Addition Of Salt Research Articles

Metal-Mediated Chlorine Transfer for Molten Salt-Driven Thermodynamic Change on Silicon Production.

The development of silicon (Si) material poses a great challenge with profound technological advancements for semiconductors, photo/photoelectric systems, solar cells, and secondary batteries. Typically, Si production involves the thermochemical reduction of silicon oxides, where chloride salt additives help properly revamp the reaction mechanism. Herein, we unravel the chemical principles of molten AlCl3 salt in metallothermic reduction. Above its melting temperature (Tm ≈ 192°C), three AlCl3 molecules coordinate with each metal (M) atom (e.g., conventional Al andMg, or even thermodynamically unfeasible Zn) to form metal-AlCl3 complexes, M(AlCl3)3. In the molten AlCl3 salt media, all complexes directly lead to the universal formation of AlOCl byproduct and as-reduced Si spheres through internal Cl* transfer during the reduction reaction. Intriguingly, highly oxophilic metal (i.e., Mg) establishes additional energetic shortcuts in reaction pathways, where AlCl3 directly detaches an oxygen atom, accompanied by strong metal-oxygen interactions and Cl* transfer within the same complex. Moreover, the thermodynamic stability of the metal-AlCl3 complex residue (MAl2Cl8) and the microstructure of post-treated Si do change according to the metal choice, imparting disparate physicochemical properties for Si. This work offers insights into the scalable production of tailored Si materials for industrial applications, along with cost-effective operations at 250°C.

Mechanisms of Low Temperature Thickening of Different Materials for Deepwater Water-Based Drilling Fluids

During deepwater drilling, the low mudline temperatures and narrow safe density window pose serious challenges to the safe and efficient performance of deepwater water-based drilling fluids. Low temperatures can lead to physical and chemical changes in the components of water-based drilling fluids and the behavior of low temperature gelation. As a coarse dispersion system, water-based drilling fluid has a complex composition of dispersed phase and dispersing medium. Further clarification of low temperature gelation would be helpful in developing technical approaches to enhance the flat rheology performance of deepwater water-based drilling fluids. In this paper, different components are separated in order to comprehensively analyze the gelation behavior of different materials in water-based drilling fluids at low temperatures. In the first place, the rheological and hydrodynamic radius alterations of inorganic salts, bentonite, and additives in aqueous solutions were examined at low temperatures. The effects of inorganic salts, bentonite, and additives on the purified water system were investigated at low (4 °C)–normal (25 °C)–high (75 °C) temperatures. The low temperature gelation of different materials in pure water systems are fully clarified. The mud containing 4% bentonite with weak low temperature gelation commonly used in deepwater water-based drilling fluids was selected as the basic test system. Inorganic salts, additives, and solid-phase materials were added to the mud containing 4% bentonite. The effects of the interactions between different materials and bentonite particles on the low temperature gelation behavior of mud were analyzed. The higher the bentonite dosage, the stronger the low temperature gelation behavior of mud. The higher the addition of inorganic salts, the more serious the low temperature gelation behavior of mud. Inorganic salts should be avoided as much as possible to add too much. The low temperature gelation behavior of mud with low-viscosity additives is weak. However, the viscosity of mud with high-viscosity additives has a small change in viscosity with increasing temperature. The low temperature gelation of mud with the addition of solid-phase particulate materials with reactive groups on the surface is strong, and the low temperature gelation with the addition of inert particles is weak. This paper elucidates the low temperature gelation mechanism of bentonite, inorganic salts, additives, and solid-phase materials in deepwater water-based drilling fluids. The conclusion can also be used to guide the construction of a drilling fluid system, which is of great significance for the research and development of deepwater water-based drilling fluid additives and the safe and efficient performance of deepwater drilling fluids.

