Presence Of Other Hydrocarbons Research Articles

Gas chromatography-mass spectrometry and scanning electron microscopy with energy-dispersive radiograph analysis of biodeteriorative metabolites produced by Aspergillus species

Background and objectives Fungal deterioration of cultural heritage is a major problem that causes physical and chemical damage as well as esthetic alteration. In the current research, fungal species that exist on a brick sample obtained from Egyptian historical places were isolated and identified. Moreover, various metabolic products produced by the isolated fungal species were detected, which may play an important role in the deterioration of many historical buildings.Materials and methods Various fungi existing on brick samples collected from an Egyptian historical place were identified phenotypically and then confirmed molecularly based on the 18 S rDNA technique. The metabolites found in the chloroform extract of the isolated fungi were detected by gas chromatography-mass spectrometry. Quantitative mineralogical analysis of the deteriorated brick was studied by radiograph diffraction. Moreover, scanning electron microscopy-energy-dispersive radiograph was employed to identify the mineral compositions and surface structural morphology of the collected brick sample.Results and conclusion Three fungi showed the highest occurrence and were identified as Aspergillus niger, Aspergillus terreus, and Aspergillus flavus. The metabolites found in the chloroform extract of the three fungi were detected by gas chromatography-mass spectrometry, which showed that 5­octadecene, (E) was common among A. niger, A. terreus, and A. flavus; nonadecane and E­15­heptadecenal were common between A. niger and A. flavus; α­cadinol, tetradecane, and hexadecane were common between A. niger and A. terreus; and trans­caryophyllene, α­humulene, tau­muurolol, and octadecane were common between A. terreus and A. flavus. In addition, there was a presence of other hydrocarbons and various organic acid esters that play a vital role in the brick deterioration. Moreover, radiograph diffraction and scanning electron microscopy-energy-dispersive radiograph results showed that the brick sample contains Si, Fe, Ca, and Al, with small amounts of Na, Mg, and Cl. The fungal hyphae penetrating the brick sample were also detected. Our results demonstrate that fungi existence could result in physical deterioration by extending their hyphae through the brick pores resulting in stress. Fungi could also lead to chemical deterioration due to the production of different acids and acid derivatives that cause the brick demineralization via chelation of various metal. In addition, the production of various aliphatic and aromatic hydrocarbons by the fungi could play an important role in the deterioration process.

Oxidative Dehydrogenation of 1-Butene to 1,3-Butadiene over a Multicomponent Bismuth Molybdate Catalyst: Influence of C3–C4 Hydrocarbons

The influence of light hydrocarbons, such as n-butane, isobutane, propylene, cis- and trans-2-butenes, and isobutene on the oxidative dehydrogenation of 1-butene to 1,3-butadiene over BiMoKNiCoFePOx/SiO2 catalyst has been studied using a gas flow reactor. The inhibition effect of the listed hydrocarbons on the target reaction increased in the order of n-butane ~ isobutane < propylene < 2-butenes < isobutene. In addition, in contrast to 1-butene, isobutene has shown significant contribution to coke formation. It was suggested, that the coke formation and therefore the rate of the catalyst regeneration exercise a significant influence on the efficiency of 1-butene transformation into 1,3-butadiene in the concurrent presence of other hydrocarbons.

Predicting the biodegradation of target hydrocarbons in the presence of mixed contaminants in soil

The aim of this study was to investigate the prediction of 14C-phenanthrene and 14C-hexadecane biodegradation in the presence of other hydrocarbons in soil using β- and α-cyclodextrin (CD) solutions, respectively. Prediction of the biodegradation of 14C-phenanthrene using the β-CD extraction was robust under single, co-contaminant and multiple contaminant conditions ( r 2 = 0.92, slope of best fit line = 0.87, intercept = 7.24, n = 84). Prediction of 14C-hexadecane using the α-CD extraction was robust under single and co-contaminant conditions ( r 2 = 0.92, slope of best fit line = 0.97, intercept = 1.24, n = 60); however, the α-CD could not accurately predict 14C-hexadecane biodegradation in the presence of multiple contaminants. The presence of multiple contaminants enhanced 14C-hexadecane mineralisation, but did not enhance extractability. The results from this study provide further evidence for the application of HPCD extractions for the measurement of microbial accessibility in soil.

Peroxidase-catalyzed removal of phenols from a petroleum refinery wastewater

The phenol content of a petroleum refinery wastewater was reduced below the discharge limit following treatment with horseradish peroxidase and H2O2. Approximately 58% of COD, 78% of BOD5, and 95% of toxicity were removed along with the phenols. As a result of treatment, phenols were transformed into less biodegradable compounds which could be removed by subsequent coagulation and precipitation. Optimization of the peroxide concentration led to 20% enzyme savings. The use of PEG and chitosan as protective additives resulted in 4 and 25-fold reductions in enzyme requirements, respectively. Phenol removal did not appear to be adversely affected by the presence of other hydrocarbons that are frequently present in refinery wastewaters.

