Low Sulfur Content Research Articles

Engine Performance Using Blended Fuels of Biodiesel and Eco Diesel

Diesel engines is an internal combustion engine with high thermal efficiency, which also uses biodiesel fuel, an environmentally friendly, non-toxic, and low sulfur content. Biodiesel has been around for a long time due to its similar characteristics to diesel fuels which has limited availability. However, several disadvantages are associated with biodiesel, such as poor volatility and high viscosity, which reduces engine performance. Therefore, this study was carried out to improve the diesel engine performance by mixing biodiesel with ecodiesel (ED), an additive produced from natural ingredients that is dissolvable in biodiesel. The biodiesel fuel properties used are density 860 kg/, dynamic viscosity 4.50E-06 /s, cetane number 45, and flashpoint 52°C. The results showed that biodiesel-ED mixture could improve engine performance and the optimum performance was at a speed of 3000 rpm on 43.30 (kW), 124.93 (N.m) of the engine torque, and 2.45E−5 (kg/kW.s) of the specific fuel consumption. According to paired sample t-test, the difference in the engine performance is only experienced in the torque, which has a significant increase in the composition of the biodiesel+ED by 0.07 gr mixture.

Elucidating the reaction mechanism of SO2 with Cu-CHA catalysts for NH3-SCR by X-ray absorption spectroscopy.

The application of Cu-CHA catalysts for the selective catalytic reduction of NOx by ammonia (NH3-SCR) in exhaust systems of diesel vehicles requires the use of fuel with low sulfur content, because the Cu-CHA catalysts are poisoned by higher concentrations of SO2. Understanding the mechanism of the interaction between the Cu-CHA catalyst and SO2 is crucial for elucidating the SO2 poisoning and development of efficient catalysts for SCR reactions. Earlier we have shown that SO2 reacts with the [Cu2II(NH3)4O2]2+ complex that is formed in the pores of Cu-CHA upon activation of O2 in the NH3-SCR cycle. In order to determine the products of this reaction, we use X-ray absorption spectroscopy (XAS) at the Cu K-edge and S K-edge, and X-ray emission spectroscopy (XES) for Cu-CHA catalysts with 0.8 wt% Cu and 3.2 wt% Cu loadings. We find that the mechanism for SO2 uptake is similar for catalysts with low and high Cu content. We show that the SO2 uptake proceeds via an oxidation of SO2 by the [Cu2II(NH3)4O2]2+ complex, resulting in the formation of different CuI species, which do not react with SO2, and a sulfated CuII complex that is accumulated in the pores of the zeolite. The increase of the SO2 uptake upon addition of oxygen to the SO2-containing feed, evidenced by X-ray adsorbate quantification (XAQ) and temperature-programmed desorption of SO2, is explained by the re-oxidation of the CuI species into the [Cu2II(NH3)4O2]2+ complexes, which makes them available for reaction with SO2.

Sulfur‐rich mafic magma injection into the felsic magma chamber beneath Asama volcano, central Japan: Records in olivine‐hosted melt inclusions from the Itabana and Tenmei eruptions

AbstractEven though no basalts have erupted at Asama volcano, its large, felsic magma chamber standing beneath the summit is frequently replenished by cryptic injections of mafic magma of basalt‐basaltic andesite composition. This mafic magma is preserved within melt inclusions trapped in olivine phenocrysts collected from the old Itabana pumice of the Kurofu stage and the Tenmei pumice of the current Maekake stage. The trapped mafic melts provide a detailed and vivid record of cryptic mafic magma injection into the felsic chamber where they admix to erupt andesite magma. The main phenocrysts of plagioclase, orthopyroxene, and clinopyroxene, commonly seen in the erupted products, are derived from the felsic magmas and trapped felsic melts of dacite‐rhyolite compositions, containing low sulfur contents (0.3 wt% of SO3 or less; most are lower than 0.10 wt%). In contrast, the mafic melts, entrapped by olivine phenocrysts, show high concentrations of SO3, up to 1.06 wt% for Itabana and SO3 0.65 wt% for Tenmei. In addition, the olivine phenocryst commonly encloses early crystalline phases precipitated from the sulfur‐rich mafic magma, such as Cr‐spinel, Mg‐rich orthopyroxene, Fe, Cu, and Ni‐bearing sulfides, and often Al‐rich clinopyroxene. The olivine‐hosted mafic melt inclusions always contain numerous vesicles. Furthermore, they are often included as hourglass‐shaped trapped melts, exhibiting snapshots of intense foaming and gas phase exsolution during the olivine growth and probably in the process of the cryptic injection into the felsic magma beneath the Asama summit. Our new data contributes to a better understanding of the magmatic system of the Asama volcano but also highlight the importance of the “Excess sulfur problem”, especially concerning the 1783 Tenmai eruption, which was contemporary to the Laki Fires.

