SEARCH · PubMed Health

Results for “Pyrolysis”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 883 records · Page 49Linked to original sources

PubMed1991

Pulmonary response to perfluoropolymer fume and particles generated under various exposure conditions.

Combustion-product toxicity of perfluorinated polymers in small-scale tests varied markedly under various exposure conditions. The toxicity of perfluoropolymer fumes is associated with submicron pyrolysis particles (0.03-0.15 microns) in the fumes. The toxicity of pyrolysis products was not observed in rats exposed to the fumes filtered to remove the particles. The particles in the fume were agglomerated by aging or a water-treatment process, and the toxicity of particles was markedly reduced when rats were exposed to aged or water-treated fumes. Some agglomerated particles showed chain-aggregation and ultimately attained nonrespirable size. The reduced toxicity of pyrolysis fume is believed to be due to a decreased number of toxic particles resulting from particle agglomeration. Aged particle agglomerate was not toxic when instilled intratracheally into the rats. However, the particle agglomerate became toxic when rats were exposed by the inhalation to fumes evolved from the reheated agglomerate. The fumes contained numerous toxic submicron particles evolved from thermal decomposition of agglomerates by reheating. Rats exposed to the pyrolysis fumes died with pulmonary edema and hemorrhage due to Type I pneymocyte damage. The edematous lungs revealed some agglomerated particles, but it was difficult to distinguish small pyrolysis particles from contaminating dust or cellular debris.

Administration, Inhalation↗

PubMed2005

Characterization of non-discriminating tetramethylammonium hydroxide-induced thermochemolysis-capillary gas chromatography-mass spectrometry as a method for profiling fatty acids in bacterial biomasses.

Thermochemolysis using tetramethylammonium hydroxide (TMAH) as a method for profiling fatty acids (FAs) as methyl esters (FAMEs) was studied with respect to discrimination of bacterial fatty acid patterns in Gram-negative Pseudomonas putida in comparison with patterns obtained by classical preparation schemes (pressurized solvent extraction, alkaline saponification). A new, non-discriminating pyrolysis approach was used in these experiments. In this method, pyrolysis is carried out inside a deactivated stainless steel capillary constituting a part of the column train. This approach made it possible to distinguish analyte discrimination brought about by (i) the pyrolyzer set-up in conventional pyrolysis and (ii) chemical thermochemolysis reaction itself. Our results showed no significant discrimination for saturated, monounsaturated and cyclopropane FAs when using thermochemolysis temperatures up to 550 degrees C with the non-discriminating, capacitive-discharged based approach. Likewise, the cis/trans ratio of monounsaturated FAs was preserved. This is in sharp contrast to conventional pyrolysis systems (both Curie-point or flash pyrolyzers) using much longer thermochemolysis times. When using these systems, artificial monounsaturated FAMEs were formed during heat treatment resulting in biased species identification/classification. Hydroxy-FAs, chiefly bound covalently in lipopolysaccharides, could be almost quantitatively liberated by TMAH using non-discriminating pyrolysis (beyond 90%), whereas the recoveries were lower with conventional approaches. The new method makes it possible to profile fatty acids in very small amounts of both solid and liquid samples without significant sample preparation. This was exemplified by the results of TMAH-thermochemolysis of a fermentation broth taken from an in situ bioremediation reactor to monitor enhanced natural attenuation processes, and tomato roots which were subjected to cellulolytic bacteria attacks (Streptomyces), resulting in adsorption of these carboxymethyl-cellulose decomposing bacteria onto the root.

Biomass↗

PubMed2003

High-precision position-specific isotope analysis of 13C/12C in leucine and methionine analogues.

