Pyrolysis Of Organic Matter Research Articles

Study on the damage characteristics and damage model of organic rock oil shale under the temperature effect

Thermal damage is of great importance to oil shale in situ mining. In this study, the relationship between the P-wave velocity, peak strength, and elastic modulus of samples from Nong’an County, Jilin Province, China, and temperature is analysed (at temperatures of 25–700 °C), and damage factors are defined to evaluate the damage degree. The effect of organic matter pyrolysis on the damage degree is investigated, and thermal damage is explained at the microscale according to scanning electron microscopy (SEM) images. Under the assumption that the strength of a micro-element obeys the power function distribution and micro-element failure follows the Mohr-Coulomb (M-C) strength criterion, a thermal damage constitutive model is established. It is found that when the temperature threshold is exceeded, organic matter pyrolysis becomes the main driver of the increase in thermal damage. The thermal damage rapidly increases, which is notably different from the damage process below the temperature threshold. This difference is clearly reflected in the physical and mechanical properties, damage factors, microstructure, and determined model parameters. The relationship between the mass loss rate, which can directly reflect the pyrolysis degree, and damage degree is notable. The research results have a certain theoretical significance that can help to better understand the thermal damage process of oil shale and the thermal damage difference between organic and inorganic rocks and can provide a reference for relevant engineering practices.

Petrographic features and diagenetic alteration in the shale strata of the Permian Lucaogou Formation, Jimusar sag, Junggar Basin

Reservoir quality is the key parameter controlling shale oil enrichment. However, the complicated lithofacies, which control diagenesis, result in reservoir heterogeneity in the shale strata, creating challenges for reservoir prediction. Combining with the detail analysis of inorganic and organic geochemistry, characteristics of the main lithofacies and diagenetic alteration were investigated in Permian Lucaogou Formation, Jimusar sag, Junggar Basin. Laminated rocks with laminae combinations containing pyroclastic and terrigenous clastic laminae, terrigenous clastic and dolomite laminae, and pyroclastic and carbonate laminae were identified. Massive rocks mainly includes dolomicrite, dolomitic tuff, silt dolostone, dolomitic siltstone, and tuffaceous siltstone. Feldspar dissolution and carbonate cementation were the two dominant diagenetic types, further causing heterogeneity of the shale oil reservoirs. Feldspar dissolution generally occurred in laminated rocks containing pyroclastic laminae with low content of carbonate minerals (PL1), as well as in their adjacent interbedded siltstones. Carbonate cementation generally occurred in laminated rocks containing carbonate laminae, as well as in their adjacent interbedded siltstones. Whether in laminated and massive rocks, sparry carbonate crystals were also precipitated adjacent to organic matter and in microfractures. In the burial processes, enriched transition metal elements of V and Ti in pyroclastic laminae promote catalytic pyrolysis of organic matter. Abundant CO 2 produced during the catalytic pyrolysis promoted feldspar dissolution. Dissolution of sedimentary carbonate minerals by organic acids and CO 2 provided the material sources for secondary carbonate cements. It promoted the recrystallization and re-precipitation of sparry carbonate crystals adjacent to organic matter and in the terrigenous clastic laminae or interbedded siltstones. Ca 2+ , Mg 2+ Sr 2+ , Fe 2+ , and Mn 2+ produced by the transformation of smectite to illite in the pyroclastic laminae also provided Ca source for secondary carbonate cements. External diagenetic fluids providing materials along microfractures is another genesis of carbonate cements in the Permian Lucaogou Formation. • Petrographic features in the shale strata in Permian Lucaogou Formation were identified based on in situ analytical method. • Differential feldspar dissolution and carbonate precipitation generally occurred in different lithofacies. • Catalytic pyrolysis of organic matter in presence of transition metal elements in pyroclastic laminae promoted dissolution. • Development of carbonate cements in the shale strata were mainly provided by three material sources.

