Reactivity Of Carbon Research Articles

High-voltage operation by mechanical interlocking adhesion of nickel-rich cathode and functional separator in lithium-ion batteries

High-voltage operating is an effective route to provide upgrading the energy density of advanced lithium-ion batteries (LIBs). However, detrimental capacity decay caused by the high-voltage cycling makes it difficult to obtain stable long-term operation. Use of electrolyte additive can suppress fast capacity decay, but the prolonged effectiveness is hindered by the increased gaseous product at the electrode. In this work, we apply a functional separator having an adhesive layer on the ceramic-coated separator in high-voltage operating LIB. Mechanical interlocking adhesion between the electrode and separator prevents delamination resulting in high-capacity retention during the 500 charge–discharge cycles with the cut-off voltage of 4.5 V even with the reactive vinylene carbonate additive. This was evidenced by the X-ray inspection designed for the detection of gas pockets in pouch cells, caused by the continuous gas pressure build-up during the early cycles. Results indicate that the suppression of the gas pocket led to the prevention of capacity decay and provided a powerful strategy to extend the effect of increasing operating voltage. The approaches in this study not only highlight the importance of mechanical interlocking between the electrode and separator but also present insights into the electrode interfaces, which are still not fully understood.

Metal Mobilization From CO2 Storage Cap-Rocks: Experimental Reactions With Pure CO2 or CO2 SO2 NO

CO2 geological storage will be needed as part of the transition to lower greenhouse gas emissions. During CO2 storage, the mobilization of metals from minerals to formation water via CO2 water rock reactions may be a concern for water quality. The sources, behavior, and fate of metals, however, are not well understood. Metals in minerals of calcite cemented sandstone, feldspar-rich sandstone, and ironstone seal drill cores from a target storage site were characterized. The cores were reacted with low-salinity water and pure supercritical CO2 or impure CO2 with SO2 and nitric oxide (NO), under reservoir conditions. Calcite cemented core underwent calcite dissolution with chlorite, plagioclase, and sulfide alteration. The highest concentrations of calcium and manganese were released in the reaction of calcite cemented sandstone seal, with the lowest mobilized arsenic concentration. Pure CO2 reaction of the feldspar-rich sandstone seal resulted in calcite dissolution, with plagioclase, chlorite, kaolinite, illite, and sulfides corroded. Impure CO2 reaction of the feldspar-rich sandstone led to additional corrosion of apatite, pyrite, and sphalerite cements. Generally, dissolved iron, lead, zinc, and arsenic were released and then re-precipitated in oxide minerals or adsorbed. Calcium, manganese, and strontium were released primarily from calcite cement dissolution. Plagioclase corrosion was a second source of dissolved strontium, and chlorite dissolution a second source of manganese. Although sulfides contained higher concentrations of metals, the higher reactivity of carbonates meant that the latter were the main sources contributing to dissolved metal concentrations. The mineral content of the seal cores, and the injected gas mixture, had an impact on the type and concentration of metals released. The ubiquitous presence of carbonate minerals means that this study is applicable to understanding the potential risk factors for water quality changes, and the mobilization and fate of environmentally regulated metals, in both CO2 storage complexes and overlying drinking water aquifers worldwide.

Tetrathienyl Corannulene Compounds with Highly Sensitive Photochromism.

We have designed and synthesized photochromic tetrathienyl corannulene compounds, 1,2,7,8-tetrakis(2-methyl-5-phenylthiophen-3-yl)corannulene (1) and 1,2,7,8-tetrakis(2,4-dimethyl-5-phenylthiophen-3-yl)corannulene (2), by fusing two units of photochromic terarylene with a curved aromatic corannulene with a promising antenna effect. Compound 1 exhibited highly sensitive photoreactivity, with a large molar absorption coefficient of 8.2×104 M-1 cm-1 and practically photon-quantitative photocyclization. On the other hand, a terarylene derivative with a planar aromatic phenanthrene, 9,10-bis(2,4-dimethyl-5-phenylthiophen-3-yl)phenanthrene (4) showed no photoreactivity. The reason for such a difference was attributed to the predominance of the photoreactive atropisomers amplified by energy migration, and the shortened distance between reactive carbons induced by the curved structure.

