Concentration Of Functional Groups Research Articles

Dissolved organic matter thiol concentrations determine methylmercury bioavailability across the terrestrial-marine aquatic continuum

The most critical step for methylmercury (MeHg) bioaccumulation in aquatic food webs is phytoplankton uptake of dissolved MeHg. Dissolved organic matter (DOM) has been known to influence MeHg uptake, but the mechanisms have remained unclear. Here we show that the concentration of DOM-associated thiol functional groups (DOM-RSH) varies substantially across contrasting aquatic systems and dictates MeHg speciation and bioavailability to phytoplankton. Across our 20 study sites, DOM-RSH concentrations decrease 40-fold from terrestrial to marine environments whereas dissolved organic carbon (DOC), the typical proxy for MeHg binding sites in DOM, only has a 5-fold decrease. MeHg accumulation into phytoplankton is shown to be directly linked to the concentration of specific MeHg binding sites (DOM-RSH), rather than DOC. Therefore, MeHg bioavailability increases systematically across the terrestrial-marine aquatic continuum as the DOM-RSH concentration decreases. Our results strongly suggest that measuring DOM-RSH concentrations will improve empirical models in phytoplankton uptake studies and will form a refined basis for modeling MeHg incorporation in aquatic food webs under various environmental conditions.

Stabilization of Graphene Oxide Dispersion in Plasma-like Isotonic Solution Containing Aggregating Concentrations of Bivalent Cations.

Four types of GO commercially available aqueous dispersions (with different particle structures) were diluted, sonicated and studied in the presence of BSA and physiological cation concentrations. Nanoparticle populations sizes, electrical conductivity, zeta potential (Zetasizer NanoZS), structure (TEM and CryoTEM), functional groups content (micro titration) and dispersion pH were analyzed in consecutive preparation stages. BSA effectively prevented the aggregation of GO in precipitating concentrations of physiological bivalent cations. The final polydispersity indexes were reduced from 0.66-0.91 to 0.36-0.43. The GO-containing isotonic dispersions were stable with the following Z-ave results: GO1 421.1 nm, GO2 382.6 nm, GO3 440.2 nm and GO4 490.1 nm. The GO behavior was structure-dependent. BSA effectively stabilized four types of GO dispersions in an isotonic dispersion containing aggregating bivalent physiological cations.

Combined biochar and water-retaining agent application increased soil water retention capacity and maize seedling drought resistance in Fluvisols

Global climate change has accelerated the occurrence of agricultural drought events, which threaten food security. Therefore, improvements in the soil water retention capacity (WRC) and crop drought resistance are crucial for promoting the sustainability of the agricultural environment. In this study, we explored the effects of applying biochar and water-retaining agent (WRA) on soil WRC and crop drought resistance in a Fluvisols, along with their potential mechanisms. We applied two types of biochar (based on wheat and maize straw) and two WRAs (polyacrylamide and starch-grafted sodium acrylate) to Fluvisols with different textures, and then evaluated soil water retention and crop drought physiological resistance. The combined biochar and WRA treatment increased the WRC in both the sandy loam and clay loam Fluvisols. Biochar and WRA increased the relative content of soil hydrophilic functional groups. Compared with the control (CK), the combined application of biochar and WRA increased the field capacity, reduced soil water volatilization under drought conditions, and slowed water infiltration into the Fluvisols. The soil WRC was higher with the wheat straw biochar (WBC) treatment than with the maize straw biochar (MBC) treatment. It was also higher with polyacrylamide treatment than with the starch-grafted sodium acrylate treatment. The combined application of biochar and WRA improved crop drought physiological resistance by significantly increasing the maize seedling potassium (K) and soluble sugar contents, increasing antioxidant enzyme activity, and reducing the malondialdehyde (MDA) content. The results indicate that the application of biochar and WRA alleviated drought stress by increasing the soil WRC and improving crop drought resistance in Fluvisols.

Effect of Solvent Treatment on the Composition and Structure of Santanghu Long Flame Coal and Its Rapid Pyrolysis Products.

