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We report an ab initio, full-dimensional, potential energy surface (PES) for CO2--H2O, in which twobody interaction energies are fit using a basis of permutationally invariant polynomials and combined with accurate potentials for the non-interacting monomers. This approach which we have termed "plug and play" is extended here to improve the precision of the 2-body fit in the long range. This is done by combining two separate fits. One is a fit to 47 593 2-body energies in the region of strong interaction and approaching the long range, and the second one is a fit to 6244 2-body energies in the long range. The two fits have a region of overlap which permits a smooth switch from one to the other. All energies are obtained at the CCSD(T)-F12b/aug-cc-pVTZ level of theory. Properties of the full PES, i.e., stationary points, harmonic frequencies of the global minimum, etc., are shown to be in excellent agreement with direct CCSD(T)-F12b/aug-cc-pVTZ results. Diffusion Monte Carlo calculations of the dimer zeropoint energy (ZPE) are performed, and a dissociation energy, D0, of 787 cm-1 is obtained using that ZPE, De, and the rigorous ZPEs of the monomers. Using a benchmark De, D0 is 758 cm-1. Vibrational self-consistent field (VSCF)/virtual state configuration interaction (VCI) MULTIMODE calculations of intramolecular fundamentals are reported and are in good agreement with available experimental results. Finally, the full dimer PES is combined with an existing ab initio water potential to develop a potential for the CO2 hydrate clathrate CO2(H2O)20(512 water cage). A full normal-mode analysis of this hydrate clathrate is reported as are local-monomer VSCF/VCI calculations of the fundamentals of CO2. [ABSTRACT FROM AUTHOR]

A straightforward means to include explicit hydrogen bonds within the Universal Force Field (UFF) is presented. Instead of treating hydrogen bonds as non-bonded interaction subjected to electrostatic and Lennard-Jones potentials, we introduce an explicit bond with a negligible bond order, thus maintaining the structural integrity of the H-bonded complexes and avoiding the necessity to assign arbitrary charges to the system. The explicit hydrogen bond changes the coordination number of the acceptor site and the approach is thus most suitable for systems with under-coordinated atoms, such as many metalorganic frameworks; however, it also shows an excellent performance for other systems involving a hydrogen-bonded framework. In particular, it is an excellent means for creating starting structures for molecular dynamics and for investigations employing more sophisticated methods. The approach is validated for the hydrogen bonded complexes in the S22 dataset and then employed for a set of metal-organic frameworks from the Computation-Ready Experimental database and several hydrogen bonded crystals including water ice and clathrates. We show that the direct inclusion of hydrogen bonds reduces the maximum error in predicted cell parameters from 66% to only 14%, and the mean unsigned error is similarly reduced from 14% to only 4%. We posit that with the inclusion of hydrogen bonding, the solvent-mediated breathing of frameworks such as MIL-53 is nowaccessible to rapid UFF calculations, which will further the aim of rapid computational scanning of metal-organic frameworks while providing better starting points for electronic structure calculations. [ABSTRACT FROM AUTHOR]

We use one-electron non-adiabatic mixed quantum/classical simulations to explore the temperature dependence of both the ground-state structure and the excited-state relaxation dynamics of the hydrated electron. We compare the results for both the traditional cavity picture and a more recent non-cavity model of the hydrated electron and make definite predictions for distinguishing between the different possible structural models in future experiments. We find that the traditional cavity model shows no temperature-dependent change in structure at constant density, leading to a predicted resonance Raman spectrum that is essentially temperature-independent. In contrast, the non-cavity model predicts a blue-shift in the hydrated electron's resonance Raman O-H stretch with increasing temperature. The lack of a temperature-dependent ground-state structural change of the cavity model also leads to a prediction of little change with temperature of both the excited-state lifetime and hot groundstate cooling time of the hydrated electron following photoexcitation. This is in sharp contrast to the predictions of the non-cavity model, where both the excited-state lifetime and hot ground-state cooling time are expected to decrease significantly with increasing temperature. These simulationbased predictions should be directly testable by the results of future time-resolved photoelectron spectroscopy experiments. Finally, the temperature-dependent differences in predicted excited-state lifetime and hot ground-state cooling time of the two models also lead to different predicted pumpprobe transient absorption spectroscopy of the hydrated electron as a function of temperature. We perform such experiments and describe them in Paper II [E. P. Farr et al., J. Chem. Phys. 147, 074504 (2017)], and find changes in the excited-state lifetime and hot ground-state cooling time with temperature that match well with the predictions of the non-cavity model. In particular, the experiments reveal stimulated emission from the excited state with an amplitude and lifetime that decreases with increasing temperature, a result in contrast to the lack of stimulated emission predicted by the cavity model but in good agreement with the non-cavity model. Overall, until ab initio calculations describing the non-adiabatic excited-state dynamics of an excess electron with hundreds of water molecules at a variety of temperatures become computationally feasible, the simulations presented here provide a definitive route for connecting the predictions of cavity and non-cavity models of the hydrated electron with future experiments. [ABSTRACT FROM AUTHOR]