Tailoring the Fenton-like mechanisms of surface functional groups by corrosive structural defects for superior pollutant degradation on platform carbon

The high abundance, low cost and no toxicity of solid catalyst play governing roles in Fenton-like catalysis via non-radical pathways. Reactive carbons exhibit low capacity for PMS activation and pollutant degradation, although they possess unique material properties. Herein, a simple and efficient two-step strategy of “chemical reduction + acidic corrosion” was proposed and validated to refine platform carbon for Fenton-like catalysis in environmental decontamination. Platform carbon treated by NaBH4 reduction and H2SO4 corrosion exhibited much superior reactivity and selectivity as well as stability for PMS activation to degrade phenolic pollutants in various water matrix. Effects of tailoring condition, catalyst dosage, pollutant concentration, pH range and PMS concentration were studied. Control tests with other catalysts, catalyst reusability and technical applicability were carried out. Reaction mechanisms were elucidated by ESR and radical quenching as well as electrochemical tests. Radical pathway was not a critical role, while catalysis was controlled by catalyst-oxidant surface interactions and non-radical pathways (1O2 and electron transfer), the latter played the dominant role mediated by surface CO group. Our findings provided a new chance to utilize platform carbon and other inert materials in selective Fenton-like catalysis for safe water purification.

Synthesis of reactive phosphorus-based carbonate for flame retardant polyhydroxyurethane foams

Polyurethane (PU) foams are widely used for many applications, however the use of toxic isocyanate monomers for their synthesis has recently led researchers to non-isocyanate PU foams. The most promising alternative is the aminolysis of cyclic carbonate which yields polyhydroxyurethanes (PHU). Nevertheless, the obtained foams suffer from significant flammability and require the introduction of flame retardants to improve their flame retardant properties. Hence, this article demonstrates the first synthesis of PHUs foams containing phosphorus-based flame retardants. The flame retardant were allowed to react with the monomers to prevent any leaching from the foams. Moreover, several structures of cyclic carbonates were analyzed in order to determine the influence of aromatic rings on both thermal stability and mechanical properties of foams by thermogravimetric analyses, differential scanning calorimetry and dynamic mechanical analyses. The flame retardant properties were studied with a cone calorimeter and pyrolysis combustion flow calorimeter. The best results were obtained by the foam containing 2 wt% of phosphorus and two aromatic rings in the cyclic carbonate structure. Cone calorimeter analysis showed a total heat release of 13.1 KJ.g−1 versus 19.1 KJ.g−1 for the DOPO-free foam.

Photodegradation of pyrogenic dissolved organic matter increases bioavailability: Novel insight into bioalteration, microbial community succession, and C and N dynamics

Photodegradation and biodegradation of pyrogenic dissolved organic matter (pyDOM) play crucial roles in regulating greenhouse gas emissions and stabilizing organic matter. In this study, we conducted a 56-day microbial laboratory incubation to investigate the biodegradation patterns of pristine and photobleached pyDOM leached from a thermal series of chars (300, 450, and 600 °C) based on FT-ICR-MS, gas analysis, N speciation, and 16S rDNA sequencing. As the pyrolysis temperature increased, the among of biomineralized carbon of pyDOM decreased, while the molecular diversity and aromaticity increased. Photobleaching increased the among of biomineralized carbon of pyDOM from 40%–70% to 60%–80%, but decreased the molecular diversity, molecular weight, and aromaticity, with a major removal of lignin-like compounds. Microbial incubation lowered the molecular diversity but increased the molecular weight and aromaticity of both pristine and photobleached samples. Tannin-like structures, carbohydrates, and aliphatic/protein were preferentially biodegraded, while lipid, lignin-like structures, unsaturated hydrocarbons, and condensed aromatics were more likely to be preserved or newly produced. The photobio-resistant components were mainly comprised of lignin-like and tannin-like structures. Photobleached pyDOM samples released more CO2 but less N2O, as they may possess high denitrification rate due to their high carbon reactivity. The bacterial richness and diversity in pyDOM were lower than the original inoculum. In addition, distinct differences were noted between the bacterial community structure of the original inoculum and that of pristine and photobleached pyDOM samples following various incubation times. Specifically, proteobacteria was increased and remained the predominant phylum in all pyDOM solutions compared to the original inoculum, while Actinobacteriota, Bdellovibrionota, Firmicutes, or Nitrospirota phyla were increased in several samples either after 7 or 56 days of incubation. In particular, photobleached pyDOM pyrolyzed at 600 °C exhibited the strongest filtration effects on the bacterial microflora. These results help to elucidate the biogeochemical cycling and turnover of pyDOM in sunlit and dark aquatic environments such as fluvial and groundwater networks, lakes, and the ocean.

