Carbon Phase Research Articles

Experimental study of the interaction between garnets of eclogitic and lherzolitic parageneses and H2O-CO2 fluid under the P-T parameters of the lithospheric mantle

Experimental modeling of the interaction between garnets of mantle parageneses with H2O–CO2 fluid was performed in order to determine the characteristic features and trends in garnet compositions due to metasomatic alterations, and to study the patterns of formation of carbon and carbon-bearing phases in these processes. Experiments were carried out in the lherzolitic garnet–CO2–H2O–C and eclogitic garnet–CO2–H2O–C systems at 6.3 GPa in the temperature range of 950–1550 °C using double graphite+platinum ampoule on a multi-anvil high-pressure apparatus of a split-sphere type (BARS). The interaction of mantle garnets with H2O–CO2 fluid was found to cause garnet recrystallization and formation of new phases, namely magnesian carbonate, coesite, kyanite, corundum–eskolaite solid solution and silicate–carbonate melt, as well as metastable graphite (950–1550 °C) and diamond growth on seeds (1250–1550 °C). It was established that the garnet-fluid interaction was accompanied by the bivalent cations' redistribution between recrystallized garnet, carbonate and carbonate–silicate melt. In these processes calcium was preferentially partitioned in the melt, while magnesium was partitioned in garnet and carbonate. Recrystallization of garnets of lherzolitic and eclogitic parageneses under effect of H2O–CO2 fluid resulted not only in compositional changes, but in the formation of carbonate, kyanite, coesite, graphite, corundum–eskolaite solid solution and carbonate-silicate melt inclusions in these garnets. The revealed patterns of variations in garnet compositions, as well as the typical inclusions in them, can be regarded as indicators of metasomatic alteration of garnets of mantle parageneses involving H2O–CO2 fluid. The obtained results allow one to infer that H2O–CO2 fluids play a crucial role in redistribution of divalent cations under the P-T parameters of the lithospheric mantle and control over the composition of carbonate–silicate melts coexisting with the eclogitic and lherzolitic assemblages. Another important result of this study is the experimental demonstration that graphite capsules on their own fail to ensure reliable hermeticity with respect to the fluid and melt phases in the high-pressure, high-temperature experiments. It was substantiated that the procedure involving a hermetically sealed platinum ampoule with inner graphite capsule prevents uncontrollable loss of matter in long-term petrological experiments and is optimal for modeling systems containing melts and fluids.

X-ray diffraction as a highly selective and sensitive tool for the identification of Mg-rich carbonate phases in terms of the limestone with magnesium practical application

This article presents the theory about the usability and effectiveness of X-Ray Diffraction in identifying carbonate phases varied in magnesium content in the practical application of limestone-rich magnesium. Results of research on the Triassic limestone samples using this method are presented there. The samples were taken from the area of Opole Silesia in Poland. It is a Polish part of the Germanic Basin. X-ray diffraction was used to identify the following phases: low-Mg calcite, high-Mg calcite, dolomite, and huntite. Low-Mg calcite dominates in the limestones. In some samples, there is also a lower amount of high-Mg calcite. Moreover, dolomite and huntite were identified. The study results have shown that X-ray diffraction is the perfect method to identify carbonate phases with different magnesium content. Limestone, including carbonates rich in magnesium, can be used as a fertilizer, animal feed additive, sorbent to desulfurize flue gases or material in road building. The research results indicate the possibility of application of the Muschelkalk limestones rich in magnesium from the area of Opole Silesia in different branches of industry. Therefore, it would not be necessary to carry out selective exploitation in a way to avoid the magnesium-rich limestone zones in the deposits.

Evaluating the Potential of Biodegradable Carbohydrates and the Aqueous Extract of Potato Pulp to Inhibit Calcium Carbonate Scale in Petroleum Production

