Mixture Of Saturated Hydrocarbons Research Articles

Effect of Pd content in multi-component alloys [CoFeNi]Pdx on their behavior in hydrocarbon-containing atmosphere

Multicomponent metal systems attract growing interest today, especially as catalysts for various processes. In the present work, a series of [CoFeNi]Pdx alloys (equal atomic content of base metals) doped with palladium in the amount of 0–10 at.% were synthesized via thermolysis of multicomponent precursors. The resulting [CoFeNi]Pdx alloys were found to be single-phase solid solutions with a fcc structure represented by agglomerates of grains fused. The performance of the alloys was explored in a mixture of saturated hydrocarbons (C2–C4) within the temperature range of 600–675 °C. As a result of interaction with the reaction mixture, spontaneous disintegration of the alloys containing above 2 at.% Pd occurs with the formation of dispersed particles responsible for the catalytic growth of carbon nanofibers (CNF). The dependence of the productivity of the [CoFeNi]Pdx alloys towards CNFs on the x parameter was studied. The highest CNF yield (YC = 25–46 g/gcat, 30 min) was achieved at an optimal Pd concentration of 8 at.% within the entire temperature range. According to TEM and EDX data, regardless of the reaction temperature and Pd concentration in the alloy, the catalyst particles have the same composition as defined at the synthesis of the alloys. The resulting CoFeNiPd@CNF composite can be considered as a catalyst for other heterogeneous catalysis processes.

MODIFYING TEMPERATURE CORRELATIONS IN MELTING PROPERTIESCALCULATIONS FOR ACCURATE PREDICTION OF WAX DEPOSITION

The formation of paraffin deposits is a common problem faced by oil production companies, as it complicates the production and transportation of hydrocarbons. Paraffins are a mixture of saturated hydrocarbons (alkanes) contained in oil in a dissolved or, depending on temperature, crystalline state. Paraffins in the form of crystals can be released from oil if its temperature drops below a certain value - the temperature at which paraffins begin to crystallize. The crystallization temperature of paraffins depends on the chemical composition of the oil and the molecular weight of the paraffins dissolved in it. Thermodynamic modeling plays an important role in preventing wax formation. The article analyzes modifications of temperature correlations (melting point and pour point) included in the calculations of fusion properties. Temperature correlation data is used in thermodynamic prediction models of wax precipitation.Two correlations were taken for the study: Won's (1986) correlation and Nichita's (2001) correlation, and by modifying them, new correlations were obtained that give more accurate results with the experimental data. For the experiment, 3 samples with calculated molecular weights were taken from field X. As a result, the modified correlation for determining the melting point gives an accuracy of calculation results compared to the correlation of Won (1986) by 5%. The modified correlation for determining the solid-state transition temperature gives an accuracy of the calculation results compared to the Nichita (2001) correlation by 17.5% for the X field. These results provide valuable information for the practical application of modified theoretical temperature correlations, which will make it possible to more accurately characterize the behavior of the oil mixture, increase the accuracy of calculations, and improve the predictive model of wax deposition for various oils.

Hydrocarbon poisoning in pediatric practice

The review presents data on the epidemiology of poisoning by petroleum products, their chemical and toxicological characteristics, clinical and radiological signs, and considers issues of treatment and prognosis. Numerous studies show the world-wide prevalence of hydrocarbon poisoning in children under 5 years of age. The largest number of messages comes from the regions of the Middle East and South Asia. The mechanisms of pathogenesis and clinical manifestations of poisoning by such petroleum distillates as gasoline and kerosene are well studied. In the last two decades, poisoning with ignition fluids, which are a mixture of saturated hydrocarbons, has been relevant for the Russian Federation. Their toxic effect upon oral administration is realized mainly through the development of aspiration pneumonitis, which is clinically manifested by cough and respiratory failure. Systemic effects are not typical, and neurological disorders are associated primarily with pulmonary hypoxia. A significant risk factor for severe aspiration is the presence of vomiting, attempts to induce it, and gastric lavage. One of the rare but characteristic manifestations of lung damage in hydrocarbon poisoning is the formation of a pneumatocele. Treatment for hydrocarbon poisoning has not been developed enough; respiratory support plays a leading role, in severe cases, early mechanical ventilation. Infusion therapy is not a means of detoxification, and, if carried out to fill the physiological need, should be carried out in a limited amount due to the risk of pulmonary edema. The effectiveness of antibiotics and glucocorticosteroids has not been established. In most cases, hydrocarbon poisoning ends in recovery, lethal outcomes are observed in rare cases. An unfavorable prognosis can be determined, first, by massive aspiration, as well as the presence of alcohols, unsaturated, halogenated and aromatic compounds in the composition of the liquid taken.