We report an automated method for high-precision position-specific isotope analysis (PSIA) of carbon in amino acid analogues. Carbon isotope ratios are measured for gas-phase pyrolysis fragments from multiple sources of 3-methylthiopropylamine (3MTP) and isoamylamine (IAA), the decarboxylated analogues of methionine and leucine, using a home-built gas chromatography (GC)-pyrolysis-GC preparation system coupled to a combustion-isotope ratio mass spectrometry system. Over a temperature range of 620-900 degrees C, the characteristic pyrolysis products for 3MTP were CH4, C2H6, HCN, and CH3CN and for IAA products were propylene, isobutylene, HCN, and CH3CN. Fragment origin was confirmed by 13C-labeling, and fragments used for isotope analysis were generated from unique moieties with > 95% structural fidelity. Isotope ratios for the fragments were determined with an average precision of SD(delta13C) < 0.3% per thousand, and relative isotope ratios of fragments from different sources were determined with an average precision of SD(delta(delta)13C) < 0.5% per thousand. Delta(delta)13C values of fragments were invariant over a range of pyrolysis temperatures. The delta(delta)13C of complementary fragments in IAA was within 0.8% per thousand of the delta(delta)13C of the parent compounds, indicating that pyrolysis-induced isotopic fractionation is effectively taken into account with this calibration procedure. Using delta(delta)13C values of fragments, delta(delta)13C values were determined for all four carbon positions of 3MTP and for C1, C2, and the propyl moiety of IAA, either directly or indirectly by mass balance. Large variations in position-specific isotope ratios were observed in samples from different commercial sources. Most dramatically, two 3MTP sources differed by 16.30% per thousand at C1, 48.33% per thousand at C2, 0.37% per thousand at C3, and 5.36% per thousand at C(methyl). These PSIA techniques are suitable for studying subtle changes in intramolecular isotope ratios due to natural processes.

Acetonitriles↗

PubMed1993

Bacterial and human cell mutagenicity study of some C18H10 cyclopenta-fused polycyclic aromatic hydrocarbons associated with fossil fuels combustion.

A number of isomeric C18H10 polycyclic aromatic hydrocarbons (PAHs), thought to be primarily cyclopenta-fused PAHs, are produced during the combustion and pyrolysis of fossil fuels. To determine the importance of their contributions to the total mutagenic activity of combustion and pyrolysis samples in which they are found, we characterized reference quantities of four C18H10 CP-PAHs: benzo[ghi]fluoranthene (BF), cyclopenta[cd]pyrene (CPP), cyclopent[hi]acephenanthrylene (CPAP), and cyclopent[hi]aceanthrylene (CPAA). Synthesis of CPAA and CPAP is described. The availability of reference samples of these isomers also proved to be an essential aid in the identification of the C18H10 species often found in combustion and pyrolysis samples. Chemical analysis of selected combustion and pyrolysis samples showed that CPP was generally the most abundant C18H10 isomer, followed by CPAP and BF. CPAA was detected only in pyrolysis products from pure PAHs. We tested the four C18H10 PAHs for mutagenicity in a forward mutation assay using S. typhimurium. CPP, BF, and CPAA were roughly twice as mutagenic as benzo[a]pyrene (BaP), whereas CPAP was only slightly active. These PAHs were also tested for mutagenic activity in human cells. In this assay, CPP and CPAA were strongly mutagenic but less active than BaP, whereas CPAP and BF were inactive at the dose levels tested. Also, the bacterial and human cell mutagenicity of CPAA and CPAP were compared with the mutagenicity of their monocyclopenta-fused analogs, aceanthrylene and acephenanthyrlene. Although the mutagenicities of CPAP and acephenanthrylene are similar, the mutagenic activity of CPAA is an order of magnitude greater than that of aceanthyrlene.

Cell Line↗

PubMed1989

Spectrometric and chromatographic methods for the analysis of polymeric explant materials.

Several analytical pyrolysis methods, namely pyrolysis mass spectrometry (Py-MS), time-resolved pyrolysis mass spectrometry (TRPy-MS), and pyrolysis short column gas chromatography mass spectrometry (Py-GC/MS) were used to analyze polymers of clinical interest both before and after implantation. A sample of Biomer, a poly(ether urethane urea) used in the Utah artificial heart, was analyzed using these methods. Two poly(ether urethanes) (Tecoflex and Pellethane) and a poly(dimethylsilicone) (Silastic) sample were analyzed using Py-GC/MS. The direct Py-MS of Biomer identified the components used in the manufacture of Biomer. Py-GC/MS of Biomer, Tecoflex, Pellethane, and Silastic also identified the components used in their manufacture. The analysis of explanted Biomer detected the presence of adsorbed cholestadiene, the reaction of chloride ions with a stabilizer, and the presence of a siloxane contaminant. The cholestadiene was detected on the outside housing of an artificial heart which had been implanted for 297 days. The cholestadiene was detected at low levels and was identified by library search on the MS data system. The siloxane contaminant was also identified by the MS data system. All of the methods demonstrated required only short instrumental analysis times (10 min or less). Data analysis required much more time, but much of the data analysis can be automated.

Biocompatible Materials↗

PubMed1996

Mass spectrometric studies of the thermal decomposition of carbohydrates using 13C-labeled cellulose and glucose.