Structure and reactivity of residual carbon from circulating fluidized bed coal gasification fine ash

Due to the high carbon and ash content of coal gasification fine ash (CGFA) produced by circulating fluidised bed gasifiers, it is mainly dissipated in landfills, resulting in soil and water pollution and energy wastage. The presence of carbon limits the application of CGFA in building materials and ceramics. Large-scale dissipation of CGFA can be achieved if the carbon in CGFA has active oxidation properties and potential as a material for the preparation of carbon. Therefore, exploring the form of carbon present in CGFA is crucial for the resourceful and harmless use of CGFA. Demineralisation of different types of CGFA from a circulating fluidised bed gasifier with a gas production capacity of 40,000 Nm3/h was carried out to obtain demineralised carbon (DC) and to investigate the structure and reactivity of the DC. The d002 and Lc values of the DC increased, the cross-linkage decreased, the main microcrystalline structural parameters of the aromatic carbon network layer with swelling effect increased in the vertical direction, the aromatic carbon and aliphatic hydrocarbon functional groups increased and the oxygen-containing functional groups all tended to decrease to different degrees. Based on the changes of CGFA chemical structure before and after acid treatment, a CGFA chemical structure model was constructed. Through TG experiments and Raman analysis of the samples, the activation energy value of the DC carbon was less than 70 kJ/mol, and the relationship between the carbon structure and combustion reactivity of the Raman characterisation was constructed. The DC had a specific surface area above 350 m2/g and was prepared as activated carbon after KOH and high temperature activation. The activated carbon had a specific surface area of 1636.2211 m2/g, a pore volume of 1.6796 cm3/g and a density of 1 g/cm3. The above indicates that CGFA has the potential to be used as a fuel for combustion, secondary gasification and DC can be used as an adsorbent or a pressed precursors for activated carbon.

Variations in the mineral structures dominating solute mobilization during clay compaction

Microbial-mediated redox reactions typically control the solute mobilization in groundwater systems, in which the clay aquitard is usually a triggering factor of the release of the dissolved organic carbon, ammonium, and iron into the aquifer during pore water discharge and clay compaction. However, solute mobilization inside the aquitard during clay compaction is generally mistaken for a similar water–rock interaction process in aquifers controlled by microbial-mediated redox reactions. Through a simulation experiment on argillaceous sediment compaction, we tested the currently accepted solute mobilization mechanism and determined that the variation in the mineral structure dominates it. The variation in the mineral structure occurs in low symmetry minerals, such as clay minerals, and is controlled by the sediment moisture content, the liquid-plastic limit, and the effective stress. When the sediment moisture content decreases to below the plastic limit through pore water discharge and compaction, sudden changes in the mineral structure occur, releasing iron and capturing ammonium through variations in the relative position of the Si-O tetrahedrons and isomorphism of similar atoms without the participation of microbial-mediated redox reactions. These results suggest that the biochemical reactivities of organic carbon, iron, and ammonium are sometimes overestimated, i.e., when the role of the physical processes is ignored, in solute mobilization during clay compaction, which warrants more attention and investigation.

New Perspectives on the Marine Carbon Cycle-The Marine Dissolved Organic Matter Reactivity Continuum.

This perspective challenges our current understanding of the marine carbon cycle, including an alternative explanation of bulk 14C-DOM measurements. We propose the adoption of the carbon reactivity continuum concept previously established for lakes and sediments for the oceans using kinetic data and term this the marine DOM reactivity continuum. We need to gain a fundamental understanding of the biogeochemical drivers of surface water DOM concentrations and reactivity, biological carbon pump efficiency, and the autotrophic communities that are the ultimate but variable sources of marine DOM. This perspective is intended to shift our focus to a more inclusive kinetic model and may lead us to a more accurate assessment of the active and dynamic role marine DOM plays in the global carbon cycle. Currently, the kinetic data to establish and validate such a marine DOM reactivity continuum model are still lacking, and their resolution depends on the discovery of new organic tracers that span large differences in reactivity and microbial degradation rates. We may need to refocus our efforts in deciphering the structure and reactivity of marine organic molecules in a kinetic context, including the microbial and physicochemical constraints on molecular reactivity that are present in the deep ocean.

