Complex Mixture Of Hydrocarbons Research Articles

Development of a new reagent for the prevention of asphaltene-resin-paraffin deposits

Asphaltene-Resin-Paraffin deposits (ARPD) form a certain proportion of the crude oil mass, separating as temperature and pressure decrease and adsorbing to the surfaces of the reservoir wellbore zone, downhole equipment and tubulars. These deposits precipitate in the wellbore zone, oilfield equipment and pipes,resulting in reduced system productivity, reduced pumping efficiency of the pumping equipment and other negative consequences. Asphalt-resin and paraffin deposits (ARPD) are a complex mixture of solid paraffin hydrocarbons, asphalt-resin substances (ARS), water and mechanical impurities. The strength and composition of ARPD depend on the composition and properties of oil, geological, physical and technological conditions of field development. Chemical methods for removing deposits are currently the most widely used, as they are highly effective and technologically advanced. To this end, new reagents have been developed and their physico-chemical properties have been studied. Subsequently, the selected reagents were tested on oil samples from Oil and Gas Production Department (OGPD) with a paraffin content of more than 6 %. It was also shown that paraffin inhibitors have individual effects; a reagent that is effective on oil from one field may not have the same effect on oil from other fields. The research includes studies of selected reagents for paraffinic oils from different fields. Using the «cold finger» method, the efficacy of the selected reagents against paraffin deposition was investigated and their optimum doses were determined. Keywords: reagent; sendiment; paraffin; asphaltene; resin; well bottom zone; viscosity; depressor.

A hybrid modeling approach: dynamic simulation of two-phase fluid flow in compacting gas condensate reservoirs using potential flow theory

Simulating the flow processes of complex hydrocarbon mixtures, such as gas condensate mixtures and volatile oils, in deep reservoirs is one of the most challenging problems in reservoir hydrodynamics. The challenge lies in meeting three requirements simultaneously when creating a simulator: high accuracy, low computational cost, and high reliability. These metrics determine the performance of the simulation. Meeting all these requirements at the same time necessitates a hybrid approach to solving the problem and optimizing the computational algorithm in terms of CPU time. A new technique has been developed for hybrid modeling of the development of deposits of complex hydrocarbon mixtures. This technique integrates the theory of potential flow, the Binary Flow Model (which accounts for rock compaction, PVT properties of reservoir fluids, phase transformation, and mass transfer between phases), and the material balance equations of the hydrocarbon system using time discretization. In this case, to linearize nonlinear differential equations for the flow of a gascondensate mixture, the method of averaging reservoir pressure along the radial coordinate was used. By introducing the Khrestianovich function, an algorithm was obtained to determine the rate of inflow of the gas-condensate mixture to the well. Using material balance equations for gas and condensate, it was possible to obtain differential equations that describe changes in reservoir pressure and condensate saturation over time. Based on this technique, a simulator for a gas condensate reservoir was created, enabling computer studies to be conducted. The results demonstrated the proposed technique's good accuracy compared with the results of the semi-analytical solution. Keywords: dynamic modeling; simulation; monitoring; streamline; hybrid modeling; binary model.

Biodegradation of a complex hydrocarbon mixture and biosurfactant production by Burkholderia thailandensis E264 and an adapted microbial consortium.

Bioremediation is considered to be an effective treatment for hydrocarbon removal from polluted soils. However, the effectiveness of this treatment is often limited by the low availability of targeted contaminants. Biosurfactants produced by some microorganisms can increase organic compound solubility and might then overcome this limitation. Two different inocula producers of biosurfactants (Burkholderia thailandensis E264 and SHEMS1 microbial consortium isolated from a hydrocarbon-contaminated soil) were incubated in Bushnell-Haas medium supplemented with hydrocarbons to investigate their biodegradation potential. Experimental results showed their ability to degrade 9.1 and 6.1% of hydrocarbons respectively after 65 days of incubation with an initial total hydrocarbon concentration of 16 g L-1. The biodegradation was more effective for the light and medium fractions (C10 to C36). B. thailandensis and SHEMS1 consortium produced surfactants after 14 days of culture during the stationary phase with hydrocarbons as the sole carbon and energy source. However, biosurfactant production did not appear to directly increase hydrocarbon degradation efficiency. The complexity and recalcitrance of hydrocarbon mixture used in this study appeared to continue to limit its biodegradation even in the presence of biosurfactants. In conclusion, B. thailandensis and SHEMS1 consortium can degrade recalcitrant hydrocarbon compounds and are therefore good candidates for the bioremediation of environments polluted by total hydrocarbons.