Easily soluble organic components in Santanghu long flame coal (SLFC) from Hami (Xinjiang, China) were separated by CS2 and acetone mixed solvent (v/v = 1:1) under ultrasonic condition, and the extract residue was stratified by carbon tetrachloride to obtain the light raffinate component (SLFC-L). The effect of solvent treatment on the composition and structure of the coal and its rapid pyrolysis products was analyzed. Solvent treatment can reduce the moisture content in coal from 9.48% to 6.45% and increase the volatile matter from 26.59% to 28.78%, while the macromolecular structure of the coal changed slightly, demonstrating the stability of coal's complex organic structure. Compared with raw coal, the relative contents of oxygen-containing functional groups and aromatic groups in SLFC-L are higher, and the weight loss rates of both SLFC and SLFC-L reached the maximum at about 450 °C. In contrast, the loss rate of SLFC-L is more obvious, being 33.62% higher than that of SLFC. Pyrolysis products from SLFC at 450 °C by Py-GC/MS are mainly aliphatic hydrocarbons and oxygenated compounds, and the relative contents of aliphatic hydrocarbons decreased from 48.48% to 36.13%, while the contents of oxygenates increased from 39.07% to 44.95%. Overall, the composition and functional group in the coal sample were changed after solvent treatment, resulting in a difference in the composition and distribution of its pyrolysis products.

Humic acids on fire? Physico-chemical, thermal, flammability features and extraction process of different humic acids in support of their possible applications

Humic acids (HA) consist in a multitude of heterogeneous organic molecules surviving the biological and chemical degradation of both vegetal and animal biomasses. The great abundance and chemical richness of these residues make their valorisation one of the most promising approaches to move towards a circular economy. However, the heterogeneity of the biomass from which HA are extracted, as well as the production process, significantly affects the nature and the relative content of functional groups (i.e. quinones, phenols and carboxylic and hydroxyl moieties), eventually changing HA reactivity and ultimately determining their application field. Indeed, depending on their properties, these substances can be used as flame retardants in the case of pronounced resilience degree (i.e., absent or low reactivity), or as antioxidant or antimicrobial agents in the case of pronounced reactivity, thanks to their redox behaviour.In this work we investigated the flammable, the thermal and the physico-chemical features of HA extracted from different composted biomasses to identify the reactivity or the resiliency of these moieties. Several techniques, including flammability characterization (LIT and MIE), laser diffraction granulometry, TG, XRD analyses, FTIR spectroscopy on both solid and gaseous phases, and Raman spectroscopy were integrated to investigate the correlation among the safety parameters, the distributions of particle sizes, as well as the thermal, the chemical properties of HA powders and the influence of post-extraction processes on HA final properties.

Effect of demineralization on waste tire pyrolysis char physical, chemical characteristics and combustion characteristics

Waste tire carbon black particles (CBp) are the main pyrolysis products of waste tires (WT), and CBp is difficult to use directly. This work mainly focuses on the physicochemical and combustion characteristics of demineralized CBp (DCBp) to explore the resourceful utilization of CBp resources in large quantities. This work also provides a comprehensive comparison with CBp and other carbon-based solid fuels. The results show that most of the minerals in CBp can be removed by chemical demineralization treatment (Ash content of DCBp <0.11 %). DCBp has a more developed pore structure than CBp. The deashing process affects the degree of loosening and stacking of the graphitic carbon microcrystalline structure, and the relative content of oxygen-containing functional groups in CBp to a minor extent. The deashing process leads to a decrease in the relative strength of the cross-linked stable structure and an increase in the disordered structure of carbon in CBp. The volatile fraction to fixed carbon ratio of DCBp is only 0.0467, and a large number of catalytic alkali metal elements and alkaline earth metal elements are removed in the demineralization process, which makes the early combustion of DCBp more difficult. As the combustion reaction proceeds, the internal pores of the particles are opened, and the micropores and mesopores in DCBp provide a larger surface area for the reaction. In addition, the decrease in the relative strength of the cross-linked stable structure and increases in the disordered structure of carbon can increase the intermolecular collision frequency during the combustion process, thus improving the burnout characteristics of DCBp. The above results indicate that DCBp has the potential to be used as fuel for large-scale resource utilization.

