Determination of hydrocarbons in water by evanescent wave absorption spectroscopy in the near-infrared region

An home-made EFA (Evanescent Field Absorbance)-sensor has been tested for the determination of hydrocarbons in water. The investigations have been performed both with crude oil emulsions and petrol solutions. Cuvette and evanescent wave spectra of crude oil and petrol in the near-infrared region are presented and discussed. The concentration of aromatic compounds in crude oil can be determined semiquantitatively by the standard addition method. The sorption behaviour of the hydrocarbons in the cladding of the fiberoptic sensor has been investigated and a correlation between the sensor signal and the concentration of the aqueous hydrocarbon emulsion/solution could be shown. The desorption of the enriched molecules after the measurements is also presented. The petrol molecules evaporate in ambient air so that the sensor is easily regenerated. In case of oil measurements the hydrocarbon molecules cannot be removed by rinsing the sensor with clear water or by evaporating them in ambient air. It has to be regenerated by washing it with a high volatile solvent instead.     

A comprehensive analysis of the properties of light crude oil in oxidation experimental studies

The analysis of light crude oil for oxidation reaction experiments is a kind of important technological for evaluating an air injection project in a reservoir. In this study, the paper comprehensively analyzes the variations of Jilin crude oil composition comparing crude oil component’s variations before and after oxidation, and investigates the effluent gas composition and hydrocarbon, analyzes the mechanism of low temperature oxidation reaction (LTO), and rebuilds the light crude oil cracking reaction of intermediate component in a new pattern. In the early stage of the oxidation reaction, firstly, oxygen is captured by forming chemical bond in liquid hydrocarbon. And then oxygen takes part in the free radical chain reaction by forming hyperoxide and decomposes to ketones, aldehydes, alcohols, and so on. Meanwhile, chain scission reaction comes up. Research result shows that the intermediate components (C_7–17) of crude oil make great contribution to crude oil cracking. The experimental result shows that Jilin reservoir has the potential of implementing air injection project.     

Enhanced Biodegradation of Alkane Hydrocarbons and Crude Oil by Mixed Strains and Bacterial Community Analysis

In this study, two strains, Acinetobacter sp. XM-02 and Pseudomonas sp. XM-01, were isolated from soil samples polluted by crude oil at Bohai offshore. The former one could degrade alkane hydrocarbons (crude oil and diesel, 1:4 (v/v)) and crude oil efficiently; the latter one failed to grow on alkane hydrocarbons but could produce rhamnolipid (a biosurfactant) with glycerol as sole carbon source. Compared with pure culture, mixed culture of the two strains showed higher capability in degrading alkane hydrocarbons and crude oil of which degradation rate were increased from 89.35 and 74.32?±?4.09 to 97.41 and 87.29?±?2.41 %, respectively. In the mixed culture, Acinetobacter sp. XM-02 grew fast with sufficient carbon source and produced intermediates which were subsequently utilized for the growth of Pseudomonas sp. XM-01 and then, rhamnolipid was produced by Pseudomonas sp. XM-01. Till the end of the process, Acinetobacter sp. XM-02 was inhibited by the rapid growth of Pseudomonas sp. XM-01. In addition, alkane hydrocarbon degradation rate of the mixed culture increased by 8.06 to 97.41 % compared with 87.29 % of the pure culture. The surface tension of medium dropping from 73.2?×?10^?3 to 28.6?×?10^?3 N/m. Based on newly found cooperation between the degrader and the coworking strain, rational investigations and optimal strategies to alkane hydrocarbons biodegradation were utilized for enhancing crude oil biodegradation.     

Preparative HPLC of the Lipid Fraction of Teucrium canadense L.

Abstract

The petrol extract of higher plants usually afford phytosterols, triterpenes, hydrocarbons and triglycerides as the major components. The separation of these by conventional column chromatography can be very time-consuming. The use of HPLC methods can effect a considerable reduction in analysis time.     

