Structure Of Hydrocarbons Research Articles

Investigation of enterobacter aerogenes effects on heavy oil from biological degradation aspects by GC*GC technique

The main cause of oil pollution of soil is the emergency situations within oil production, transportation and processing in the boundaries of industrial sites of chemical and petrochemical industries. Oil pollution leads to the deterioration of the agrophysics soil characteristics, namely to the dysfunction of the water, air, thermal, oxidation-reduction and nutrient regimens. Microbial technologies are becoming accepted worldwide as cost-effective and environmentally friendly approaches to improve oil production. One of the methods to purify oil residue is bioremediation, in this way we Investigate Enterobacter Aerogenes effects on heavy oil by SARA, FT-IR, GC and GCxGC methods. The material required for the growth of Enterobacter Aerogenes is Carbon and Phosphate. On the one hand, this bacterium takes these nutrients from carbohydrates in our body. In addition, the crude oil is full of Hydrocarbon structures. So, the Enterobacter Aerogenes is injected with Thioglycollate broth to crude oil which was distillated and the samples were put for a month in an incubator for 30 days. The results this research illustrate this bacterium has been able to survive in oil by isolating straight-run carbons with short and weak bounds from asphaltene and resin structures, as well as utilizing sulfur, nitrogen and oxygen in the oil. Also, it is found out this bacterium has had a positive effect on making light oil from heavy crude oil. It should be noted this bacterium releases CH4, which can be used again if the gas is collected.

Synthesis of closo-1,2-H2C2B8Me8 and 1,2-H2C2B8Me7X (X = I and OTf) Dicarbaboranes and Their Rearrangement Reactions.

Methyl-camouflaged dicarbaboranes closo-1,2- and 1,10-H2C2B8Me8 have been prepared in high yields either from nido-5,6-H2C2B8H10 or closo-1,2-H2C2B8H8 via electrophilic methylation reactions and cluster-rearrangement methods. Prepared were also monosubstituted derivatives of general formulation closo-H2C2B8Me7-X (X = I or OTf). The permethylated compounds exhibit extreme air stability in comparison to unprotected counterparts as a consequence of rigid, egg-shaped hydrocarbon structures incorporating inner C2B8 carborane scaffolding. The structures of all compounds isolated were confirmed unambiguously by multinuclear (11B, 1H, 13C, and 19F) NMR measurements, supported by X-ray diffraction analyses and geometry optimization methods on several compounds.

The dynamics of trace elements and heavy metals content in the soil profile of gray forest soil under the long-term use of fertilizers in crop rotation

The results of investigations of changes in the content of mobile forms of trace elements and heavy metals under the systematic use of organic and mineral fertilizers in field crop rotation on gray forest soil are given. It was established that the use of fertilizers had little effect on the accumulation of these indicators in the soil relative to the initial state, but the excess of the MPC level was not observed for all elements. The most organoleptic fertilizer system (12 t/ha manure + N 60 P 60 K 68 ) was found to be the most effective both in the processes of accumulation of the most significant microelements in the life of plants and in the creation of a high level of productivity of the crop rotation. Under these conditions, a rational ratio between calcium and magnesium is noted. The use of organic fertilizers, creating conditions for the reproduction of humus stocks and optimization of the structure of hydrocarbons, does not provide optimal parameters for available forms of nutrients in the soil environment for field crop rotation crops. Application of purely mineral fertilizers at high loads in fertilizer systems is agronomically unworkable.