Analisis Sifat Fisis dan Mekanik Biodegradable Foam Berbahan Dasar Selulosa Jerami Padi dan Polivinyl Alcohol

Research has been carried out on analyzing the physical and mechanical properties of biodegradable foam made from rice straw cellulose with a polyvinyl alcohol binding matrix. This study aims to produce a substitute for styrofoam, which is considered not environmentally friendly and harmful to health. The composition of straw fiber and polyvinyl alcohol was varied by the mass ratio of the mixture of rice straw fiber and PVA (%) 40:20%, 30:30%, 20:40%, 50:10%, with the size of the fiber passing through the 80 mesh sieve. The results of the characterization using FT-IR showed that the highest content of functional groups was carbon (C), which corresponds to the content of conventional biofoam, which consists of the elements carbon (C) and hydrogen (H). The highest biofoam tensile strength value is in the comparison fraction (20:40%) of 18.11 MPa. The highest percentage of biofoam water absorption was obtained in the fraction ratio (50:10%) of 0.8928% in the treated sample and 1.1928% in the untreated sample. The percentage of biofoam water content closest to conventional biofoam water content is obtained at a fraction ratio (40:20%) of 0.78%. The highest degradation rate was obtained in samples with a comparative fraction (50:10%) of 0.04237%/day in treated and 0.06403%/day in untreated samples. The results of this study stated that the resulting biofoam did not contain harmful substances. After identifying the functional groups using the FT-IR test, the tensile strength of biofoam still did not meet the SNI 7188.7: 2016 bioplastic standard.

Research on the inhibition characteristics of ultrafine water mist on gas/dust two-phase mixture explosions

Inhibition of water mist on the gas/dust two-phase explosions and its influence factor were studied inside the vessel. The effects of mist and methane concentrations on the pressure and its rise rate, flame propagation characteristics and its temperature were explored. Especially the explosion products were analyzed by the infrared spectroscopy. The weakening effect was revealed based on the corresponding relationship and changing rule of explosion parameters. As the flame developed and changed, the pressure rise showed the same correspondence. However, the corresponding moment was evidently prolonged compared with the case no mist. The mist could effectively inhibit the intensity of mixture explosions, causing a dark-irregular structure in the early stage and accelerating its extinction in the later stage. After the mist concentration increased, the explosion parameter was evidently reduced. As the methane concentration increased (4% ≤ c ≤ 10%), the explosion parameters appeared a trend of firstly rising and then reducing. As c = 6%, the explosion intensity was the greatest. After adding mist, the explosion parameter exhibited the same change regular. And the weakening effect of mist on the weaker flame was more outstanding and was constantly enhanced as the rise of mist concentration. Besides, the mist could effectively inhibit the pyrolysis and combustion reactions of macromolecular functional groups, further leading to evident increase in the functional group content inside the coal dust as the mist concentration increased.

RESEARCH OF PHYSICAL AND CHEMICAL PROPERTIES OF WOOD PULSE ACTIVATED BY HYDRODYNAMIC METHOD

The work studied the effect of mechanical activation, hydrodynamically, on the physico-chemical properties of soft waste from mechanical processing of wood (sawdust). As a result of research, it has been established that during cavitation treatment, the chemical structure of sawdust is transformed, which ensures the production of hydrodynamically activated wood particles with a high content of reactive surface functional groups, which is caused by a change in the ligno-carbohydrate complex. It has been established that as a result of hydrodynamic activation, the amount of difficult-to-hydrolyze polysaccharides is reduced by 37%, while the proportions of easily hydrolyzable substances and substances of phenolic nature increase, respectively, by 12 and 25%. The transformation of the ligno-carbohydrate complex of wood particles during cavitation largely determines the change in the characteristics of their porous structure. An increase in the number of micropores by 1.5 times and large transport pores by 3 times during the cavitation process was established. The results obtained largely prove that the physical and chemical properties of hydrodynamically activated wood particles largely determine the possibility of obtaining non-toxic wood materials with high physical and mechanical properties without piezo-thermal effects.