Summary Scale is a significant operational concern in petroleum production that is commonly addressed by using chemical inhibitors. However, commercial inhibitors can potentially be pollutants depending on their composition and method of disposal. Consequently, evaluating the potential of biodegradable molecules to inhibit scale has gained attention. This study evaluates the effect of a series of carbohydrates (i.e., glucose, fructose, sucrose, maltose, maltodextrin, and soluble starch) and the aqueous extract of potato pulp on calcium carbonate precipitation and scale formation. Precipitation tests were conducted by combining aqueous solutions of sodium bicarbonate (3000 mg L−1) and calcium chloride (4000 mg L−1) in the presence of each carbohydrate, the aqueous extract of potato pulp, or a commercial inhibitor (1000 mg L−1). The precipitation was monitored through RGB (red, green, and blue) image analysis and pH measurements. The induction time in the presence of glucose, fructose, maltose, and sucrose is two to three times longer than in the blank test (in the absence of an inhibitor). This effect is slightly more pronounced in the presence of maltodextrin and soluble starch (approximately four times longer). However, the drop in pH and the mass of solids recovered is similar for all the carbohydrates tested (~0.5 mg and 120 mg, respectively), suggesting that carbohydrates slightly influence the precipitation kinetics but do not affect the precipitation equilibrium. Scanning electron microscopy (SEM) and X-ray powder diffraction (XRD) analysis reveals that calcium carbonate precipitates as calcite and vaterite in the blank test. In the presence of glucose, fructose, maltose, and maltodextrin, calcium carbonate exclusively precipitates as calcite. However, in the presence of sucrose and soluble starch, calcium carbonate precipitates as both calcite and vaterite. Interestingly, a more prominent amount of vaterite was observed in the presence of soluble starch. All carbohydrates decrease the crystallite size of calcite, while sucrose and soluble starch increase the crystallite size of vaterite. The crystalline phases were also identified by Raman spectroscopy, ruling out the presence of any amorphous calcium carbonate phase. The inhibitory effect of soluble starch and the aqueous extract of potato pulp on calcium carbonate scale formation was evaluated in a dynamic scale loop (DSL) system. Soluble starch slightly delays scale formation even at high concentrations (1000 mg L−1). Conversely, the aqueous extract of potato pulp demonstrates enhanced performance by delaying scale formation by approximately 20 minutes for a 1-psi increase in the pressure of the tube and by more than 40 minutes for a 4-psi increase. As a result, it exhibited an impact on the kinetics of solid deposition. This agrees with the precipitation test in the presence of the potato extract (PE), which increases the induction time (from 2 minutes to 32 minutes), decreases the mass of solids (from 116 mg to 35 mg), and forms more distorted and smaller particles of calcite. These findings suggest a promising approach for the development of green scale inhibitors utilizing aqueous extracts of starchy foods or even starchy foods waste water.

Crystals structures of carbonate phases with Mg in Triassic rocks, mineral formation and transitions

Detailed data on carbonate minerals different in magnesium content including their crystal structures were presented in this article. The samples were collected from the formations of the Lower Muschelkalk and the Upper Muschelkalk. X-ray diffraction and electron microprobe analysis were used for carbonate phases determination. The following minerals with different Mg content were identified: low-Mg calcite, high-Mg calcite, proto-dolomite, ordered dolomite and de-huntite. The content of Mg in high-Mg calcite is higher than in low-Mg calcite but lower than that of proto-dolomite. Proto-dolomite is characterized by lower content of Mg than typical for stoichiometric value for dolomite—ordered dolomite. Due to the reduced Mg content in identified huntite, this carbonate phase was named as de-huntite. The research results are significant because they are a source of new data on carbonate phases with different Mg content which build studied Triassic rocks and crystal structures of these minerals.

A robust methodology for triple (∆47, ∆48, ∆49) clumped isotope analysis of carbonates