Application of static headspace GC–MS for detection of residual trichloroethylene and toluene solvents in β-cyclodextrin

Trichloroethylene (TCE) and toluene (TOL), which have been used for β-cyclodextrin (β-CD) synthesis, need to be properly inspected for quality assurance and safety of food additives. In this study, a combination of static headspace separation and gas chromatography-mass spectrometry (SH-GC–MS) was optimized for detecting those residual solvents in β-CD in the compatible safe and green chemistry. Sample injection amount for SH was determined to 100 μL with the minimum volume that provides the suitable accuracy. For the safety and accuracy of analysis, equilibrium conditions of solvents were considered and selected to 60 °C for 45 min. Also, we found that the addition of salt, like CaCl2, adversely affected recovery efficiency. Under the proposed condition, coefficients of determination (R2) of both TCE and TOL were more than 0.99 between 0.05–10 mg/L concentrations. Recovery rates and relative standard deviation (RSD) of tested solvents were between 91.7–106.0 % and 1.0–8.9 %, respectively. From validation with two commercial β-CDs, both TCE and TOL presented lower than regulatory limits for food additives (1 ppm) with satisfactory RSDs (<20 %). Collectively, the proposed analytical methods can contribute to safer, simpler, and greener inspection of residual chemicals present in foods for public health.

Cysteine-coated Magnetite Nanoparticles for the Removal of Carmoisine Edible Dye from Aqueous Medium.

In this study, cysteine-coated magnetite nanoparticles (Fe3O4@Cys MNPs) were synthesized by chemical method and applied as a recoverable and efficient adsorbent for the removal of carmoisine dye from aqueous solutions. The synthesized MNPs were characterized by FT-IR, XRD, SEM, and TEM studies. The effect of various experimental parameters on the dye removal efficiency was studied using Taguchi orthogonal array design (L16 array). Under the optimum conditions (pH = 2, stirring time = 30 min, adsorbent amount = 0.1 g and without salt addition), more than 92% of carmoisine was removed from the aqueous solutions. The kinetic studies showed rapid adsorption dynamics by a pseudo second-order kinetic model, confirming that diffusion controls the adsorption process. Dye adsorption equilibrium data were fitted well to the Freundlich isotherm, and the synthesized adsorbent showed high removal efficiency. The obtained results showed that the synthesized MNPs act as a reusable adsorbent for carmoisine removal with an easy procedure.

Synergistic flocculation performance and underlying mechanisms of a novel bioflocculant flocan with coagulant iron salt

Flocculation is an integral part of wastewater treatment units and various flocculants have been employed to strengthen the flocs formation and produce clean water. Natural polysaccharides have been employed as eco-friendly bioflocculants for the treatment of turbid water. In the study, flocan is a named exopolysaccharide (EPS) isolated from a coastal mudflat with a high yield of 8.3g/L. Flocan consisted of glucose, mannose, galactose, and glucuronic acid in a molar ratio of 2:3:1:1, along with pyruvate modifications. As the bioflocculant agent, flocan exhibited more than 85% removal efficiency in kaolin suspension in terms of a concentration of 10mg/L at pH 3. The addition of iron salts with flocan showed high flocculation efficiency in acidic kaolin suspension (99.37%) and acidic coal wastewater (99.44%). The carboxyl/hydroxyl groups and branched structure of flocan provided ionic interactions and promoted higher bridging between bioflocculants and negatively charged particles. Coagulants FeCl3 enhanced the flocculating activity via neutralizing and stabilizing the residual negative charge of functional groups. Treatment with EDTA decreased the ionic interactions and reversed the flocculation significantly. Compared with the current bioflocculants, the superior production, low dosage, and excellent flocculating activity implied that flocan showed great potential in acidic wastewater treatment industrially. The coagulants/bioflocculants combination appears to be a promising and sustainable technology for wastewater flocculation.

Nanoarchitectonics of SiO2 composite hydrogel in inorganic solution: Simulation and experimental analysis

Polyacrylamide hydrogels are widely used in medicine, petrochemical, water treatment and other fields, among which polyacrylamide hydrogels play an important role in oilfield Profile control and water shutoff and enhanced oil recovery, however, there are few reports on the effect of different inorganic salt solutions on the properties of SiO2 composite hydrogel. In this paper, a cross-linked SiO2 composite hydrogel was constructed using Materials Studio software for the first time, and its structure and properties in inorganic salt aqueous solutions were studied. The results show that the addition of inorganic salts can weaken the interaction between water molecules and hydrogels, and this effect is minimal in calcium chloride solution. The radial distribution function shows that there are strong hydrogen bonds between nitrogen and oxygen atoms in the amide group and water molecules, but there are van der Waals forces between oxygen and water atoms, and the addition of inorganic salts will enhance the hydration of nitrogen atoms in the amide group and the interaction between monovalent ions and amide groups was greater than that between bivalent ions. At the same time, the addition of inorganic salts can also enhance the diffusion ability of water molecules and the fluidity of polymer chains. Among the four inorganic salt solutions, Calcium chloride solution has the least effect on the polymer chain and the cross-linked SiO2 composite hydrogel has the best expansion performance in calcium chloride solution, which is basically consistent with the experimental results, this has a potential application prospect in the reservoir with high calcium content for profile control and water plugging and enhanced oil recovery.