The mechanism of the thermal decomposition of carbohydrates is very important to the development of fuels, fibers, and paper products. To help gain more insight into the pyrolysis chemistry of cellulose, we have carried out experimental studies using Acetobacter xylinum cellulose grown on D-(1-13C)-glucose medium with incorporation levels of 1-13C of 14%, as determined by 13C NMR analysis. Samples of the labeled cellulose, as well as D-(1-13C)- and D-(2-13C)-glucose, were pyrolyzed under fast-heating conditions and the products analyzed by molecular beam mass spectrometry (MBMS). From the labeled cellulose samples, statistically significant levels of enrichment were observed for the pyrolysis products that occur at m/z 110, 114, 126, 144, and 191, but not at m/z 98, 60, or 31. The lack of enrichment in the latter fragments indicates that they do not incorporate C-1. Samples were treated with 0.1% aqueous KOH to favor the formation of glycolaldehyde, but even in this case this major product was not enriched. These results suggest that the m/z 60 ion is an EI fragment ion of levoglucosan, formed by loss of neutral species containing C-1. However, the m/z 191 ion was found to contain two C-1 carbons. Collision-induced dissociation results for this ion suggest that it consists of a formate group. The structure of this ion is proposed to be the protonated formate of levoglucosan at the C-4 position, derived from either a reverse aldol reaction or a (+/-)-Diels-Alder reaction. The (1-13C)-glucose pyrolysis product distribution is similar to that for (1-13C)-labeled cellulose. The (2-13C)-glucose pyrolysis product distribution shows significant contribution from C-2 at the M + 1 peaks of m/z 32, 43, 60, 73, 85, and 97, indicating major incorporations of C-2 in glycolaldehyde in contrast to the lack of incorporation of the C-1 position in this major product.

Analysis of Variance↗

PubMed1985

Role of minerals in the thermal alteration of organic matter--I: generation of gases and condensates under dry condition.

Pyrolysis experiments were carried out on Monterey formation kerogen and bitumen and Green River formation kerogen (Type II and I, respectively), in the presence and absence of montmorillonite, illite and calcite at 200 and 300 degrees C for 2-2000 hours. The pyrolysis products were identified and quantified and the results of the measurements on the gas and condensate range are reported here. A significant catalytic effect was observed for the pyrolysis of kerogen with montmorillonite, whereas small or no effects were observed with illite and calcite, respectively. Catalytic activity was evident by the production of up to five times higher C1-C6 hydrocarbons for kerogen with montmorillonite than for kerogen alone, and by the dominance of branched hydrocarbons in the C4-C6 range (up to 90% of the total amount at any single carbon number). This latter effect in the presence of montmorillonite is attributed to cracking via a carbonium-ion [carbocation] intermediate which forms on the acidic sites of the day. No catalytic effect, however, was observed for generation of methane and C2 hydrocarbons which form by thermal cracking. The catalysis of montmorillonite was significantly greater during pyrolysis of bitumen than for kerogen, which may point to the importance of the early formed bitumen as an intermediate in the production of low molecular weight hydrocarbons. Catalysis by minerals was also observed for the production of carbon dioxide. These results stress the importance of the mineral matrix in determining the type and amount of gases and condensates forming from the associated organic matter under thermal stress. The literature contains examples of gas distribution in the geologic column which can be accounted for by selective mineral catalysis, mainly during early stages of organic matter maturation.

Bentonite↗

PubMed2006

Pyrolytic characteristics of sewage sludge.

In this study, a number of different sewage sludge including sludge samples from industrial and hospital wastewater treatment plants were characterized for pyrolysis behavior by means of thermogravimetric analysis up to 800 degrees C. According to the thermogravimetric results, five different types of mass loss behaviors were observed depending on the nature of the sludge used. Typical main decomposition steps occurred between 250 and 550 degrees C although some still decomposed at higher temperatures. The first group (Types I, II and III) was identified by main decomposition at approximately 300 degrees C and possible second reaction at higher temperature. Differences in the behavior may be due to different components in the sludge both quantitatively and qualitatively. The second group (Types IV and V), which rarely found, has unusual properties. DTG peaks were found at 293, 388 and 481 degrees C for Type IV and 255 and 397 degrees C for Type V. Kinetics of sludge decomposition can be described by either pseudo single or multicomponent overall models (PSOM or PMOM). The activation energy of the first reaction, corresponding to the main pyrolysis typically at 300 degrees C, was rather constant (between 68 and 77 kJ mol(-1)) while those of second and third reactions were varied in the range of 85-185 kJ mol(-1). The typical order of pyrolysis reaction was in the range of 1.1-2.1. The pyrolysis gases were composed of both saturated and unsaturated light hydrocarbons, carbon dioxide, ethanol and chloromethane. Most products, however, evolve at a quite similar temperature regardless of the sludge type.

