Saturated hydrocarbons were extracted from fatty tissue of beef heart and identified by combined gas chromatography-mass spectrometry. A complete series of normal alkanes from C₁₄ to C₃₅ was identified together with three isoprenoid hydrocarbons, 2, 6, 10, 14- tetramethylpentadecane (pristane), 2, 6, 10, 14- tetramethylhexadecane (phytane), and 2, 6, 10- trimethyltridecane. In addition, a C₁₇ branched alkane with an isoprenoid-like fragmentation pattern was identified but the spectrum could not be matched with that of a C₁₇ isoprenoid hydro-carbon reported in sediments. The distribution pattern of the ṉ-alkanes is very similar to that reported in pasture plants, indicating that the ṉ-alkanes are derived from the steer's diet. The isoprenoids have not yet been reported in plant tissues, suggesting that they might be produced in the steer from the phytol side chain of chlorophyll a.

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LD2668 .T4 1966 C518 / Master of Science

Thesis. 1976. Ph.D. cn--Massachusetts Institute of Technology. Dept. of Mechanical Engineering. / Vita. / Includes bibliographical references. / by Peter W. Huber. / Ph.D.cn

School of Chemical and Metallurgical Engineering, Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, South Africa 26 February 2016 / Many reports in the open literature have focused on Fischer-Tropsch (FT) kinetics, yet none of them appear to be able to explain FTS completely. Few of the FT models consider the production of olefins and paraffins separately. To study whether the selectivity to olefins and paraffins follows similar trends and if kinetics alone suffices to explain FT phenomena, a series of FT experiments were conducted in a fixed bed reactor loaded with 10% Co/TiO2. FT feeds were periodically switched from syngas to syngas + N2 by adjusting the total reactor pressure so that the reactant partial pressures (PCO and PH2) remained constant. During the initial deactivation (the first 1200 hours), it was found that the formation rates of olefins remained fairly constant (in some cases they increased) while those of paraffins decreased. This indicates the deactivation is mainly caused by the decrease in the paraffin formation rate. Currently, none of the published kinetic models can explain the phenomenon that the decay of the reaction rates of olefins and paraffins were not the same during the deactivation. At steady state (1055 to 2700 hours, overall reaction rate fairly constant), adding extra N2 decreased the selectivity to the light hydrocarbons. These results suggest that by feeding the extra N2 there could be an increase in selectivity and formation rates to long chain hydrocarbons (C5+). Plotting molar ratios of paraffin to olefin (P/O) with carbon number n+1 versus the ratio with carbon number n revealed linear relationships which are independent of feed gases, catalyst activity and reaction temperature. These results imply that product distributions might be determined by some sort of equilibrium. Another plot of normalised mole fractions of CnH2n, Cn+1H2n+2, and CnH2n+2 in ternary diagrams showed that after disturbances these product distributions tended to stable points. It is suggested that this could be due to slow changes in the liquid composition after the disturbances. Although not all the results are explained, the researcher emphasises that normal kinetics alone cannot explain these results completely. There might be factors, iii including vapour-liquid equilibrium or reactive distillation, which are worthy of consideration to explain FTS. / MT2016

Microbial biodegradation methods of hydrocarbon contaminated soils that can occur through biodegradation, bio augmentation, bio stimulation, and phytoremediation, have gained significant interest in recent years when compared to the conventional methods. The study was designed to explore the influence of petroleum hydrocarbon contamination on physicochemical and microbial characteristics of soils as well as determining the possibility of hydrocarbon biodegradation using biostimulation. The process involved soil characterisation and modification of nitrogen and phosphorus content to stimulate naturally adapting microorganisms. Characterisation process determined that hydrocarbon contamination of Murowa soils introduced hydrophobicity to the naturally wettable sandy loam soils. Naturally adapting microbial species capable of degrading hydrocarbons identified using Direct microscopy, Gram and Melzer’s iodine staining included Pseudomonas, Bacillus, Serratia marcescens, Flavobacterium, Micrococcus, Streptomyces Staphylococcus, Penicillium and yeasts. The N: P nutrient ratio and moisture levels were identified as potential limiting factors and hence experiments focused on manipulation of N: P nutrients to stimulate the identified hydrocarbon degrading organisms (bio stimulation). Hydrocarbons were identified by solvent extraction using hexane and gas chromatography. These included decane, undecane, hexadecanal, 2-ethylcridine, octadecane and 1-iodo. Soils weighing 10kgs with hydrocarbons levels of about 265mg/kg were subjected to eight (8) treatments with seven (7) different combinations of N (6000-12000mgN): P (600- 3000mgP) concentration ranges including the control. Nitrogen The moisture was adjusted and tilling for aeration was done on a weekly basis. Changes in Total Petroleum Hydrocarbon (TPH), C: N: P ratio, microbial mass and pH were evaluated over 111 consecutive days. The optimum N:P ratio was the determined to 2:1 molar ratio in form of 6000mgN:3000mgP. TPH concentration was reduced by 73% from the initial concentration within the first 74 days. Beyond 74 days there were no significant changes in the TPH concentration and this was attributed to the presence of more complex insoluble hydrocarbons which needed more time and an additional bio surfactant to complete mineralization. The conclusion was that a combination of natural attenuation and biostimulation methods can be used to bioremediate Murowa hydrocarbon contaminated soils using the 2:1 molar ratio of what / College of Agriculture and Environmental Sciences / M. Sc. (Environmental Science)