The structure of the hydrated electron, particularly whether it exists primarily within a cavity or encompasses interior water molecules, has been the subject of much recent debate. In Paper I [C.-C. Zho et al., J. Chem. Phys. 147, 074503 (2017)], we found that mixed quantum/classical simulations with cavity and non-cavity pseudopotentials gave different predictions for the temperature dependence of the rate of the photoexcited hydrated electron's relaxation back to the ground state. In this paper, we measure the ultrafast transient absorption spectroscopy of the photoexcited hydrated electron as a function of temperature to confront the predictions of our simulations. The ultrafast spectroscopy clearly shows faster relaxation dynamics at higher temperatures. In particular, the transient absorption data show a clear excess bleach beyond that of the equilibrium hydrated electron's ground-state absorption that can only be explained by stimulated emission. This stimulated emission component, which is consistent with the experimentally known fluorescence spectrum of the hydrated electron, decreases in both amplitude and lifetime as the temperature is increased. We use a kinetic model to globally fit the temperature-dependent transient absorption data at multiple temperatures ranging from 0 to 45 °C. We find the room-temperature lifetime of the excited-state hydrated electron to be 137±40 fs, in close agreement with recent time-resolved photoelectron spectroscopy (TRPES) experiments and in strong support of the "non-adiabatic" picture of the hydrated electron's excited-state relaxation. Moreover, we find that the excited-state lifetime is strongly temperature dependent, changing by slightly more than a factor of two over the 45 °C temperature range explored. This temperature dependence of the lifetime, along with a faster rate of ground-state cooling with increasing bulk temperature, should be directly observable by future TRPES experiments. Our data also suggest that the red side of the hydrated electron's fluorescence spectrum should significantly decrease with increasing temperature. Overall, our results are not consistent with the nearly complete lack of temperature dependence predicted by traditional cavity models of the hydrated electron but instead agree qualitatively and nearly quantitatively with the temperature-dependent structural changes predicted by the non-cavity hydrated electron model. [ABSTRACT FROM AUTHOR]

The local environmental sensitivity of infrared (IR) spectroscopy to a hydrogen-bonding structure makes it a powerful tool for investigating the structure and dynamics of excess protons in water. Although of significant interest, the line broadening that results from the ultrafast evolution of different solvated proton-water structures makes the assignment of liquid-phase IR spectra a challenging task. In this work, we apply a normal mode analysis using density functional theory of thousands of proton-water clusters taken from reactive molecular dynamics trajectories of the latest generation multistate empirical valence bond proton model (MS-EVB 3.2). These calculations are used to obtain a vibrational density of states and IR spectral density, which are decomposed on the basis of solvated proton structure and the frequency dependent mode character. Decompositions are presented on the basis of the proton sharing parameter δ, often used to distinguish Eigen and Zundel species, the stretch and bend character of the modes, the mode delocalization, and the vibrational mode symmetry. We find there is a wide distribution of vibrational frequencies spanning 1200-3000 cm-1 for every local proton configuration, with the region 2000-2600 cm-1 being mostly governed by the distorted Eigen-like configuration. We find a continuous red shift of the special-pair O...H+...O stretching frequency, and an increase in the flanking water bending intensity with decreasing δ. Also, we find that the flanking water stretch mode of the Zundel-like species is strongly mixed with the flanking water bend, and the special pair proton oscillation band is strongly coupled with the bend modes of the central H5O+2 moiety. [ABSTRACT FROM AUTHOR]

We combine results from several different experiments to investigate the photophysics of acridine (Ac) and its hydrated clusters in the gas phase. Our findings are also compared with results from condensed phase studies. Similar to measurements of Ac dissolved in hydrocarbons, the lifetime of the first electronically excited state of isolated Ac in vacuum is too short for typical resonantly enhanced multiphoton ionization (REMPI) and laser induced fluorescence (LIF) experiments, hence no signal from REMPI and LIF can be attributed to monomeric Ac. Instead, sensitized phosphorescence emission spectroscopy is more successful in revealing the electronic states of Ac. Upon clustering with water, on the other hand, the lifetimes of the excited states are substantially increased to the nanosecond scale, and with two water molecules attached to Ac, the lifetime of the hydrated cluster is essentially the same as that of Ac in aqueous solutions. Detailed REMPI and ultraviolet-ultraviolet hole-burning experiments are then performed to reveal the structural information of the hydrated clusters. Although the formation of hydrogen bonds results in energy level reversal and energy separation between the first two excited states of Ac, its effect on the internal geometry of Ac is minimal, and all clusters with 1-3 water molecules demonstrate consistent intramolecular vibrational modes. Theoretical calculations reveal just one stable structure for each cluster under supersonic molecular beam conditions. Furthermore, different from mono- and di-water clusters, tri-water clusters consist of a linear chain of three water molecules attached to Ac. Consequently, the fragmentation pattern in the REMPI spectrum of tri-water clusters seems to be dominated by water trimer elimination, since the REMPI spectrum of Ac+.W3 is largely reproduced in the Ac+ mass channel, but not in the Ac+.W1 or Ac+.W2 channel. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hydrate tends to favor CO 2 , and impurity gas SO 2 have less effect. • The gas fractionation of CO 2 -SO 2 enriches SO 2 in the aqueous solution. • SO 2 promotes hydrate crystal growth rates. • SO 2 can act as hydrate-based CO 2 sequestration promoter. Sulfur dioxide (SO 2), an impurity in flue gas, could reduce capture costs if it could be co-sealed with carbon dioxide (CO 2) as hydrates. This paper investigated the one-dimensional growth process and selectivity of diffusive flux-controlled CO 2 -SO 2 hydrates using in situ Raman spectroscopy at different temperatures (278.15 and 283.15 K), pressures (5 and 10 MPa), and feed gas concentrations (4 % and 7 % SO 2). It is found that, macroscopically, separation factors (S.F.) at the hydrate-aqueous solution interface reveal that the hydrate is more selective for CO 2 (S.F. < 1), with SO 2 more inclined to dissolve in water. Microscopically, the less abundant SO 2 in the aqueous solution would be locally depleted, providing heterogeneous nucleation sites for the surrounding dissolved CO 2 , promoting CO 2 hydrate formation. The increase in SO 2 concentration would increase the hydrate growth rate and accelerate the CO 2 sequestration process. The results provide valuable insights into the synchronized sequestration of CO 2 -SO 2 by hydrates. [ABSTRACT FROM AUTHOR]