Granitic‐melt and carbonic‐fluid inclusions in diopside megacrysts from ankaramitic basalt dikes at Kamisano, Yamanashi prefecture, northeastern Japan

AbstractLarge phenocrysts, known as megacrysts, are focal points for research due to their ability to encapsulate large inclusions suitable for precise chemical analyses. Ankaramite, a distinctive type of undifferentiated volcanic rock, stands out due to its high MgO and CaO contents and the presence of abundant Ca‐rich clinopyroxene (diopside) and less common Mg‐rich olivine phenocrysts. In this study, granitic melt inclusions together with carbonic fluid inclusions were identified within diopside megacrysts of ankaramitic basalt dikes in the Kamisano region, Yamanashi Prefecture, Japan. The identified melt inclusions are completely crystallized and primarily composed of quartz, alkali feldspar, and plagioclase, with smaller amounts of pargasite, augite, apatite, and sulfides. Small amounts of residual glass were also occasionally observed in the inclusions. The average chemical composition of these granitic melts within the inclusions corresponds to that of calc‐alkaline granodiorite and the melts are characterized by low water content (0.38 wt%) and high concentrations of sulfur (7000 ppm), copper, and iron. The findings suggested that the composition of granitic melt inclusions may provide insights into the characteristics of near‐surface hydrothermal metal ore deposits. The diopside megacrysts also contain CO2H2O fluid inclusions, which are completely crystallized and mainly comprised of calcite and chlorite, along with small amounts of quartz. The crystals are interpreted to have formed by the reaction of original CO2H2O fluids and host diopside. The diopside megacrysts are estimated to have started crystallization from tholeiitic basalt at a depth of ~30 km in the lower crust, and trapped fluids and granitic melts as inclusions at a shallower depth when the tholeiitic magma ascended.

Физико-химическая характеристика образцов нефти Тагульского месторождения

The article presents the data of a comprehensive study of three samples of high-viscosity borehole oil of the Tagulskoye field. Using the instrumentation and methodological base of JSC «MidVolgaNIINP», information was obtained on the composition and properties of samples of high-viscosity oil (HVO) after preliminary dehydration and desalination, as well as oil distillate fractions and residues from distillation obtained in laboratory conditions according to GOST 11011, ASTM D 2892/5236. In addition, it is shown that the objects of the study have valuable properties: a low content of total sulfur, a low content of paraffins and a fairly low pour point for heavy oils. The authors have proposed options for further use of the studied objects. In general, valuable basic information has been obtained for the long-term planning of production and the choice of options for the use /processing of unique raw materials.

Quantitative assessment of soil condition, basic environmental factors and productivity of Linum usitatissimum in the steppe zone of Kazakhstan using the remote sensing method.