Control of V accumulation in organic-rich shales by clay-organic nanocomposites

Organic-rich shales exhibit a wide range of vanadium (V) concentrations in deep-time successions. Although V accumulation is generally acknowledged to be related to redox state, organic matter and clay mineral content, previous studies have failed to explain the mechanism of variable V enrichment in organic-rich shales. Here, we hypothesize that clay-organic nanocomposites control authigenic V uptake in organic-rich shales. Specifically, V is scavenged by dissolved organic matter in seawater, which is then taken up by smectite during transport or deposition, followed by V incorporation into illite through illitization of smectite and pyrolysis of organic matter during diagenesis. To test this hypothesis, lower Cambrian black shales from South China were investigated by field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) at a micro- and nanoscale. Results show that only 1M/1Md-type illite, generated through transformation from a smectite precursor, has significant V concentrations (0.7–4.8 wt%), whereas 2M1-type illite and other minerals contain little or no V. All 1M/1Md-type illite was closely associated with organic matter, occurring as clay-organic nanocomposites. Our results are significant in (i) showing clay-organic nanocomposites play a key role in V cycling in the marine system, (ii) providing a mechanism for understanding variations in the V concentrations of deep-time organic-rich shales, and (iii) improving strategies for prospecting and extraction of V ores.

Occurrence, mineralogy and geochemistry of fracture fillings in tight sandstone and their constraints on multiple-stage diagenetic fluids and reservoir quality: An example from the Kuqa foreland thrust belt, Tarim Basin, China

Sandstone reservoirs with a depth of over 6000m of the Lower Cretaceous Bashijiqike Formation in the Kuqa foreland thrust belt, Tarim Basin in NW China provide a good example for studying multiple-stage diagenetic fluid activities and effects of fractures on reservoir quality in tight sandstone. Three types of fractures can be identified in the sandstone: fully sealed fractures, partly filled fractures and minimally filled fractures. Fracture fillings are mainly composed of ferruginous dolomite, dolomite, calcite, quartz and gypsum. The ferruginous dolomite is mainly accumulated in the fully sealed fractures. The dolomite primarily occurs in the partly filled fractures and fully sealed fractures. The calcite and gypsum frequently occur in the fully sealed fractures, partly filled fractures and minimally filled fractures. The quartz is distributed at inner edges of the partly filled fractures. Contents of Co, Ni and V in the ferruginous dolomite are generally higher than that in the dolomite, calcite and gypsum, and contents of REE and LREE gradually decrease in turn from the ferruginous dolomite to the dolomite, and to the calcite. The δ13C of the ferruginous dolomite, dolomite and calcite ranges from 3.78‰ to −1.49‰ with an average value of −2.82‰, and their δ18O ranges from −16.43‰ to −12.3‰ with an average value of −14.62‰, respectively. The fully sealed fractures, ferruginous dolomite, partly filled fractures, quartz, dolomite, minimally filled fractures, calcite and gypsum successively occur from early to late stage. Data of δ13C and δ18O of the carbonate minerals in the fractures indicate that these minerals are formed in freshwater which is oxidizing with low salinities, and average formation temperature of the ferruginous dolomite, dolomite, and calcite is 89 °C, 109 °C and 123 °C, respectively. Formation of these carbonate minerals in the fractures is primarily related to hydrothermal fluids originated from pyrolysis of organic matter. The fully sealed fractures serve as a barrier for fluid flow whereas the partly filled fractures and minimally filled fractures both provide channels for hydrocarbon migration and accumulation.

Very low-grade metamorphism of the Dezadeash Formation (Jura-Cretaceous): Constraints on the tectonometamorphic history of the Dezadeash flysch basin and implications regarding the tectonic evolution of the Northern Cordillera of Alaska and Yukon

