that apparent discrepancy is that populations of bacteria resident in the lung—many species of which are as nitroreductase-proficient as the Salmonella strains used in Ames testing—may be largely responsible for that activation. Citation Format: Gary Blackburn. A case for re-examination of the contribution of nitro-PAHs to combustion-product carcinogenesis [abstract]. In: Proceedings of the AACR Special Conference on Environmental Carcinogenesis: Potential Pathway to Cancer Prevention; 2019 Jun 22-24; Charlotte, NC. Philadelphia (PA): AACR; Can Prev Res 2020;13(7 Suppl): Abstract nr A02.

Comprehensive Two-Dimensional Gas Chromatography Hyphenated with a Vacuum Ultraviolet Spectrometer To Analyze Diesel—A Three-Dimensional Separation (GC × GC × VUV) Approach

Effective separation of individual components continues to pose the greatest challenge in the characterization of complex hydrocarbon mixtures. Recent research has tackled this problem using severa...

Analysis of the nanoscale phase characteristics of bitumen and bitumen in mastics and mixtures via AFM.

A peak force quantitative nanomechanical mode (PF-QNM) can be used to simultaneously measure the topographical and nanomechanical property maps of samples. Currently, few studies used this mode to investigate the phase characteristics of bitumen in mastics and mixtures. The present study adopted hot-bitumen-pouring methods to prepare base bitumen surface samples and further used frozen-storage and low-temperature-cutting methods to prepare the internal samples of base bitumen in mastics and mixtures. Then, the atomic force microscopy (AFM) PF-QNM mode was used to collect data on the topographical and nanomechanical properties of bitumen and bitumen in mastics and mixtures. The results indicated that a typical bee structure only appeared on the bitumen surface. In contrast to the bitumen surface, the bitumen interior showed two phases, A- and B-phase, which were close in some properties to the periphase and paraphase of the bitumen surface, respectively. Furthermore, the addition of mineral aggregates affected the phase characteristics of the free bitumen interior. With an increase in the mineral aggregate surface area, the proportion of A-phase decreased and that of B-phase increased in the free bitumen interior. LAY DESCRIPTION: Bitumen is a complex mixture of hydrocarbons primarily applied for pavement materials. In the pavement industry, the bituminous mixture is a multilevel system, in which bitumen acts as a binder binding the aggregates and fillers to form bituminous mixture. Currently, atomic force microscopy (AFM), which is an advanced microscopy technology, has been used to investigate bitumen surface phase characteristics at the nanoscale. However, few studies have directly explored the nanoscale phase characteristics of bitumen in mastics or mixtures. Recently, with the progress of technology, a peak-force-quantitative-nanomechanical mode (PF-QNM) can be used to simultaneously measure the topographical and nanomechanical property maps of samples. Relying on this advanced mode, this study analyzed the nanoscale phase characteristics of the bitumen surface and interior, and further explored the effect of mineral aggregates on bitumen interior phase characteristics. In detail, we used hot-bitumen-pouring methods to prepare bitumen surface samples and adopted frozen-storage and low-temperature-cutting methods to prepare the internal samples of bitumen in mastics and mixtures. Subsequently, AFM PF-QNM mode was used to collect topographical and nanomechanical property maps of bitumen and bitumen in mastics and mixtures. The results indicated that the bitumen interior only consisted of two phases, where the A-phase presented low adhesion, deformation, and dissipation, while the B-phase presented high adhesion, deformation, and dissipation. A-phase and B-phase of the bitumen interior were close to the periphase and paraphase of the bitumen surface, respectively. Furthermore, the addition of mineral aggregates significantly affected the bitumen interior phase characteristics.

Fragmentation of Saturated Hydrocarbons upon Atmospheric Pressure Chemical Ionization Is Caused by Proton-Transfer Reactions.