The influence of environmental factors, such as lack of water and uneven rainfall, depletion of nutrients in the soil and reduced soil fertility, planting patterns and plant density, uneven growth stages, are the main limiting factors that hinder the growth of agricultural production in arid regions. The aim of the study was to assess the potential of Sentinel-2 to quantify soil conditions, which can improve the understanding of spatiotemporal dynamics in organic agriculture in the steppe zone of Kazakhstan and improve productivity management of Linum usitatissimum. In the course of the research, the influence of individual factors of the general environmental impact, such as the influence of humidity, meteorological conditions, the content of individual nutrient components of the soil on the yield, was studied. The meteorological conditions in this region in 2021 and the data of agrochemical analysis of the soil on which the oilseed crop was grown were evaluated. Sentinel-2 satellite images were used to determine the NDVI and GNDVI indices. A high content of nitrate nitrogen (12.3-16.2 mg/kg), a very low level of available phosphorus (3-10 mg/kg), and a high content of potassium (289-420 mg/kg) were found in the soil. A low content of humus (2.68-3.31%) and sulfur (1.1-4.9 mg/kg) was found. A study of the NDVI growth index showed that the highest value was reached by the period of July 20, 2021. After this period, a decrease in the vegetation index was observed. In conditions of severe drought, this change occurred earlier than under favorable conditions, and correlated with low flax yield (1.6-6.9 c/ha). This study demonstrates the potential of Sentinel-2 for quantifying soil conditions, which not only improves our understanding of spatial-temporal dynamics and environmental components in organic agriculture in the steppe zone of Kazakhstan, but also improves the management of Linum usitatissimum productivity.

Procena mehaničkih i termičkih karakteristika briketa od kukuruzne ljuske kao alternativnog izvora energije

This paper presents the mechanical and thermal characteristics evaluation of maize husk briquette as an alternative energy source to enhance sustainability and efficiency. The experimental test conducted for a 0.6kg weight of briquette showed the volatility and moisture content to have a mean value of 62.52 and 0.27%; while the compressive strength was revealed to be 3.06k N/m 2. The thermal evaluation showed that the mean burn temperature of the maize husk briquette rose from 70.70 o C to 83.34 o C in 8 minutes, 98.72 o C in 10 minutes and finally 100 o C in 12 minutes; when compared to fire wood which burns slowly from 46 o C in 5 minutes, to 53 o C in 9 minutes, 68 o C in 10 minutes, 82 o C in 12 minutes, 94 o C in 18 minutes and finally to 100 o C in 21 minutes. Further, the comparative analysis result revealed that the maize husk briquette has more oxygen and nitrogen at 44.64 and 4.22%, compared to charcoal. It also has more ash content of 11.47% due to its volatility to burn effectively. On the other hand, the maize husk briquette has a low carbon and sulfur contents after burning at 43.55 and 0.051%. These findings will help address the disposal challenges of accumulated maize husk at and crop residues as an alternative sustainable source to meet green environmental and technological demands.

Geochemistry and organic petrology of the bituminite shales from the Kapurdi mine, Rajasthan of NW India: implications for waxy oil generation potential

This study examines the geochemical and petrographic characteristics of seven bituminite shales from the Kapurdi mine in the Rajasthan, NW India, in order to assess their organic matter inputs and evaluate the oil-prone potentials. These bituminite shale samples exhibit high total organic carbon (TOC) content (up to 45.11 wt.%). The high TOC contents were correlated with low total sulfur content of less than 1 wt.% and suggest that these bituminite shales were deposited in a fresh lacustrine environment. The dominance of such lacustrine environmental setting was confirmed by the presence of the Botryococcus algae. The analyzed bituminite shales are characterized by a bimodal distribution of normal alkanes and relatively low isoprenoid Pr/Ph, Pr/n-C17 and Ph/n-C18 ratios. These characteristics suggest that these bituminite shales contain a blend of organic matter that was derived primarily from algal lacustrine and other aquatic organic matter, with terrigenous land plants and deposited under suboxic to anoxic environmental conditions. Such findings of the organic matter (OM) input and environmental conditions are consistent with mainly Types I and II kerogen and small amounts of Type II/III kerogen, thus yielding both oil and gas prone to higher concentrations of oil generation potential. The dominance of hydrogen-rich kerogen and oil generation potential is in agreement with the findings of high hydrogen index (HI = 240–425 mg HC/g TOC) and H/C atomic ratio of more than 1.20. The abundance of n-alkene and n-alkane doublets in the pyrolysis–gas chromatography (Py–GC) also indicates that these bituminite shales have potential to generate high concentrations of paraffinic waxy oil. Most of the maturity indicators show that the bituminite shales from the Kapurdi mine have not yet entered the main stage of oil generation window, exhibiting a range of immature stages. Therefore, as highlighted in this study, these bituminite shales can be considered as a good candidate for oil shale reoterting processes to release commercial amounts of oil upon using artificial heating techniques such as hydrothermal conversion.