Hot Temperature↗

PubMed2002

Pyrolytic kinetics of sludge from a petrochemical factory wastewater treatment plant--a transition state theory approach.

The pyrolysis of hydrocarbon-rich sludge in an oxygen-free environment can provide useful liquefaction products and residues. When applied to sewage sludge, energy and time costs are the major factors that affect the operation. Therefore, it is important to understand how the process is affected by temperature. The pyrolysis kinetics of sludge from a petrochemical factory wastewater treatment plant was studied to reveal the effects of temperature on the reaction rate and the magnitude of deltaH and deltaS of the reaction barrier. Oven-dried sludge samples were pyrolyzed in an isothermal reactor under six different temperatures. The residues were weighed at frequent intervals within a total 30-min experiment period. Data analysis indicated that a first order reaction model could describe the pyrolysis kinetics, across all experimental temperature ranges. When transition state theory was applied, the results indicated that the major reaction barrier came from the entropy term of the activation free energy. Therefore, increasing the pyrolysis temperature to overcome the reaction barrier yielded no apparent improvement, but strategies that reduced the entropy should significantly improve the reaction.

Chemical Industry↗

PubMed2001

Simulated cometary matter as a test for enantiomer separating chromatography for use on comet 46P/Wirtanen.

The Cometary Sampling and Composition Experiment on board of European Space Agency's cornerstone mission ROSETTA is designed to identify organic molecules in cometary matter in situ by a combined pyrolysis gas chromatographic and mass spectrometric technique. Its capillary columns coated with chiral stationary phases received considerable attention, because they are designed for separations of non-complex enantiomers to allow the determination of enantiomeric ratios of cometary chiral organic compounds and consequently to provide information about the origin of molecular parity violation in biomolecules. To get gas chromatographic access to organic compounds on the comet, where macromolecules and complex organic polymers of low volatility are expected to make up the main organic ingredients, the combination of two injection techniques will be applied. The pyrolysis technique performed by heating cometary samples stepwise to defined temperatures in specific ovens resulting in thermochemolysis reactions of polymers and a chemical derivatization technique, in which the reagent dimethylformamide dimethylacetal assists pyrolysis derivatization reactions in producing methyl esters of polar monomers. The combination of the reagent assisted pyrolysis gas chromatographic technique with enantiomer separating chromatography was tested with laboratory-produced simulated cometary matter.

Ammonia↗

PubMed1996

Correction of mass spectral drift using artificial neural networks.

For pyrolysis mass spectrometry (PyMS) to be used for the routine identification of microorganisms, for quantifying determinands in biological and biotechnological systems, and in the production of useful mass spectral libraries, it is paramount that newly acquired spectra be compared to those previously collected. Neural network and other multivariate calibration models have been used to relate mass spectra to the biological features of interest. As commonly observed, however, mass spectral fingerprints showed a lack of long-term reproducibility, due to instrumental drift in the mass spectrometer; when identical materials were analyzed by PyMS at dates from 4 to 20 months apart, neural network models produced at earlier times could not be used to give accurate estimates of determinand concentrations or bacterial identities. Neural networks, however, can be used to correct for pyrolysis mass spectrometer instrumental drift itself, so that neural network or other multivariate calibration models created using previously collected data can be used to give accurate estimates of determinand concentration or the nature of bacteria (or, indeed, other materials) from newly acquired pyrolysis mass spectra. This approach is not limited solely to pyrolysis mass spectrometry but is generally applicable to any analytical tool which is prone to instrumental drift, such as IR, ESR, NMR and other spectroscopies, and gas and liquid chromatography, as well as other types of mass spectrometry.

Ampicillin↗

PubMed1980

Benzocyclobutene-o-xylylene valence tautomerization: Oxygen and sulfur analogs.

