Ether Solution Research Articles

Synthesis of Aminodiborane through the Reaction of Ammonia Borane with Acids.

A facile method for the synthesis of aminodiborane (NH2B2H5, ADB) has been developed through the reaction of ammonia borane (NH3BH3, AB) with an ether solution of hydrogen chloride (HCl·Et2O) at room temperature. In addition, N-alkyl substituted ADB derivatives were synthesized by reacting N-alkyl substituted AB with HCl·Et2O at 50 °C. The mechanistic studies indicated that the nucleophilic substitution reaction of the B-H bonding pair electrons and the dihydrogen bonding interaction play an important role. This work paves an alternative way to prepare amine borane compounds.

Evaluation of physical and chemical isolation methods to extract and purify Campylobacter jejuni extracellular polymeric substances.

The pathogenic bacterium Campylobacter jejuni is a major food safety concern as it can form biofilms that increase its survival and infective potential. Biofilms consist of microbial cells and extracellular matrix (ECM), which is made of water and extracellular polymeric substances (EPS), which are critical for structural integrity and pathogenicity. The aim of this study was to optimize a protocol for the isolation of C. jejuni ECM. We employed eight physical and chemical isolation methods to extract and purify ECM, followed by different qualitative and quantitative analyses using gel electrophoresis and spectroscopy. This comprehensive approach enabled the evaluation of ECM composition in terms of polysaccharides, proteins, and extracellular DNA. The isolation methods resulted in different yields and purities of the extracted ECM components. Centrifugation in combination with chemical treatments proved to be most effective, isolating higher concentrations of polysaccharides and proteins. Additionally, extraction with ether solution facilitated the recovery of high-molecular-weight extracellular DNA. Overall, we provide a refined methodology for ECM extraction from C. jejuni. As polysaccharides and proteins participate in biofilm stability and microbial communication, and extracellular DNA participates in genetic exchange and virulence, our study contributes towards a better understanding of the persistence of this pathogen in the food industry.

Cascade CO2 Insertion in Carbanion Ionic Liquids Driven by Structure Rearrangement.

The CO2 chemisorption in state-of-the-art sorbents based on oxide/hydroxide/amine moieties is driven by strong chemical bonding formation in the carbonate/bicarbonate/carbamate products, which in turn leads to high energy input in sorbent regeneration. In addition, the CO2 uptake capacity was limited by the active sites' utilization efficiency, with each active site incorporating one CO2 molecule or less. In this work, a new concept and generation of sorbent was developed to achieve cascade insertion of multiple CO2 molecules by leveraging structure rearrangement as the driving force, leading to in situ generation of extra CO2-binding sites and significantly reduced energy input for CO2 release. The designed ionic liquids (ILs) containing carbanions with conjugated and asymmetric structure, deprotonated (methylsulfonyl)acetonitrile ([MSA]) anion, allowed the cascade insertion of two CO2 molecules via consecutive C-C and O-C bond formations. The proton transfer and structure rearrangement of the carboxylic acid intermediates played critical roles in stabilizing the first integrated CO2 and generating extra electron-rich oxygen sites for the insertion of the second CO2. The structure variation and reaction pathway were confirmed by operando spectroscopy, magnetic resonance spectroscopy (NMR), mass spectroscopy, and computational chemistry. The energy input in sorbent regeneration could be further reduced by harnessing the phase-changing behavior of the carbanion salts in ether solutions upon reacting with CO2, avoiding the energy consumption in heating the solvent. The fundamental insights obtained herein provide a promising approach to greatly improve the CO2 sorption performance via sophisticated molecular-scale structural engineering of the sorbents.