Evaluation of a Thermionic Ionization Detector for Selective Detection of Oxygenated Volatile Organic Compounds

Thermionic ionization detectors (TIDs) consist of a catalytically active, low work function, heated source. The detector responds to molecules with high electron affinity that can extract an electron from the surface of the source to form negative ions. They are used as selective detectors for nitrogen and phosphorus compounds. In this research, a TID is used for selective detection of oxygenated volatile organic compounds in the presence of other hydrocarbons. The effects of various TID operating parameters are studied.

Pharmacokinetics of benzene in a human after exposure at about the permissible limit.

This limited range of experimental human exposure indicates that: 1. In the single experimental subject, the amount of benzene retained in the body 10 hours and more after exposure depends on the multiple of the concentration and duration of exposure. 2. At concentrations about the threshold limit value, the presence of other hydrocarbons does not affect the retention or elimination of benzene. 3. The amount of benzene retained in the body for 10 or more hours is dependent on the energy expenditure of the subject during exposure. There is reason to think that elimination after exposure is similarly affected. 4. While the principal route for elimination of benzene is the metabolite, conjugated phenol, in urine, the proportion eliminated in breath depends on the duration of exposure in the 1- to 8-hour range. 5. Three or four distinct compartments for retaining benzene are apparent and these may be identified with specific groups of organs in the body. 6. Mathematical modelling of the system can provide a reasonably accurate representation of benzene behavior in the body, and should enable dosage to individual or groups of organs to be estimated after occupational exposure. 7. Diurnal variation in the elimination of benzene after exposure may introduce a factor of uncertainty of about two into the prediction of exposure from biological monitoring. 8. Patterns of retention and elimination of toluene are very similar to those of benzene, though the principal metabolite in urine is different, and there may be a limit to the maximum amount that can be excreted by that route due to the relatively low solubility of hippuric acid in aqueous solutions.

Determination of hydrocarbons in the parts per 10 9 range using glass capillary columns coated with aluminium oxide

The properties and limitations of a highly efficient gas chromatographic separation column are described. The column is of importance in the analysis of hydrocarbon emissions as it has the following advantages: high separation efficiency; good detection performance owing to a high signal-to-noise ratio; simultaneous determination of aromatics in the presence of other hydrocarbons in the C 1–C 9 range in a short time and without the need for a multi-column techniqe; simple on-line computer connection even in the parts per 10 9 range. The preparation of the column and its applications and use with suitable measuring equipment are described in detail.

An Analysis of the Convergence Pressure Concept For Hydrocarbon And Hydrocarbon Non-Hydrocarbon Systems

Abstract This paper evaluates the convergence pressure concept for the correlation of K-factors in hydrocarbon systems. It is shown that, even in the case of binary and ternary systems containing non-hydrocarbon components, the concept breaks down and leads to unacceptable errors in the predicted K-factors. INTRODUCTION THE CONCEPT OF CONVERGENCE PRESSURE as a parameter for the correlation of K-factors has been accepted by worker's in the hydrocarbon processing industry for many years. Working charts of tables for these K-factors are available in many forms, but undoubtedly the most systematic and comprehensiv treatment for hydrocarbon systems is the one prepared by the Natural Gas Processors Suppliers Association and made available through their Engineering Data Book Although the concept originated more than two decades ago, and although its shortcomings have long been recognized, it is still widely accepted and widely used. Calculations based on K-factors obtained using the convergence pressure principle will continue to be made for many years to come. Within the past five to ten years, several alternative methods for allowing for the effect of temperature, pressure and composition on K-factor calculations have been suggested. Significant among these are correlations based directly on an equation of state such as the RWR equation, on the regular solution theory incorporated into the Chao-Seader(3) correlation or on the recent work of Prausnitz and Chueh(9). It can be argued that these approaches are more sound theoretically, but in spite of this they all have their limitations ill one way or another. For this reason, many situations exist in which K-factors based on convergence pressure are still as reliable as any. The purpose of this paper is to critically evaluate the concept by making some comparisons between K-factors for hydrocarbons in the presence of other hydrocarbons with the same hydrocarbons in the presence of hydrogen sulphide OR carbon dioxide, evaluated at the same convergence pressure, pressure and temperature. The analysis will show that the basic convergence pressure postulate breaks down even in the case of binary and ternary systems when non-hydrocarbons are present. CONVERGENCE PRESSURE CONCEPT The convergence pressure concept has been clearly explained by Katz and Kurata(7) for a binary system, The convergence pressure for a binary system is the critical pressure of the particular binary mixture that has the temperature in question as its critical temperature. Thus, for a given binary system, the convergence pressure depends only on temperature. Basically, the postulate means that the K-factor for component A in an A-B binary should be the same as for component A in an A-C binary wherever the systems have the same temperature, pressure and convergence pressure. The basic convergence pressure concept has also been analyzed quantitatively by Holland(8) for ternary and more complex systems. It is shown that for a ternary system only one graph of log P vs log K, exists for each component at a given temperature and convergence pressure. Thus, for ternary systems the concept should be just as valid as it is for binary systems.