Mineral oil contamination in basil pesto from the Italian market: Ingredient contribution and market survey

Mineral oil hydrocarbons (MOH) are complex mixtures of saturated hydrocarbons (MOSH) which bioaccumulate in human tissues, and aromatic hydrocarbons (MOAH) which include genotoxic and carcinogenic substances. This work aimed to investigate these emerging food contaminants in basil pesto from the Italian market, and ingredient contribution to the final product contamination. Twelve market samples and 4 additional samples (and related ingredients) produced in a pilot plant, were analyzed by on-line high-performance liquid chromatography (HPLC)- gas chromatography (GC), preceded by matrix-tailored sample preparation. Method performance was good with recoveries from 94% to 109%, residual standard deviations (RSD) less than 10%, and a limit of quantitation (LOQ) of 0.5 mg/kg (for total MOAH). Vegetable oils, followed by cashews, which showed a similar contamination profile to foods transported in jute bags, were the major contributors to contamination, while cheese and basil contribution was negligible. Sunflower oil alone accounted for more than 80–85% of the total contamination. Samples from the Italian market had an average of 5.6 and 0.6 mg/kg of MOSH and MOAH, respectively, and a contamination profile that confirmed that the main contributors to total contamination were sunflower oil and cashews. Mitigation actions should be directed toward careful control of these two ingredients.

Deep hydrocarbon cycle

Research subject. Experimental modelling of the transformation of complex hydrocarbon systems under extreme thermobaric conditions was carried out. The results obtained were compared with geological observations in the Urals, Kamchatka and other regions.Material and methods. The materials for the research were a model hydrocarbon system similar in composition to natural gas condensate and a system consisting of a mixture of saturated hydrocarbons and various iron-containing minerals enriched in 57Fe. Two types of high-pressure equipment were used: a diamond anvils cell and a Toroid-type high-pressure chamber. The experiments were carried out at pressures up to 8.8 GPa in the temperature range 593–1600 K.Results. According to the obtained results, hydrocarbon systems submerged in a subduction slab can maintain their stability down to a depth of 50 km. Upon further immersion, during contact of the hydrocarbon fluid with the surrounding iron-bearing minerals, iron hydrides and carbides are formed. When iron carbides react with water under the thermobaric conditions of the asthenosphere, a water-hydrocarbon fluid is formed. Geological observations, such as methane finds in olivines from ultramafic rocks unaffected by serpentinization, the presence of polycyclic aromatic and heavy saturated hydrocarbons in ophiolite allochthons and ultramafic rocks squeezed out from the paleo-subduction zone of the Urals, are in good agreement with the experimental data.Conclusion. The obtained experimental results and presented geological observations made it possible to propose a concept of deep hydrocarbon cycle. Upon the contact of hydrocarbon systems immersed in a subduction slab with iron-bearing minerals, iron hydrides and carbides are formed. Iron carbides carried in the asthenosphere by convective flows can react with hydrogen contained in the hydroxyl group of some minerals or with water present in the asthenosphere and form a water-hydrocarbon fluid. The mantle fluid can migrate along deep faults into the Earth’s crust and form multilayer oil and gas deposits in rocks of any lithological composition, genesis and age. In addition to iron carbide coming from the subduction slab, the asthenosphere contains other carbon donors. These donors can serve as a source of deep hydrocarbons, also participating in the deep hydrocarbon cycle, being an additional recharge of the total upward flow of a water-hydrocarbon fluid. The described deep hydrocarbon cycle appears to be part of a more general deep carbon cycle.