The development of a method for the qualitative and quantitative determination of petroleum hydrocarbon components using thin-layer chromatography with flame ionization detection

An analytical scheme to determine groups of petroleum hydrocarbon compounds in crude oil was developed and used for the qualitative and quantitative characterization of crude oil samples from the Shengli oilfield, the second largest oilfield in China. Crude oil samples were fractionated and analyzed by thin-layer chromatography with flame ionization detection (TLC-FID). Relative standard deviation (RSD) values for retention time, peak height and half peak width were less than 5.2% for all classes of compounds, based on nine independent replicates. The crude oil light fraction was further analyzed by GC–MS and the majority of identified compounds were methyl- or hydro-derivatives of long-chain hydrocarbons and aromatic compounds. The external standard method used in the present study can lower detection limits of petroleum hydrocarbon compound classes to 20.0 mg L⁻¹, and the crude oil concentration in the range of 30 and 35,000 mg L⁻¹ has a high linear correlation (r² > 0.97, P < 0.05) with peak area. A comparison between elution chromatography (EC) and TLC-FID regarding the recovery of petroleum hydrocarbon compounds was carried out with aged crude oil contaminated soils of 50, 80, 200 and 300 mg g⁻¹. The tested TLC-FID method showed a 10% higher recovery for total extractable materials than the reference EC method. The calibration factor was fraction-dependent and varied with the recovery rate of TLC/EC. Regarding the tested extraction procedures, accelerated solvent extraction (ASE) had a higher extraction efficiency for crude oil contaminated soils than Soxhlet and ultrasonic extractions.     

结合直观推导式演进特征投影法分析原油中非烃结构和含量

提出一种分析原油非烃结构和含量的方法。用直观推导式演进特征投影法分辨有关二维数据以获得非烃的纯色谱和纯质谱,再将所获质谱在标准质谱库中检索,并结合色谱保留指数分析等来进行单个非烃化合物结构鉴定;利用实验数据,根据分辨获得的纯色谱峰面积所建立的规一化模型,进行非烃化合物定量分析。用本法确定了一原油样品中168个含氮化合物和该油样一个馏分中60个其它非烃化合物的结构和含量。本方法具有系统分析原油非烃结构和含量的通用性;标准化合物加标回收实验表明,其准确度很好。     

Comparaison de Differentes Methodes Analytiques Appliquees au Dosage des Hydrocarbures Dissousdans L'Eaua L'etatde Traces

Abstract

Many physical-chemical methods are employed for the evaluation of trace hydrocarbons dissolved, in underground or surface waters.

Comparison is done of three techniques chosen amongst the most commonly used in the studies conducted on water pollution caused by oil products:

infrared spectroscopy;

ultraviolet spectrofluorimetry;

gas chromatography.

To enable the application of these techniques to very low concentrations of hydrocarbon all these techniques require a concentration step.

This can be carried out, either by the liquid-liquid extraction of the hydrocarbons with the assistance of an organic solvent and in this case, the concentration ratios are poor, or by the trapping technique, where the hydrocarbon concentration is effected by adsorption on a resin, followed by desorption by a relatively small amount of an appropriate organic solvent. The water amounts so treated can be 10 to 100 larger than those treated by a liquid-liquid extraction.

A trapping system is described which has been used in an initial phase for the detection and quantitation of aromatic hydrocarbons up to C₉. The operational conditions are described for the measurement of heavier hydrocarbons (sampled water quantity and flow, desorption solvent, amount of resin).

The importance of the concentration method and of the sensitivity of the analytical techniques chosen for the definition of the detection threshold of the dissolved hydrocarbons is pointed out.

In addition to the detection level problems for certain types of hydrocarbons, the selectivity of these techniques is considered.

In conclusion, the various methods are compared amongst themselves from the point of view of their application, of the quality of the results which are obtained and of their applicability to the different real water samples polluted by hydrocarbons.     

Uptake of Hydrocarbons in Aqueous Solution by Encapsulation in Acyclic Cucurbit[n]uril‐Type Molecular Containers

The ability of two water‐soluble acyclic cucurbit[n]uril (CB[n]) type containers, whose hydrophobic cavity is defined by a glycoluril tetramer backbone and terminal aromatic (benzene, naphthalene) sidewalls, to act as solubilizing agents for hydrocarbons in water is described. ¹H NMR spectroscopy studies and phase‐solubility diagrams establish that the naphthalene‐walled container performs as well as, or better than, CB[7] and CB[8] in promoting the uptake of poorly soluble hydrocarbons into aqueous solution through formation of host–hydrocarbon complexes. The naphthalene‐walled acyclic CB[n] container is able to extract large hydrocarbons from crude oil into aqueous solution.     