CuS modified graphite from spent Li-ion batteries towards building high energy Na-ion capacitors via solvent-co-intercalation process

Sodium-ion capacitors (NICs) are one of the most modern hybrid energy storage devices, and they involve two different energy storage mechanisms (faradaic and non-faradaic). The NICs are bridging the gap between the Na-ion batteries and the capacitors with enhanced power and energy densities. This work explores a new combination electrode material, i.e., recovered graphite (RG) decorated with copper sulphide (CuS, CS) as the anode for the NIC application, in which graphite undergoes the solvent-co-intercalation process, and CuS adopts the conversion reaction. We also report the possibility of efficient direct recovery of the anode of dead/spent Li-ion batteries and upcycling as a battery-type component for NIC with commercially available activated carbon (AC) as the capacitor-type cathode. First, the Na-storage property is analyzed in the half-cell configuration, where the Na/RG-CS half-cell displayed excellent cyclic stability with a stable specific capacity of 113 mAh g−1 after 500 cycles with >96% coulombic efficiency in ether solutions. With a pre-sodiated form of RG-CS as anode and mass-balanced AC as a cathode, the NIC is fabricated. The NIC displayed a superior energy density of 64.6 Wh kg−1 with ultra-long cyclability for more than 10,000 cycles with >85% capacity retention. The compatibility of the NIC in different environmental conditions is also studied, and the cell renders better performance in all temperature conditions.

Study of antibacterial properties of extracts of the herb Speranskia tuberculata (Bunge) Baill

The article deals with the problem of developing antibacterial drugs of plant origin, focusing on the properties of the herb Speranskia Tuberculata (Bunge) Baill, which is still understudied. The aim was to determine the antibacterial activity of preparations of the herb Speranskia Tuberculata (Bunge) Baill, extracted with different solvents. Materials and methodology. Crude extracts were obtained using four solvents: petroleum ether, ethyl acetate, n-butanol, and aqueous solutions. Subsequently, the dried extracts were weighed and dissolved in dimethylsulfoxide to prepare working solutions with 10 to 500 µg/mL concentrations. Colonies of three types of bacteria, Staphylococcus aureus, Escherichia coli, and Propionibacterium Acnes, were used as the object of the study. The degree of antibacterial activity was determined by measuring the antibacterial zone formed after treating bacteria with different concentrations of extracts compared to the control group (treatment with distilled water). In addition, the total content of phenolic compounds and flavonoids was determined by chemical methods. Antioxidant activity, volume of the dry residue of crude extracts, and content of flavonoids and phenolic compounds were compared with the results of liquid chromatography-mass spectrometry on the presence of antibacterial substances in the extracts known from the literature. It was shown that the ethyl acetate extract among the 4 studied extracts had a clearly expressed antibacterial effect. The calculated value of IC50 for this extract varied between 112‒135 μg/mL for different bacteria. Other solvents did not show a pronounced antibacterial effect. The weakest effect was associated with petroleum ether extracts. At the same time, the mass of the dry residue, when extracted with petroleum ether, was the maximum among all solvents; on the contrary, with ethyl acetate, it was the minimum. Regarding the content of phenolic compounds and flavonoids, the results of the studies were opposite; namely, the maximum concentrations were characteristic of the ethyl acetate extract, and the minimum concentrations were characteristic of the petroleum ether extract. According to the literature, twelve compounds found in the extracts have pronounced antibacterial activity. Suppose the presence of an aromatic ring and a carbon-linked hydroxyl group OH- is taken as the main sign of belonging to phenolic compounds. In that case, 8 of 12 invented antibacterial compounds belong to phenols and flavonoids. Experimentally proven high antibacterial activity of preparations of the herb Speranskia Tuberculata (Bunge) Baill based on ethyl acetate extracts. This property is related to the extract's high content of phenolic compounds and flavonoids.