Terrestrial organic carbon age and reactivity in the Yellow River fueling efficient preservation in marine sediments

The Yellow River is one of the largest suppliers of sediments and organic carbon (OC) to the ocean. Previous studies have revealed that OC transported by the Yellow River largely derives from the erosion of the Chinese Loess Plateau, which is dominated by pre-aged soil carbon and could be efficiently preserved in marine sediments. Here, we used ramped oxidation radiocarbon analysis (RPO-14C) to characterize the age and reactivity distribution of OC in two Yellow River suspended sediment samples and six Bohai Sea and Yellow Sea (BS–YS) surface sediments from a transect along the sediment transport pathway. RPO-14C independently characterizes the full spectrum of OC thermal stability and isotope compositions to reveal the source, age and reactivity structure of OC transported by the Yellow River and preserved in Chinese marginal sea sediments. We calculated the activation energy (E) distribution—a proxy for bonding environment and by extension reactivity—which, combined with 14C and stable carbon isotope (δ13C) compositions, reveals OC origin and stability. Our data suggest that 96% of OC in Yellow River suspended sediments is biospheric and weathered petrogenic, while unweathered petrogenic OC only accounts for 4% which is almost an order of magnitude lower than the fossil OC estimates (32%) based on compound specific 14C analysis. RPO data reveal the prevalence of aged biospheric loess OC in the Yellow River. We use δ13C, 14C and RPO-derived activation energy data to quantify the contribution of terrestrial OC to surface sediments in the BS–YS. The resulting estimates of terrestrial OC proto-burial efficiencies yield an average value of 89 ± 30%, revealing overall very high terrestrial OC preservation in the BS–YS. Additionally, and somewhat counter intuitively, we find that the preservation of terrestrial OC decreases with increasing E. This pattern may arise from an enhanced preservation of a pre-aged C4 plants derived fraction of the loess-derived OC associated with secondary clays characterized by smaller grain size and higher surface area. Alternatively, the high E component of the Yellow River OC might comprise partially weathered petrogenic carbon, undergoing further mineralization during transport from rivers to marginal sea sediments via marine organic matter priming.

Supercritical, liquid, and gas CO[formula omitted] reactive transport and carbonate formation in portland cement mortar

In this study, we investigate carbonate formation and reactive transport rate in variably saturated portland cement mortars when high concentrations of gas, liquid, or supercritical CO2 flow through their pore network. X-ray computed tomography completed during CO2 flow is used to quantify the microstructural evolution as the mortar carbonates. After in situ tests, higher resolution scans, thermogravimetric analysis, and desorption isotherm analysis are performed to further quantify microstructural changes. We found that at dry conditions supercritical CO2 moves more rapidly through the pore space and precipitates more carbonates than liquid or gas CO2. However, at 50% degree of saturation (DOS) the CO2 state did not affect the rate of transport in that each specimen exposed to a different CO2 state carbonated within the first hour of CO2 exposure. When the pore space is at 50 or 100% DOS, supercritical CO2 did not react with hydration products more rapidly nor did it result in more carbonate formation during exposure compared to gas or liquid CO2. The amount of Ca(OH)2 that contributes to CaCO3 formation is correlated to the DOS. For the mortar composition analyzed, Ca(OH)2 contributes to approximately 40% of the carbonates formed in the 50% DOS specimens and 15% in the 100% DOS specimens. In other words, as the amount of moisture in the pore space increases, phases other than Ca(OH)2 contribute to more than 50% of the total CaCO3 formed.

Coupled Sorption and Oxidation of Soil Dissolved Organic Matter on Manganese Oxides: Nano/Sub-nanoscale Distribution and Molecular Transformation.