Indiana University-Purdue University Indianapolis (IUPUI) / Organic-rich substrates such as soil provide an excellent carbon source for bacteria. However, hydrocarbons such as those found in various ignitable liquids can also serve as a source of carbon to support bacterial growth. This is problematic for fire debris analysis as samples may be stored at room temperature for extended periods before they are analyzed due to case backlog. As a result, selective loss of key components due to bacterial metabolism can make identifying and classifying ignitable liquid residues by their chemical composition and boiling point range very difficult. The ultimate goal of this project is to preserve ignitable liquid residues against microbial degradation as efficiently and quickly as possible. Field and laboratory studies were conducted to monitor microbial degradation of gasoline and other ignitable liquids in soil samples. In addition to monitoring degradation in potting soil, as a worst case scenario, the effect of soil type and season were also studied. The effect of microbial action was also compared to the effect of weathering by evaporation (under nitrogen in the laboratory and by the passive headspace analysis of the glass fragments from the incendiary devices in the field studies). All studies showed that microbial degradation resulted in the significant loss of n-alkanes and lesser substituted alkylbenzenes predominantly and quickly, while more highly substituted alkanes and aromatics were not significantly affected. Additionally, the residential soil during the fall season showed the most significant loss of these compounds over the course of 30 days. To combat this problem, a chemical solution is to be immediately applied to the samples as they are collected. Various household and commercial products were tested for their efficacy at low concentrations to eliminate all living bacteria in the soil. Triclosan (2% (w/v) in NaOH) proved to be the most effective at preserving ignitable liquid residues for at least 30 days.

Indiana University-Purdue University Indianapolis (IUPUI) / Ignition of a combustible mixture by a transient jet of hot reactive gas is important for safety of mines, pre-chamber ignition in IC engines, detonation initiation, and in novel constant-volume combustors. The present work is a numerical study of the hot-jet ignition process in a long constant-volume combustor (CVC) that represents a wave-rotor channel. The mixing of hot jet with cold mixture in the main chamber is first studied using non-reacting simulations. The stationary and traversing hot jets of combustion products from a pre-chamber is injected through a converging nozzle into the main CVC chamber containing a premixed fuel-air mixture. Combustion in a two-dimensional analogue of the CVC chamber is modeled using global reaction mechanisms, skeletal mechanisms, and detailed reaction mechanisms for four hydrocarbon fuels: methane, propane, ethylene, and hydrogen. The jet and ignition behavior are compared with high-speed video images from a prior experiment. Hybrid turbulent-kinetic schemes using some skeletal reaction mechanisms and detailed mechanisms are good predictors of the experimental data. Shock-flame interaction is seen to significantly increase the overall reaction rate due to baroclinic vorticity generation, flame area increase, stirring of non-uniform density regions, the resulting mixing, and shock compression. The less easily ignitable methane mixture is found to show higher ignition delay time compared to slower initial reaction and greater dependence on shock interaction than propane and ethylene. The confined jet is observed to behave initially as a wall jet and later as a wall-impinging jet. The jet evolution, vortex structure and mixing behavior are significantly different for traversing jets, stationary centered jets, and near-wall jets. Production of unstable intermediate species like C2H4 and CH3 appears to depend significantly on the initial jet location while relatively stable species like OH are less sensitive. Inclusion of minor radical species in the hot-jet is observed to reduce the ignition delay by 0.2 ms for methane mixture in the main chamber. Reaction pathways analysis shows that ignition delay and combustion progress process are entirely different for hybrid turbulent-kinetic scheme and kinetics-only scheme.