A highly efficient oxygen tolerant visible-light mediated RAFT polymerization

Recently, oxygen-tolerant reversible addition-fragmentation chain transfer (RAFT) polymerization has attracted increasing attention in polymer chemistry. Inspired by the monomers containing glycol ethers group have high polymerization rates and even achieved a desirable oxygen tolerance. Herein, we proposed a simple, effective, low-cost, and eco-friendly strategy to accomplish the oxygen-tolerant visible-light activated RAFT polymerization of acrylates and acrylamides in a mixed solution of glycol ether and water at ambient temperature. This photo-mediated RAFT polymerization does not require additives, prior deoxygenation, or inert gas protection. The acrylates and acrylamides with high conversion under irradiation for 2 h, and the resulting polymers were narrow unimodal and narrow molecular weight distributions (PDI<1.3). In addition, the “living” and well-controlled behaviors of this oxygen-tolerant photo-mediated RAFT polymerization were demonstrated through water content in solvents, headspace, initial concentration of monomers, various monomers, chain lengths, light ON/OFF experiment, and high-end group fidelity of block copolymers. This RAFT polymerization also opens up a wide avenue for the industrial production of functional polymeric materials via an in situ chain extension strategy. These results indicate that the mixed solution of glycol ethers and water are effective green media for promoting photo-mediated RAFT polymerization without additives or tedious degassing processes.

First Isolation of Solvated MgCl+ species as the Sole Cations in Electrolyte Solutions for Rechargeable Mg Batteries

Synthesis of complex magnesium cations in ethereal solutions, is receiving a lot of attention due to their potential utilization in rechargeable magnesium batteries (RMB). The simplest complex cation, namely, solvated MgCl+, was hypothesized and reported as the most important cation in nonaqueous magnesium electrolyte solutions chemistry. However, such ions have never isolated as the only cationic species in ethereal solutions developed for RMB. In this study, we report on a successful isolation of the pure electrolyte MgCl(THF)5 + - PhAlCl3 - , and on the electrochemical behaviour of its ethereal solutions. The structure of this compound was proved by single-crystal X-ray diffraction, Raman, and, NMR spectroscopies. The novel MgCl(THF)5PhAlCl3/THF electrolyte solutions exhibit reversible Mg deposition/dissolution processes with anodic stability up to 2.7 V. The application of electrochemical cleaning pre-treatment for these solutions enabled to profoundly increase the coulombic efficiency of their Mg deposition/dissolution processes. Examining Mg prototype batteries with Mg foil anodes, composite MgxMo6S8Chevrel phase (CP) cathodes containing these solutions exhibited a viable battery performance, indicating that upon a further optimization, electrolyte solutions based on the complex MgCl(THF)5 + - PhAlCl3 - electrolyte may be suitable for practical RMB. Figure 1

Lithium-Ion Transport Properties in DMSO and TEGDME: Exploring the Influence of Solvation through Molecular Dynamics and Experiments.

This study explores the properties of aprotic electrolytes via the application of experimental methods, including nuclear magnetic resonance spectroscopy and electrochemical techniques, along with molecular dynamic modeling. The aim is to provide a quantitative description of the physico-chemical properties of two well-established electrolytes (case studies), each exhibiting significantly distinct dielectric properties: a LiTFSI (Lithium bis(trifluoromethanesulfonyl)imide) solution in dimethyl sulfoxide (DMSO, dielectric constant =46.68) and a LiTFSI solution in tetraethylene glycol dimethyl ether (TEGDME, =7.71). We obtained a comprehensive insight into the properties of the electrolytes at both the macroscopic-collective and molecular levels with particular emphasis on the interactions between the Li ions and solvent molecules. We discovered remarkable disparities in the structural arrangements, solvation behaviors, and bulk-related properties of these electrolyte systems, particularly in response to temperature changes.

Enhanced forward osmosis desalination of brackish water using phase-separating ternary organic draw solutions of hydroxypropyl cellulose and propylene glycol propyl ether.