<abstract> <p>Mesozoic convergence of the Wrangellia composite terrane with the western margin of North America resulted in the collapse of intervening flysch basins. One of these basins, the Jurassic-Cretaceous Gravina-Nuzotin belt, comprises from south to north, the Gravina sequence and Gravina belt in southeastern Alaska, the Dezadeash Formation in Yukon, and the Nutzotin Mountains sequence in eastern Alaska. Previous work shows that the Gravina sequence and Gravina belt were underthrust > 20 km beneath the margin of North America in mid-Cretaceous time, culminating in amphibolite facies metamorphism. This tectonometamorphic scenario was subsequently applied to the entire Gravina-Nutzotin belt, despite any detailed studies pertaining to the tectonometamorphic evolution of the Dezadeash Formation. The present analysis of the Dezadeash Formation reveals that metamorphic mineral assemblages in sandstone and tuff document subgreenschist, high temperature zeolite facies metamorphism; Kübler indices of illite and Árkai indices of chlorite in mudstone record diagenetic to high anchizone metapelitic conditions; and the color of organic matter (i.e., the Thermal Alteration Index of palynomorphs and the Conodont Alteration Index) and pyrolysis of organic matter in mudstone and hemipelagite beds document thermal maturation at catagenesis to mesogenesis stages. Collectively, the mineralogic and organic thermal indicators in the Dezadeash Formation suggest that strata experienced maximum pressure-temperature conditions of 2.5 ± 0.5 kbar and 250 ± 25 ℃ in the Early Cretaceous. The inferred tectonometamorphic evolution of the Dezadeash Formation does not support the northern part of the Gravina-Nutzotin belt being underthrust > 20 km beneath the western margin of North America in mid-Cretaceous time, thus contrasting sharply with the Gravina sequence and Gravina belt in the southern part of the Gravina-Nutzotin belt. The diverse tectonometamorphic histories recorded by the southern and northern parts of the Gravina-Nutzotin belt may be a manifestation of oblique collision and diachronous south-to-north accretion of the Wrangellia composite terrane to North America.</p> </abstract>

Photochemistry after fire: Structural transformations of pyrogenic dissolved organic matter elucidated by advanced analytical techniques

Pyrogenic organic matter (pyOM) is the solid residue left after pyrolysis of organic matter, a process occurring in nature during forest fires. Upon rain events, pyrogenic dissolved organic matter (pyDOM) leaches into the rain water and is transferred to the aquatic environment where it has been identified as an important component of the global carbon cycle. Overall, pyDOM consists of highly condensed aromatic compounds (ConAC) and poorly characterized aliphatic molecules. While the ConAC are thought to be persistent in the environment, a large ConAC accumulation that would match the calculated fluxes of pyDOM formation and export has not been observed. Photo-degradation has been identified as a major pyDOM sink, and it can potentially account for the discrepancy in the global mass balance of pyDOM.Photochemistry of pyDOM has been studied to a certain extent, but neither the structural transformation pathways of pyDOM nor how they relate to pyrolysis temperature and parent feedstocks are well understood. In response to this need, we have examined the products after photo-irradiation of pyDOM derived from a temperature series (250, 400, 525, 650 °C) of oak biochars made under controlled laboratory conditions, which can be considered model pyrogenic substances. Ultrahigh resolution mass spectrometry (FT-ICR-MS), one-dimensional 1H NMR, and two-dimensional 1H-1H total correlation spectroscopy (TOCSY) NMR were used to evaluate the compositional changes that occurred with photo-irradiation.In agreement with previous studies, pyDOM aryl groups were the most photo-labile, and alkyl and O-alkyl groups were photo-produced. A new finding is that polysubstituted olefinic moieties of pyDOM were also photo-degraded. Using TOCSY we identified several small molecular weight compounds whose abundances changed non-linearly across the combustion continuum which suggests that different radical processes occur in the different char leachates. Using mass spectrometric data we observed that pyDOM from oak chars made at lower temperatures (250 and 400 °C), as well as pyDOM from a grass char prepared at 650 °C, photo-transformed to a more hydrogenated and oxygenated composition. In contrast, pyDOM from higher temperature char leachates (525 and 650 °C) transformed predominantly into smaller aliphatic compounds. To explain these differences, we propose a photo-transformation mechanism for ConAC which includes oxygenation of ConAC, ring-opening reactions, and sequential decarboxylation yielding small aliphatic N-rich molecules (marine-like composition). These structures could be further polymerized by reactive oxygen species to form straight-chain alkanes if not consumed by microorganisms. Results from these controlled experiments reveal that the extent of photo-transformation appears to be a function of production temperature and parent feedstock. This study enhances our understanding of ConAC and pyDOM, their terrestrial-to-marine transfers, geochemical stability, and eventual fate in sunlit environments. Here we also show the value of structural characterization of pyDOM, and reveal the many unknowns left to be answered for this complex and analytically challenging type of organic matter.