Coordinated Anions Tune Z-Type Ligand Displacement from Colloidal CdSe and InP Nanocrystal Surfaces.

Neutral metal salts coordinate to the surfaces of colloidal semiconductor nanocrystals (NCs) by acting as Lewis acid acceptors for the NC surface anions. This ligand coordination has been associated with increased emission due to the passivation of surface hole traps. Here, variation of the anionic ligands of metal salts is used to study anion effects on metal complex Lewis acidity and surface coordination at CdSe and InP NCs. To resolve dynamic ligand exchange processes, the tetracarbonylcobaltate anion, [Co(CO)4]-, is used as a monoanionic ligand for which IR spectroscopy can readily identify displacement of neutral M[Co(CO)4]x species (M = Cd or In; x = 2 or 3, respectively) upon addition of neutral donor ligands. Notably, although Cd[Co(CO)4]2 is more Lewis acidic than cadmium oleate, the former is more readily displaced from the NC surfaces. Lewis acidity and X-type anion exchange are, therefore, factors to be considered when performing postsynthetic addition of metal salts for NC photoluminescence emission enhancement.

Large-Scale Production of Nanotube Silicon for Lithium-Ion Batteries

Silicon’s relatively high energy density in comparison to the more common anode material, graphite (3580 mA h g-1 for silicon compared to 371 mA h g-1 for graphite) has made silicon an intriguing anode material for lithium-ion batteries. However, during lithiation, the volume of silicon increases by approximately 300% causing irreversible capacity loss. During the initial charging of an anode, a solid electrolyte interface (SEI) forms on the surface of the anode. The formation of the SEI consumes lithium, resulting in irreversible capacity loss. The large volume expansion of silicon can break the SEI layer. This results in a new SEI layer needing to be formed and further irreversible capacity loss. In addition, the expansion of the silicon particles can lead to silicon particles being isolated from the anode where they can no longer participate in the charging and discharging process, lowering the capacity of the anode. To accommodate for this large volume expansion, silicon nanoparticles on the scale of 50 microns are often used to accommodate for the large volume expansion and help retain capacity. Silicon nanotubes provide additional benefits such as increased structural stability, faster lithium-ion diffusion, and greater electrical conductivity than silicon nanoparticles. This work details a process to produce silicon nanotubes from halloysite on a large scale. Halloysite is an alumina-silica-based structure composed of natural nanotubes. Silicon can be obtained from halloysite by etching off the alumina components and further reducing the silica to silicon through a magnesiothermic reduction. However, both the etching step and reducing step are very exothermic. If the heat transfer is not controlled correctly, the heat released during these reactions can destroy the natural tube structure. The reaction temperature is dependent on a variety of variables including: reactor temperature, ramp rate, addition of salts, and quantity of reactants. The processes and parameters used to successfully manage the heat released as a part of scale up this process are described. BET and SEM imaging were used to determine the surface area and structure of the produced silicon. In addition, the electrochemical performance of the silicon was tested and investigated in patch cells. Figure 1

Influence of salt and temperature on the rheological and filtration properties of cellulose Nanofiber/bentonite water-based drilling fluids