In soil environments, the sequestration and transformation of organic carbon are closely associated with soil minerals. Birnessite (MnO2) is known to strongly interact with soil dissolved organic matter (DOM), but the microscopic distribution and molecular transformation of soil DOM on birnessite are still poorly understood. In this study, the coupled sorption and oxidation of soil DOM on birnessite were investigated at both the microscopic scale and the molecular level. Spherical aberration corrected scanning transmission electron microscopy (Cs-STEM) results revealed, at the nano- to sub-nanoscale, that DOM was located both on the surfaces and within the interflakes or pore spaces of birnessite, and DOM within the interflakes displayed a higher oxidation state than that on the surfaces. Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) results suggested that a portion of phenolic compounds were preferentially sorbed and oxidized, resulting in the formation of compounds with higher oxygen contents and polymeric products. Our Cs-STEM and FT-ICR-MS results highlighted the significance of organo-mineral associations in the microscopic mineral structure for the reactivity of organic carbon and provided the molecular evidence for the transformation of soil DOM by birnessite, which contributed to the understanding of the dynamics of soil dissolved organic carbon.

Highly Reactive Cyclic Carbonates with a Fused Ring toward Functionalizable and Recyclable Polycarbonates.

Monomer design plays an important role in the development of polymers with desired thermal properties and chemical recyclability. Here we prepared a class of seven-membered ring carbonates containing trans-cyclohexyl fused rings. These monomers showed excellent activity for ring-opening polymerization (ROP) with turnover frequency (TOF) up to 6 × 105 h-1 and catalyst loading down to 50 ppm, which yielded high-molecular-weight polycarbonates (Mn up to 673 kg/mol) with great thermostability (Td > 300 °C). Ultimately, the resulting polycarbonates can completely depolymerize into their corresponding cyclic dimers that can repolymerize to synthesize the starting polymers in moderate yields, demonstrating a potential route to achieve chemical recycling. Postfunctionalization of the unsaturated polycarbonate was conducted through cross-linking reaction and "click" reaction under UV irradiation.

Incorporating hollow natural fiber (HNF) to enhance CO2 sequestration and mechanical properties of reactive magnesia cement (RMC)-based composites: Feasibility study

Reactive magnesia cement (RMC) hydrates and carbonates to harden, which can sequestrate CO2 from ambient air. However, the application of RMC-based composites in construction material is still limited by the inadequate CO2 diffusion through the dense microstructure of MgO carbonates. This work for the first time investigates and demonstrates the feasibility of utilizing hollow natural fibers (HNFs) to enhance the carbonation and mechanical properties of RMC. In this study, 2 vol.% sisal or PVA microfibers were added RMC-based matrix to make fiber-reinforced composites. The compressive test shows that addition of sisal fibers significantly enhanced the 14-day compressive strength (10 % CO2 curing) from 20.9 MPa to 39.3 MPa, while PVA fibers only marginally enhanced the strength to 25.0 MPa; the carbonation test of the composites, e.g., phenolphthalein color indication, FTIR, and XPS, shows that the lumens in the natural fibers served as the pathway for CO2 penetration, which significantly increased the carbonation depeth and degree and thus the material strength. The tensile strength of sisal fibers were tested after conditioning in oversaturated Mg(OH)2 or Ca(OH)2 solution, the result shows that the fibers deterioration in RMC-based matrix is minimal, almost neglible compared to that in Portland cement (PC)-based composites. Collectively, these experimental results indicate that RMC and HNF are complementary to each other and can potentially make a new class of sustainable building materials.

Heterogeneous compositions of oxygen-containing functional groups on biochars and their different roles in rhodamine B degradation

The reactivity of pyrogenic carbon has attracted a great deal of research attentions recently. The oxygen-containing structures are rich on the surface of biochars, and involved in accepting and donating electrons during the interactions between biochar and organic contaminants. In this work, the species and content of oxygen-containing functional groups on biochar surface were regulated through chemical modification, and batch sorption/degradation experiments were carried out for rhodamine B (RhB). Based on the comparison of surface functional groups, biochars produced below 200 °C mediated RhB degradation through phenol hydroxyl group, while semiquinone and carboxylic acid groups were the main reaction active sites for biochars produced at higher than 500 °C. Considering that various biochar properties play roles in mediating organics degradation, the strategies in manipulating biochar properties should be carefully considered.