Mineral oil: safety and use as placebo in REDUCE-IT and other clinical studies.

Mineral oil is often used as a clinical trial placebo. Pharmaceutical-grade mineral oil consists of a mixture of saturated hydrocarbons, with a purity and chemical structure that differs substantially from food-grade or technical-/industrial-grade mineral oils. Interest in mineral oil was piqued by suggestions that a portion of the substantially positive results of the Reduction of Cardiovascular Events with Icosapent Ethyl–Intervention Trial (REDUCE-IT) might be attributable to the theoretical negative effects of mineral oil rather than being due to the clinical benefits of icosapent ethyl. The objective of this review was to explore possible mineral oil safety and efficacy effects and contextualize these findings in light of the REDUCE-IT conclusions. A literature search identified studies employing mineral oil placebos. Eighty studies were identified and relevant data extracted. Adverse events associated with mineral oil were generally gastrointestinal and consistent with use as a lubricant laxative. Changes in triglycerides, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, high-sensitivity C-reactive protein, and other biomarkers were inconsistent and generally not statistically significant, or clinically meaningful with mineral oil, as were changes in blood pressure. There was no consistent evidence that mineral oil in the amounts used in the REDUCE-IT or Effect of Vascepa on Progression of Coronary Atherosclerosis in Patients With Elevated Triglycerides on Statin Therapy (EVAPORATE) trials affects absorption of essential nutrients or drugs, including statins. These results were then considered alongside publicly available data from REDUCE-IT. Based on available evidence, mineral oil does not appear to impact medication absorption or efficacy, or related clinical outcomes, and, therefore, does not meaningfully affect study conclusions when used as a placebo at the quantities used in clinical trials.

CFD MODELING OF HEAT TRANSFER AND HYDRODYNAMICS PROCESSES IN A HEAT STORAGE TANK

Background. Today, heat storage tanks are an integral part of heating systems. However, modern designs of capacitive storage tanks are characterized by the phenomenon of thermocline and high thermal inertia. To minimize the aforementioned disadvantages, it is proposed to use a “thermal core”, for the formation of which it is necessary to select a substance with a high value of heat capacity.Objective. The purpose of the presented study is to simulate the process of heat and mass transfer in a storage tank with a “thermal core”, in the form of the binary tube located on the central axis, the inter tube space of which is filled with paraffin (a mixture of saturated hydrocarbons with melting point – from 45 °C to 65 °C; dense – 0.880–0.915 g/cm3 at 15 °C).Methods. Fluent software determines the temperature distribution in the heat storage tank under free convection conditions. The resulting data were then converted into a calculation module of the Transient Thermal software complex ANSYS, where further calculations of the non-stationary temperature distribution of the “thermal core” were carried out.Results. It is determined that the heat storage tank with a capacity of 1400 liters, heated for one hour by a heat transfer agent with a temperature of 115 °C, is cooled to 50 °C in 4 hours. The analysis of the hydrodynamic structure of the flow based on the distribution of the trajectories of movement of free-convective flows in the water column of the storage tank indicates the need to improve the design of the tank. It is determined that the use of the “thermal core”, regardless of the type of paraffin used for its formation, helps to reduce the stratification of temperature by tank height. The type of paraffin used to form the “heat core” has no significant effect on the cooling time of the heat storage tank as a whole. However, when using “ceresin” as a filler for the “heat core”, the average tank temperature is generally about 0.5 °C higher than for other paraffin types studied. Thus, it is “ceresin” that should be used as a “thermal core”.Conclusions. The result of the calculation of the inhomogeneous temperature field of all elements of the heat storage tank was used to determine the time of its complete cooling. The conducted research allows automating the process of calculation of the storage tanks as well as carrying out their modernization to increase the efficiency of use.

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.