Effects of Moisture and Synthesis-Derived Contaminants on the Mechanical Properties of Graphene Oxide: A Molecular Dynamics Investigation.

This paper reports on the effects of the chemical composition of graphene oxide (GO) sheets on the mechanical properties of bulk GO. Three key factors were analyzed: (i) the oxygenated functional groups' concentration, (ii) the content of intersheet water (moisture), and (iii) the presence of residual contaminants observed from the synthesis of GO. Molecular dynamics simulations using the reactive force field ReaxFF were conducted to model tensile strength, indentation, and shear stress tests. The structural integrity of the carbon basal plane was the primary variable that determined mechanical behavior of GO slabs. Hydrogen-bond networks played an essential role in the tensile fracture mechanism, delaying the onset of fracture whenever strong hydrogen bonds existed in the intersheet space. The presence of interlayer sulfate ion contaminants negatively impacted the tensile strength, stiffness, and toughness of GO. Moreover, it was observed that intersheet sulfate ions improved the resistance to fracture of GO at low sulfur concentrations, while lower fracture strains were observed beyond a critical concentration. Alike the tensile stress findings, the indentation properties were determined by the integrity of the carbon basal plane. Our findings agree with experimental mechanical property measurements and reveal the importance of considering synthesis-derived contaminants in molecular models of GO.

Geochemistry of Accessory Apatite from the Cu–Ni–Sulfide-Bearing Ultramafic–Mafic Rocks of the Khudolaz Complex (South Urals) as a Monitor of Magmatic and Metasomatic Processes

Abstract —We present results of mineralogical and geochemical studies (optical and electron microscopy, probe microanalysis, and LA-ICP-MS) of accessory apatite from the rocks of four ore-bearing massifs of the Khudolaz Complex: Vostochnyi Buskun, Severnyi Buskun, Malyutka, and Tashly-Tau. Two groups of apatite are recognized by morphology and chemical composition: (1) “magmatic” unaltered apatite (Ap-1) in unaltered and slightly altered rocks and (2) “metasomatized” apatite (Ap-2) surrounded by secondary silicates that replaced primary minerals. Ap-1 is represented by euhedral and subhedral hexagonal crystals with a high content of chlorine (0.7–1.2 wt.% Cl) and an extremely low content of sulfur (<0.05 wt.% SO3). It is enriched in REE (ΣREE = 2.2–3.0 wt.%), shows a pronounced negative Eu anomaly (Eu/Eu* = 0.36–0.58), and is depleted in Co, Ni, and chalcophile trace elements (Zn, Pb, and Bi). The distribution of major and trace elements in Ap-1 made it possible to identify its two generations, early and late, in the Khudolaz Complex. The early generation, characterized by a low content of Ca (Т ≥ 1000 °C, CaO < 54 wt.%), crystallized almost simultaneously with Ca-plagioclase (An81–61). The late generation, characterized by a high content of Ca (Т ≥ 700 °C, CaO > 55 wt.%), is associated with Na-plagioclase (An28–8), amphibole, and phlogopite. Ap-2 is represented by highly cracked grains and is characterized by a low content of chlorine (0.0n–0.5 wt.% Cl) and a high content of sulfur (0.06–0.93 wt.% SO3). The content of fluorine in both groups of apatite varies in the same range (0.6–1.7 wt.% F), which determines its relative inertness during metasomatic processes. Ap-2 is less enriched in REE (ΣREE = 1.1–2.1 wt.%) and shows a less pronounced Eu anomaly (Eu/Eu* = 0.61–0.77) but has high contents of Co, Ni, and chalcophile trace elements. The Ap-1 and Ap-2 show different variations in contents of major elements (Fe, Mg, Na, etc.), which is due to the impact of hydrothermal fluid on the mineral at the postmagmatic stage. It is shown that the low content of sulfur in apatite from unaltered rocks does not indicate a low sulfide ore potential of the Khudolaz Complex. The Cu–Ni sulfide signature of the complex is more clearly evidenced by the composition of metasomatized apatite enriched in S, Co, Ni, and chalcophile elements as a result of their hydrothermal removal from primary sulfide minerals. The high Eu/Eu* value indicates an increase in oxygen fugacity at the postmagmatic stage.