Preparation and Molecular Structural Characterization of Fulvic Acid Extracted from Different Types of Peat.

Humic acid is a type of polymeric, organic weak acid mixture with a core aromatic structure and main-component oxygen-containing functional group. Fulvic acid is a type of humic substance that can be dissolved in acid, alkali, or water. This study discusses the influence of different peptides on the molecular structure of fulvic acid, which was extracted from herbaceous, woody, and mossy peats using alkaline dissolution and acid precipitation methods. Analyses using infrared, UV-Vis, 13C-NMR, and X-ray photoelectron spectroscopies, as well as X-ray diffraction (XRD), were conducted to compare the effects of different peat types on the content and molecular structure of fulvic acid. The woody peat fulvic acid content was the highest among all peat fulvic acids (0.38%). However, the yield of fulvic acid from herbaceous peat was the highest (2.53%). Herbaceous peat fulvic acid contains significant quantities of carbonyl, amino, methylene, carboxyl, and phenolic hydroxyl groups and ether bonds. Woody peat fulvic acid contains carbonyl and methoxy groups, benzenes, aromatic carbons, aromatic ethers, and phenols. The degree of aromatization of woody peat fulvic acid was the highest. Mossy peat fulvic acid contains high levels of hydroxy, methyl, methylene, and phenol groups and aromatic ethers. The structural differences in fulvic acids in the different types of peat were primarily manifested in the content of functional groups, with little influence from the types of functional groups. XRD analysis of the different peats revealed that their structures all comprised benzene rings. However, mossy peat contained more C=O and -COOH groups, whereas herbaceous peat contained more C-O groups.

Comparative study of calcium phosphate deposition on nanotubular and sandblasted large grit acid-etched titanium substrates

Titanium and its alloys are widely used in biomedical applications due to their excellent properties such as biocompatibility, good corrosion resistance, low density, and high elastic modulus. However, their bioinert behavior often results in prolonged osseointegration periods. Therefore, surface modification techniques have been investigated to improve the bioactivity of titanium. In this study, the morphological and chemical properties of sandblasted, large grit, acid-etched (SLA), and nanotubular (NT) surfaces were investigated before and after the deposition of calcium phosphate (CaP) compounds by a chemical conversion method. Various techniques were used to characterize these surface modifications applied to titanium, including microhardness tests, atomic force microscopy, water contact angle measurements, scanning electron microscopy, grazing angle X-ray diffraction, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The results showed that the SLA surface was rougher than the NT surface, and the hydrophilic behavior of both samples was enhanced after immersion in NaOH and chemical conversion. The higher concentration of Ca, P, and phosphate functional groups on the NT surface indicates that a greater amount of CaP was deposited on this surface. The CaP-modified NT surface exhibited a favorable surface topography and chemical composition, which may be advantageous for use in titanium dental implants. In addition, in vitro assays showed that the samples prepared here are promising candidates for biomedical use, as they exhibited high cell viability, non-toxicity, and osteogenic properties.

Influences of Evolution of Pore Structures in Tectonic Coal under Acidization on Methane Desorption.