DISJUNCTIVE DISLOCATION AND THEIR ROLE IN STRUCTURE AND TRAP FORMATION

The results of data generalization оf tectonic disturbances value in formation of hydrocarbon structures and traps are presented. The double role of disjunctives in the processes of oil and gas accumulation, known and possible screening factors is considered. Disjunctive dislocations in dependence of their nature and geological conditions of existence in the process of oil and gas accumulation can play a structuring role, be a main component in the formation of disjunctly screened traps, or act as fluids migration ways. Genetic and morphologic characteristics of disjunctives in many cases control the possibility of forming and conservation of deposits and the nature of oil and gas territories of their development. Numerous characteristics of disjunctive tectonic disturbances that are differentiated by a set of different features are considered. Predominantly structural forming are deep faults and Earth crust rupture. Among intra-sedimentary-cover ruptures, which are predominantly structure complicating forse, the function of forming structures is most commonly inherent to lystric disjunktives. Deep faults function as main ways of heat and mass transferring from mantle sources, including hydrocarbon compounds. The role of an oil anaerobic oxidation on contact with aquifers across rupture plane accentuated as a possible factor forming disjunctive screened traps.

Liquid Structure of Shock-Compressed Hydrocarbons at Megabar Pressures.

We present results for the ionic structure in hydrocarbons (polystyrene, polyethylene) that were shock compressed to pressures of up to 190GPa, inducing rapid melting of the samples. The structure of the resulting liquid is then probed using insitu diffraction by an x-ray free electron laser beam, demonstrating the capability to obtain reliable diffraction data in a single shot, even for low-Z samples without long range order. The data agree well with abinitio simulations, validating the ability of such approaches to model mixed samples in states where complex interparticle bonds remain, and showing that simpler models are not necessarily valid. While the results clearly exclude the possibility of complete carbon-hydrogen demixing at the conditions probed, they also, in contrast to previous predictions, indicate that diffraction is not always a sufficient diagnostic for this phenomenon.

Graphene oxide quantum dots stimulate indigenous bacteria to remove oil contamination.

Oil spills occur frequently worldwide, resulting in severe damage to water and to human health. Polycyclic aromatic hydrocarbons (PAHs) are the primary toxic components in oil contamination. PAH-degrading microbes have attracted significant attention, but difficulty in their selection and proliferation limits their applications. Graphene oxide quantum dots (GOQDs) improve the proliferation of an indigenous PAH-degrading strain, Bacillus cereus, more effectively than large graphene oxide flakes. Bacillus cereus can metabolize a variety of xenobiotic aromatic compounds as carbon sources and is used in bioremediation. GOQDs contain a variety of aromatic hydrocarbon structures, explaining why the bacteria achieve strong tolerance to PAHs. GOQD-activated cytokinesis increases the secretion of substances important for biofilm formation (extracellular polymeric substances), which further accelerates PAH removal. Proteomic analysis reveals the molecular mechanisms underlying GOQD-induced microbial proliferation. GOQDs induce the overexpression of microbial divisomal proteins associated with division initiation, DNA replication and peptidoglycan hydrolysis/synthesis. Importantly, PAH removal mediated by GOQD-treated Bacillus cereus does not require the addition of GOQDs. The effects of GOQDs on a strain persist for at least 20 generations, suggesting their possible use in low-cost applications. This work proposes a strategy to remove oil contamination using an indigenous bacterial system enhanced by nanomaterials.

Macromolecular-clustered facial amphiphilic antimicrobials

Bacterial infections and antibiotic resistance, particularly by Gram-negative pathogens, have become a global healthcare crisis. We report the design of a class of cationic antimicrobial polymers that cluster local facial amphiphilicity from repeating units to enhance interactions with bacterial membranes without requiring a globally conformational arrangement associated with highly unfavorable entropic loss. This concept of macromolecular architectures is demonstrated with a series of multicyclic natural product-based cationic polymers. We have shown that cholic acid derivatives with three charged head groups are more potent and selective than lithocholic and deoxycholic counterparts, particularly against Gram-negative bacteria. This is ascribed to the formation of true facial amphiphilicity with hydrophilic ion groups oriented on one face and hydrophobic multicyclic hydrocarbon structures on the opposite face. Such local facial amphiphilicity is clustered via a flexible macromolecular backbone in a concerted way when in contact with bacterial membranes.