Comparative analysis of the effects of hydrogen and formic acid on the vacuum residue hydrocracking

The improvement of the existing technologies aimed at deeper processing of heavy oils and oil residues and development of new ones is an urgent task of modern oil refining. Experiments in a flow installation using a quartz reactor were performed to determine the formic acid decomposition pathway. The experiments showed that the formic acid decomposition over the Ni-Mo/Al2O3 catalyst predominantly yielded hydrogen and CO2. Therefore, in this study comparative experiments on the effects of hydrogen and formic acid on the vacuum residue hydrocracking in the presence of the Ni-Mo/Y-Al2O3 and Ni-Mo/Al2O3 catalysts were performed at 375–400 °C and 0.45 MPa pressure. The concentration of hydrogen or formic acid in argon was 10 vol%. The catalysts were prepared by impregnation of the corresponding supports with the aqueous solution obtained using nickel hydroxide, ammonium heptamolybdate and citric acid. Electron microscopy and XRD studies of the Ni-Mo/Y-Al2O3 and Ni-Mo/Al2O3 catalysts demonstrated that the active component in the studied catalysts was in a finely dispersed state. The size of Ni-Mo particles was 0.4–0.6 nm in the Ni-Mo/Y-Al2O3 catalyst and 0.3–0.6 nm in Ni-Mo/Al2O3. For both catalysts Ni-Mo/Y-Al2O3 and Ni-Mo/Al2O3 higher vacuum residue conversion to liquid products was observed in the presence of formic acid than in the presence of hydrogen. Hydrogen substitution for formic acid vapor during the vacuum residue hydrocracking also results in the lower sulfur content in the liquid reaction products. The use of formic acid as a hydrogen donor significantly simplifies the process hydrocracking.

Theoretical exploration of the structural evolution of sodium sulfide clusters in Na-S batteries

The nanosized sodium sulfide species greatly enhance the performance of Na-S batteries. However, as a typical ionic compound, the diminished stability with decreasing cluster size has been rarely considered. Numerous theoretical works only simulated the Na-S binary system based on quite small sodium sulfide clusters, with no account of the stability of the sub-nanoscale cluster. Here, by using an advanced structure search algorithm, we built a binary phase diagram of the sodium sulfide clusters (NSCs). The commonly studied monomer model with low sulfur concentrations is indeed energetically unfavorable, especially for the final discharge product, the Na2S monomer. Therefore, the aggregation of monomers should take place to form multimers. According to the energy, charge, and geometry, relatively stable clusters with low sulfur concentrations are located, including (Na2S5)2, (Na2S4)2, (Na2S3)3, (Na2S2)4, and (Na2S)6 clusters. Furthermore, these multimers bind more intensely to four typical models of carbon-based substrates. The B-doped carbon material exhibits outstanding affinity to NSCs, which may facilitate overcoming the shuttle effect in applications. This work represents a significant step toward understanding the evolution mechanism of NSCs that may guide the future development of high-performance Na-S batteries.