Investigation of oxidation and heat treatment to improve mass transport ability in coals

In this paper, the permeability of coal after oxidation treatment and heat treatment was measured. Combined with industrial analysis, infrared spectrum and other experimental means, the mechanism of heat treatment and oxidation treatment on improvement of mass transport ability in coals was analyzed comprehensively. After 240 h oxidation treatment, the average permeability enhancement multiple of coal treated by 15 wt% H2O2 was 5.79, and the average permeability enhancement multiple of coal treated by 0.2 wt% ClO2 was 3.75. A large number of micro fractures and dissolution pores were generated in coal during the oxidation process, which significantly improved the connectivity of pores. The increase of the associated hydroxyl and carboxyl groups weakening the hydrophilicity which were beneficial to the production of coalbed methane. Under the condition of 200 °C heat treatment, the average permeability enhancement multiple of coal was 36.45. After heat treatment, coal composition changed significantly, only water loss occurred when the temperature was lower than the threshold temperature, and organic matter pyrolysis escaped when the temperature was higher than the threshold temperature. Furthermore, the synergistic mechanism of heat treatment and oxidation treatment was discussed. The heat - oxidation treatment enhanced the water phase self-imbibition capacity of the coal, make a large number of oxidants enter into the matrix quickly, and reduce the coal fracture toughness, which was conducive to improving the effect of the oxidation treatment. For the oxidation – heat treatment, the threshold temperature and mechanical strength of the oxidized coal were reduced by the coal structure recombination.

Permeability of Oil Shale Under In Situ Conditions: Fushun Oil Shale (China) Experimental Case Study

Oil shale is a critical strategic energy source with very large reserves, and it is acknowledged as an alternative energy source to crude oil. Oil shale in situ retorting is the only technologically feasible method to achieve large-scale industrial development. In situ permeability is one of the most critical technical parameters for successful implementation of oil shale in situ retorting. In this study, the permeability of Fushun oil shale at different temperatures was investigated using a triaxial permeability testing machine under in situ conditions. The results show that the permeability of the oil shale under three-dimensional stress can be divided clearly into three stages from 20 °C to 600 °C. First, the oil shale remains almost impermeable from 20 °C to 200 °C. Second, in the temperature range from 200 °C to 350 °C, the permeability of the oil shale first increased and then decreased to almost zero at 350 °C owing to the dual constraints of the surrounding stress and additional expansion stress under in situ conditions. Third, from 350 °C to 600 °C, the permeability of the oil shale increased sharply and reached a maximum of 100 × 10−5 μm2 at 600 °C. Thermal cracking and solid organic matter pyrolysis were the main factors controlling the change in oil shale permeability in the test temperature range. The results suggest that the threshold temperature for oil shale permeability change was 350 °C under in situ conditions. In addition, under in situ conditions, the oil shale permeability decreased with increasing pore pressure at different temperatures. This work has direct applications for oil shale in situ large-scale exploitation.