Effect of the Kerogen Molecular Structure on the Formation of Methane During Kerogen Pyrolysis

In this study, density functional theory (DFT) at the GGA/RPBE level was employed to examine the effects of the kerogen microstructure on the formation mechanism of methane during the pyrolysis of kerogen. The calculations prove that the evolution of CH4 during kerogen pyrolysis corresponds to demethylation, and the process of forming methane involves the interaction of intramolecular hydrogen atom transfer and assistant hydrogen atom transfer. In all reaction paths, the energy barrier of path 5 is the smallest at 260.56 kJ mol−1. The energy barrier of path 6 is the largest at 554.36 kJ mol−1. The results indicate that CO is favourable for demethylation, and CO2 is not conducive to demethylation. Path 1 is the formation of methane by the transfer of assistant hydrogen atoms, and the required energy barrier is 379.45 kJ mol−1. The side chain structure of the aromatic hydrocarbon structure is liable to demethylation to form methane. A comparison of the reaction energy barriers follows the order: path 1 < path 15 < path 14 < path 10, which indicates the that difference in the demethylation reaction is based on the microstructure. In the same reaction process, the benzene ring and the aliphatic hydrocarbon structure are more susceptible to demethylation to form methane. In the heterocyclic bicyclic structures containing O and S, a comparison of the reaction energy barriers follows the order: path 11 ≈ path 12 < path 13, so paths 11 and 12 are close, but path 13 is more difficult to occur, indicating that it is more difficult to demethylate with heteroatoms in the same ring. From a thermodynamic point of view, in the process of assisting the formation of methane by hydrogen atoms, the demethylation reaction is mainly an endothermic reaction. During the transfer of intramolecular hydrogen atoms, the demethylation reaction is mainly an exothermic reaction, and most reactions are spontaneous.

Interplay between Aromaticity and Radicaloid Character in Nitrogen-Doped Oligoacenes Revealed by High-Level Multireference Methods.

Aromaticity is a multivariable concept in organic chemistry that plays a central role for understanding the structure, stability, and reactivity of polycyclic aromatic hydrocarbons (PAHs). Several types of PAHs are characterized as singlet biradicaloid species and their chemical stability is intimately linked to the degree of aromatic character. In this study, theoretically designed routes to tune the biradical character (and thereby its chemical stability) of nitrogen-substituted octacenes have been investigated on the basis of the high-level multireference averaged quadratic coupled-cluster MR-AQCC method necessary for the appropriate description of polyradicaloid systems. The influence of nitrogen centers on the aromaticity of octacene is probed through structural (HOMA) and electron localization (ELF) indices by comparing the N- against NH-doping cases. These analyses reveal that the aromaticity and biradical character of octacene is only slightly affected by replacing one pair of CH groups with N atoms, i.e., by N-doping. However, a significant aromatic stabilization can be obtained when NH-doping is applied at the inner octacene rings; this is also accompanied by an overall decrease of the open-shell character, as evidenced by the gradual quenching of the unpaired electrons and increase in the singlet-triplet splittings when the NH doping groups are moved toward the center of the octacene molecule. Our findings aid in the rational design of new PAH compounds with balanced biradicaloid character and chemical stability which is important, e.g., for practical applications in organic solar cells based on the singlet-fission mechanism.

The aromatic universe

The rich molecular structures of polycyclic aromatic hydrocarbons—essentially planar flakes of fused benzene rings—and their fullerene cousins are revealed through their vibrational and electronic spectra.

Features of bitumoids composition of bottom sediments of the coastal zone of the East Siberian Sea

An anthropogenic influence, in particular, oil contamination on the Arctic ecosystems is studied. For this composition of the chloroform bitumoids extracted from the samples of bottom sediments is explored. The samples were taken near seaport Kolyma River and a coastal zone of the East Siberian Sea. In bottom sediments of the seaport the yeild of bitumoid reached 25500 mkg g-1. As appeared, their samples were oil contaminated. Hydrocarbons prevailed significantly over the sum of resinous components in their composition as aliphatic compounds dominated over oxygen groups in chemical structure. N-alkanes maked up 28% of the sum of the identified hydrocarbons with a distribution maximum in the area nC15,16. CPI is typical for oil and oil products. The values of ratio of isoprenoids to n-alkanes and the distribution of isoprenoids point to processes of biodegradation of oil hydrocarbons. In the sea samples the yield of bitumoid much less 193-1577 mkg g-1 and oil contamination traces aren’t found. The future of chemical structure and distribution of individual saturated hydrocarbons reveal a strong relationship with terrigenous organic matter of recent deposits. The prevalence of odd hydrocarbons nC23-nC35 and high concentrations nC27, nC29, nC31 is characteristic for lipids of highest land plants.