Water-based drilling fluids (WBDFs) are popular due to their lower cost and superior environmental friendliness. The high thermal stability, high aspect ratio, and fiber-like structure of cellulose nanofibers (CNFs) have made them viable candidates for rheology and filtration modification in bentonite WBDFs (BT-WBDFs), because they can produce high levels of hydration and entanglement when dispersed in water, even at very low concentrations under harsh drilling condition. However, the rheology and filtration performance of CNF/BT-WBDFs in high temperature and high saline conditions remains largely unexplored. Herein, the influence of high temperature and high salt content on the rheological and filtration properties of CNF/BT-WBDFs was investigated. Two types of CNFs, i.e., TEMPO-mediated oxidized CNFs (T-CNFs) and mechanically disintegrated CNFs (M-CNFs) were applied. It was observed that the M-CNFs exhibited more effectiveness in enhancing the rheological properties of BT-WBDFs, while T-CNFs demonstrated superior filtration-reducing properties of BT-WBDFs. M-CNFs often exhibit a highly branched and tangled network, resulting in superior rheological properties; whereas the presence of more negative charge on the surface of T-CNFs enhanced the electrostatic repulsion with bentonite particles, preventing bentonite from flocculating or aggregating, resulting in reduced fluid loss. Furthermore, the T-CNF/BT-WBDFs showed better resistance to salt contamination compared to hot rolling, whereas the M-CNF/BT-WBDFs demonstrated better defense against hot rolling than salt contamination. However, the addition of salt in combination with high-temperature hot rolling severely affected the rheological properties as well as the filtration-reducing capabilities of both T-CNF/BT- and M-CNF/BT-WBDFs. The study highlighted the importance of CNF types on the rheological and filtration properties of WBDFs under high temperature and saline conditions, providing valuable insights for the potential application of CNFs in temperature-resistant and salt-tolerant drilling fluids.

Reduction of 4‐Nitrophenol Catalyzed by Gold Nanoclusters with Aggregation‐Induced‐Emission: Emission Intensity Correlated Activity and Mechanistic Exploration

AbstractThiolate‐protected Au nanoclusters (NCs) have developed as a promising class of model catalysts to achieve fundamental understanding of metal nanocatalysis. Whereas, the packing mode of peripheral ligand on metal core is changeful in the reaction medium and show elusive impact on catalytic activity. In this work, using glutathione (GSH) protected Au NCs (Au@GSH NCs) with aggregation‐induced‐emission (AIE) characteristics as model catalyst for the hydrogenation of 4‐nitrophenol (4‐NP), photoluminescence (PL) intensity correlated catalytic activity of Au@GSH NCs was successfully mediated by the addition of Ag+ in the preparation or poor solvent in the reaction medium, showing a relationship of “as one falls, another rises.” Au NCs with intense PL implied a dense packing of peripheral ligand, which hampered the accessibility of active site and thus exhibited slowest catalytic reaction kinetics of the reduction of 4‐NP and vice versa. Based on this methodology, a case study of the effect of salt additives on the catalytic activity is carried out, different mechanisms are distinguished by the change in the PL intensity, and with the combination of diagnostic deuterium isotope experiments, it has been demonstrated that the proton from water solvent is involved in the reaction and that the proton transfer process is the rate‐determining step, the contribution of ionic additives to the hydrogen bonding network determines their effect on the reaction kinetics. The correlation between PL intensity and catalytic activity of Au NCs could provide an efficient way to design highly active Au NC catalysts and give a new insight to understand the unique optoelectronic properties of Au NCs and reaction mechanism.

Expanding the Analytical Toolbox for the Nondenaturing Analysis of siRNAs with Salt-Mediated Ion-Pair Reversed-Phase Liquid Chromatography.

Short interfering RNA (siRNA) represents a rapidly expanding class of marketed oligonucleotide therapeutics. Due to its double-stranded nature, the characterization of siRNA is twofold: (i) at the single-strand (denaturing) level for impurity profiling and (ii) at the intact (nondenaturing) level to confirm duplex formation and quantify excess single strands (including single strand-derived impurities). While denaturing analysis can be carried out using conventional ion-pair reversed-phase liquid chromatography (IP-RPLC), nondenaturing characterization of siRNA is a significantly less straightforward task. Typical IP-RPLC conditions have an intrinsic denaturing effect on siRNA, thereby limiting the development of viable approaches for the intact duplex analysis. In this study, we demonstrate, through the design of experiments of siRNA melting temperatures and chromatography analyses, that the simple addition of salts, such as phosphate-buffered saline and ammonium acetate, to eluents enhances the suitability of IP-RPLC for the nondenaturing analysis of siRNA during both UV- and mass spectrometry-based analysis. This work represents a milestone in overcoming the challenges associated with nondenaturing analysis of siRNAs by IP-RPLC and offers a fresh angle for exploring IP-RPLC of siRNAs.