Technological Potential Analysis and Vacant Technology Forecasting in Properties and Composition of Low-Sulfur Marine Fuel Oil (VLSFO and ULSFO) Bunkered in Key World Ports

Analysis of the very-low-sulfur fuel oil (VLSFO) and ultra-low-sulfur fuel oil (ULSFO) bunkered in key ports in Asia, the Middle East, North America, Western Europe, and Russia is presented. The characteristics of said fuels, including density, sulfur content, kinematic viscosity, aluminum and silicon content, vanadium and nickel content, as well as pour point are investigated. Furthermore, the main trends and correlations are also discussed. Based on the graphical and mathematical analysis of the properties, the composition of the fuels is predicted. The key fuel components in Asian ports, the most important of which is Singapore, are hydrodesulfurized atmospheric residues (AR) (50–70%) and catalytic cracker heavy cycle oil (HCO) (15–35%) with the addition of other components, which is explained by the presence of a number of large oil refining centers in the area. In the Middle East ports, the most used VLSFO compositions are based on available resources of low-sulfur components, namely hydrodesulfurized AR, the production facilities of which were recently built in the region. In European ports, due to the relatively low sulfur content in processed oils, straight-run AR is widely used as a component of low-sulfur marine fuels. In addition, fuels in Western European ports contain on average significantly more hydrotreated vacuum gas oil (21%) than in the rest of the world (4–5%). Finally, a mixture of hydrotreated (80–90%) and straight-run fuel oil (10–15%) with a sulfur content of no more than 2.0–2.5% is used as the base low-sulfur component of marine fuels in the ports of Singapore and the Middle East.

Sea Port SO2 Atmospheric Emissions Influence on Air Quality and Exposure at Veracruz, Mexico

In this work, we identify the current atmospheric sulfur dioxide emissions of the Veracruz port, an important Mexican seaport experiencing rapid growth, and its influence on the surrounding areas. Sulfur dioxide emissions based on port activity, as well as meteorology and air quality simulations, are used to assess the impact. It was found that using marine fuel with low sulfur content reduces emissions by 88%. Atmospheric emission estimates based on the bottom-up methodology range from 3 to 7 Mg/year and can negatively impact air quality up to 3 km downwind. After evaluating different characteristics of vessels in CALPUFF, it was found that maximum sulfur dioxide concentrations ranging between 50 and 88 µg/m3 for a 24-h average occurred 500 m from the port. During 2019, five days had unsatisfactory air quality. The combination of a shallow planetary boundary layer, low wind speed, and large atmospheric emissions significantly degraded local air quality.

Физико-химические свойства трудноизвлекаемой нефти в Арктике

In the article, the author summarizes information about the extraction of hard-to-recover oil in various Arctic zones — Russian, Scandinavian and North American. Various estimates of the Arctic hydrocarbon reserves are presented, but the Russian Arctic occupies a leading position in terms of its reserves. The number of deposits in the Russian sector exceeds the number of deposits in the North American and Scandinavian sectors of the Arctic by 4 and 8 times, respectively. For Russia, the Arctic has become one of the main driving forces of the growth of the Russian oil and gas industry in the coming decades. The problems of stabilization and growth of the level of development of hard-to-recover oil in modern conditions of oil production are indicated. Based on the analysis of information from the database of the Institute of Petroleum Chemistry, consolidated information on the development of hard-to-recover oil production in the Arctic zone of Russia, in particular, in the European and Siberian parts of the macroregion, on the physico-chemical properties of hard-to-recover oil, conditions of occurrence and spatial distribution. It has been established that heavy and viscous oils of the Siberian part of the Arctic are characterized by lower viscosity values, low concentrations of asphaltenes, sulfur and metals compared to similar European Arctic oils. The solidification temperature is in the negative temperature range. The established differences determine the features of the development, production and transportation of heavy and viscous oils at critically low temperatures. The article may be of interest to companies in the oil and gas sector net monitor Arctic projects and prospects for their implementation.

Analysis of the use of magnesium-containing additives in the charge of iron flux in order to reduce CO2 emissions