Biochar amendment increases tree growth in nutrient-poor, young Scots pine stands in Finland

Biochar is charred material formed by the pyrolysis of organic matter. The addition of biochar to soil may offer a chance to mitigate climate change by increasing soil carbon stocks, improving soil fertility and enhancing plant growth. Vast majority of biochar studies are conducted in agricultural soils, and field experiments studying the effect of biochar on tree growth in boreal forests are lacking. We applied spruce biochar amendments of 5 and 10 Mg ha−1 to the soil surface in young boreal Scots pine (Pinus sylvestris L.) forests in Southern Finland and studied the responses in tree growth and needle nitrogen (N) and 15N concentrations during the first three years after treatment. The biochar amendment of 10 Mg ha−1 increased the diameter growth of dominant trees significantly, on average by 1 mm year−1, which corresponded to 25% increase compared to control during the three years study period. The positive growth responses were less pronounced in height than in diameter growth. The biochar amendment of 5 Mg ha−1 increased the height growth of dominant trees by 0.16 m or 12% compared to the control during three years. Biochar amendments did not affect N and 15N concentrations in needles. The results suggest that wood biochar amendment can be a climate-friendly method to increase tree biomass production in nutrient poor, xeric, young Scots pine forests.

The application of comprehensive two-dimensional gas chromatography to the analysis of wildfire debris for ignitable liquid residue

Arsonous wildfires are complex investigations due to the high abundance of natural background compounds and subsequent pyrolysis by-products formed during combustion. These interfering compounds can be present in large concentrations and overwhelm the marker compounds used to identify ignitable liquid residue (ILR). Complex matrix effects often interfere with the identification of ILR, providing ambiguous results. The use of comprehensive two-dimensional gas chromatography with time of flight mass spectrometry (GC×GC-TOFMS) separates natural compounds from interfering with ILR compounds of interest. When compared to standard gas chromatography-mass spectrometry (GC–MS) analysis, GC×GC was able to reduce the number of tentative results by 20%. Certain compounds were determined to be unusable for the identification of ILR in wildfire debris samples, in particular the Three Musketeer Group (ethylbenzene, m,p-xylene, and o-xylene), which are ubiquitous in all samples, as well as long chain n-alkylbenzenes, which are formed in the pyrolysis of organic matter. Conversely, the presence of C1- and C2-alkylnaphthalenes were excellent indicators of the presence of gasoline-type ILR. A sizeable number of background samples were collected that helped to provide additional lines of evidence when classifying samples for ILR. Given the complicated matrices encountered in arsonous wildfires, it is evident that GC×GC provides better capabilities at identifying ILR than the standard GC–MS analytical technique.

Biosphere Conversion of Substances and Energy in the Formation of Continents

The sedimentary stratum of the oceanic crust with a thickness of up to 3 kilometers and younger than the Jurassic age deposits of organic matter (OM) sediments, is saturated with O2 absorbed and dissolved in the ocean with binding energy in the range of 5–15 kJ/mol. During subduction of the oceanic crust into the mantle with T = 170–500°C, fluids of O2, H2O, CO2 are released and are subsequently filtered to the surface of the suprasubduction roof. The fluid O2 oxidizes the matters of the sedimentary cover, the mantle and the roof with O2 energy release of 14.97 kJ/kg. This results in the formation of a magma chamber. The melts of the chamber are divided with respect to density and composition into light-acidic enriched in SiO2 and compact—basic enriched in Са, Мg, K. The discharged acidic melts form a crust of a continental type. Energy saturation of the magma chamber is increased by exogenic energy of OM pyrolysis. At depths of subduction at T = 500–1200°C, OM undergoes deep metamorphism with the release of oil and gas fluids which form a planetary system of hydrocarbons. The continental crust and the hydrocarbon system are formed in many respects due to the biosphere conversion of solar energy, oxygen, and OM to the composition of the Earth’s outer shells.

Potential of Integrating Biochar and Deficit Irrigation Strategies for Sustaining Vegetable Production in Water-limited Regions: A Review