This study introduces draw solutions for application in forward osmosis (FO) processes, combining mono propylene glycol propyl ether (PGPE) with the cellulose derivative hydroxypropyl cellulose (HPC). A total of 16 unique single-solute and ternary organic draw solutions were prepared and evaluated, leading to the selection of three promising solutions for further investigation. Notably, eight of the initial organic draw solutions demonstrated osmotic pressures exceeding 2.4MPa. The dynamic viscosities of all draw solutions exhibited a significant reduction with increasing temperature. Among the investigated solutions, the 0.25HPC-3.75PGPE demonstrated the most favorable FO performance, achieving average experimental water fluxes of 11.062 and 9.852 Lm-2h-1 (LMH) against a 1g/L NaCl brackish feed solution across two FO runs. PRACTITIONER POINTS: Hydroxypropyl cellulose (HPC, MW ~100,000) was mixed with propylene glycol propyl ether (PGPE) as draw solutes for FO processes. Seven combinations of HPC and PGPE produced osmolalities greater than 1000 mOsm/kg. 0.5HPC-7.5PGPE ternary draw solution achieved experimental water fluxes of 11.062 and 9.852 LMH against 1g/L NaCl brackish feed solution. Leveraging the LCSTs of these ternary organic solutions holds promise for improved separation and regeneration processes.

Twisted and Disconnected Chains: Flexible Linear Tetracuprous Arrays and a Decanuclear CuI Cluster as Blue- and Green/Yellow-Light Emitters.

Defined arrays of transition metal ions embedded in tailored polydentate ligand scaffolds allow for a systematic design of their physical properties. Such molecular strings of closed-shell transition metal centers are particularly interesting for Group 11 metal ions in the oxidation state +1 if they undergo metallophilic d10···d10 contact interactions since these clusters are oftentimes efficient photoluminescence (PL) emitters. Copper is particularly attractive as a sustainable earth-abundant coinage metal source and because of the ability of several CuI complexes to serve as powerful thermally activated delayed fluorescence (TADF) emitters in molecular/organic light-emitting devices (OLEDs). Our combined synthetic, crystallographic, photophysical, and computational study describes a straight tetracuprous array possessing a centrally disconnected CuI2···CuI2 chain and a continuous helically bent CuI4 complex. This molecular helix undergoes a facile rearrangement in diethyl ether solution, yielding an unprecedented nanosized CuI10 cluster (2.9 × 2.0 nm) upon crystallization. All three clusters show either bright blue phosphorescence, TADF, or green/yellow multiband phosphorescence with quantum yields between 6.5 and 67%, which is persistent under hydrostatic pressure up to 30 kbar. Temperature-dependent PL investigations in combination with time-dependent density-functional theory (TD-DFT) calculations and void space analyses of the crystal packings complement a comprehensive correlation between the molecular structures and photoluminescence properties.

A Ratiometric Fluorescent Probe Dye-Functionalized MOFs Integrated with Logic Gate Operation for Efficient Detection of Acetaldehyde.

Volatile organic compounds (VOCs) are a class of hazardous gases that are widely present in the atmosphere and cause great harm to human health. In this paper, a ratiometric fluorescent probe (Dye@Eu-MOFs) based on a dye-functionalized metal-organic framework was designed to detect VOCs, which showed high sensitivity and specificity for acetaldehyde solution and vapor. A linear correlation between the integrated fluorescence intensity (I510/I616) and the concentration of acetaldehyde was investigated, enabling a quantitative analysis of acetaldehyde in the ranges of 1 × 10-4~10-5 μL/mL, with a low detection limit of 8.12 × 10-4 mg/L. The selective recognition of acetaldehyde could be clearly distinguished by the naked eye under the excitation of UV light. The potential sensing mechanism was also discussed. Significantly, a molecular logic gate was constructed based on the whole system, and finally, a molecular logic network system for acetaldehyde detection connecting basic and integrated logic operations was realized. This strategy provided an effective guiding method for constructing a molecular-level logic gate for acetaldehyde detection on a simple platform.

The use of dimethyl ether (DME) solution in compression ignition engine

The development of compression ignition combustion engines is focused on meeting many challenges, mainly related to growing ecological requirements. Currently, however, due to technological barriers, meeting them is very difficult and requires the use of additional exhaust gas treatment systems. The use of injection of a diesel and gas solution seems to be very promising. The article presents the results of engine tests involving the use of a solution of diesel fuel and dimethyl ether. The tests were performed on a single-cylinder research engine equipped with a common rail fuel system. The obtained results suggest that the use of the solution has a positive effect on the process of creating the fuel-air mixture, resulting in a reduction in the concentration of HC and CO, while increasing the share of NOx, suggesting an improvement in the combustion process, as evidenced by the limiting injection dose.