Experiments on corrosion reactions of pulverized coal with monomeric and polymeric (mixed) acid solutions reveal that monomeric acids are listed in a descending order as HF, HCl, and CH3COOH according to their corrosion effects on tectonic coal collected in Faer Coal Mine (Liupanshui City, Guizhou Province, China). In addition, the optimal mixing ratio of mixed acids is 6% HCl + 6% HF + 3% CH3COOH + 2% KCl. The mineral grains filled in pores in coal samples treated with mixed acid solutions are dissolved, so the porosity increases. The volumes of transition pores and mesopores are obviously affected by acidization, and some transition pores are transformed into mesopores and macropores to form dissolved pores. At the same time, inkbottle-shaped pores reduce, while slit pores or open pores increase. The coal samples after acidization show a higher aromatization degree and an increased relative content of oxygen-containing functional groups, with a generally lower hydroxyl content, so the methane (CH4) adsorption capacity of coal declines, which promotes CH4 desorption. The control effect of pore structures after acidization reactions on CH4 desorption was revealed from perspectives of the diffusion coefficient (Kn), adsorption volume (ω), average pore-throat ratio (PT), and average sinuosity (τav). That is, CH4 molecules in tectonic coal after acidization turn from Knudsen diffusion to transitional diffusion, the adsorption volume of CH4 molecules shrinks, the average pore-throat ratio decreases, and the average sinuosity reduces, which promotes CH4 desorption from tectonic coal.

A computational investigation on the roles of binding affinity and pore size on CO2/N2 overall adsorption process performance of MOFs through modifying MIL-101 structure

To develop an appropriate metal-organic framework to capture CO2 from dry flue gas, understanding the roles of structural modifications, location of primary adsorption sites and underlying adsorption mechanisms is crucial. Herein, effects of type, position and concentration of nitrogen-containing functional groups and C/N-substituted ligands are investigated on overall CO2/N2 adsorption process performance and mechanism of pristine and metal-substituted MIL-101 MOFs. In this investigation, density functional theory computations, grand-canonical Monte-Carlo, and molecular dynamics simulations are applied. Taguchi-based overall evaluation criteria objective function is also used to assess the overall adsorption performances of these MIL-101 MOFs in terms of CO2 uptake capacity, CO2/N2 selectivity, isosteric heat of adsorption and mass transfer resistance. The PBE/DZVP computations resulted in the CO2-framework binding energies ranging from −3.85 to −21.01 kJ/mol implying an acid-base type of physisorption. A correlation is introduced to estimate the CO2 uptake capacity from binding affinity and pore diameter of these MIL-101 MOFs. Mechanistic investigations show that to enhance CO2 uptake capacity and CO2/N2 selectivity, functionalization of the linker ligands is more successful than functionalization of the open metal sites having strong interactions with CO2 molecules. Results also showed that the best possible scenario to improve the overall adsorption process performance of MIL-101 is to substitute the C atom(s) of the BDC ligands with the N atom(s), regardless of the central metal atom type. The comprehensive molecular design approach introduced in this work can be used as a methodology by scientists for the development of new MOFs for practical CO2 capture applications.

Spontaneous Combustion Characteristics of Activated Carbon Modified via Liquid Phase Impregnation during Drying.

Spontaneous combustion characteristics are important issues for the safe operation of the wet-modified activated carbon drying process. The spontaneous combustion characteristics of activated carbon modified via liquid phase impregnation were fully investigated in this study. The modified activated carbon was prepared using columnar activated carbon and 4-amino-1,2-butanediol solution. Physical properties and surface functional group analyses were performed for activated carbon before and after modification. The ignition temperature of activated carbon before and after modification was then characterized using the methods of GB/T20450-2006, thermogravimetry-derivative thermogravimetry (TG-DTG), and TG-mass spectrometry (TG-MS). At the same time, the activation energy of activated carbon before and after modification was calculated by using thermodynamic analysis. Furthermore, a new self-designed test platform was introduced to investigate the spontaneous combustion characteristics of wet-modified activated carbon under the drying temperatures of 150, 175, 180, and 210 °C. The results show that the specific surface area of Brunauer, Emmett, and Teller (BET) is decreased by 368 m2·g-1, the total volume of pore size is decreased by 0.17 cm3·g-1, and the content of oxygen-containing functional groups is decreased by 0.071 mmol/g compared with row activated carbon. The ignition temperatures of the sample before modification characterized by the three methods are 483, 596, and 599 °C, respectively. The ignition temperatures of the sample after modification are 489, 607, and 611 °C, respectively. The activation energy of the modified activated carbon is increased by 35 kJ/mol compared to the original activated carbon. It is concluded that the temperature that triggers the modified activated carbon combustion during the drying process is between 175 and 180 °C, and the heat is mainly gathered at the longitudinal center of the combustion chamber through the investigation of spontaneous combustion experiments. The results in this study can contribute to safe production to prevent combustion in the process of modifying activated carbon during the drying process.