Analysis of ∆48 and ∆47 values of CO2 released from phosphoric acid digestion of carbonates enables the rate-limiting kinetic processes involved in carbonate mineralization to be identified and formation temperatures to be determined by accounting for these kinetic biases. This method has the benefit of only requiring analysis of a single carbonate phase. To resolve temperature from the kinetic information, mass spectrometric measurements of highest accuracy and precision are required.Here, we outline a robust methodology for high-precision triple (∆47, ∆48, ∆49) clumped isotope analysis using turbo-pumped gas and carbonate preparation lines, a common acid bath and the dual inlet of a Thermo Scientific 253plus gas source mass spectrometer, equipped with additional m/z47.5 half mass cup. By analysis of >400 replicates each, we report long-term (50 months) ∆47, CDES 90 and ∆48, CDES 90 values for three internationally accepted (ETH-1, -2 and -3) and two internal carbonate standards (GU1, Carrara) unbiased by scale compression. In order to obtain highest accuracy and precisions closest to shot noise limit it is essential to account for a sample size effect, correct raw intensities for a negative background utilizing the half mass cup, avoid pressure imbalances between sample and reference gas and distribute samples evenly across a given analytical session.We confirm ∆47, CDES 90 values that were recently assigned to ETH-1 and ETH-2. Our long-term average ∆47, CDES 90 value of 0.6032 ‰ for ETH-3, on the contrary, occurs 10 ppm lower than its recently assigned value. As a consequence, ∆47, CDES 90 values of samples having relatively low temperatures of formation are not consistent with ∆47, I-CDES values. We show that GU1, a synthetic carbonate deriving from the hydroxylation of CO2 and exhibiting a strong anti-clumped ∆48, CDES 90 value, appears to be homogeneous in its isotopic composition. If used in combination with ETH-1, −2 and − 3, it may allow projection of background corrected raw data without any bias into ∆47-∆48 CDES 90 space, provided our long-term dual clumped isotope values for these carbonate anchors are considered.Stability of mass spectrometric measurements is related to filament age and/or room temperature fluctuations and can be monitored using reference gas m/z49 intensity. Under the most stable analytical conditions, the ∆49, CDES 90 values of equilibrated gases and carbonates reveal a trend with formation temperature. Using data from the most stable sessions, we present a temperature calibration for ∆49, CDES 90 in CO2 evolved from phosphoric acid digestion of carbonates.

Study on evolution process and electrochemical behavior of porous cathode in discharge process of the solid-state lithium-oxygen battery

Solid-state lithium‑oxygen battery is one of the lithium-metal batteries with high theoretical specific capacity and strong safety. In order to explore the evolution process and electrochemical behavior of the battery, a study of combination of simulation and experiment is conducted in this paper. Firstly, solid-state lithium‑oxygen batteries with quartz tubes as the battery shell are designed for the experiment. FTIR and Raman results show that the lithium peroxide is produced as discharge products and SEM images show the product is accumulated on the surface of carbon particles and bound the carbon particles into blocks during the cathode evolution process. Then, a 1D multi-physics coupling field model referred to the experiment is established to investigate the electrochemical behavior of the battery. The calculated discharge curves are compared with the experimental discharge curves to verify the accuracy of the model. Using the model, the electrochemical behaviors, such as discharge product volume fraction, active three-phase interface, LATP phase potential and carbon phase potential, are analyzed. At last, the reasons for discharge termination are attributed to the accumulation of lithium peroxide and the decline of active three-phase interface.

Radiocarbon signatures of carbon phases exported by Swiss rivers in the Anthropocene.

Lateral carbon transport through the land-to-ocean-aquatic-continuum (LOAC) represents akey component of the global carbon cycle. This LOAC involves complex processes, many of which are prone to anthropogenic perturbation, yet the influence of natural and human-induced drivers remains poorly constrained. This study examines the radiocarbon (14C) signatures of particulate and dissolved organic carbon (POC, DOC) and dissolved inorganic carbon (DIC) transported by Swiss rivers to assess controls onsources and cycling of carbon within their watersheds. Twenty-one rivers were selected and sampled during high-flow conditions in summer 2021, a year of exceptionally high rainfall. Δ14C values of POC range from -446‰ to -158‰, while corresponding ranges of Δ14C values for DOC and DIC are -377‰ to -43‰ and -301‰ to -40‰, respectively, indicating the prevalence of pre-aged carbon. Region-specific agricultural practices seem to have an influential effect on all three carbon phases in rivers draining the Swiss Plateau. Based on Multivariate Regression Analysis, mean basin elevation correlated negatively with Δ14C values of all three carbon phases. These contrasts between alpine terrain and the lowlands reflect the importance of overriding ecoregional controls on riverine carbon dynamics within Switzerland, despite high spatial variability in catchment properties. This article is part of the Theo Murphy meeting issue 'Radiocarbon in the Anthropocene'.