The growing requirements for the quality of finished steel products oblige to obtain steel with a low content of harmful impurities, especially sulfur. The main charge for steel production in the conditions of JSC EVRAZ NTMK is vanadium iron, the external desulfurization of which leads to large losses of valuable vanadium. Therefore, the smelting of iron with a low sulfur content is an urgent task. The main way to reduce sulfur in iron is to increase the basicity of the slag (B2), but MgO is the best desulfurizer. The paper evaluates the effectiveness of the use of various magnesium-containing materials in the conditions of the blast-furnace stage of JSC EVRAZ NTMK, taking into account CO2 emissions. The possibility of replacing limestone in the iron flux charge with dolomite, as well as with steel converter slag, is considered. Both materials will increase the proportion of MgO in blast-furnace slag, however, the use of dolomite is accompanied by a two-fold increase in CO2 emissions compared to limestone. Converter steel slag (CSS) does not contain carbonates, thus eliminating the formation of CO2 during the limestone decomposition. An additional advantage of CSS is its high content of valuable vanadium and manganese. The effect of an increase in MgO in slag on its melting point is considered. It has been established that an increase in the proportion of MgO to 14% will not cause difficulties in the processing of blast-furnace smelting products and will reduce the sulfur content in iron and the formation of titanium carbides and carbonitrides.

Influence of Organic Sulfur on Low-Temperature Oxidation of Coal and its Transition Characteristics.

The low-temperature oxidation spontaneous combustion of coal was caused by the active groups in its structure. The oxidation mechanism of carbon and oxygen functional groups in coal had been extensively studied, but there were few reports on the study of sulfur functional groups initiating the coal spontaneous combustion. To investigate the influence of organic sulfur functional groups on the spontaneous combustion of high-sulfur coal and explore its transformation characteristics, the low-temperature oxidation experimental system was used to study the spontaneous combustion tendency of coal with similar metamorphic degrees and different organic sulfur contents. The variations of element forms and organic sulfur functional groups were analyzed by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy during low-temperature oxidation of coal and model compounds. The results showed that the forms of organic sulfur in coal mainly included mercaptans, thioethers, thiophenes, sulfones (sulfoxides), and sulfates, and the low-temperature oxidation of coal was not only related to the content of organic sulfur but also related to its type. The coal samples, which possess a low content of total sulfur and a small proportion of active organic sulfur groups such as mercaptans and thioethers, had a lower concentration of indicator gas and a smaller tendency to coal spontaneous combustion. After low-temperature oxidation, the content of mercaptan, thioether, thiophene, methyl(methylene), and pyridine in coal decreased, and the content of oxygen-containing groups such as sulfone (sulfoxide), sulfate, carboxyl, and nitrogen oxide increased. The elements of S, C, and N all changed to a high-valent state. In the oxidation reaction of model compounds, mercaptans were more reactive than thiophenes in the low-temperature region, and the oxidation of thiophene could direct form sulfone (sulfoxide), while the oxidation of mercaptan formed disulfide first. It is speculated that low-valence sulfur migrated to a high-valent state by providing sulfhydryl radicals (•SH) and sulfur radicals (C-S•) combined with active oxygen atoms. After the low-temperature oxidation reaction of model compounds, some organic sulfur existed in the form of aromatic sulfur or sulfur oxides and a small part of sulfur escaped as SO2 and H2S gases in the solid oxidation product.

Coal deposition in the Barito Basin (Southeast Borneo): The Eocene Tanjung Formation compared to the Miocene Warukin Formation

Coal seams of Late Eocene (Tanjung Formation) and middle Miocene age (Warukin Formation) are present in the Barito Basin of Borneo. The seams are laterally continuous and can be traced over at least 20 km. The thickness of three Eocene seams in the TAJ Pit–1D mine ranges from 1.4 to 3.4 m. These seams (from base to top: D, C, B) were studied to reconstruct their peat–forming environment and to compare the characteristics of Eocene and Miocene coals. The comparison reveals differences in peat types, flora and climate. The study is based on 38 Eocene coal and six non–coal samples, each representing a stratigraphic interval of 0.2 m. The samples were analyzed for ash yield, carbon and sulphur contents, and maceral composition. Organic geochemical parameters (incl. biomarkers) were obtained on every second coal sample to obtain information on the peat-forming vegetation and its diagenetic alteration.The Eocene seams were deposited in rheotrophic mires with palm/fern–dominated vegetation. Transitions to local ombrotrophic mires cannot be excluded. Very low to low sulphur contents (max. 0.9 wt%) speak against a marine influence, despite a general coastal plain setting. Upward increasing sulphur contents in the lower seam D and the upper seam B are interpreted to reflect transgression, which ended peat accumulation. The seam C formed in a rheotrohpic seam with a relatively high water level. This favored the accumulation of aquatic plants.Miocene coals from the Warukin Formation in the Barito Basin were studied recently in a companion paper. The comparison of Eocene and Miocene coals shows major differences, which include: Miocene coals are significantly thicker (up to 50 m) and display a cyclic structure. Miocene coals accumulated in ombrotrophic mires dominated by more decay resistant angiosperm trees (and subordinate gymnosperms). Therefore, preserved plant tissues are more abundant in Miocene coals. In addition, Miocene coals contain a significantly higher amount of root–derived macerals (suberinite). Leaf–derived macerals (cutinite, fluorinite) and resinite are ubiquitous in Miocene coals, but even slightly more abundant in Eocene coals. At least part of the resinite in Miocene coals, but not in Eocene coals, is derived from dammar resin produced by Dipterocarpaceae. Fungal activity, recorded by high funginite percentages, was high in low-ash ombrotrophic and high-ash rheotrophic mires both in Eocene and Miocene times.