SYNTHESIS, SPECTROPHOTOMETRIC AND CHROMATOGRAPHY TECHNIQUES OF CRUDE OIL AND PETROLEUM PRODUCTS

Crude oil and petroleum products are important natural resources that have significant economic and environmental implications. Crude oil is a complex mixture of hydrocarbons that is extracted from the ground and refined to produce various petroleum products, including gasoline, diesel, and jet fuel. The composition of crude oil and petroleum products can vary widely depending on the source and the refining process used. Accurate characterization of these substances is essential for evaluating their quality, properties

Automated Equations of State Tuning Workflow Using Global Optimization and Physical Constraints

A computational model that can accurately describe the thermodynamics of a hydrocarbon system and its properties under various conditions is a prerequisite for running reservoir and pipeline simulations. Cubic Equations of State (EoS) are mathematical tools used to model the phase and volumetric behavior of reservoir fluids when compositional effects need to be considered. To anticipate uncertainty and enhance the quality of their predictions, EoS models must be adjusted to adequately match the available lab-measured PVT values. This task is challenging given that there are many potential tuning parameters, thus leading to various tuning results of questionable validity. In this paper, we present an automated EoS tuning workflow that employs a Generalized Pattern Search (GPS) optimizer for efficient tuning of a cubic EoS model. Specifically, we focus on the Peng–Robinson (PR) model, which is the oil and gas industry standard, to accurately capture the behavior of diverse multicomponent, complex hydrocarbon mixtures encountered in subsurface reservoirs. This approach surpasses the limitations of conventional gradient-based (GB) methods, which are susceptible to getting trapped in local optima. The proposed technique also allows physical constraints to be imposed on the optimization procedure. A gas condensate and an H2S-rich oil were used to demonstrate the effectiveness of the GPS algorithm in finding an optimized solution for high-dimensional search spaces, and its superiority over conventional gradient-based optimization was confirmed by automatically tracking globally optimal and physically sound solutions.

Direct Ethylene Purification from Cracking Gas via a Metal–Organic Framework Through Pore Geometry Fitting

The direct one-step separation of polymer-grade C2H4 from complex light hydrocarbon mixtures has high industrial significance but is very challenging. Herein, an ethylene-adsorption-weakening strategy is applied for precise regulation of the pore geometry of four tailor-made metal–organic frameworks (MOFs) with pillar-layered structures, dubbed TYUT-10/11/12/13. Based on its pore geometry design and functional group regulation, TYUT-12 exhibits exceptional selective adsorption selectivity toward C3H8, C3H6, C2H6, C2H2, and CO2 over C2H4; its C2H6/C2H4 adsorption selectivity reaches 4.56, surpassing the record value of 4.4 by Fe2(O2)(dobdc) (dobdc4− = 2,5-dioxido-1,4-benzenedicarboxylate). The weak π–π stacking binding affinity toward C2H4 in TYUT-12 is clearly demonstrated through a combination of neutron powder diffraction measurements and theoretical calculations. Breakthrough experiments demonstrate that C2H4 can be directly obtained from binary, ternary, quaternary, and six-component light hydrocarbon mixtures with over 99.95% purity.