Gas phase pyrolysis of o-hydroxybenzyl alcohol at 750 degrees C gave o-quinonemethide, which, on isolation, formed a mixture of the corresponding dimer and trimer. However, pyrolysis of o-hydroxy-[1-(4-pentenyl)]benzyl alcohol permitted intramolecular trapping of the intermediate o-quinonemethide, giving 3,4-trimethylene-3,4-dihydrobenzochroman. In contrast, gas phase pyrolysis of o-mercaptobenzyl alcohol readily gave benzo[b]thiete in good yield. The pyrolysis makes this interesting highly strained molecule readily available for study and synthetic application. Preliminary results showed that benzo[b]thiete readily undergoes thermal dimerization, ring-opening reactions with nucleophiles, and a variety of Diels-Alder reactions.

Journal Article↗

PubMed2006

Derivatization in mass spectrometry --7. On-line derivatisation/degradation.

The review describes on-line derivatization/degradation methods employed in mass spectrometry to solve some structural and analytical problems. Advantages and applications of various positions of reaction systems connected mainly to a mass spectrometer or a gas chromatograph/mass spectrometer are considered. Among these are reaction systems connected directly to the mass spectrometer (reaction mass spectrometry, pyrolysis-mass spectrometry or direct pyrolysis-mass spectrometry); flash-heaters as reactors in gas chromatography/mass spectrometry (GC/MS); in-line chemical reactors located before the chromatographic column [pre-column derivatization/degradation with the use of catalytic reactions, pyrolysis (pyrolysis-GC/MS), degradation in elemental analyzers-isotope ratio mass pectrometry (EA-IRMS)]; on-column derivatization and deuteration; reactor located between the chromatographic column and a mass spectrometer [post-column catalytic derivatization, gas chromatograph-combustion-isotope ratio mass spectrometer (GC-c-IRMS)]. Post-column derivatization in high performance liquid chromatography/mass spectro-metry is briefly mentioned. Application of such on-line methodology to structure elucidation of low molecular mass compounds and polymers, to the determination of isotope ratios of the most common elements, to the investigation of catalytic reactions is discussed..

Journal Article↗

PubMed1986

Role of minerals in thermal alteration of organic matter--II: a material balance.

Pyrolysis experiments were performed on Green River and Monterey Formation kerogens (Types I and II, respectively) with and without calcite, illite, or montmorillonite at 300 degrees C for 2 to 1,000 hours under dry and hydrous conditions. Pyrolysis products were identified and quantified, and a material balance of product and reactants resulted. Significant differences were found in the products generated by pyrolysis of kerogens with and without minerals. Both illite and montmorillonite adsorb a considerable portion (up to 80%) of the generated bitumen. The adsorbed bitumen is almost exclusively composed of polar compounds and asphaltenes that crack to yield low molecular weight compounds and insoluble pyrobitumen during prolonged heating. Montmorillonite shows the most pronounced adsorptive and catalytic effects. With calcite however, the pyrolysis products are similar to those from kerogen heated alone, and bitumen adsorption is negligible. Applying these results to maturation of organic matter in natural environments, we suggest that a given type of organic matter associated with different minerals in source rocks will yield different products. Furthermore, the different adsorption capacities of minerals exert a significant influence on the migration of polar and high molecular weight compounds generated from the breakdown of kerogen. Therefore, the overall accumulated products from carbonate source rocks are mainly heavy oils with some gas, whereas light oils and gases are the main products from source rocks that contain expandable clays with catalytic and adsorptive properties.

Adsorption↗

PubMed2005

Contrasting behavior in azide pyrolyses: an investigation of the thermal decompositions of methyl azidoformate, ethyl azidoformate and 2-azido-N, N-dimethylacetamide by ultraviolet photoelectron spectroscopy and matrix isolation infrared spectroscopy.

The thermal decompositions of methyl azidoformate (N3COOMe), ethyl azidoformate (N3COOEt) and 2-azido-N,N-dimethylacetamide (N3CH2CONMe2) have been studied by matrix isolation infrared spectroscopy and real-time ultraviolet photoelectron spectroscopy. N2 appears as an initial pyrolysis product in all systems, and the principal interest lies in the fate of the accompanying organic fragment. For methyl azidoformate, four accompanying products were observed: HNCO, H2CO, CH2NH and CO2, and these are believed to arise as a result of two competing decomposition routes of a four-membered cyclic intermediate. Ethyl azidoformate pyrolysis yields four corresponding products: HNCO, MeCHO, MeCHNH and CO2, together with the five-membered-ring compound 2-oxazolidone. In contrast, the initial pyrolysis of 2-azido-N,N-dimethyl acetamide, yields the novel imine intermediate Me2NCOCH=NH, which subsequently decomposes into dimethyl formamide (HCONMe2), CO, Me2NH and HCN. This intermediate was detected by matrix isolation IR spectroscopy, and its identity confirmed both by a molecular orbital calculation of its IR spectrum, and by the temperature dependence and distribution of products in the PES and IR studies. Mechanisms are proposed for the formation and decomposition of all the products observed in these three systems, based on the experimental evidence and the results of supporting molecular orbital calculations.