Studying the Characteristics of a Waste Industrial Со-Мо/Al2O3 Catalyst for the Deep Hydrotreatment of Diesel Fuel

The physicochemical properties of a waste industrial Со-Мо/Al2O3 catalyst for the deep hydrotreating of diesel fuel are studied. IR spectroscopy, thermogravimetry (TG), differential thermal analysis (DTA), and scanning electron microscopy (SEM) are used to establish that the catalyst surface is uniformly coated with a coke film. This soft coke is mostly a mixture of saturated hydrocarbons with a low degree of branching in their structure. The coke is oxidized at temperatures of 190–375°C (soft coke) and 375–525°C (hard coke); its quantitative removal is achieved by means of oxidative calcination in air for 3 h at 550°C. X-ray diffraction, scanning electron microscopy, low-temperature nitrogen adsorption, and chemical analysis are used to show that the waste catalyst undergoes considerable structural transformation with a 7.7% drop in the Mo content and the accumulation of Fe, Ha, and V impurities. As a result of sintering, its specific surface area and total pore volume are reduced by 31.5 and 28.4%, respectively. The obtained data are needed to develop a scheme for its recycling.

Hydrothermal Decarboxylation of Corn Distillers Oil for Fuel‐Grade Hydrocarbons

AbstractCatalytic hydrothermal conversion of non‐edible corn distillers oil (CDO), a low‐value by‐product of the ethanol industries, into high value fuel‐grade hydrocarbons was investigated in near‐supercritical water. The decarboxylation experiments were conducted using activated carbon in a 300 mL batch stirred tank reactor at reaction temperatures of 300–400 °C with pressure ranges from 2200–2500 psi (≈15–17 MPa), water/CDO (v/v) ratios of 2:1 to 5:1, and reaction times of 0.5 to 4 h at constant stirring speed (800 rpm). For the first time, complete removal of the −COO− group from CDO was achieved at 400 °C with 4 h of reaction time and a water/CDO (v/v) ratio of 4:1. The liquid products obtained were a mixture of saturated hydrocarbons, mainly C8–C16 (selectivity 49.7 %) and heptadecane (48.9 %) which have similar specific gravity, higher heating value (HHV), cloud points, and pour points to those of commercial fuels. 65 % liquid yield was obtained under optimal reaction conditions. The reaction mechanism was found to follow pseudo‐first‐order kinetics with an activation energy 66.1±3 kJ mol−1, which is much lower than similar reported literature values for the decarboxylation process.

Investigation of Possibility of Applying Gas Turbine Installations for Utilization of Associated Petroleum Gas with High Nitrogen Content at Oil Fields of Udmurt Republic

Статья посвящена исследованию возможности применения газотурбинных установок (ГТУ) для утилизации попутного нефтяного газа (ПНГ) с высоким содержанием азота ( N2 ) в качестве основного топлива. Компонентный состав нефтяного газа представляет собой смесь предельных углеводородов, включающую метан, этан, пропан, бутан, изобутан и другие углеводороды, процентное соотношение которых варьируется от места нефтяного промысла, в зависимости от геологических особенностей. Эксплуатируемые месторождения Удмуртской Республики (УР) характеризуются добычей тяжелой, трудно извлекаемой нефти с попутным нефтяным газом, содержащим значительное количество азота и поэтому обладающим низкой теплотой сгорания, что существенно затрудняет его методы утилизации. Обычно такой газ сразу сбрасывается в атмосферу или бесполезно сжигается на факельных установках: в обоих случаях это негативно сказывается на состоянии окружающей среды. В Постановлении Правительства Российской Федерации (РФ) от 8 ноября 2012 года № 1148 устанавливается целевой показатель сжигания ПНГ на факеле: не более 5 % от общего количества получаемого газа. При превышении этого предельно допустимого показателя применяются повышающие коэффициенты, влияющие на размер выплат штрафов. Данные меры должны стимулировать нефтяные компании к разработке проектов по эффективному использованию попутного нефтяного газа. Существует несколько рациональных методов утилизации ПНГ: например, использование его в качестве сырья для нефтехимической промышленности или топлива для различных установок, вырабатывающих электрическую энергию и теплоту. В данной статье исследуется возможность утилизации попутного нефтяного газа с высоким содержанием азота путем его сжигания в когенерационных газотурбинных установках с преимущественной выработкой электроэнергии.