Eco-friendly triboelectric nanogenerator based on degradable rape straw powder for monitoring human movement

Green energy from the surrounding environment has great potential for reducing environmental pollution and sustainable development. Triboelectric nanogenerators (TENGs) are of great interest as they can easily harvest mechanical energy from the environment. Here, we present a triboelectric nanogenerator (RS-TENG) based on rape straw (RS), which was developed from a film composed of waste RS and polyvinyl alcohol (PVA). Due to the high content of carbonyl, hydroxyl and amino acid functional groups in RS, the ability of RS/PVA to lose electrons is increased. The proposed RS-TENG device with a size of 6.25 cm2 exhibits open circuit voltage (78 V), short circuit current (5.3 μA) performance under uniform external stress at a frequency of 3.5 Hz and 10 N in the cylinder motor. 104.5 μW was obtained with a load resistance of 25 MΩ. Results obtained from degradability tests revealed that the RS/PVA film was able to degrade over a period of 30 d (In PBS solution). The RS-TENG produces a significantly high current signal under conditions of finger bending, elbow movements, and foot tapping. Practical tests of the RS-TENG have shown that it is a promising sensing device that will be widely used in the future.

High Performance Metal Oxide–Reduced Graphene Oxide Electrocatalyst for All Vanadium Redox Flow Batteries

Vanadium redox flow battery (VRFB) is one of the most favorable technologies for large-scale energy storage applications owing to its numerous gorgeous features, such as flexible design, high safety, and long cycle life. In this study, metal oxide (MOx)–reduced graphene oxide (rGO) nanohybrid was successfully synthesized via a facile hydrothermal route followed by annealing and employed as an electrocatalyst to modify the graphite felt (GF) electrode material for all-vanadium redox flow batteries (VRFBs) application. The as-synthesized MOx–rGO nanohybrid reveals good electrocatalytic reversibility and higher anodic and cathodic peak current density for V3+/V2+ and VO2 +/VO2+ redox couples compared with those of rGO and MOx samples. The voltage efficiency of the VRFB using MOx–rGO nanohybrid reaches 84% at 80 mA cm−2, which is 4% and 13% higher than the VRFBs using the rGO-loaded GF electrode and the pristine GF electrode, respectively. It still shows the voltage efficiencies of 76% and 70% at relatively high current densities of 120 mA cm−2 and 140 mA cm−2, respectively, but other samples have no effective discharge. This improvement is accredited to the uniform distribution of MOx nanoparticles on the rGO surfaces, avoiding the restacking of the rGO sheets and conquering nanoparticles aggregation, which might boost the effective active surface area and improve mass transport at the electrode-electrolyte interfaces. Besides, the existence of oxygen vacancies on MOx, the high electrical conductivity of rGO, and the high content of oxygen functional groups play the prodigious roles to facilitate the reversibility of vanadium ions redox reactions.