Water shortage is one of the major challenges faced by the current agricultural systems worldwide, especially in arid and semi-arid regions. Deficit irrigation (DI), a water-saving strategy of applying less water than crop evapotranspiration (ETc) demands, has been extensively investigated in different crops, including water-intensive vegetables. The DI strategies such as regulated deficit irrigation (RDI) and partial root zone drying (PRD) generally increase water use efficiency (WUE) and have emerged as potential practices to save water for agricultural sustainability. However, in view of the sensitivity of shallow-rooted vegetable crops to water stress, DI is often associated with yield losses. A review of 134 DI reports of vegetable crops revealed significant reductions in yield under all DI levels in 52% of cases and yields statistically similar to those of full irrigation (100% ETc in most cases) under small water deficits in 44% of cases, thereby raising concerns about the sustainability of vegetable production under DI. Biochar, a carbon-rich co-product of pyrolysis of organic matter, is increasingly undergoing study as a soil amendment to mitigate drought stress and is being explored as an additional practice with DI to minimize the yield losses due to water deficits. This work reviews the effects of biochar application on growth, yield, physiology, and WUE of different vegetable crops under DI regimes to determine the potential of biochar and DI used in combination to sustain vegetable productivity in water-limited areas. Overall, the addition of biochar under DI has helped to compensate for yield losses of vegetables and further enhanced WUE. However, field studies investigating long-term soil–biochar interactions that strongly conclude the impact of biochar under moisture stress conditions are lacking.

Laboratory studies of the behavior of organic matter of the Bazhenov deposits during thermal effects

Currently, the role of unconventional facilities for hydrocarbons is increasing. Such objects include the Domanik rocks (Republic of Tatarstan) and Bazhenov deposits (Western Siberia). The article presents the results of studying the type of organic matter of the Bazhenov suite and studying the process of pyrolysis of organic matter. It is established that the formation of new free hydrocarbon radicals occurs at temperatures up to 350°C (pyrolysis of organic matter). This indicates that the rocks of the Bazhenov suite did not fully realize their hydrocarbon potential. The deposits of the “normal” section of the Bazhenov suite not only contain a large amount of ready and hard to recover hydrocarbons, but also have an additional generation potential.

Use of raw and acidified biochars as constituents of growth media for forest seedling production

In plant nurseries devoted to the propagation of shrubs and trees for landscaping, gardening or forestry it is first concern to produce robust seedlings which resist the stress of transplanting to soil. The selection of appropriate growth media is crucial. Biochar, the product of pyrolysis of organic matter, has been suggested as a new organic amendment for soil or for soilless growth media. Biochar is usually strongly alkaline. We studied the possibility of acidifying biochar with nitric and phosphoric acids. The effects of raw and acidified biochars in peat-based substrates on rooting and growth of cuttings of Rosmarinus officinalis and in sandy soil-based substrates on growth of Phillyrea angustifolia seedlings were compared. The physical and chemical characteristics of the growth media, and the growth and nutrient content of seedlings were analysed. Results showed that biochar acidification with nitric and phosphoric acids improves the pH and enriches the biochar with N and P without excessively increasing electrical conductivity. However, a column experiment showed that nitrate was readily leached whilst phosphate was tightly retained by biochar, which questioned the practical availability of these nutrients to plants. The agronomical assays showed that both raw biochar and acidified biochar improved rooting and growth of Rosmarinus cuttings. In Phillyrea, however, the acidified biochar did not affect plant growth whilst the raw biochar gave satisfactory results both for shoot and root growth. Results led to the conclusion that biochar without further treatment might be successfully used as growth medium constituent, even at large proportions, both in organic and in mineral substrates.

Biochar in Soil Restoration: A Comprehensive Review on Enhancing Soil Health and Carbon Sequestration

This review examines the multifaceted role of biochar in soil restoration, highlighting its potential to enhance soil health and facilitate carbon sequestration. Biochar, a carbon-rich material produced through the pyrolysis of organic matter, offers unique physicochemical properties that improve soil structure, increase nutrient retention, and stimulate microbial activity. By synthesizing current research, this article discusses the mechanisms through which biochar contributes to soil fertility, addresses challenges associated with soil degradation, and evaluates its effectiveness across various soil types and agricultural systems. Additionally, the review emphasizes the dual benefits of biochar in promoting sustainable agricultural practices and mitigating climate change through long-term carbon storage. Overall, this comprehensive analysis underscores biochar’s significant potential as a tool for enhancing soil health and fostering environmental sustainability.