Raman Quantitative Measurement on the Cl− Molarity of H2O-NaCl-CO2 System: Application to Fluid Inclusions

In this study, Raman spectroscopy is applied to determine the salinity of fluid inclusions in the H2O-NaCl-CO2 system. In the work, various systems are prepared, such as H2O-NaCl, H2O-CO2, and H2O-NaCl-CO2. For the H2O-NaCl system, the addition of NaCl salts decreases the intensity of the sub-band below 3330 cm−1 but increases the intensity of the sub-band above 3330 cm−1. According to the structural analysis of the H2O-NaCl system, the spectral changes are mainly related to the interactions between Cl− and water. After the Raman OH stretching bands are fitted into two sub-bands, the intensity ratio between them is used to calculate the Cl− concentrations (molarity scale) of NaCl solutions. Additionally, based on the measured Raman spectra, the effects of CO2 on water structure may be weak. It is reasonable to ignore the impact of dissolved CO2 on Raman OH stretching bands. The procedure above can be extended to quantitatively determine the Cl− molarity of the H2O-NaCl-CO2 system. To demonstrate its reliability, this method is applied to determine the salinity of synthetic and natural fluid inclusions containing CO2.

High‐Entropy Electrolyte Driven by Multi‐Solvation Structures for Long‐Lifespan Aqueous Zinc Metal Pouch Cells

Aqueous zinc metal batteries (AZMBs) are promising for grid‐scale energy storage due to their low cost and high safety. However, poor stability and an unfavorable freezing point hinder their actual application. Herein, a ternary salts‐based high‐entropy electrolyte (HEE) composed of Zn0.2Na0.4Li0.4(ClO4)1.2·7H2O is proposed to address the above issues. The addition of perchlorate salts with different cations reduces the size of ion clusters, significantly increases the solvation structure species, and promotes the anion‐rich Zn2+ solvation structures, resulting in an enlarged electrochemical stability window, favorable viscosity and ionic conductivity, and low freezing point. Furthermore, characterization and calculations confirm that multiple types of solvation structures effectively increase the electrolyte entropy. As a consequence, the Zn/Zn symmetric cells in HEE can sustainably cycle for at least 1000 hours and 1500 hours under room and subzero temperatures, respectively. The Na0.33V2O5/Zn and polyaniline/Zn full cells can even last for 30000 and 20000 cycles without capacity decay at −20 °C, respectively. The pouch cells employing HEE deliver promising capacity and stability, even at high mass loading of active materials. This strategy of introducing multiple salts with different cations to construct a high‐entropy environment provides a facile approach for high‐performance and long‐lifespan AZMBs across a wide temperature range.

High-Entropy Electrolyte Driven by Multi-Solvation Structures for Long-Lifespan Aqueous Zinc Metal Pouch Cells.

Aqueous zinc metal batteries (AZMBs) are promising for grid-scale energy storage due to their low cost and high safety. However, poor stability and an unfavorable freezing point hinder their actual application. Herein, a ternary salts-based high-entropy electrolyte (HEE) composed of Zn0.2Na0.4Li0.4(ClO4)1.2·7H2O is proposed to address the above issues. The addition of perchlorate salts with different cations reduces the size of ion clusters, significantly increases the solvation structure species, and promotes the anion-rich Zn2+ solvation structures, resulting in an enlarged electrochemical stability window, favorable viscosity and ionic conductivity, and low freezing point. Furthermore, characterization and calculations confirm that multiple types of solvation structures effectively increase the electrolyte entropy. As a consequence, the Zn/Zn symmetric cells in HEE can sustainably cycle for at least 1000 hours and 1500 hours under room and subzero temperatures, respectively. The Na0.33V2O5/Zn and polyaniline/Zn full cells can even last for 30000 and 20000 cycles without capacity decay at -20 °C, respectively. The pouch cells employing HEE deliver promising capacity and stability, even at high mass loading of active materials. This strategy of introducing multiple salts with different cations to construct a high-entropy environment provides a facile approach for high-performance and long-lifespan AZMBs across a wide temperature range.