Systematic observations of enhanced oil recovery and associated changes at carbonate-brine and carbonate-petroleum interfaces

Enhanced oil recovery (EOR) from carbonates is obtained by injection of controlled ionic strength brines containing “active ions” (e.g., SO42−, Mg2+, Ca2+). It is generally believed that this occurs through the interaction of the active ions at the carbonate-brine interface (e.g., within a thin brine layer separating the petroleum and the carbonate phases). Here, in-situ observations show how one active ion, SO42−, alters behavior at the carbonate-petroleum interface. Displacement of petroleum from initially oil-wet carbonate rocks using brines with variable SO4 concentrations systematically changes oil recovery, in situ contact angles, and connectivity of the oil phase, confirming that the active ion alters interactions at the oil/brine/carbonate interface, as expected. Measurements of model calcite-fluid interfaces show that there is no measurable sorption of SO4 to carbonate-brine interfaces but reveals that the carbonate-petroleum interface is altered by previous exposure to SO4-containing brines. These results suggest that EOR in carbonates is controlled indirectly by active ions. We propose that this may be due to a reduced oleophilicity of the carbonate caused by chemical complexation between the active ion and petroleum’s acidic and basic functional groups. This mechanism explains how both anions and cations act as active ions for EOR in carbonates.

Double-Shock Compression Pathways from Diamond to BC8 Carbon.

Carbon is one of the most important elements for both industrial applications and fundamental research, including life, physics, chemistry, materials, and even planetary science. Although theoretical predictions on the transition from diamond to the BC8 (Ia3[over ¯]) carbon were made more than thirty years ago, after tremendous experimental efforts, direct evidence for the existence of BC8 carbon is still lacking. In this study, a machine learning potential was developed for high-pressure carbon fitted from first-principles calculations, which exhibited great capabilities in modeling the melting and Hugoniot line. Using the molecular dynamics based on this machine learning potential, we designed a thermodynamic pathway that is achievable for the double shock compression experiment to obtain the elusive BC8 carbon. Diamond was compressed up to 584GPa after the first shock at 20.5 km/s. Subsequently, in the second shock compression at 24.8 or 25.0 km/s, diamond was compressed to a supercooled liquid and then solidified to BC8 in around 1ns. Furthermore, the critical nucleus size and nucleation rate of BC8 were calculated, which are crucial for nano-second x-ray diffraction measurements to observe BC8 carbon during shock compressions. The key to obtaining BC8 carbon lies in the formation of liquid at a sufficient supercooling. Our work provides a feasible pathway by which the long-sought BC8 phase of carbon can be reached in experiments.

Persistent late Tonian shallow marine anoxia and euxinia

The increase in the complexity of eukaryotic life during the Tonian Period (ca. 1000 to 720 Ma) is commonly associated with the oxygenation of the Earth’s ocean–atmosphere system, yet the timing and duration of these redox changes remain uncertain. In particular, it is unclear how shallow marine environments, which were likely crucial habitats for early eukaryotic organisms, responded to Neoproterozoic oxygenation. This study uses trace and rare earth element geochemistry to determine shallow marine redox conditions during the deposition of the late Tonian (ca. 760 Ma) Devede Formation, northern Namibia. In this unit, although carbonate phases (microbialite, former aragonite and high Mg calcite marine cements, and primary dolomite marine cements) generally exhibit no Ce/Ce* anomaly, rare negative values (up to 0.55) are consistent with short-lived periods of oxygenation. In contrast, the dominantly positive Eu/Eu* anomalies of the same phases suggest that basinal conditions were anoxic. These phases also exhibit low concentrations of redox-sensitive (U, V, Mo) and chalcophile (Co, Cu, Cd, Zn, Pb) elements, suggesting that euxinic conditions were predominant during the deposition of the Devede Formation. Integration of this data (Ce/Ce* and Eu/Eu*) with that of analogous late Tonian (ca. 840 to 731 Ma) carbonate strata reveals that shallow marine settings were characterised by persistent anoxia and euxinia, suggesting that any potential increase in atmospheric O2 ca. 800 Ma (e.g. the Bitter Springs Anomaly) was insufficient to facilitate resilient ocean oxygenation. These findings suggest that the late Tonian oceans were likely challenging environments for complex (e.g. eukaryotic) life, and add to a growing body of evidence that the spatially variable redox conditions of late Proterozoic shallow marine settings likely reflect the complex nature of the Neoproterozoic Oxygenation Event.