Potential for bioremediation of hydrocarbon-contaminated water by alkane-oxidizing actinobacteria

Water pollution with oil and its components is common in oil-producing and industrialized countries of the world. High molecular weight alkanes, constituting significant portion of oil, exist in a solid state at room temperature and exhibit resistance to decomposition when released into the environment. Bioremediation is the most promising technology for cleaning up hydrocarbon-contaminated aquatic ecosystems because of its environmental safety and economic efficiency. This article presents data on the potential for bioremediation of hydrocarbon-contaminated objects by the alkane-oxidizing bacterium Tsukamurella tyrosinosolvens PS2. Strain PS2 was isolated from petrochemical waste and showed a significant increase to 107 CFU/ml when cultivated on a mineral medium with solid paraffin as the sole source of carbon and energy. It was found that strain PS2 has high adhesion to liquid and solid alkanes, compared to cells grown in a medium with sucrose. The degree of decomposition of solid paraffin was evaluated using gas chromatography/mass spectrometry. The results indicated that strain PS2 metabolizes alkanes with a chain length of C20-C31 in 7 days with varying efficiencies. The findings of this study demonstrate the potential of the T. tyrosinosolvens PS2 strain for the bioremediation of sites contaminated with complex mixtures of hydrocarbons.

Development of methods for calculating thermal conductivity of gas condensates-alternative motor fuels

The article is devoted to the development of methods for calculating the thermal conductivity of complex hydrocarbon mixtures such as gas condensates, which are widely used as components for motor and jet fuels. The work was carried out on the basis of the results of experimental studies of thermal conductivity of the eight most representative deposits in Central Asia in terms of group hydrocarbon composition. An analysis of existing equations for calculating the thermal conductivity of liquid petroleum products and the possibility of their use for gas condensates was carried out. A number of new equations are presented for calculating the thermal conductivity of gas condensates depending on the group hydrocarbon composition in a wide range of temperatures and pressures.

Pore chemistry and geometry control in a metal azolate framework for one-step ethylene purification from quinary gas mixture

In the petrochemical industry, obtaining polymer-grade ethylene from complex light-hydrocarbon mixtures by one-step separation is important and challenging. Here, we successfully prepared the Metal–Azolate Framework 7 (MAF-7) with pore chemistry and geometry control to realize the one-step separation of ethylene from cracking gas with up to quinary gas mixtures (propane/propylene/ethane/ethylene/acetylene). Based on the tailor-made pore environment, MAF-7 exhibited better selective adsorption of propane, propylene, ethane and acetylene than ethylene, and the adsorption ratios of ethane/ethylene and propylene/ethylene are as high as 1.49 and 2.81, respectively. The pore geometry design of MAF-7 leads to the unique weak binding affinity and adsorption site for ethylene molecules, which is clearly proved by Grand Canonical Monte Carlo theoretical calculations. The breakthrough experiments show that ethylene can be directly obtained from binary, ternary, and quinary gas mixtures. These comprehensive properties show that MAF-7 is expected to achieve one-step purification of ethylene in complex light hydrocarbon mixtures.

Failure analysis and electrochemical testing of ammonium chloride corrosion in a heat exchanger in a diesel hydrotreating unit of a petroleum refinery

Crude oil is a complex mixture of hydrocarbons and can contain various impurities, which vary depending on the source and geographical location from which it is extracted. These impurities include sulphur, nitrogen, some metals, asphaltenes, non-condensable gases and salts. Salts in oil are typically found in the form of ions, which means that they are dissolved in the water present in the crude oil, or in the form of solid salts that are later deposited in equipment, pipes, and ducts. These salts can be harmful because, when the oil is processed, the water present in the oil can separate from the hydrocarbons and cause corrosion of equipment in the oil refining plant. In addition, salts can form solid deposits that can obstruct equipment. It is therefore important to remove or reduce the presence of salts in oil during the refining process to avoid operational problems and problems with the quality of the refined product. Several occurrences are reported in the specialized literature of equipment failures in the oil refining industry involving corrosion by salts, especially ammonium chloride salts. Basically, ammonium chloride, whose chemical formula is NH4Cl, is an inorganic chemical compound consisting of ammonium ions (NH4+) and chloride ions (Cl−), It is known by several names, including “ammonium salt” or “ammonium salt” due to its composition. The aim of this paper is to investigate the failure of a shell-and-tube heat exchanger in the charge preheater system of the diesel hydrotreating unit of a Brazilian oil refinery, in which the root cause of the failure identified as responsible for the damage was ammonium chloride corrosion. A severe corrosive process was observed in the tubes of the tube bundle, including perforation in some tubes, as well as damage to the inside of the heat exchanger shell. The analysis methods employed involved the study of three different types of austenitic stainless steel in terms of corrosion resistance: 304, 316L and 317L, which were exposed to media containing sodium chloride and ammonium chloride at a concentration of 3.5 % (m/v). Two electrochemical corrosion tests were carried out in aqueous media, the first determining potentiodynamic polarization curves and the second electrochemical impedance spectroscopy. In addition to material characterization tests, such as determining the chemical composition, hardness and scanning electron microscopy of the corroded samples. The results of this paper indicate that the 317L steel samples have larger passivation regions, higher pitting potential values, lower passivation current density values, as well as lower corrosion rate values during the simulation of the equivalent electrochemical circuit, which implies greater resistance to corrosion in a medium containing ammonium chloride, compared to the others. The conclusions reached reveal the applicability of 317L austenitic stainless steel in environments containing ammonium chloride, such as in the diesel hydrotreating sections of oil refineries, in addition to the use of washing water in pipes and equipment to dissolve these salts. Due to the high corrosion resistance of 317L steel in media containing ammonium chloride, it could be extended to other refining sections, such as distillation, cracking and coking units in oil refineries. This research will enable potential gains in terms of increasing the operational life of equipment and installations, reducing corrective maintenance interventions and operational safety in the operation of the industrial plant.