IMPROVEMENT OF THE PRODUCT COMPOSITION FROM NITRIC ACID PROCESSING OF KYZYLKUM CARBONATE PHOSPHORITES

The process of producing NP-fertilizers by nitric-sulfuric acid decomposition of phosphate rock (17.20% P2O5) under thickening slurry conditions has been studied. It was shown that the higher the recycle ratio, the lower the moisture content of the final product. Increasing the HNO3 dosage above 30% and H2SO4 above 70% is undesirable, as the product's moisture content exceeds 6.03% and it has increased acidity. To avoid issues during ammoniation, an optimal rate of nitric and sulfuric acid was proposed—73.5-91%, which produced products containing 9.34-10.61% -P2O5total; 3.04-4.54% N; P2O5 digestive:P2O5 total = 73.4-82.3%; pH = 3.3-3.6, and granule strength of 2.1-2.3 MPa. The process of producing NPK-fertilizers was also studied by adding nitrogen components such as K2SO4, KCl, and K2CO3 to the products of complete nitric acid decomposition of washed and dried concentrate (24.10% P2O5) and fine fractions (18.55% P2O5). The process includes decarbonization and decomposition of the phosphate raw material (simultaneously in one apparatus), neutralization to a pH not lower than 3.5, evaporation of the slurry to a density of at least 1750 kg/m3, the addition of potassium salts at N:P2O5:K2O ratios of 1:1:1, 1.5:1:1, and 1:1.5:1, product granulation, drying in the presence of recycle, and cooling.

INSIGHTS INTO THE ELECTROCHEMICAL PROPERTIES OF GERMANIUM-COBALT-INDIUM NANOSTRUCTURES IN A WIDE TEMPERATURE RANGE

Germanium-cobalt-indium (Ge-Co-In) nanostructures are a promising material for negative electrodes of lithium-ion batteries aimed for arctic exploitation. Electrochemical impedance spectroscopy was used for a detailed study of the interaction of Ge-Co-In nanostructures with lithium in a temperature range from ‒35 to +20°C. The discharge capacity at temperatures of 20, 0, ‒10, ‒20, and ‒35°C amounted to 1400, 1228, 1040, 907, and 793 mAh g‒1, respectively. The impedance spectra measured at various lithiation degrees were found to differ but insignificantly whereas temperature variation resulted in notable changes in the spectra. A normalized charge transfer resistance for Ge-Co-In nanostructures was significantly (more than an order of magnitude) less than for Ge-In nanowires (obtained by the same method, but without the addition of cobalt salt into the electrolysis solution). It is this difference in charge transfer resistance that can explain the difference in the shapes of the impedance spectra for both objects. Also, in contrast to data for Ge-In nanowires, the dependences of the lithium diffusion coefficient in Ge-Co-In nanostructures on potential had a clearly defined minimum. The lithium diffusion coefficient in Ge-Co-In nanostructures slightly exceeded that in Ge-In nanowires, and the activation energy of lithium diffusion in Ge-Co-In nanostructures was marginally less than in Ge-In nanowires.

Enhancement of stress resistance of electroactive biofilms against hypersaline shock via exogenous electron mediator addition

Unexpected hypersaline shock from saline wastewater poses a common challenge in the biological treatment processes of WWPTs. Bioelectrochemical systems (BESs) possess an inherent advantage for treating hypersaline wastewater. The elevated salinity enhances the wastewater’s conductivity, which in turn significantly accelerates the electron and proton transfer within the system. However, excessive increases in salinity can impede electron transport capacity, potentially resulting in cell plasmolysis and system failure in severe instances. Here, we investigated the impact of electron mediator (EM) addition on the resilience of electroactive biofilms (EB) to hypersaline environments in BESs. The EB developed under anthraquinone-2,6-disulphonic disodium salt (AQDS) addition obtained preferable electrochemical properties (e.g., current output, redox peak current, conductivity, electron transfer capacity) under hypersaline shock and showed superior recovery post-hypersaline stress. Partial least squares path modeling (PLS-PM) analysis indicated that the enhanced secretion of extracellular polymeric substances (EPS) and the elevated ratio of proteins to polysaccharides are likely pivotal in the formation of EB with high electrochemical activity. Meanwhile, AQDS addition constructed more complex microbial network and enriched halotolerant bacteria (e.g., Solibacillus). Higher mean function abundance of replication & repair, stress tolerance, and biofilm formation were achieved by EM addition. The results of this study present a promising approach to augment the pressure tolerance of EBs, thereby broadening the practical applications of BESs.