Molecular characterization of organically-bound sulfur in crude oils. A feasibility study for the application of Raney Ni desulfurization as a new method to characterize crude oils

Five crude oils with varying sulfur contents (0.1 – 4.7%) were characterized on a molecular level for organically-bound sulfur. Aromatic fractions were analyzed by GC-(MS) and asphaltene and polar fractions were analyzed by flash pyrolysis-GC-(MS). The polar fractions were also desulfurized with Raney Ni and the hydrocarbons formed were analyzed by GC-MS. Major sulfur compounds in the aromatic fractions were identified as alkylbenzo- and alkyldiben-zothiophenes. The flash pyrolyzates of the asphaltene contained alkylthiophenes and alkylbenzothiophenes as major compounds, depending on the thermal maturity of the oil. Generally, the sulfur-rich crude oils contained relatively more sulfur compounds. The flash pyrolyzates of polar fractions contained a variety of sulfur compounds (alkylthiolanes, alkylthianes, terpenoid sulfides, alkylbenzothiophenes) with substantial differences between different crude oils. Raney Ni desulfurization of the polar fraction yielded hydrocarbons dominated by n-alkanes, but isoprenoid alkanes, n-alkylcyclohexanes, mid-chain methylalkanes, tricyclic terpanes, hopanes and steranes were also present. These hydrocarbons show a potential to fingerprint crude oils since their distribution patterns are more characteristic than those of the hydrocarbons present in the saturated hydrocarbon fraction.     

Computerized GC/MS detection of monoaromatic and triaromatic steroid hydrocarbons in Alamein crude oil

Series of C-ring monoaromatic steroid hydrocarbons (C₂₁, C₂₂, C₂₇ ? C₂₉) and triaromatic steroid hydrocarbons (C₂₀, C₂₁, C₂₆ ? C₂₈) have been recognized in the aromatic hydrocarbon fraction of Alamein crude oil from the western desert, Egypt. Detection of these compounds were based on mass fragmentography of the key ions m/z 253 and m/z 231 and comparison of the mass spectra and relative retention times with literature data. The predominance of the C₂₉ monoaromatic steroids and C₂₈ triaromatic steroids provide further evidence for a land plant origin of Alamein oil. The results substantiate previous evidence of the occurrence of an aromatization process with increasing maturation and indicate a moderate maturity level for Alamein oil.     

Some Aspects of Analysis of Single Fibers in Environmental and Biological Samples

Abstract

Nuclepore filters were used for sampling and evaluation of fibrous particles in ambient air, in liquids and in biological materials. The fiber counting and fiber size measurements were done by means of SEM-methods. The number of fibers and the distributions of fiber lengths and diameters were plotted. The specific identifications of asbestos, glass and other mineral fibrous particles were made by electron microprobe analysis. Certain elements proved to be approximative identification factors for different fibrous minerals in ambient air, in liquids, on material surfaces, or in biological materials.

For ambient air, asbestos, glass, and many other inorganic fibrous particles were found in the urban atmosphere as well as in the atmosphere of remote regions. Fibrous gypsum, fibrous ammonium sulfates, fibrous silicates, fibrous mica, and quartz were identified among these particles. Even in remote ambient air, relatively high concentrations of inorganic fibrous particles could be measured.     

Vapour permeation and sorption in fluoropolymer gel membrane based on ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulphonyl)imide

The emissions of hydrocarbons from fossil fuels into atmosphere entail both an economic loss and an environmental pollution. Membrane separations can be used for vapour recovery and/or vapour removal from the permanent gas stream, given that the appropriate membrane is identified. A neat poly(vinylidene fluoride-co-hexafluoropropylene) membrane is impermeable to both the representatives of aliphatic hydrocarbons and branched hydrocarbons, namely hexane and isooctane, whereas the permeation flux is enhanced by the presence of 80 mass % of the ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulphonyl)imide in the membrane, as detailed in this work. The permeabilities of hydrocarbon vapours were determined from the binary mixture containing hydrocarbon and nitrogen to simulate the real input of an air stream containing a condensable hydrocarbon. The diffusion coefficient determined from sorption measurements was higher for hexane, as would be expected for a smaller molecule, whereas both the sorption isotherms and permeabilities of the hydrocarbons studied were found to be almost identical. It is possible that the sorption effect predominates in the transport mechanism for VOCs/N₂ separations.     