The origin of aliphatic hydrocarbons in olive oil.

There are many substances that can interfere with olive oil quality. Some of them are well characterized, but many others have an unknown origin. Saturated hydrocarbons make an extraordinary complex family of numerous molecules, some of them present naturally in vegetable oils. When major natural saturated hydrocarbons are analyzed by standard chromatographic methods, this complex mixture of saturated hydrocarbons appears as a hump in the chromatogram and is commonly named as unresolved complex mixture (UCM), whose origin remains unknown. In this work we studied the occurrence and the origin of aliphatic saturated hydrocarbons in olive oil. Hydrocarbons were analyzed in olive oil and along the industrial process of oil extraction. We also analyzed n-alkanes and the UCM fraction of hydrocarbons in leaf, fruit and oil from different varieties and different locations, and we also analyzed the soils at these locations. We conclude that the hydrocarbons present in olive oil do not necessarily have their origin in a contamination during olive oil elaboration; they seem to have a natural origin, as a result of olive tree metabolism and/or as the result of an intake and accumulation by the olive tree directly from the environment during its entire life cycle. © 2017 Society of Chemical Industry.

Organic chemistry: Nickel steps towards selectivity.

Hydrocarbons called alkenes are isolated from petroleum as mixtures of isomers, often making it hard to use them as reagents for synthesis. A reaction involving a migrating nickel atom offers a possible solution. See Letter p.84 Functionalizing a specific position on a molecule other than the initial reaction site is a key challenge in synthetic chemistry. Several recent strategies for remote functionalization make use of complex transition-metal complexes to direct bond formation at distant sites. Here, Ruben Martin and colleagues use a cheap and abundant nickel catalyst that adds into a carbon–bromine bond, walks along a hydrocarbon chain and adds carbon dioxide at the terminal position, regardless of where it began. Through a two-step procedure that uses feedstock chemicals, a mixture of saturated hydrocarbons or alkenes can be transformed into a single carboxylic acid product. On carbonyl-containing substrates, the direction of chain migration can be controlled and inverted simply by raising the temperature by 30 degrees Celsius, which switches the reaction from kinetic to thermodynamic control.

Gamma Radiation Thermal Stability of Two-Phase Mixtures of Nitric Acid with Degraded TBP in a Closed Vessel

The influence of thermal and gamma radiation effects on the characteristics of the thermal explosion of mixtures of tributyl phosphate (TBP) and nitric acid was studied. The products of sequential radiolysis and pyrolysis of TBP were determined to have little effect on the thermal stability of mixtures of TBP and nitric acid. The onset temperatures of exothermic processes leading to a thermal explosion were slightly decreased only by the absorbed dose of 2 MGy. The thermal stabilities of solutions of TBP in n-dodecane and diluent C-13, consisting of a mixture of saturated hydrocarbons, were investigated. The experimental results indicate that the irradiation decreased the onset temperature of the exothermic processes in mixtures of nitric acid with TBP solutions in a hydrocarbon diluent; the onset temperature decreased by 5°C to 7°C for n-dodecane and by 9°C to 13°C for C-13, as compared to unirradiated extractants.

Assessing Energy Efficiency of Compression Heat Pumps in Drying Processes when Zeotropic Hydrocarbon Mixtures are Used as Working Agents

Presents the results of studies of innovative materials in the field of renewable energy.The paper proposes a design and a formula for assessing energy efficiency of the heat pump air dryer, which uses zeotropic hydrocarbon mixtures of saturated hydrocarbons as a working agent and applies the principle of a counter-current heat exchanger with a variable temperature of both the working and the drying agents. Energy efficiency of the heat pump is achieved by means of obtaining a greater part of heat from renewable energy sources, in this case by cooling the air and condensing the water vapors in the heat pump. A conducted analysis identified correlations in establishing the marginal real coefficient of performance of the compression heat pump dryer running on zeotropic hydrocarbon mixtures and operating a cycle with variable temperatures of both the working and the drying agent in the evaporator and the condenser of the heat pump. According to the established correlations, the marginal real coefficient of performance of the compression heat pump dryers running on zeotropic hydrocarbon mixtures of 40 mol% of R600a and 60 mol% of R601 is 1.92 times higher than that of the same dryers running on only R600 (n-butane).