Journal Article↗

PubMed2000

Highly Dispersed X/SiO(2) and C/X/SiO(2) (X=Alumina, Titania, Alumina/Titania) in the Gas and Liquid Media.

Fumed oxides, such as silica, alumina, titania, and mixed X/silicas (X=Al(2)O(3) (AS), TiO(2) (TS), CVD-TiO(2), Al(2)O(3)/TiO(2) (AST)), pristine or covered by carbon deposits formed due to pyrolysis of cyclohexene, were studied using nitrogen adsorption-desorption, photon correlation spectroscopy particle sizing, and electrophoresis. A significant influence of the nature of surface-active sites and structural features of oxides (individual silica, mixed fumed, or prepared using chemical vapor deposition (CVD)) on the pyrolysis of cyclohexene is observed with respect to the pore size distributions due to differences between primary particles in aggregates and on their outer surfaces in the filling of channels by pyrocarbon, resulting also in a decrease in fractal dimension. Structural characteristics and dependences of the particle size distribution and electrokinetic potential of X/SiO(2) and C/X/SiO(2) on the pH of aqueous suspensions suggest that the carbon deposit covers mainly acidic sites at the X/SiO(2) interfaces and X phase patches possessing catalytic activity in pyrolysis, as the negative charge of particles is reduced by pyrocarbon grafting. Copyright 2000 Academic Press.

Journal Article↗

PubMed2005

Determination of cadmium in coal using solid sampling graphite furnace high-resolution continuum source atomic absorption spectrometry.

This work describes the development of a method to determine cadmium in coal, in which iridium is used as a permanent chemical modifier and calibration is performed against aqueous standards by high-resolution continuum source atomic absorption spectrometry (HR-CS AAS). This new instrumental concept makes the whole spectral environment in the vicinity of the analytical line accessible, providing a lot more data than just the change in absorbance over time available from conventional instruments. The application of Ir (400 microg) as a permanent chemical modifier, thermally deposited on the pyrolytic graphite platform surface, allowed pyrolysis temperatures of 700 degrees C to be used, which was sufficiently high to significantly reduce the continuous background that occurred before the analyte signal at pyrolysis temperatures <700 degrees C. Structured background absorption also occurred after the analyte signal when atomization temperatures of >1600 degrees C were used, which arose from the electron-excitation spectrum (with rotational fine structure) of a diatomic molecule. Under optimized conditions (pyrolysis at 700 degrees C and atomization at 1500 degrees C), interference-free determination of cadmium in seven certified coal reference materials and two real samples was achieved by direct solid sampling and calibrating against aqueous standards, resulting in good agreement with the certified values (where available) at the 95% confidence level. A characteristic mass of 0.4 pg and a detection limit of 2 ng g(-1), calculated for a sample mass of 1.0 mg coal, was obtained. A precision (expressed as the relative standard deviation, RSD) of <10% was typically obtained when coal samples in the mass range 0.6-1.2 mg were analyzed.

Cadmium↗

PubMed1987

The role of minerals in the thermal alteration of organic matter--III. Generation of bitumen in laboratory experiments.

A series of pyrolysis experiments, utilizing two different immature kerogens (from the Monterey and Green River Formations) mixed with common sedimentary minerals (calcite, illite, or Na-montmorillonite), was conducted to study the impact of the mineral matrix on the bitumen that was generated. Calcite has no significant influence on the thermal evolution of bitumen and also shows virtually no adsorption capacity for any of the pyrolysate. In contrast, montmorillonite and illite, to a lesser extent, alter bitumen during dry pyrolysis. Montmorillonite and illite also display strong adsorption capacities for the polar constituents of bitumen. By this process, hydrocarbons are substantially concentrated within the pyrolysate that is not strongly adsorbed on the clay matrices. The effects of the clay minerals are significantly reduced during hydrous pyrolysis. The strong adsorption capacities of montmorillonite and illite, as well as their thermocatalytic properties, may in part explain why light oils and gases are generated from certain argillaceous source-rock assemblages, whereas heavy immature oils are often derived from carbonate source rocks.

Bentonite↗