Removal and Reoccurrence of LLZTO Surface Contaminants under Glovebox Conditions.

The reactivity of Li6.4La3Zr1.4Ta0.6O12 (LLZTO) solid electrolytes to form lithio-phobic species such as Li2CO3 on their surface when exposed to trace amounts of H2O and CO2 limits the progress of LLZTO-based solid-state batteries. Various treatments, such as annealing LLZTO within a glovebox or acid etching, aim at removing the surface contaminants, but a comprehensive understanding of the evolving LLZTO surface chemistry during and after these treatments is lacking. Here, glovebox-like H2O and CO2 conditions were recreated in a near ambient pressure X-ray photoelectron spectroscopy chamber to analyze the LLZTO surface under realistic conditions. We find that annealing LLZTO at 600 °C in this atmosphere effectively removes the surface contaminants, but a significant level of contamination reappears upon cooling down. In contrast, HCl(aq) acid etching demonstrates superior Li2CO3 removal and stable surface chemistry post treatment. To avoid air exposure during the acid treatment, an anhydrous HCl solution in diethyl ether was used directly within the glovebox. This novel acid etching strategy delivers the lowest lithium/LLZTO interfacial resistance and the highest critical current density.

Effect of guar gum on dynamic wetting the fat coal surface with octyl phenol polyoxyethylene ether solution

To study the effect of guar gum (GG) on the surface of octyl phenol polyoxyethylene ether dynamic wetting fat coal, the effect of GG addition concentration on physical parameters, sedimentation rate, contact angle, maximum dimensionless wetting length (Ldw(max)) and maximum dimensionless wetting area (Adw(max)) in mixed dust suppression solutions was studied by experimental and molecular dynamic simulation methods. The results show that adding GG does not significantly alter the mixed dust suppression solution surface tension, but it increases the solution viscosity. When the GG concentration is greater than 0.1%, the viscosity of the mixed dust suppression solution increasing extent becomes larger. The impact wetting experiment and contact angle experiment show that when GG concentration is 0.01%, the mixed dust suppression solution contact angle is the smallest, the Ldw(max) and Adw(max) are the largest, and the solution wettability is the best. Compared with the Ldw(max), the Adw(max) has a smaller standard deviation and higher repeatability. Molecular dynamics simulation shows that after adding a trace amount of GG to the water/OP surfactant/fat coal system, the relative concentration coincidence area and interaction energy absolute value between coal and water in the system increases, the water molecules diffusion coefficient decreases, and the system wettability is further enhanced, which further illustrates the experimental results accuracy.

A low pollution surface pretreatment of PC‐ABS under acidic conditions

AbstractIn the present study, the low pollution acidic potassium permanganate system has been used in the study of its micro‐etching effect on polycarbonate‐acrylonitrile butadiene styrene (PC‐ABS). Prior to micro‐etching using a N methyl pyrrolidone (NMP)‐glycol butyl ether solution was used as the swelling system of PC‐ABS. Reasonable swelling conditions were determined, a 2‐min expansion period at a temperature of 35°C with an NMP concentration of 80%. After the swelling processes, the effects of the volume ratio of :, micro‐etching temperature, and micro‐etching duration on the PC‐ABS surface morphology, surface roughness, surface hydrophilicity, and peel strength, have been investigated. It was finally determined that the best micro‐etching effect could be obtained by reacting at : = 1:2 and a temperature of 60°C for 25 min. The surface of the PC‐ABS copolymers was characterized by x‐ray photoelectron spectroscopy, atomic force microscopy, and Fourier‐transform infrared spectroscopy. The results showed that the micro‐etching process changed the morphology of the PC‐ABS surface and generated cavities. In addition, the surface roughness increased from the initial Ra = 9.69 to Ra = 197 nm. Also, the water contact angle on the PC‐ABS surface decreased from 92.2° to 28.6°, and the peel strength increased to 0.98 kN/m.