A Study of V(IV/V) and V(II/III) Reactions on Carbon Based Electrodes

The vanadium redox flow battery (VRFB) is one of the most promising energy storage technologies for large scale commercialization. Carbon based electrodes, such as carbon felts or carbon paper, are used for V(II/III) and V(IV/V) reactions. To improve the vanadium redox reaction kinetics, the carbon electrodes are usually activated by a variety of methods such as thermal treatment, heteroatom doping, catalyst incorporation etc. [1] It is generally considered that surface functional group such as C–OH, C=O play an important role in vanadium redox reaction [1-6]. Even though there are reports showing higher surface functional group content e.g. total C–O content leads to improved vanadium redox reaction kinetics [2-6], qualitative correlation of the surface property of the carbon materials and the vanadium redox reaction is not reported. There is a need for fundamental understanding of the surface properties of the carbon electrodes and their relation with the reaction kinetics, including the key parameters that determine them.In this work, using cyclic voltammetry (CV), we studied the surface properties of a variety of carbon based electrodes (glassy carbon (GC), edge plane pyrolytic graphite, base plane pyrolitic graphite, graphite (from Pine Research, called graphite-Pine thereafter), graphite rod, and H2SO4 soaked graphite rod), and the V(II/III) and V(IV/V) reaction kinetics on these electrodes. The goal of soaking the graphite rod electrode in H2SO4 is to activate the electrode and make it comparable to the carbon felt electrode [1]. XPS was also used to analyze the functional group. The relationship between the surface properties and the reaction kinetic parameters was analyzed.Fig. 1 compares the cyclic voltammograms (CV) of the edge plane, basal plane graphite and GC electrodes in 2 M H2SO4. Two redox couples are observed, ascribed to C=O and COOH group redox peak respectively [7]. On basal plane electrode, these two redox peaks are less significant, and an extra reduction peak is observed at 0.24 V due to the C–OH reduction. On the GC electrode, the C=O redox peak is still discernable but the COOH redox peak is almost undetectable. A capacitance region appears between 0.6 – 0.75 V vs Ag/AgCl for all these electrodes. Similar features are observed with the graphite-Pine, graphite rod and H2SO4 soaked graphite rod electrodes with significantly enhanced redox peaks and larger capacitance. The H2SO4 soaked graphite rod electrode presents the highest surface functional group density and capacitance. XPS also shows that the H2SO4 soaked graphite rod electrode has the highest total C–O content.CV of V(IV/V) and V(II/III) were measured using these electrodes at different scan rates. Fig. 2 shows the CV of V(IV/V) reaction on these electrodes. The three graphite rod electrodes show better reversible feature than the edge plane, basal plane and GC electrodes. Diffusion coefficient, transfer coefficient and reaction rate constant were obtained from the CVs. The diffusion coefficient follows the sequence of soaked graphite rod > graphite rod > Graphite-Pine > Edge plane > GC > basal plane electrode. The transfer coefficient and reaction rate constant are also different for these electrodes. Similarly, the diffusion coefficient, transfer coefficient and reaction rate constant are obtained for the V(II/III) reaction. The diffusion coefficient and reaction rate constant for the V(II/III) reaction are smaller than that for the V(IV/V) reaction on the corresponding electrodes. For both V(IV/V) and V(II/III), a linear relationship was found for diffusion coefficient versus the logarithm of capacitance and C=O group functional group. Higher value of log(capacitance) and log(C=O density) leads to larger diffusion coefficient. However, there is no clear relationship between transfer coefficient, reaction rate constant vs capacitance or C=O density. It seems that the capacitance and C=O functional group density are the importance parameters determining the vanadium redox reaction kinetics.References He, Y. Lv, T. Zhang, Y. Zhu, L. Dai, S. Yao., W. Zhu, L. Wang, Chem. Eng. J., 427 (2022) 131680Zhang, J. Xia, Z. Li, H. Zhou, L. Liu, Z. Wu, X. Qiu, Electrochim. Acta 89 (2013) 429– 435Liu, L. Yang, Q. Xu, C. Yan, RSC Adv., 2014, 4, 55666Choi, H. Noh, S. Kim, R. Kim, R. Kim, J. Lee, J. Heo, H.-T. Kim, J. Energy Storage, 21 (2019) 321 – 327Eifert, R. Banerjee, Z. Jusys, R. Zeis, J. Electrochem. Soc., 165 (2018) A2577 – A2586Leuna, D. Priyadarshani, A. K. Tripathi, M. Neergat, J. Electroanal. Chem., 878 (2020) 114590K. Singh, M. Pahlevaninezhad, N. Yasri, E. P. L. Roberts, ChemSusChem 2021, 14, 2100–2111 Figure 1