The relationship between the fabrication and characteristics of nitrogen-doped graphene

Since the 21st century, with the popularization of computers and mobile phones to the upgrading of various kinds of electronic products, human needs are also changing, among which the flexible touch screen has received wide attention. To achieve a wide application of flexible touch screens, this paper needs to make more materials innovations, and graphene’s unique and excellent performance has attracted wide attention. Among them, the metal doping, non-metallic doping, metallic and non-metallic co-doping of graphite phase carbon nitride has broad development prospects, widely used, or may be widely used in the production and production of flexible touch screen. This paper briefly analyzes and compares three nitrogen-containing graphene materials’ properties and preparation methods (metal doping, non-metal doping, metal, and non-metal co-doping) in 2D nanomaterials, and discusses the possible applications in the field of flexible touch screens. Urea-reduced GO graphene, Fe-P co-doped graphite phase nitride carbon and potassium ion-doped graphite phase nitride carbon all have easy raw materials, simple production mode, electrical, and excellent optical properties; meanwhile, different doping methods and dosage change the performance of graphene in different directions. Therefore, nitrogen-containing graphene materials have a lot for development in the part of flexible touch screens.

A Continuous Action Space Tree search for INverse desiGn (CASTING) framework for materials discovery

Material properties share an intrinsic relationship with their structural attributes, making inverse design approaches crucial for discovering new materials with desired functionalities. Reinforcement Learning (RL) approaches are emerging as powerful inverse design tools, often functioning in discrete action spaces. This constrains their application in materials design problems, which involve continuous search spaces. Here, we introduce an RL-based framework CASTING (Continuous Action Space Tree Search for inverse design), that employs a decision tree-based Monte Carlo Tree Search (MCTS) algorithm with continuous space adaptation through modified policies and sampling. Using representative examples like Silver (Ag) for metals, Carbon (C) for covalent systems, and multicomponent systems such as graphane, boron nitride, and complex correlated oxides, we showcase its accuracy, convergence speed, and scalability in materials discovery and design. Furthermore, with the inverse design of super-hard Carbon phases, we demonstrate CASTING’s utility in discovering metastable phases tailored to user-defined target properties and preferences.

The mineralogy and alteration history of the Yamato-type (CY) carbonaceous chondrites

The CY chondrites are a group of thermally metamorphosed carbonaceous chondrites. Although they share similarities with the CM and CI chondrites, their primary properties argue for a distinct classification. Previous studies have highlighted their isotopically heavy bulk compositions (δ17O = 10 ‰, δ18O = 21 ‰, Δ17O = 0 ‰) and exceptionally high sulphide abundances (10–30 vol%). In this work we explore their petrography and alteration history. The CYs accreted low abundances of chondrules (15–20 area%) with average apparent diameters slightly larger (∼320–340 µm) than the CM chondrites. In contrast to the CMs, the CYs record an early episode of brecciation prior to the main window of aqueous alteration. Subsequent fluid activity produced a range of alteration extents with both CY2 and CY1 chondrites documented. Phyllosilicate minerals in the CYs were a mix of serpentine and saponite (including occurrences of Na-saponite) with minor quantities of chlorite (within chondrules). An initial generation of Fe-sulphides formed by sulfidation of metal, and by precipitation from S-rich fluids. Three generations of carbonates are recognized, an early generation that infilled voids left by brecciation and co-precipitated with sulphide, a later generation that co-precipitated with magnetite and a final Fe-Mg-bearing generation which formed large (>100 µm) clasts. Only the first-generation carbonates are found in the CY2s, while the CY1s preserve all three generations. Phosphates occur as Ca-apatite or rarely as Mg-bearing apatite and have hydroxylapatite compositions, indicating low halogen activities in the alteration fluids. Refractory oxides (ilmenite and Cr-spinel) occur as precipitates adhering to the margins of phyllosilicates. They formed late in the alteration sequence and attest to oxidizing conditions. During the late-stages of aqueous alteration Fe-sulphides were replaced by magnetite. Thermal metamorphism (Stage II-IV: ∼300–750 °C) overprinted aqueous alteration leading to dehydration and recrystallization of the phyllosilicate matrix and the decomposition of some carbonate phases. Most Fe-sulphide grains survived heating without decomposition as initial partial decomposition from pyrrhotite to troilite under closed system conditions led to elevated ƒS2 gas and resulted in a stabilizing effect. Retrograde reactions between trapped S2 gas and metal/magnetite formed a final generation of Fe-sulphides. The survival of Fe-sulphides and their stochiometric troilite compositions are evidence for near-closed system heating. Analysis of organic matter by Raman spectroscopy supports an interpretation of short-duration heating (on the scale of minutes to days), at peak temperatures between 750 and 900 °C. Thus, an impact event was the most likely cause of metamorphic heating.