Rapid Determination of Sulfur in Sixty Geological Reference Materials by High Resolution Inductively Coupled Plasma‐Mass Spectrometry

In this study, a rapid method for the quantification of sulfur mass fractions in geological materials using high‐resolution sector field‐inductively coupled plasma‐mass spectrometry (SF‐ICP‐MS) was developed. The effects of HNO3, Lefort, aqua regia, and HCl on the recoveries of sulfur in three different geological samples were evaluated. It was found that 0.5‐1 h digestion at 90 °C was enough to completely recover sulfur from BCR‐2 (basalt rock), GSS‐25 (loess), and GSD‐7 (stream sediment) using 2 ml aqua regia in both closed and open vessels. Compared with that of traditional digestion methods (e.g., HF‐HBr‐HNO3 acid digestion method), the efficiency of this proposed aqua regia digestion is improved by a factor of approximately 20. No loss of sulfur was observed because sulfur released from geological materials is directly oxidised to sulfate, which inhibits the volatilisation of sulfur. In addition, the effect of the heating‐condensing system combined with two different skimmer cones on the analytical sensitivity of sulfur was investigated. Compared with that of the normal sampling mode, the signal intensity of sulfur is enhanced by a factor of approximately 22 and 10 at a temperature of 140 °C using the S + X cone combination and S + H cone combination, respectively. This improvement is of importance for the determination of sulfur in samples with low sulfur content. The developed method was successfully applied to the determination of sulfur in geological reference materials. Most of the measured sulfur values of sixty geological materials, using both closed and open vessel digestion, are in good agreement with reference values. Compared with closed vessel digestion, the more flexible open vessel acid digestion is simple, fast, and shows great potential for the rapid quantification of sulfur in a large batch of geological and environmental samples.

Optimization and application of passive air sampling method for gaseous elemental mercury in Ulsan, South Korea.

We compared uptake rates and concentrations of gaseous elemental mercury (GEM) by passive sampling conditions and investigated the spatial distribution of GEM in Ulsan, the largest industrial city in South Korea. For the optimization of sampling conditions, two outer sampling containers (cylindrical polyethylene terephthalate and two stainless steel bowls), two different sulfur contents of the sorbent (16.3% and 26.3%), and three sampling periods (1, 2, and 3months) were considered. The uptake rates of GEM were not statistically different by the sampling container, but they were increased with the sulfur contents of activated carbon. A sampling condition using two stainless bowls and lower sulfur contents of activated carbon for 2-3months was preferred with the highest precision of GEM concentrations. With the same method, passive air samples were collected for 3months in duplicate from 10 sites in Ulsan. The concentrations of GEM ranged from 3.13 to 11.2ng/m3 (mean 4.65ng/m3), and the highest concentration was measured at a non-ferrous industrial complex. A zinc smelter in the non-ferrous industrial complex was identified as a major mercury source in Ulsan. This study is the first passive air sampling study investigating the spatial distributions of GEM in different types of industrial areas as well as residential areas of Ulsan.