Ultrasonic Velocity and Related Parameters Study of PCE Water-Soluble Polymer

Density, viscosity and ultrasonic velocity of aqueous solutions of polycarboxylate ether [PCE] superplastiziser polymer at one of a thoughtful concentrations and temperatures (298.15, 303.13, 308.15 and 313.15)K. different interplay parameters were calculated by the investigational values of density, viscosity and ultrasonic velocity of polycarboxylate ether Water-Soluble Polymer. The viscosity of superplastiziser polymer solution will increase with growing awareness of aqueous answers of polycarboxylate ether. The ultrasonic speed increases from 298.15 K to 308.15K, at that time yet again decreases for 313.15K because the temperature will increase, density, adiabatic compressibility and intermolecular free length duration lower and ultrasonic velocities, acoustic impedance, molar volumes and molar sound velocities turned into discovered to will increase. The ultrasonic velocities to start with boom then decreases with growing consciousness of polycarboxylate ether. For 0.05 polycarboxylate ether it indicates most ultrasonic velocities

Protective Al2O3 Thin Film Coating by ALD to Enhance the Anodic Stability of Metallic Current Collectors in Ethereal Mg Electrolyte Solutions

Rechargeable magnesium batteries (RMBs) have the potential to contribute towards alternative energy storage due to their low cost, high abundance, dendrites free deposition of Mg and high volumetric energy density. Organometallic complex-based electrolytes in ethereal solutions have been extensively studied in the context of RMBs due to their ability to facilitate highly reversible magnesium deposition in rechargeable magnesium batteries, while demonstrating wide enough electrochemical stability windows. However, these solutions containing unique mixture of organo-halo aluminate complexes have detrimental effect on the anodic stability of metallic current collectors for cathodes, like Ni and Al foils. In this work, we were able to synthesize and isolate Mg2Cl3(THF)6Ph2AlCl2/THF electrolyte as the sole electroactive species using simple precursors: Ph2AlCl and MgCl2 in THF, via atom efficient mono-chloro abstraction Schlenk technique. We characterized the anodic stability of Ni, Ni@C, Al, and Al@C current collectors by monitoring their electrochemical behavior. In addition, we investigated the anodic stability enhancement of various current collectors by Al2O3 thin films coating using Atomic Layer Deposition (ALD). Linear sweep voltametric studies showed that coating current collectors enhanced the oxidative stability of Al and Ni foils by 0.1–0.3 V vs Mg/Mg2+ compared to the uncoated foils. In particular, Al2O3 coated Al@C showed an improved oxidative stability of 2.8 V vs Mg/Mg2+. Our findings show that current collectors protection by ALD coating can help in long-term stability and improving RMBs’ energy density by using high voltage cathode materials, a crucial step in developing practical rechargeable Mg batteries.

Rapid and sensitive quantification of efavirenz in rat plasma using HPLC-MS/MS method

This article aims to analyze the development of a rapid and sensitive HPLC–MS/MS method for quantification of efavirenz in rat plasma. The developed method included a liquid-liquid extraction process with methyl-tert-butyl ether solution, where hydrochlorothiazide was used as internal standard. The analyte was separated on an ACE Phenyl C18 column and eluted by a system consisting of mobile phase A (0.2% acetic acid) and mobile phase B (acetonitrile) at a proportion of 35:65 (v/v), pumped with a flow rate of 1.0 mL min-1 (run time &lt; 4 min). Mass spectrometric detection was performed on a triple quadrupole instrument using multiple reaction monitoring. The electrospray ionization source was performed in negative ion mode. The precursor/product ion pairs monitored were m/z 313.644→68.800 and m/z 295.541→268.700 for efavirenz and internal standard, respectively. The limit of quantification was 10.0 ng mL-1 and calibration curves were linear over 10.0–1,500 ng mL-1. Intra-day and inter-day precision at three levels were 1.80–10.49% and 4.72–10.28%, respectively. Accuracy ranged between 93.54% and 105.73%. Finally, the described method was applied to rats administered with efavirenz, demonstrating the suitability for quantification of efavirenz in a pharmacokinetic study. Therefore, it can be used in normal, hemolyzed or lipemic samples for efavirenz quantification.