Structure and Reactivity of Residual Carbon from Circulating Fluidized Bed Coal Gasification Fine Ash

Structure and Reactivity of Residual Carbon from Circulating Fluidized Bed Coal Gasification Fine Ash

Efficiency of using peroxide-carbonate compounds in reagent complexes for leaching gold hard to recover from placer

The article deals with the data of theoretical and experimental studies of the processes of activation gold leaching using reactive peroxide carbonate compounds, obtained by electrophotochemical treatment of solutions of initial reagents of the corresponding composition, in the composition of reagent complexes. The obtained results of the experiments on the interaction of various carbonate and peroxide-carbonate compounds with sodium cyanide in the process of mixing activated and non-activated solutions with aqueous cyanide solutions in different order definitely prove that supramolecular percarbonate-cyanide compounds are being formed in them. It has been established that these activated solutions, prepared on the basis of the initial hydrocarbonate ones, contain metastable compounds that provide a higher rate of gold extraction from crude minerals than standard aqueous cyanic solutions of the same initial concentration.

The effect of biodiesel and CeO2 nanoparticle blends on the CRDI diesel engine: A special focus on combustion, particle number, PM2.5 species, organic compound, and gaseous emissions

This study aimed to investigate the effect of biodiesel and CeO2 nanoparticles (NPs) blends on organic carbon (OC) and elemental carbon (EC), organic compounds, size distribution, gaseous emissions, and combustion reactivity from a CRDI diesel engine at the steady-state mode. To ensure that gaseous pollutants do not depend on a filter device, the research engine was allowed to operate without a diesel particulate filter. The nano-additive of 20 ppm was included in various biodiesel blends through the ultrasonication process. Experimental results revealed that the addition of biodiesel in CeO2 NP blends significantly improved the in-cylinder pressure and heat released rate (HRR) of the engine. As for the B15C20 fuel, significant reductions in CO and HC emissions were observed by 32.16% and 45.59%, respectively, with a rise in NOx of 5.97% compared to B0. It was also found that the B0 and B0C20 fuels generate more particles within a diameter size range over 50 nm compared to B10C20 and B15C20 that generate particles of diameter ranging from ∼10 nm to 37 nm. EC-soot was slightly higher compared to OC for all test fuels, which could be explained by the catalytic effect of metals on soot oxidation as a result of the low amount of total PM2.5 mass present. The toxic pollutants such as polycyclic aromatic hydrocarbons (PAHs) and n-alkanes decreases when the ratio of biodiesel increases in CeO2 NPs. This might reduce the effect of cancer and direct eye irritants that cause an allergic response in humans and animals.

Turn-on mode fluorescent diarylethene containing neopentyl substituents that undergoes all-visible-light switching.

This paper presents a strategy for improving the all-visible-light switching response of turn-on mode fluorescent diarylethene derivatives. Introduction of neopentyl or isobutyl substituents at the reactive carbons (2- and 2'-positions) of an oxidized bis(benzothienyl)perfluorocyclopentene derivative, which undergoes both cyclization and cycloreversion reactions upon irradiation with visible light, was effective in increasing the cycloreversion quantum yield by one or two orders of magnitude in comparison with the yield of an ethyl-substituted derivative. Any significant influence on the cyclization and fluorescence quantum yields was not observed by the introduction of neopentyl or isobutyl substituents.

Modeled Emission of Hydroxyl and Ozone Reactivity from Evaporation of Fragrance Mixtures.

Volatile chemical products (VCPs) account for increasing fractions of organic carbon emitted to the atmosphere, particularly in urban areas. Fragrances are potentially reactive components that are added to many VCPs. To better constrain these emissions, 11 commercially available liquid fragrance mixtures were characterized for their composition and their evaporation modeled. Emissions of mass, hydroxyl reactivity, and ozone reactivity were estimated by modeling under four different scenarios. Fragrance compounds were generally less than one-half the mass of fragrance mixtures, with the balance comprised of solvents and plasticizers and unresolved mass thought to be dominated by plasticizers. The results showed that terpenes and terpenoids account for nearly all of the emitted mass and reactivity while only comprising ∼10% w/w on average of the liquid fragrance mixtures. Most of the reactivity is emitted within hours, with ozone reactivity evolving more rapidly than OH reactivity and comprised almost entirely of terpenes. Limonene, a common fragrance constituent, dominates the reactivity of emitted carbon. Generally, 20-40% of the potential hydroxyl reactivity contained in the fragrance mixture does not evaporate on time scales sufficient to have an impact on local or regional air quality.