Chemical characterization of complex mixtures of large saturated hydrocarbons is critically important for numerous fields, including petroleomics and renewable transportation fuels, but difficult to achieve. Atmospheric pressure chemical ionization (APCI) mass spectrometry has shown some promise in the analysis of saturated hydrocarbons. However, APCI causes extensive fragmentation to these compounds, which impedes its effectiveness. To prevent this fragmentation, its causes were examined via gas-phase ion-molecule reactions in vacuum in a linear quadrupole ion trap mass spectrometer. The results demonstrate that the mechanism proposed previously for ionization of saturated hydrocarbons upon APCI, hydride abstraction by carbocation reagent ions, is not correct. Instead, the fragmentation is caused by ionization of saturated hydrocarbons via exothermic proton-transfer reactions involving highly acidic, protonated atmospheric molecules, such as nitrogen and water. Accordingly, the extent of fragmentation was found to correlate with the proton affinities of the atmospheric molecules studied. Remarkably, controlled experiments involving isolated atmospheric ions and neat saturated hydrocarbons in vacuum yielded almost identical mass spectra as APCI involving atmospheric pressure conditions, the presence of many different chemicals, and an electrical discharge. In order to prevent or reduce the extent of fragmentation of saturated hydrocarbons upon APCI, and therefore enable accurate mass spectrometric characterization of complex mixtures of saturated hydrocarbons, the ion source should be purged of air to remove nitrogen and water and fill it with an inert gas with a substantially lower proton affinity.

Evaluation of ethylic and methylic esterification reactions to reduce acidity of crude bio‐oil

AbstractBio‐oil produced from triglycerides thermal cracking is a complex mixture of hydrocarbons and oxygenated compounds and is a potentially renewable source for fuel and chemical production. The presence of carboxylic acids results in a high acid index making it difficult to refine and use it as a fossil fuel substitute. This high acidity causes corrosion and may interfere on the final applications. In this work, soybean oil was thermally cracked, and the bio‐oil was characterized and submitted to esterification reactions in order to evaluate the effect of temperature and reactants mass ratio. Before esterification, crude bio‐oil showed 8.61% of carboxylic acids in GC–MS characterization and an acid index of 133.33 mg KOH/g. The reactions were conducted for 90 min, from 50 to 65°C for methanol and from 60 to 75°C for ethanol, and the bio‐oil‐alcohol mass ratio from 10:1 to 1:1. Methylic and ethylic esterification at 1:1 mass ratio of bio oil to alcohol at 65°C and 75°C showed decrease of 97.5 and 90.4% in the acid index, reaching values of 3.35 and 12.65 mg KOH/g, respectively. These results demonstrate the potential of using esterification in bio‐oil to reduce its acidity and improve its quality.

Zebrafish CYP1A expression in transgenic Caenorhabditis elegans protects from exposures to benzo[a]pyrene and a complex polycyclic aromatic hydrocarbon mixture

Polycyclic aromatic hydrocarbons (PAHs) are environmental toxicants primarily produced during incomplete combustion; some are carcinogens. PAHs can be safely metabolized or, paradoxically, bioactivated via specific cytochrome P450 (CYP) enzymes to more reactive metabolites, some of which can damage DNA and proteins. Among the CYP isoforms implicated in PAH metabolism, CYP1A enzymes have been reported to both sensitize and protect from PAH toxicity. To clarify the role of CYP1A in PAH toxicity, we generated transgenic Caenorhabditis elegans that express CYP1A at a basal (but not inducible) level. Because this species does not normally express any CYP1 family enzyme, this approach permitted a test of the role of basally expressed CYP1A in PAH toxicity. We exposed C. elegans at different life stages to either the PAH benzo[a]pyrene (BaP) alone, or a real-world mixture dominated by PAHs extracted from the sediment of a highly contaminated site on the Elizabeth River (VA, USA). This site, the former Atlantic Wood Industries, was declared a Superfund site due to coal tar creosote contamination that caused very high levels (in the [mg/mL] range) of high molecular weight PAHs within the sediments. We demonstrate that CYP1A protects against BaP-induced growth delay, reproductive toxicity, and reduction of steady state ATP levels. Lack of sensitivity of a DNA repair (Nucleotide Excision Repair)-deficient strain suggested that CYP1A did not produce significant levels of DNA-reactive metabolites from BaP. The protective effects of CYP1A in Elizabeth River sediment extract (ERSE)-exposed nematodes were less pronounced than those seen in BaP-exposed nematodes; CYP1A expression protected against ERSE-induced reduction of steady-state ATP levels, but not other outcomes of exposure to sediment extracts. Overall, we find that in C. elegans, a basal level of CYP1A activity is protective against the examined PAH exposures.