Multidimensional Gas Chromatography–Mass Spectrometry Method for Fingerprinting Polycyclic Aromatic Hydrocarbons and Their Alkyl-Homologs in Crude Oil

The composition of polycyclic aromatic hydrocarbons in crude oil is usually too complex to use standard capillary gas chromatography to separate all of the components. In this study, a multidimensional gas chromatography–mass spectrometry (GC-MS) technique was used to analyze polycyclic aromatic hydrocarbon fractions of crude oil collected from the Dongying oil field in the Bohai Sea. A DB-17MS column (30?m?×?0.25?mm?×?0.25?µm) was used as a prefractionating column and only selected heart-cuts were transferred to the second chromatographic dimension (HP-5MS, 15?m?×?0.25?mm?×?0.25?µm) by a pressure-adjusted continual flow-type switching device for quantification of the polycyclic aromatic hydrocarbons. The chromatographic elements and parameters, such as detector selection and column combinations, were optimized. Naphthalene, phenanthrene, fluorene, dibenzothiophene, chrysene, and their C₁–C₄ alkyl homologs were identified. The profile of the polycyclic aromatic hydrocarbons obtained using the multidimensional GC-MS method was compared with the results obtained by traditional one-dimensional GC-MS.     

The effect of treating air samples with magnesium perchlorate for water removal during analysis for non-methane hydrocarbons

A comparison has been made between two cryogenic preconcentration - high resolution gas chromatography techniques for the analysis of non-methane hydrocarbons in ambient air, one involving treatment of air samples with magnesium perchlorate to remove water, the other involving analysis without treatment. Recoveries of C₁-, C₂-, and C₃-substituted benzenes in treated samples were 80%, 50%, and 50%, respectively. Incomplete recovery of C₇-C₉ n-1-olefins was also observed. C₂-C₈ hydrocarbons and C₂-C₆ n-1-olefins were recovered with greater than 90% efficiency. Analyses of certified audit samples containing a mixture of C₂-C₈ aliphatic and aromatic hydrocarbons at the 20 ppbv level in humidified zero-grade air indicated that the accuracy of the technique for untreated air samples was approximately 90%. The use of magnesium perchlorate for water removal cannot be recommended for the analysis of non-methane hydrocarbons in ambient air.     

A modified square well model in obtaining the surface tension of pure and binary mixtures of hydrocarbons

A model based on the perturbation theory of fluids was proposed to correlate the experimental data for surface tension of pure hydrocarbons in a wide range of temperature. The results obtained for the pure hydrocarbons were directly used to predict the surface tension for binary hydrocarbon mixtures at various temperatures. In the proposed model, a modified form of the square well potential energy between the molecules of the reference fluid was taken into account while the Lennard–Jones dispersion energy was considered to be dominant amongst the molecules as the perturbed term to the reference part of the model. In general, the proposed model has three adjustable parameters which are chain length, m, size, σ, and energy, ε/κ, parameters, but in some cases the number of parameters was reduced to two, thereby setting the chain length to be unity for pure hydrocarbons. The regressed values of these parameters were obtained using the experimental data for pure hydrocarbons at different temperatures. The results showed that these parameters can be related to the molar mass of hydrocarbons. The model was also extended to predict the surface tension of binary hydrocarbon mixtures using the parameters obtained for the pure compounds. It is worth noting that no additional parameter has been introduced into the model in the extension of the model to the mixtures studied in this work. The results showed that the proposed model can accurately correlate the surface tension of pure hydrocarbons. Also the results showed that the surface tension for binary mixture of hydrocarbons can be accurately predicted using the proposed model over a wide temperature range.     