Flow transportation inside shale samples during low temperature combustion: The effect of desorption and pyrolysis

Flow transportation inside shale formations is a complex process mainly including slip flow, transition flow, and free molecular diffusion. Recently, using combustion to promote gas transportation inside shale formations for gas extraction has been studied. In this study, the shale samples were combusted at 280 °C and 400 °C respectively, to obtain transient pressure variation behaviors inside the shale samples. The effects of organic matter pyrolysis and adsorbed gas desorption on internal flow transportation were investigated. Moreover, a mathematic scaling power law was used to predict the pressure rising and declining processes. It was found that the pressure exhibited similar trend under 280 °C and 400 °C. Shale internal pressure built up quickly and reached peak value after combustion began. Then the pressure declined close to ambient pressure within a short period. Under 400 °C, the pressure of inner and outer holes were close to each other; the peak pressure could rise up to 7000 Pa. Both the gas generated from the thermal cracking of kerogen and gas desorbed from the pore surface contributed to pressure rising. However, at lower combustion temperature (280 °C), the rising of the pressure is mainly owing to the desorption gas from the surface to the pore volume. The peak pressure was only 780 Pa, much lower than that under 400 °C. By selecting an appropriate exponential m in the power law of scaling pressure, pressure rising and declining processes inside shale samples could be well simulated.

Stöber silica’s microporosity

Substantial knowledge gap still exists in understanding Stober silica’s confusing microporosity. In this work, we utilized simultaneous thermal analysis coupled with Fourier transform infrared spectroscopy to characterize Stober silica samples prepared with various post-treatments including water or ethanol washing and drying at different temperatures. The results suggest that ammonia-catalyzed ethoxylation between ethanol and silanol groups can take place during drying, and the resulting ethoxyl groups along with Si-containing oligomers may contribute to serious micropore blocking. On the other hand, water washing is effective to hydrolyze and remove these pore-blocking materials and thus enable cleared micropores. Several interesting findings including the very sharp DSC peaks, high evolving temperature of ethanol, and pyrolysis of organic matters are linked to Stober silica’s micropores. Our work has undoubtedly improved the mechanistic understanding of Stober silica’s microporosity and will thus facilitate the practical optimization and application of this material.

Application of different thermal analysis techniques for the evaluation of petroleum source rocks

In the paper, various laboratory pyrolytic methods were used to evaluate selected petroleum source rocks. The methods used are: Rock–Eval pyrolysis, Py–GC pyrolytic technique and TG/DTG/DSC. The experiments of the last method were performed according to three different procedures. Each of them provided different, specific data. The selected rock sample material was diversified in terms of stratigraphical position, structural unit and place of collection (outcrop or borehole). Based on the Rock–Eval analysis results, kerogen in samples can be classified as type II. Additional information on the quality of pyrolysis products was obtained from the Py–GC analysis. Thanks to the combination of the all three implemented pyrolytic techniques, the quality of the generation potential of the source rocks can be evaluated in details. In some samples, the oxidation and pyrolysis of organic matter occur in two stages, what is the evidence of the complex nature of the organic substance. The maximum of pyrolysis reaction is detected by TG/DTG measurement in the range of temperature from 450 to 580 °C, depending on the maturity of organic matter. The maturity level increases with the rock stratigraphic position. The proportions of loss in mass observed in respective stages of pyrolysis in course of TG/DTG experiment are in correspondence with the observations of the released fractions in the Py–GC analysis. The Carpathian Menilite shales could be classified as source rocks with high oil generation potential. Also, the Lower Silurian and Ordovician shales are characterized by high oil-producing potential with a lower content of mineral matter. Cambrian rocks show a different character and gas-prone generation potential.