Formation of diamond and lonsdaleite in ureilites by impact shock processing of graphite

AbstractThe origin of diamond in ureilites has been frequently debated. We investigated carbon phase assemblages (CPAs) in five ureilitic samples of the brecciated asteroid 2008 TC3, found within the Almahata Sitta (AHS) strewn field, by transmission electron microscopy, Raman spectroscopy, synchrotron X‐ray diffraction, and cathodoluminescence. Samples MS‐MU 006, MS‐187, and MS‐170, are of low to moderate shock degree (U‐S2 and U‐S3), and samples MS‐MU 027 (U‐S4) and MS‐MU 045 (U‐S5) have a higher shock degree. In MS‐MU 006 and MS‐187, we did not find any diamond grains. MS‐170 contains disordered and distorted graphite with diamond grains up to 12 μm in size and containing inclusions of Fe,Ni‐metal, FeS, Fe‐phosphide, and Cr,Fe‐oxide. These diamond grains formed under relatively low (5–15 GPa) shock pressures through a catalytic process in the presence of a Fe,Ni,Cr,S,P‐rich melt. The highly shocked and fine‐grained ureilites MS‐MU 027 and MS‐MU 045 have three different types of CPAs, namely a nanopolycrystalline assemblage of diamond and defect‐rich diamond/lonsdaleite, disordered and distorted graphite, and polycrystalline diamond with abundant Fe‐rich mineral inclusions. The CPAs that have only diamond and planar defect‐rich diamond (e.g., MS‐MU 027) most likely formed through martensitic transformation of graphite to diamond and lonsdaleite at >15 GPa and >2000 K. The assemblage of diamond, defect‐rich diamond, and disordered and distorted graphite (e.g., MS‐MU 045) formed by martensitic transformation of graphite to diamond and lonsdaleite, followed by back‐transformation to disordered graphite. We did not find any conclusive evidence to support the formation of diamond grains under high static pressure.

Nanostructured carbon films obtained by CH4 plasma deposition and annealing at high temperature: structural features and their effects on electrical and optoelectronic properties

This article is dedicated to the study of the structural, electrical, and optoelectronic properties of nanostructured carbon films obtained by methane plasma deposition, followed by annealing at high temperatures (650–800 °C). The conditions for obtaining the films affected the final physicochemical parameters. We studied the film morphology using atomic force microscopy, scanning electron microscopy, Raman spectroscopy, X-ray energy-dispersive analysis, and analysis of the current voltage (C-V) characteristics. The film thickness ranged from 20 to 150 nm, with a C/O ratio of 4:1. Structural studies have shown that the resulting nanostructured carbon films consist mainly of nanographite flakes, the lateral dimensions of which lie in the lateral size (La) range of 5 to 12 nm, and contain different fractional concentrations of sp3/sp2 crystalline phases of carbon. We have established that with an increase in the annealing temperature, the defectiveness of the carbon film structure increases; however, at the same time, the degree of graphitization increases, as indicated by the Raman spectroscopy data and the calculated values of layer resistances from the C-V characteristics. The values of photocurrents were calculated, from which it was found that the samples exhibited photosensitivity in the temperature range of room temperature to –173 °C, based on the temperature dependences of the C-V. The obtained results can be useful in creating day and night light sensors as well as temperature sensors suitable for use at low temperatures.

MnNCN@C nanocomposite as an anode for Li-ion battery

In order to find other anode materials for lithium-ion batteries, manganese carbodiimide with N-doped C coating (MnNCN@C) has been reported. Initially a gel of precursors was prepared and then calcined for 1.5 h at 700 °C in the atmosphere of N2. The MnNCN phase was identified by X-ray diffraction, X-ray Photoelectron Spectroscopy (XPS) and electron diffraction. Further, carbon phase was established by transmission electron microscopy (TEM), FTIR and Raman spectroscopy. The doping of N in carbon phase was confirmed from XPS study. Distribution of pore size as well as specific surface area of MnNCN@C composites were investigated from the BET technique, and their values were 9.19 × 103cm2/g and 7.512 nm, respectively. The cell with this material as anode could be cycled for 100 times. After 100 cycles, the capacity turns out to be around 200 mAh/g. However, the cell was capable to deliver suitable capacity at even higher currents.

Experimental and Theoretical Evaluation of the Thermodynamics of the Carbonation Reaction of ZIF-8 and Its Close-Packed Polymorph with Carbon Dioxide.