The catalytic recycle and deactivation kinetics of Zn/CMK-3 catalyst for acetylene acetoxylation

Mesoporous carbon material CMK-3 was synthesized by pyrolysis and acid washing using sucrose and SBA-15 as precursors. It served as an excellent support for the adsorption of zinc acetate in acetylene acetoxylation. The content of the oxygen-containing functional group on the surface of CMK-3 was controlled by adjusting the calcination temperature, it was found that the specific activity of Zn/CMK-3 increased with carbonyl content of CMK-3 support. Zn/CMK-3 was directly blew by C2H2 without the presence of acetic acid, vinyl acetate (VAc) was still generated even if there was no external acetic acid supply, indicating that the acetate (CH3COO−) in VAc was from the zinc acetate component. XRD, TEM, TG and XPS characterizations displayed that the catalytic recycles of acetylene acetoxylation was that zinc acetate changed to ZnO after the adsorption of C2H2, and then ZnO adsorbed the acetic acid to become zinc acetate. The deactivation kinetics of Zn/CMK-3 catalyst was proposed, catalyst deactivation was caused through one-center adsorption of feed species, and the loss of the active Zn component was the main reason for the deactivation of Zn/CMK-3 catalyst.

Stable and highly efficient HMDS terminated m-Cresol inhibitor for inhibiting coal spontaneous combustion

A stable and highly efficient 1, 1, 3, 3, 3-hexamethyldisilazane (HMDS) terminated m-Cresol inhibitor was synthesized based on the protection-deprotection strategy. The inhibitory effect of HMDS terminated m-Cresol inhibitor on spontaneous combustion of lignite was explored through temperature-programmed oxidation tests, in-situ infrared analysis and thermogravimetric analysis. Results show that, the oxidation of active phenolic hydroxyl groups in the m-Cresol inhibitor can be hindered by the protection of HMDS. After encountering coal, the HMDS terminated inhibitor can be gradually deprotected to regenerate the m-Cresol inhibitor that contains massive active phenolic hydroxyl groups, thus improving the chemical inhibition efficiency of coal spontaneous combustion. For the coal sample inhibited with HMDS terminated m-Cresol inhibitor, the initial contents of the active functional groups are lower and more stable during heating, and the inhibition rate reaches 70% at 130 °C. Moreover, the crossing-point temperature rises by 32.4 °C–181.2 °C. The activation energy increases by 11 kJ/mol and 18 kJ/mol at below and above 130 °C respectively. The peak temperature at maximum weight loss rate rises by 65 °C–431.2 °C, and the corresponding residual carbon rate increased by 31.3%–61.6%. The inhibition mechanism of the HMDS terminated m-Cresol inhibitor on coal spontaneous combustion was deduced.

Influence of Long-Term Immersion in Water at Different Temperatures on Spontaneous Combustion Characteristics of Coal.

The effect of hydrothermal coupling on the risk of spontaneous combustion of coal (SCC) soaked at different water temperatures was studied. The results showed that the porosity and permeability of coal increased significantly after immersion in water at different temperatures. The increase at a water temperature of 30 °C was the largest, the porosity was 22.77% higher, and the permeability was 3.44 times that of raw coal. The relative content of oxygen-containing functional groups, aliphatic functional groups, and hydroxyl functional groups reached 1.8-4.5, 1.1-4.4, and 0.7-1.48 times that of raw coal after soaking in water at different temperatures. The increase ratio of functional groups is the largest under the water temperature of 30 °C. The activation energy of coal samples soaked at water temperatures of 30 and 45 °C decreased by 9.4 and 2.9%, respectively. Under the condition that the coal sample temperature was lower than 110 °C, the highest oxygen consumption rate and heat release rate were coal samples soaked at water temperatures of 30 °C, and the lowest was raw coal. When the coal temperature was higher than 170 °C, all coal samples soaked in different water temperatures are higher than that of raw coal, and the water temperature of 30 °C is the highest. The risk of spontaneous combustion of coal is highest after long-term soaking at 30 °C water.