Molecular and detailed isotopic structures of petroleum: Kinetic Monte Carlo analysis of alkane cracking

The compositional and bulk isotopic signatures of hydrocarbon compounds are routinely characterized to constrain the origin of oils and natural gases in sedimentary basins. Recent developments in clumped isotope geochemistry have given rise to a suite of measurements that provide new information on the thermal history of low molecular weight hydrocarbon gases. However, to date no study has linked these compositional, bulk and clumped isotope constraints to any mechanistic understanding of how these signatures develop and evolve. In this study, we developed a kinetic Monte Carlo method to predict consistent and simultaneous molecular distributions, bulk isotopic content, and detailed (multiply substituted and site-specific) isotopic structures of hydrocarbons from a cracking model. The detailed isotopic structure of the source (initially modeled as long alkanes), the intermediates, and the product molecules is followed as a function of the level of conversion due to cracking reactions. The bulk 13C content of gaseous alkane products generated via the model is shown to follow the linear natural gas plot at low conversion, but to deviate at high conversions. As examples of the information generated, the populations of center vs. terminal 13C-substituted propane are reported as a function of the starting alkane chain length and conversion and the population of doubly-13C-substituted ethane is described as a function of conversion and for different 13C substitution patterns in the source. The results are compared to experiment where possible and highlight the possibility of constraining hydrocarbon source isotopic structure and the nature of the generation processes leading to the formation of natural hydrocarbon deposits.

Flow and thermal analyses of supercritical hydrocarbon fuel in curved regenerative cooling channel around cavity in rocket based combined cycle engine

Various studies in straight channels have been investigated to promote the development of regenerative thermal protection technique. However, the combined effects of curved structure and pyrolytic reaction of hydrocarbon fuel have not been adequately investigated. In this article, the effects of inlet temperature, unilateral heat flux and pyrolytic reaction on flow and heat transfer processes in a 90° curved channel around cavity are numerically analyzed in fluid-solid coupled and uncoupled models, considering variable thermophysical properties and chemical components. Results show that there is strong secondary flow around the corner of cooling channel and the vortices form a heat transfer deterioration region at the center of bottom wall which results in transverse temperature difference. With increasing inlet temperature, the vortices magnitude is increasing and the transverse nonuniformity of temperature decreases by 60.3%. And when the inlet temperature reaches the value with maximum pyrolytic rate, the increasing heat flux is mostly taken by the pyrolysis reaction which results in insignificant changes of vortices magnitude. The pyrolysis reaction intensifies the stratifications of pressure and density, which correspondingly strengthens the magnification effect of vortices around the corner and decrease the transversal temperature difference.

The General (α,3)-Path Connectivity Indices of Polycyclic Aromatic Hydrocarbons

The general (α,t)-path connectivity index of a molecular graph originates from many practical problems such as three-dimensional quantitative structure-activity (3D QSAR) and molecular chirality. It is defined as Rtα(G)=∑Pt=vi1vi2⋯vit+1⊆G[d(vi1)d(vi2)⋯d(vit+1)]α, where the summation is taken over all possible paths of length t of G and we do not distinguish between the paths vi1vi2⋯vit+1 and vit+1⋯vi2vi1. In this paper, we focus on the structures of Polycyclic Aromatic Hydrocarbons (PAHn), which play a role in organic materials and medical sciences. We try to compute the exact general (α,3)-path connectivity indices of this family of hydrocarbon structures. Furthermore, we exactly derive the monotonicity and the extremal values of R3α(PAHn) for any real number α. These valuable results could produce strong guiding significance to these applied sciences.