We report the first experimental and theoretical evaluation of the thermodynamic driving force for the reaction of metal-organic framework (MOF) materials with carbon dioxide, leading to a metal-organic carbonate phase. Carbonation upon exposure of MOFs to CO2 is a significant concern for the design and deployment of such materials in carbon storage technologies, and this work shows that the formation of a carbonate material from the popular SOD-topology framework material ZIF-8, as well as its dense-packed dia-topology polymorph, is significantly exothermic. With knowledge of the crystal structure of the starting and final phases in the carbonation reaction, we have also identified periodic density functional theory approaches that most closely reproduce the measured reaction enthalpies. This development now permits the use of advanced theoretical calculations to calculate the driving forces behind the carbonation of zeolitic imidazolate frameworks with reasonable accuracy.

X-ray diffraction as a highly selective and sensitive tool for the identification of Mg-rich carbonate phases in terms of the limestone with magnesium practical application

This article presents the theory about the usability and effectiveness of X-Ray Diffraction in identifying carbonate phases varied in magnesium content in the practical application of limestone-rich magnesium. Results of research on the Triassic limestone samples using this method are presented there. The samples were taken from the area of Opole Silesia in Poland. It is a Polish part of the Germanic Basin. X-ray diffraction was used to identify the following phases: low-Mg calcite, high-Mg calcite, dolomite, and huntite. Low-Mg calcite dominates in the limestones. In some samples, there is also a lower amount of high-Mg calcite. Moreover, dolomite and huntite were identified. The study results have shown that X-ray diffraction is the perfect method to identify carbonate phases with different magnesium content. Limestone, including carbonates rich in magnesium, can be used as a fertilizer, animal feed additive, sorbent to desulfurize flue gases or material in road building. The research results indicate the possibility of application of the Muschelkalk limestones rich in magnesium from the area of Opole Silesia in different branches of industry. Therefore, it would not be necessary to carry out selective exploitation in a way to avoid the magnesium-rich limestone zones in the deposits.

Mechanism of retaining graphite phase in the graphite/SiC composite by condense layer with fine SiC grain reaction formed via nano carbon black

For the reaction-formed graphite/SiC composites, the drastic consumption of vast amounts of carbon phase by violent reaction with liquid silicon is a prominent problem during reactive melt infiltration, resulting in low carbon content of the composites. To retain adequate graphite phase, in this work, hybrid carbon powders (PFC@G), adhered with nano carbon black via a binder, were employed as carbon sources for fabricating the graphite/SiC composites with high carbon content. The mechanism of retaining graphite phase in the graphite/SiC composites by reaction-formed SiC layer with nano carbon black was investigated. The results indicate that a carbon content of 43.03 vol% was obtained for graphite/SiC composites when the content of nano carbon black is 10 wt% in the carbon source. The microscopy results revealed that the PFC@G was protected effectively by the condense layer with fine SiC grains generated via the reaction between nano carbon black and liquid silicon.

Passive remediation of mine waters from Parys Mountain (Wales): Laboratory column experiments

This study evaluates the effectiveness of dispersed alkaline substrate (DAS) technology to treat highly acidic and contaminated leachates from the oxidation of sulfide-rich mining wastes under wet temperate oceanic climate conditions. To address this issue, leachates from the abandoned mine at Parys Mountain (NW Wales) were passed through two sets of multistep columns filled with a mixture of a fine-grained alkaline reagent (i.e., limestone, MgO, or BaCO3) scattered in an inert matrix. The set of columns with the limestone-DAS plus MgO-DAS combination achieved a near total removal of Fe, Al, Zn, Cu, Mn, As, Co, Cd, and Ni. However, the elimination of SO4 was not significant (around 7%). The limestone-DAS plus BaCO3-DAS combination also achieved a high effectiveness for base metal/loids, allowing the removal of Fe, Al, Zn, Cu, As, and Cd with rates of nearly 100%. In addition, the system with the BaCO3-step had a higher effectiveness in eliminating SO4 (around 53%) than the combined treatment with the MgO-step. According to PHREEQC code calculations, the precipitation of oxy-hydroxy-sulfates (i.e., schwertmannite and basaluminite) and carbonate (i.e., malachite, hydrozincite and calcite) phases may have controlled the solubility of pollutants during the passive treatment. The chemical compositions of the treated waters complied with the threshold values defined by irrigation standards, except for Mn in the BaCO3-DAS output.