Pyrostegia venusta heptane extract containing saturated aliphatic hydrocarbons induces apoptosis on B16F10-Nex2 melanoma cells and displays antitumor activity in vivo.

Background:Pyrostegia venusta (Ker. Gawl.) Miers (Bignoniacea) is a medicinal plant from the Brazilian Cerrado used to treat leucoderma and common diseases of the respiratory system.Objective:To investigate the antitumor activity of P.venusta extracts against melanoma.Materials and Methods:The cytotoxic activity and tumor induced cell death of heptane extract (HE) from P. venusta flowers was evaluated against murine melanoma B16F10-Nex2 cells in vitro and in a syngeneic model in vivo.Results:We found that HE induced apoptosis in melanoma cells by disruption of the mitochondrial membrane potential, induction of reactive oxygen species and late apoptosis evidenced by plasma membrane blebbing, cell shrinkage, chromatin condensation and DNA fragmentation, exposure of phosphatidylserine on the cell surface and activation of caspase-2,-3,-8,-9. HE was also protective against singeneyc subcutaneous melanoma HE compounds were also able to induce cell cycle arrest at G2/M phases on tumor cells. On fractionation of HE in silica gel we isolated a cytotoxic fraction that contained a mixture of saturated hydrocarbons identified by 1H NMR and GC-MS analyses. Predominant species were octacosane (C28H58-36%) and triacontane (C30H62-13%), which individually showed significant cytotoxic activity against murine melanoma B16F10-Nex2 cells in vitro and a very promising antitumor protection against subcutaneous melanoma in vivo.Conclusion:The results suggest that the components of the heptane extract, mainly octasane and triacontane, which showed antitumor properties in experimental melanoma upon regional administration, might also be therapeutic in human cancer, such as in the mostly epidermal and slowly invasive melanomas, such as acral lentiginous melanoma, as an adjuvant treatment to surgical excision.

Insight of unresolved complex mixtures of saturated hydrocarbons in heavy oil via GC×GC-TOFMS analysis

The saturated hydrocarbon fraction of a heavily biodegraded crude oil from Liaohe oilfield was analyzed by using comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GC×GC-TOFMS). The “humps”, which was termed as unresolved complex mixtures (UCMs) in conventional gas chromatographic analysis, was separated for identification of the individual compound. Main compounds of UCMs were identified according to the combined information of characteristics of GC×GC chromatogram and time-of-flight mass spectra. It’s found that UCMs are mainly composed of great number of ring compounds with extremely low concentration. The ring compounds are separated according to their boiling point diversity in the first dimension column, then to their polarity or ring number variety in the second dimension column. In the sample there are two groups of UCMs, i.e., the first group compounds with boiling point lower that of C24 and the second group compounds with boiling point higher than that of C24. The first group of UCMs mainly consists of monocyclic, bicyclic and tricyclic ring compounds. The first group of UCMs is mainly composed of saturated hydrocarbons, in which the percentage of ring compounds with signal-to-noise ratio above 100 is about 75% of the total quantity of saturated hydrocarbon, while its mass is over 80% of the total saturated hydrocarbon. The second group of UCMs is mainly composed of tetracyclic and pentacyclic ring compounds, in which the percentage of UCM compounds with signal-to-noise ratio over 100 is about 17% of the total quantity of saturated hydrocarbon, and its mass is about 0.5% of the total saturated hydrocarbon. The results of this study are helpful for heavy oil developing and genesis mechanism understanding.