Ecological Implications Of Bacterial Degradation Of Alkanes In Petroleum-Contaminated Environments: A Review Of Microbial Community Dynamics And Functional Interactions


 This review explores the ecological implications of bacterial degradation of alkanes in petroleum-contaminated environments, with a focus on microbial community dynamics and functional interactions. The complex interplay between alkane-degrading bacteria and other microorganisms shapes the fate and behavior of petroleum hydrocarbons, influencing ecosystem functioning and stability. The microbial community structure in petroleum-contaminated environments is characterized by a diverse assemblage of alkane-degrading bacteria (Such as Pseudomonas sp., Alcaligenes sp., Bacillus sp., Acinetobacter sp). These bacteria exhibit varying abilities to degrade different hydrocarbon fractions, leading to distinct patterns in community composition. Factors such as hydrocarbon concentration, environmental conditions, and the presence of co-contaminants influence the abundance and distribution of alkane-degrading taxa, shaping the microbial community dynamics. Functional interactions among alkane-degrading bacteria are essential for efficient degradation processes. Synergistic interactions and metabolic cooperation between different microbial species enhance the degradation capabilities of the community as a whole. Co-metabolism and cross-feeding relationships among bacteria enable the degradation of complex hydrocarbon mixtures. Furthermore, non-degrading microorganisms contribute to the overall alkane degradation process by providing essential metabolic intermediates or modulating environmental conditions. The presence of alkane-degrading bacteria affects the diversity and abundance of other microbial communities, leading to cascading effects on the broader ecosystem. Molecular tools, such as high-throughput sequencing and metagenomics, have advanced our understanding of microbial community structure and function. This review provides valuable insights into the ecological implications of bacterial degradation of alkanes in petroleum-contaminated environments. It highlights the importance of microbial community dynamics and functional interactions in shaping the fate of petroleum hydrocarbons and emphasizes the potential of harnessing these interactions for effective bioremediation strategies. Further research is needed to unravel the complex ecological networks involved in alkane degradation and to develop innovative approaches for sustainable environmental management.

Flammability of complex hydrocarbon mixtures in air and nitrogen diluted atmosphere at ambient conditions and at elevated pressures

An innovative experimental method was introduced to study flammability limits and limiting oxygen concentration of complex hydrocarbon mixtures simulating crude oil vapour composition. Flammability experiments were conducted in a 10L spherical vessel at 25 °C and initial pressures of 100 kPa, 1100 kPa and 2600 kPa in air with additional nitrogen. Based on the experimental data, applicability of selected empirical methods and two calculated adiabatic flame temperature based methods was validated for ambient initial conditions. The experimental results confirmed relative decrease below 6.5% for lower flammability limit and below 3% for limiting oxygen concentration with increasing pressure within the examined range. The upper flammability limit increased with initial pressure. Vapour-liquid equilibrium was found to be a constraint in the fuel-rich region at elevated pressures to keep the constant initial composition of the vapour phase. At ambient conditions the calculated adiabatic flame temperature based methods were able to approximate the experimental data well. Empirical mixing rules showed accuracy highly dependent on source literature data.