Hydrocarbon Type Separation of Lubricating Base Oil in Multigram Quantity by Preparative HPLC

Abstract

A preparative High Pressure Liquid Chromatography (HPLC) method has been developed to separate lubricating base oil into its three major hydrocarbon fractions: saturates, aromatics, and polars. The results are directly comparable to ASTM Method D2007, hydrocarbon type analysis by gradient elution liquid chromatography. The new method employs a preparative HPLC unit with dual, radially compressed columns consisting of clay and alumina/silica gel columns. Multigram quantities of minor components (1 to 2% by wt.) of a base oil can be isolated for further study.     

Synthesis of Conjugated Optically Active Polymetallocenes

The development of methodology for synthesizing new materials in which metal atoms are linked by hydrocarbons whose electronic conjugation is unbroken is described. The fundamental idea is to twist the hydrocarbons into helices. By attaching bulky groups to their precursors, the helices can be made to twist mainly in one direction. The molecules synthesized are helicenes capped by five-membered rings to which metals are attached. If the size of the helix is chosen appropriately, a polymeric structure forms in which hydrocarbon rings and metal atoms alternate. An oligomer with Structure 22 is the first such material prepared. It and related structures might be precursors of molecular solenoids, examples of which are not yet known.     

Significance of Photosensitized Oxidation of Alkanes During the Photochemical Degradation of Petroleum Hydrocarbon Fractions in Seawater

Abstract

A crude oil hydrocarbon fraction was photooxidized as a surface film on seawater under simulated environmental conditions. After irradiation, gas chromatography and gas chromatography/mass spectrometry analyses allowed to demonstrate the presence of relatively high quantities of compounds deriving from the photosensitized oxidation of n-alkanes, pristane and phytane, being among the non-acidic photoproducts of this fraction. The results suggest that the photochemical degradation of alkanes should be considered in studies of the fate of petroleum crudes in the marine environment.     

Managed bioremediation of soil contaminated with crude oil soil chemistry and microbial ecology three years later

Analysis of samples taken from three experimental soil lysimeters demonstrated marked long-term effects of managed bioremediation on soil chemistry and on bacterial and fungal communities 3 yr after the application of crude oil or crude oil and fertilizer. The lysimeters were originally used to evaluate the short-term effectiveness of managed (application of fertilizer and water, one lysimeter) vs unmanaged bioremediation (one lysimeter) of Michigan Silurian crude oil compared to one uncontaminated control lysimeter. Three years following the original experiment, five 2-ft-long soil cores were extracted from each lysimeter, each divided into three sections, and the like sections mixed together to form composited soil samples. All subsequent chemical and microbiological analyses were performed on these nine composited samples. Substantial variation was found among the lysimeters for certain soil chemical characteristics (% moisture, pH, total Kjeldahl nitrogen [TKN], ammonia nitrogen [NH₄-N], phosphate phosphorous [PO₄-P], and sulfate [SO₄ ⁻²]). The managed lysimeter had 10% the level of total petroleum hydrocarbons (TPH-IR) found in the unmanaged lysimeter. Assessment of the microbial community was performed for heterotropic bacteria, fungi, and aromatic hydrocarbon-degrading bacteria (toluene, naphthalene, and phenanthrene) by dilution onto solid media. There was little difference in the number of heterotrophic bacteria, in contrast to counts of fungi, which were markedly higher in the contaminated lysimeters. Hydrocarbon-degrading bacteria were elevated in both oil-contaminated lysimeters. In terms of particular hydrocarbons as substrates, phenanthrene degraders were greater in number than naphthalene degraders, which outnumbered toluene degraders. Levels of sulfate-reducing bacteria seem to have been stimulated by hydrocarbon degradation.     

Effect of Crude Oil Aging on Asphaltene Inhibitor Product Recommendation

Aging refers to the deterioration of hydrocarbon fluids that manifests as changes in the physicochemical characteristics of the fluid upon exposure to ambient conditions. In order to understand the effect of aging of crude oils on asphaltene inhibitor product recommendation, simulated aging studies were performed on a crude oil from Wyoming with known asphaltene issues. The results clearly show that aging of crude oil affects the stability of the oil with respect to asphaltenes and caution must be exercised when recommending asphaltene inhibitor if the evaluations were performed on fluids after long-term storage. A real case study where ambient storage in the lab adversely affects the stability of the crude oil and renders asphaltene inhibitor ineffective further confirms results from simulated aging.