Phase change materials as hydrogen explosion suppressants: An experimental and kinetic investigation

To investigate the potential application of phase change materials as H2 explosion suppressants, in the present work, the inhibition effect of Na2HPO4·12H2O, K2HPO4·3H2O, and Na2CO3·10H2O on H2 explosion were experimentally studied. The corresponding explosion suppression mechanism was calculated by using a comprehensive combustion model. Results showed that the selected phase change materials inhibited the H2 explosion, and Na2CO3·10H2O has the most significant effect for fuel-lean H2-air mixtures when 12 g was added. Of which the maximum explosion pressure (Pmax) and maximum rate of pressure rise (dp/dt)max were reduced by 26.6 % and 28.1 %, and maximum pressure increase time (tb) and peak pressure time(tc) were increased by 112.2 % and 120.3 %. The inhibition mechanism of Na2CO3·10H2O on H2 was revealed by numerical simulation. The adiabatic flame temperature (AFT) and laminar burning velocity (LBV) of H2-air mixture decrease with increasing hydrated salt addition, the free radicals H, O and OH have a decisive influence on the explosion process during which H decreases by 86.4 % at most. The chain initial reaction O + H2 ⇌ H + OH and the sodium-containing primitive reaction NaO + H + M ⇌ NaOH + M have the most significant influence on the combustion processes. The results of present work give a theoretical foundation for application the phase change materials in H2 explosion safety industry.

Evaluation of the Glass Transition Temperature and Intermolecular Interaction of Poly(ethylene oxide) with Addition of Lithium Perchlorate or/and Titanium Dioxide

The high crystallinity of poly (ethylene oxide) (PEO) has urged the need for adding salt or nanofiller. The effect of the glass transition temperature (Tg) and intermolecular interaction of PEO upon the addition of salt or nanofiller become a debatable topic due to the lacking of the understanding of the role of salt or nanofiller in PEO. Hence, the evaluation of the Tg and intermolecular interaction of PEO with addition of lithium perchlorate (LiClO4) salt or/and titanium dioxide (TiO2) nanofiller are presented and discussed. The solid polymer electrolytes with addition of nanofiller are prepared by solution casting technique. The optimum composition of PEO and LiClO4 salt is used as host matrix and TiO2 as nanofiller. The Tg and intermolecular interaction of the polymer-based electrolytes have been studied by differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy. PEO-LiClO4 serves as the classical model of polymer-salt systems with good polymer-salt molecular interaction at low salt concentration (WS ≤ 0.107) whereas TiO2 without any surface treatment when added to PEO, serves as a classical model of polymer-nanofiller systems with weak polymer-nanofiller molecular interaction. Results have shown that LiClO4 salt gives notable effect on the Tg and intermolecular interaction of PEO. Whereas, TiO2 do not provide a substantial effect on the Tg and intermolecular interaction of PEO-based polymer electrolytes. This work provides a better understanding and knowledge of the effect of addition of salt or/and nanofiller in the Tg and intermolecular interaction of the PEO systems.

Effect of inorganic salt composition on strength, microstructure and leaching toxicity of coal-based solid waste backfill materials

This study explores the potential of coal-fired slag, desulfurized gypsum and modified magnesium slag as cementing agents for coal-based solid waste backfill materials. Inorganic salts like CaCl2, Na2SO4 and Na2SiO3 were used as excitants to investigate their combined impact on the mechanical properties, microstructure and leaching risk of hazardous elements from the coal-based solid waste backfill materials. The findings show that the addition of inorganic salt boosts the alkalinity within the liquid-phase reaction system. This disrupted the hydration-blocking membrane, accelerating the dissolution and reaction rate of the silica-alumina mineral components within the cementitious material. Concurrently, the inorganic salt ions consumed the early alkaline hydration products, destroying the hydration reaction equilibrium and facilitating the formation of hydration products like AFt, C-S-H gel, C-A-S-H gel, and Friedel's salt. This increase in the solid-phase volume content and microscopic densities in the reaction system improved the early mechanical properties of the coal-based solid waste backfill materials. Additionally, after a 28-day curing period, the leaching concentration of deleterious elements in the coal-based solid waste backfill material containing inorganic salt components was below the permissible concentration limit of the Class III groundwater quality standard. This eco-friendly backfill material is promising for mine backfilling, a potential substitute for traditional cement-based backfill material.