Atmospheric Pressure Laser-Induced Acoustic Desorption Chemical Ionization Mass Spectrometry for Analysis of Saturated Hydrocarbons

We present atmospheric pressure laser-induced acoustic desorption chemical ionization (AP/LIAD-CI) with O(2) carrier/reagent gas as a powerful new approach for the analysis of saturated hydrocarbon mixtures. Nonthermal sample vaporization with subsequent chemical ionization generates abundant ion signals for straight-chain, branched, and cycloalkanes with minimal or no fragmentation. [M - H](+) is the dominant species for straight-chain and branched alkanes. For cycloalkanes, M(+•) species dominate the mass spectrum at lower capillary temperature (<100 °C) and [M - H](+) at higher temperature (>200 °C). The mass spectrum for a straight-chain alkane mixture (C(21)-C(40)) shows comparable ionization efficiency for all components. AP/LIAD-CI produces molecular weight distributions similar to those for gel permeation chromatography for polyethylene polymers, Polywax 500 and Polywax 655. Coupling of the technique to Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS) for the analysis of complex hydrocarbon mixtures provides unparalleled mass resolution and accuracy to facilitate unambiguous elemental composition assignments, e.g., 1754 peaks (rms error = 175 ppb) corresponding to a paraffin series (C(12)-C(49), double-bond equivalents, DBE = 0) and higher DBE series corresponding to cycloparaffins containing one to eight rings. Isoabundance-contoured plots of DBE versus carbon number highlight steranes (DBE = 4) of carbon number C(27)-C(30) and hopanes of C(29)-C(35) (DBE = 5), with sterane-to-hopane ratio in good agreement with field ionization (FI) mass spectrometry analysis, but performed at atmospheric pressure. The overall speciation of nonpolar, aliphatic hydrocarbon base oil species offers a promising diagnostic probe to characterize crude oil and its products.

Oxidations of organic matter present in the phosphoric acid 54% by the ozone: characterization of groups carbonyls upstream and downstream of the ozonation

This study was focused on the oxidation of organic matter in phosphoric acid 54% by ozone. In order to understand the mechanisms involved in this process, the identification of this matter upstream and downstream of the ozonation was necessary. For the identification, after an extraction by a mixture (dichloro-methanol), the organic phase was divided into two parts: the residue and the extract:-The residue was studied by infrared spectroscopy Fourier Transform (IR-TF). It contains Kérogène which is a mixture of saturated hydrocarbons with high molecular weights. The absorption bands of the FT-IR showed that the residue contains also quantities of amino that correspond to the remains of dinoflagellate cysts, which are abundant in sediments.-The extract has been the subject of a detailed study by, chromatography on silica column, IR-TF spectroscopy and CG-SM. The passage of this extract on a silica column yielded two fractions (saturated fraction and polar fraction). Both of these fractions were analyzed by CG-SM. The yield of the reduction of the organic matter content in the phosphoric acid 54% could not exceed 29%. Therefore, we can conclude that the reduction in the rate of organic matter remains limited by the fact that some compounds are inert towards ozone.

Multiple responses of gram-positive and gram-negative bacteria to mixture of hydrocarbons

Most of our knowledge about pollutants and the way they are biodegraded in the environment has previously been shaped by laboratory studies using hydrocarbon-degrading bacterial strains isolated from polluted sites. In present study Gram-positive (Mycobacterium sp. IBBPo1, Oerskovia sp. IBBPo2, Corynebacterium sp. IBBPo3) and Gram-negative (Chryseomonas sp. IBBPo7, Pseudomonas sp. IBBPo10, Burkholderia sp. IBBPo12) bacteria, isolated from oily sludge, were found to be able to tolerate pure and mixture of saturated hydrocarbons, as well as pure and mixture of monoaromatic and polyaromatic hydrocarbons. Isolated Gram-negative bacteria were more tolerant to mixture of saturated (n-hexane, n-hexadecane, cyclohexane), monoaromatic (benzene, toluene, ethylbenzene) and polyaromatic (naphthalene, 2-methylnaphthalene, fluorene) hydrocarbons than Gram-positive bacteria. There were observed cellular and molecular modifications induced by mixture of saturated, monoaromatic and polyaromatic hydrocarbons to Gram-positive and Gram-negative bacteria. These modifications differ from one strain to another and even for the same bacterial strain, according to the nature of hydrophobic substrate.