Improved numerical methods for simulating complex mixture transport across asymmetric polymer membranes using a Maxwell–Stefan model

Improved numerical methods are presented for predicting the total flux and permeate composition of complex hydrocarbon mixtures permeating through asymmetric glassy polymer membranes. The proposed methods are comprehensively compared against a suite of existing methods for several challenging test cases; namely, three and nine component mixtures permeating through a glassy polymer, SBAD-1, and a five component mixture permeating through a glassy polymer, PIM-1. We find that the proposed shooting algorithm is the most accurate, efficient, and robust for these test cases. In comparison, existing methods based on common model simplifications suffered from large errors and frequent convergence failures for higher component mixtures, while those based on numerical discretization techniques suffered from higher cost and needed much more careful tuning to provide reliable solutions.

Unleashing synergistic potential of microbially enhanced anaerobic co-digestion of petroleum refinery biosludge and yard waste: Impact of nutrient balance and microbial diversity

Petroleum refinery sludge, an egregious solid residue generated from the wastewater treatment plants poses an environmental hazard owing to its intricate hydrocarbon composition, necessitating competent treatment for secure disposal. The study proposes a green solution through anaerobic co-digestion of nitrogen-rich petroleum refinery sludge (PS) with carbon-rich yard waste (YW), balancing the nutrients and moisture content for efficient microbial proliferation. Using Central Composite Design-Response Surface Methodology, 1 L batch experiments were conducted with varying carbon/nitrogen (C/N) ratios and pH to achieve maximum biogas yield within 50 days of co-digestion. However, the sluggish biogas recovery (40%) indicated a slow rate-limiting hydrolysis, necessitating pretreatment. Feedstock incubation with Bacillus subtilis IH1 strain, isolated from the microbially-enriched PS, at 108 colony forming units (CFU) per mL for 5 days maximized the soluble chemical oxygen demand and volatile fatty acids by 2.2 and 1.4 folds respectively compared to untreated feedstock. Scale-up Bacillus subtilis aided co-digestion studies further augmented biogas by 76% against untreated monodigestion of PS with significant total petroleum hydrocarbons, emulsions, and lignocellulosic degradation. Further identification of major organic pollutants in the batch digestate revealed significant degradation of the toxic organic hydrocarbon pollutants apotheosizing the efficacy of the synergistic sustainable technique for the management of PS. Environmental implicationThe effluent treatment plants (ETPs) of petroleum refining industries generate sludge which is a complex mixture of petroleum hydrocarbons, oil–water (O/W) emulsions and heavy metals. These petroleum hydrocarbon constituents can be linear/cyclic alkanes, polyaromatics, resins and asphaltenes, whose intricate composition is reportedly carcinogenic, cytogenic and mutagenic, classifying it as hazardous waste. Biological treatment of these sludge through anaerobic digestion leads to utilization of petroleum hydrocarbons with subsequent energy recovery. Co-digestion of these sludge with competent co-substrates leads to nutrient balance, diverse microbial proliferation and toxicant dilution. Microbially aided co-digestion further augments methane rendering a digestate with utmost pollutant degradation.

Separation and thermal conversion of group components from medium‐low‐temperature coal tar pitch

AbstractMedium‐low‐temperature coal tar pitch (MLP) is a complex mixture of varied heavy organic hydrocarbons, which was generally used as the raw materials to produce artificial carbon materials. It was great significance for the high value‐added utilization of MLP to understand the property of components of MLP. The methanol, n‐heptane, n‐butanol, and dimethyl sulfoxide were used as the solvents to separate the components from medium‐low‐temperature coal tar pitch, and the eight kinds of components (include four kinds of solubles and four kinds of insolubles) were obtained after solvent separation. In addition, the liquid phase carbonization and calcination of medium‐low‐temperature coal tar pitch and its group components were carried out to obtain the corresponding pitch coke. The structural properties of components and pitch cokes have been studied in detail by FTIR, 1H‐NMR, TGA, optical microscope, scanning electron microscope, Raman spectrum, and X‐ray diffraction. The results showed that the optical microstructure of pitch coke prepared from the soluble group components of n‐heptane was mainly fibrous structure and leaflet structure, and the content can reach as 72.83%. In other words, the soluble group composition of n‐heptane was a suitable and excellent precursor for the production of needle coke. The optical microstructure of DMSOS‐C and HI‐C was only composed of fine mosaic structure, which was more suitable for the production of isotropic coke (a kind of special coke and also named as fine mosaic coke).