Petroleum hydrocarbon and microbial community structure successions in marine oil-related aggregates associated with diatoms relevant for Arctic conditions

Oil-related aggregates (ORAs) may contribute to the fate of oil spilled offshore. However, our understanding about the impact of diatoms and associated bacteria involved in the formation of ORAs and the fate of oil compounds in these aggregates is still limited. We investigated these processes in microcosm experiments with defined oil dispersions in seawater at 5 °C, employing the Arctic diatom Fragilariopsis cylindrus and its associated bacterial assemblage to promote ORA formation. Accumulation of oil compounds, as well as biodegradation of naphthalenes in ORAs and corresponding water phases, was enhanced in the presence of diatoms. Interestingly, the genus Nonlabens was predominating the bacterial communities in diatom-supplemented microcosms, while this genus was not abundant in other samples. This work elucidates the relevance of diatom biomass for the formation of ORAs, microbial community structures and biodegradation processes in chemically dispersed oil at low temperatures relevant for Arctic conditions.

Computational modeling of the dinuclear metal complexes with di-o-quinones comprising paramagnetic acene linker groups

Abstract The magnetically-active dinuclear metal complexes with previously unstudied di-o-quinone ligands comprising paramagnetic acene linkers have been investigated with the use of density functional theory quantum-chemical calculations (UTPSSh/UB3LYP/6-311++G(d,p)). Two types of linker groups are considered: linear acenes comprising various number of six-membered cycles and polycyclic hydrocarbons containing terminal five-membered rings. In sodium complexes replacement of terminal six-atomic hydrocarbon rings of the acene chain by five-membered cycles results in changing the type of the exchange interactions involving o-semiquinone radical-anions from antiferromagnetic to ferromagnetic. All paramagnetic centers in copper complexes with dicatecholate forms of the redox-active ligands are antiferromagnetically coupled. The performed computational modeling has shown that the nature and strength of the exchange interactions between paramagnetic centers of the compounds under study depend on the structure of the polycyclic hydrocarbon determined by the type of terminal rings and oxidation state of the redox-active moieties.

Improvement of working parameters of ships with the use of water-fuel emulsions

The object of research is the process of preparing and burning watered fuels on ships. One of the most problematic places in the use of such fuels is the complexity of the process of preparing a water-fuel emulsion and the lack of data that unequivocally indicate the maximum allowable values of water concentration in a marine diesel. As a result of research, it has been established that the presence of water in fuel under certain operating conditions of a marine ship may lead to an improvement in the combustion process. In this case, harmful emissions are reduced, flue gas temperature decreases and fuel costs are descended. In the course of the study, a new technology of ship treatment of water-fuel emulsions was used. The proposed method of mixing water with fuel provided structural changes in the molecular composition of the emulsion in comparison with the initial structure of hydrocarbons and provided increased dispersion when it was sprayed in the combustion flame. The basis for creating a technology for preparing water-fuel emulsions was two processes – cavitation and mechanical mixing of water and fuel at high speeds. It has been found that the improvement of the main performance indicators of ships in various load modes of the main engine can be achieved with a water concentration in the fuel of up to 15 % . This is due to the fact that the quality of fuel combustion increases due to a decrease in the deposits and in sediments on the inner surfaces of the working cylinders. The process of using water-fuel emulsions on ships has a number of features that are determined by the used equipment. A very important issue is the question of the sustainability of the combustion flame created by the injectors of the ship’s main engine. Due to the quality preparation of the water-fuel emulsion, a decrease in the total fuel consumption is observed while maintaining the ship’s performance at a constant level. Compared to similar ships operating on standard fuel, the reduction of thermal stress of the ship’s main engine is achieved by reducing the temperature of flue gases emitted into the atmosphere.