Modified Gypsum-Cement-Pozzolan Concrete for 3DCP

3D concrete printing (3DCP) is an innovative and promising method for constructing buildings and structures. Compositions of fine-grained concrete based on Portland cement are widely used as raw material mixtures in this technology. An alternative to the use of cement binder is the use of gypsum-cement-pozzolan binder, which can significantly reduce the cost of the finished product and, accordingly, increase its competitiveness. The raw material mixtures based on gypsum-cement-pozzolan binder presented on the construction market do not fully meet the requirements of 3DCP. Achieving optimal performance of gypsum-cement-pozzolan mixtures in 3DCP is possible by regulating the content of fine aggregate in the composition of fine-grained concrete, as well as the use of multicomponent modifying additives. The purpose of this work is to develop modified gypsum-cement-pozzolan concretes for 3DCP based on optimization of aggregate content and multifunctional additive, providing optimal rheotechnological properties of raw mixtures and technological characteristics of finished products. The formation of samples during experimental studies was carried out using the layer-by-layer extrusion method on a workshop construction 3D printer “AMT S-6044”. Modified gypsum- cement-pozzolan concretes have been developed for 3DCP with increased ultimate shear stress of the mixture (87.6 Pa), dimensional stability (23 cm), average composite density (1920 g/m3), flexural strength (8.4 MPa) and compression (30.6 MPa) and water resistance (0.85). The possibility of targeted regulation of the structure and properties of gypsum-cement- pozzolan mixtures and concrete due to the synergistic effect of the components of the developed multifunctional complex additive, including an aqueous solution of a polycarboxylate ether, a copolymer based on carboxylic acid esters, and a homogeneous mixture of oligoethoxysiloxanes, has been proven. The results obtained are consistent with the results of the differential thermal analysis of modified gypsum-cement-pozzolanic stone.

Experimental investigation on the methane storage by forming sH hydrate

Methane storage via clathrate hydrates is a promising method, the structure H (sH) hydrate can be formed at more moderate conditions compared to structure I (sI) hydrate and has a larger storage capacity than structure II (sII) hydrate. In this work, CH4 storage by forming sH hydrate in the tert-butyl methyl ether (TBME) solution was explored at an initial pressure of 5.0 MPa and within the temperature range of 274.15– 278.15 K. The CH4/TBME hydrate phase equilibrium condition was first determined with the isochoric pressure searching method, and the results revealed that the measured equilibrium data of CH4/TBME hydrate at different TBME concentrations were almost consistent. The effect of TBME concentration (0– 4.29 mol%), promoter type and sub-cooling on the hydrate formation kinetics and gas uptake was systematically investigated. The results showed that the hydrate formation rate increased with the increase of TBME concentration. The CH4 uptake achieved 117.7 ± 3.6 v/vw (volume ratio of gas to water at standard condition) in the 4.29 mol% TBME system, which was significantly increased than that of pure water (44.1 ± 5.0 v/vw). The cocamidopropyl dimethylamine (CDA) further improved the CH4/TBME hydrate formation kinetics and gas uptake, the CH4 storage capacity attained 145.6 ± 1.7 v/vw, which was slightly higher than that of the sodium dodecyl sulfate (SDS) system (143.6 ± 3.0 v/vw). As the sub-cooling increased, the formation kinetic profiles of CH4/TBME hydrate changed from a two-step to a one-step drop, indicating that the shift of mixed sH and sI hydrates to single sH hydrate. Additionally, the time taken for hydrate growth in the presence of TBME was significantly decreased than the pure water system, and the adding of CDA and SDS further shorten it. The CH4 recovery in each test was above 95.0 % and no foam generated during hydrate dissociation for the CDA-contained system. The stability test of CH4/TBME hydrate indicated that around 86 % CH4 was still enclosed in the hydrate phase after one week. This study would contribute to the application of the hydrate-based methane storage technology in future.