Exploring new dimensions: Single and multi-block analysis of essential oils using DBDI-MS and FT-IR for enhanced authenticity control

BackgroundEssential oils (EOs) are complex mixtures of volatile hydrocarbons with a wide range of applications in the pharmaceutical, fragrance and food industry. The composition of EOs is highly variable and can affect their quality and pharmaceutical efficacy. Moreover, the high economic value of EOs, such as those obtained from Rosa damascena, make falsification and misclassification a lucrative business. Consequently, adulterations can lead to serious health consequences for consumers. While current quality control methods for EOs involve analysing their chromatographic profile or comparing their Fourier transform infrared (FT-IR) spectra, these methods can be time-consuming or lack sensitivity. To address these issues, we compared state-of-the-art quality control methods, including gas chromatography flame ionization detection (GC-FID) quantification and enantiomeric ratio determination, FT-IR spectrometry with dielectric barrier discharge ionization coupled to triple quadrupole mass spectrometer (DBDI-MS), in a chemometric single- and multi-block approach. ResultsOur results show that the best classification accuracy of 94.7% for R. damascena samples was obtained using GC-FID combined with partial least square discriminant analysis (PLS-DA). Comparatively, the enantiomeric ratios did not improve classification accuracy. In contrast, fragmentation data from DBDI-MS (Q3), which was acquired in a fraction of the analysis time and without extensive sample preparation, achieved a classification accuracy of 84.2%. We also found that combining FT-IR with parent ion DBDI-MS (Q1) data in a multi-block sequentially orthogonalized partial least squares linear discriminant analysis (SO-PLS-LDA) model improved classification accuracy, compared to their respective single-block PLS-DA models. SignificanceOverall, our study demonstrates that DBDI, as an ambient ionization method, has significant potential for high-throughput screening. When combined with MS, it can produce comparable classification accuracies to conventional methods, while offering the added benefits of speed and convenience. As such, DBDI-MS is a promising tool for EO quality control.

Physico-Chemical Studies on Crude Oil of Western Onshore

Abstract: Crude oil is a complex mixture of hydrocarbons with non-metallic elements such as sulphur, nitrogen, oxygen, and other elements. Hydrocarbons are chemicals that are mostly composed of the elements carbon and hydrogen. Crude oil comprises a variety of hydrocarbon molecules that fall into three categories: alkane, cycloalkane, and aromatic. Crude oil is distinguished by a number of chemical and physical features that play an essential role in the oil industry. These qualities are critical in making decisions in the exploration and production of crude oil. Characteristics like density, specific gravity, API gravity, water content, and sulphur content, to name a few, contribute value to the price of crude before it is transported to markets and refineries, so controlling these parameters significantly saves damage to infrastructure like pipelines and refineries. As a result, the study of physical and chemical properties becomes crucial for the petroleum industry. The current work deals with the investigation of physico-chemical characteristics of crude oil of Western onshore.

Unexpected Structural Effects on the Onset of Thermal Reactions of Aromatic Hydrocarbons