Mapping and quantifying isomer sets of hydrocarbons ( ≥ C12) in diesel exhaust, lubricating oil and diesel fuel samples using GC × GC-ToF-MS

Abstract. Airborne particles and vapours, like many other environmental samples including water, soils and sediments, contain complex mixtures of hydrocarbons, often deriving from crude oil either before or after fractionation into fuels, lubricants and feedstocks. Comprehensive 2D gas chromatography time-of-flight mass spectrometry (GC × GC-ToF-MS), offers a very powerful technique that separates and identifies many compounds in complicated hydrocarbon mixtures. However, quantification and identification of individual constituents at high ionization energies would require hundreds of expensive (when available) standards for calibration. Although the precise chemical structure of hydrocarbons does matter for their environmental impact and fate, strong similarities can be expected for compounds having very similar chemical structures and carbon numbers. There is, therefore, a clear benefit in an analytical technique which is specific enough to separate different classes of compounds and to distinguish homologous series while avoiding the need to handle each isomer individually. Varying EI (electron impact) ionization mass spectrometry significantly enhances the identification of individual isomers and homologous compound groups, which we refer to as “isomer sets”. Advances are reported in mapping and quantifying isomer sets of hydrocarbons (≥ C12) in diesel fuel, lubricating oil and diesel exhaust emissions. By using this analysis we report mass closures of ca. 90 and 75 % for diesel fuel and lubricating oil, and identify 85 and 75 % of the total ion current for gas- and particulate-phase diesel exhaust emissions.

Accumulation of Polycyclic Aromatic Hydrocarbons in Soils and Mosses of Southern Tundra at Different Distances from the Thermal Power Plant

A number of polycyclic aromatic hydrocarbon (PAH) structures have been identified in organic horizons of surface-gley tundra soils (Stagnic Cambisols) and the moss Pleurozium schreberi. The total content of polyarenes in soils and P. schreberi exceeds the background values in 3.5–5 times. A tendency of increasing content of polyarenes with the distance from the source to 1 km has been revealed. High coefficients of variation have been found between the contents of PAHs in snow cover, organic soil horizons, and mosses. Light hydrocarbons dominate in the composition of PAHs from the snow and ground covers and mosses. Naphthalene dominates on the surface of mosses in all of the studied plots, which is largely related to its intensive uptake by mosses under pollution conditions. It has been found that when the input of polyarenes onto the surface of tundra phytocenoses increases, the bioaccumulation of PAHs by P. schreberi is intensified, and PAHs begin to penetrate into moss. The increase in the concentration of high-molecularweight polyarenes in the environment plays the key role in the activation of PAH bioaccumulation by moss. It has been shown that P. schreberi can be used as an indicator species for monitoring the contamination of tundra phytocenoses by polyarenes. Both living and dead parts of P. schreberi are suitable for the environmental monitoring of PAH contamination.

Prediction of the temperature dependence of densities and vapor pressures of nonpolar hydrocarbons based on their molecular structure and refractive index data at 20 °C

In a previous publication, a one-parameter equation based on the perturbed chain version of the statistical associating fluid theory, assisted by a group contribution method (1P-PC-SAFT) was proposed for cases where limited experimental data are available (Evangelista and Vargas, Ind. Eng. Chem. Res., 2017). The method was proven to be robust when a single vapor pressure data point was used for the PC-SAFT parameter tuning. Motivated by this fact, a methodology for estimating a saturation data point from refractive index and molecular weight was developed in this work. The proposed correlations also represent an alternative method for calculating critical properties and acentric factor for non-polar hydrocarbons as a function of their molecular weight and refractive index. These alternative correlations to find critical properties can be readily applied to cubic equations of state or methods based on the principle of the corresponding states. The predictive capability of the proposed methodology was assessed over a wide range of temperatures and pressures. Average absolute deviations of 8.24% in vapor pressure and 2.04% in saturated liquid density were obtained for ten representative compounds consisted of aliphatic, aromatics, and cyclic nonpolar hydrocarbons. The results obtained in this work confirm that with the proposed methodology it is possible to relate molecular structure and refractive index of liquid nonpolar hydrocarbons at 20 °C to their density and vapor pressure at high temperatures.