Abstract 4021: The evaluation of carcinogenicity evidence of dibenzanthracenes

Abstract Dibenzanthracenes (DBAs) are identified as carcinogens and are on the California Proposition 65 list. DBAs are five-ring polycyclic aromatic hydrocarbons (PAHs). This chemical group consists of three isomers: DB[a,c]A, DB[a,h]A, and DB[a,j]A. DBAs are products of the incomplete combustion or pyrolysis of organic matter and can be formed during high temperature cooking. They are air pollutants present in engine exhaust, tobacco and marijuana smoke, and may also contaminate soil and water. DB[a,h]A is a well-studied International Agency for Research on Cancer (IARC) Group 2A carcinogen, whereas fewer studies relevant to carcinogenicity have been conducted with DB[a,c]A and DB[a,j]A. Carcinogenicity evidence from multiple data streams was integrated in the hazard identification of this chemical group. These data streams include animal cancer bioassays, mechanistic studies and other relevant data, including high-throughput studies (e.g., ToxCast), toxicogenomic studies, and information from quantitative structure-activity relationship (QSAR) models. Structure activity comparisons across the three DBAs and related carcinogenic PAHs served to bridge the data gaps for the two less studied isomers. The results of our analyses showed that each of the DBAs share similar biological activities in animals: all induce tumors in mice, are mouse skin tumor initiators, form DNA adducts, are genotoxic, and form metabolites that are also genotoxic and initiators of mouse skin tumors. All three DBAs activate the aryl hydrocarbon receptor (AhR) in reporter gene assays, and DB[a,h]A and DB[a,c]A have been shown to bind to the AhR. In addition to strong evidence of genotoxicity, other carcinogenic mechanisms are likely also operative, including receptor activation (e.g., AhR), immune suppression, altered cell proliferation, apoptosis, and cell cycle regulation. There are strong structure-activity similarities among the DBAs and several carcinogenic 4-, 5- and 6-ring PAHs, including benzo[a]pyrene and dibenzo[a,h]pyrene. In addition, DB[a,c]A and DB[a,j]A were predicted to be mutagenic and carcinogenic in several QSAR models, including VEGA, Lazar and OECD QSAR Toolbox. Integration of the evidence from these multiple data streams resulted in the identification of the DBAs as a chemical group as carcinogens. Citation Format: Feng Tsai, Jennifer C. Hsieh, Gwendolyn Osborne, Martha Sandy. The evaluation of carcinogenicity evidence of dibenzanthracenes [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4021.

Cation exchange capacity of biochar: An urgent method modification

Biochar, produced through pyrolysis of organic matter, is negatively charged, thus contributing to electrostatic adsorption of cations. However, due to its porous structure and contents of alkaline ashes, the determination of the cation exchange capacity (CEC) is challenging. Literature values for the CEC of biochar are surprisingly variable and are often poorly reproducible, suggesting methodological problems. Here, we modify and critically assess different steps in the existing ammonium acetate (NH4OAc) method (pH 7), where ammonium (NH4+) is displaced by potassium chloride (KCl), following removal of excess NH4OAc with isopropanol, in batch mode. We used pigeon pea biochar to develop the method and conducted a test on three additional biochars with different acid neutralizing capacity. A pretreatment step of biochar was introduced, using diluted hydrochloric acid, to decrease biochar pH to near neutral, so that 1 M NH4OAc effectively buffers the biochar suspension pH at 7. This allows the CEC of all biochars to be determined at pH 7, which is crucial for biochar comparison. The dissolution of ashes may cause relatively large weight losses (e.g. for cacao shell biochar), which need to be accounted for when computing the CEC of raw biochar. The sum of NH4OAC-extractable base cations provided a smaller and better estimate of the CEC than KCl-extractable NH4+. We hypothesize that the overestimation of the CEC based on KCl-extractable NH4+ is due to the ineffectiveness of the relatively large isopropanol molecules to remove excess NH4OAc in biochars rich in micro-pores, due to size exclusion. The amount of base cations removed in the pretreatment was about three (rice husk biochar) to ten times (pigeon pea biochar) greater than the amount of exchangeable cations. The CEC values of biochar increased from 10.8 cmol/Kg carbon to 119.6 cmol/Kg carbon. These values are smaller than reported CEC values of soil organic carbon.