This work aims to study the reactivity of a broad range of aromatic hydrocarbons to better understand the reactivities of more complex hydrocarbon mixtures. A set of closed-system pyrolysis experiments were conducted on a diverse range of ∼30 polycyclic aromatic hydrocarbons (PAHs) at the thermal onset reaction temperature of 400 °C to understand structural effects on reactivities and shed light on the early events of thermal reaction mechanisms. Thermal transformations, including methyl transfer (alkylation/dealkylation), rearrangement, condensation, molecular growth, and other chemical transformations, are often indicated by dark carbon materials composed of complex mixtures. Thermal transformation was confirmed by phenomenological changes (color and solubility) and chemical analysis using nuclear magnetic resonance, thermogravimetric analysis, gas chromatography, and electron spin resonance. Unsubstituted PAHs (e.g., phenanthrene, anthracene, pyrene, chrysene, etc.) were unaffected by heating at this temperature, with the exception of tetracene and pentacene which readily transformed into dark and insoluble materials. The reactivity of these unsubstituted PAHs is consistent with aromaticity predicted by the Clar theory. On the contrary, most alkyl-substituted PAHs can be transformed into carbon materials at 400 °C; however, alkyl-substituted phenanthrenes (2,7-dimethyl, 2-ethyl, or 7-ethyl) and benzenes (xylenes and pentamethylbenzene) were unreactive. CH2-containing PAH molecules were unreactive if in a five-membered ring (e.g., fluorene and benzofluorene) but became reactive if in a six-membered ring (9,10-dihydroanthracene), likely as a result of aromatization of the latter. The reactivity of the aryl–aryl linkage depends upon the aromatic moieties to which it is connected. While it is unreactive when connecting phenyl groups, such as in p-terphenyl, it is reactive when connecting pyrenes, such as in 1,1′-bispyrene. These results were unexpected and challenge the conventional thinking about hydrocarbon reactivities. Explanations and possible hypotheses are proposed, but more questions remain unanswered to understand the structural effects on reactivities. These findings are conducive to the sustainable use of aromatic hydrocarbons for higher value carbon materials and relevant to numerous pyrolysis studies on oil shale kerogens, biomass, and waste plastics.

Lanolin.

Lanolin is a complex mixture of high molecular weight esters, aliphatic alcohols, sterols, fatty acids, and hydrocarbons that has been widely used for centuries for its emollient properties. The purification of crude lanolin into lanolin wax and the processing of this wax into various derivatives began in 1882 and continue to this day with newer highly purified anhydrous lanolins. Controversy as to lanolin's allergenicity began in the 1920s and remains an issue. The most appropriate patch test preparation(s) for detecting allergy remain disputed. Detection of lanolin-induced contact dermatitis in diseased skin by patch testing on normal skin may lead to false negative results. Patients with a positive patch test to lanolin may tolerate use of lanolin on normal skin. Although lanolin is a weak sensitizer and the frequency of contact allergy to it in the European population reportedly is 0.4%, there are high-risk concomitant conditions: stasis dermatitis, leg ulcers, perianal/genital dermatitis, and atopic dermatitis (AD). Children and the elderly are also at greater risk of developing contact allergy to lanolin, partly because of comorbidities (AD and stasis dermatitis/leg ulcers, respectively). Finally, in the United States, non-Hispanic white patients are more likely than their non-Hispanic black counterparts to be lanolin allergic.

Biodegradación de petróleo crudo presente en aguas residuales: evaluación de la producción de biosurfactantes y actividad de catecol 2,3 dioxigenasa

Water demand is increasing because of demographic and urban development in the last decades. Crude oil is an essential energy resource for many anthropogenic activities. However, it is associated with the generation of environmental pollution. In the present work, a native microbial consortium was used to study hydrocarbon biodegradation of crude oil and its potential use to remove organic pollutants in wastewater. The kinetic degradation of crude oil was analyzed to determine the production of biosurfactants and the enzyme activity of catechol 2,3 dioxygenase. The degradation of the hydrocarbon was determined by aromatic-hydrocarbons (96.11%) and total-hydrocarbons (74.23%). The maximum values of the biosurfactant production were evaluated by oil displacement (206.95 mg/L) and emulsification capacity (DO600 0.2895). The kinetic analysis showed that the complex mixture of hydrocarbons was the main responsible for generating the stress to synthesize biosurfactants through a native microbial consortium. However, the decrease in catechol 2,3 dioxygenase activity and biosurfactant production was related to the degradation of aromatic hydrocarbons. The microbial consortium was capable to produce biosurfactants during crude oil degradation, and it has a great potential to remove aromatic hydrocarbons present in wastewater.