Same volume of solutions of different concentrations yielding different crystalline hydrates. [Display omitted] • Hydrates of divalent Co and Zn complexes and their interconversions are presented. • Crystallization of different hydrates from same components but at different concentrations. • Top-down as well as bottom-up of unit cells explain interconversions among these hydrates. • Stacking differences plays a major role in interconversions. • Aggregation induced emissions of hydrates of zinc complexes are presented. Different hydrates [(H 3 anthraimmida)M(26pdc) 2 ]⋅nH 2 O⋅mCH 3 OH {(M = Co; n, m = 4, 0 or n, m = 4.5: 0 or n, m = 2, 2 and M = Zn; n, m = 4, 0 or n, m = 1, 1.5) N-(anthracen-9-ylmethyl)-3-(1H-imidazolium-1-yl)propan-1-amommonium cation (H 3 anthraimmida), 2,6-pyridinedicarboxylates (26pdc)} of N-(anthracen-9-ylmethyl)-3-(1H-imidazolium-1-yl)propan-1-ammonium zinc(II) or cobalt(II) 2,6-pyridinedicarboxylate were crystallized from solutions of same reacting components but each at different concentration. Among these hydrates, the ones having methanol also as solvent of crystallization were metastable, easily transformed to corresponding tetrahydrate. The crystals of the metastable hydrate of zinc complex (monoclinic) transformed to tetrahydrate (triclinic) by halving of unit cell dimension of the metastable form. This transformation was observed under an optical microscope in real time. The transformation of the metastable hydrate of the cobalt complex also resulted the corresponding tetrahydrate. In this case, the unit-cell of the metastable form was doubled than the unit-cell dimension of the corresponding tetrahydrate. The crystals of the metastable form of the zinc complex (monoclinic) transformed to the tetrahydrate (triclinic) though a top-down approach, whereas the crystals of the metastable hydrate of the cobalt complex underwent a bottom-up approach. Diffused light scattering studies have revealed that the average particle sizes of the metastable hydrate of the zinc or cobalt complex dissolved in methanol, were decreased or increased upon addition of water to the solution. The zinc complexes in methanol showed aggregation induced emission enhancement at 415 nm upon addition of water. [ABSTRACT FROM AUTHOR]

• Synthesis and characterization of new C-26 monensin succinate ester hydrate (2-H 2 O) and its sodium salt (2-Na). • Structures of 2 and 2-Na have been studied by X-ray diffraction. • Dimers with dual linear O − H ⋅⋅⋅O hydrogen bonds are present in the crystals of 2-H 2 O and 2-Na. Monensin succinate ester hydrate (2-H 2 O) has been synthesized by the succinylation of C-26 hydroxyl group of monensin (1) using a simple reaction with succinic anhydride. Additionally, the sodium salt (2-Na) of monensin succinate ester has been obtained. Molecular structures of both compounds (2-H 2 O and 2-Na) were studied using X-ray diffraction of single crystals and spectroscopic methods. According the crystallographic studies of 2-H 2 O and 2-Na , the molecules are held together as dimers linked by the centrosymmetric pairs of intermolecular hydrogen bonds between the carboxylic groups. The crystal structures of compounds 2-H 2 O and 2-Na are compared to those of the known monensin acid hydrate (1-H 2 O) and 1:1 inclusion complex of monensin A sodium salt with acetonitrile (1-Na-CH 3 CN) and that of newly obtained monensin sodium salt monohydrate (1-Na-H 2 O). Comparison of these structures showed a significant impact of C-26 succinate ester moiety on the coordination of the Na+ cation and hydrogen bond. [Display omitted] [ABSTRACT FROM AUTHOR]

Marine sediments are ideal locations for carbon storage because of the high-pressure and low-temperature conditions. The complex marine sediment environment significantly influences the formation of CO 2 hydrates, affected by factors such as the hydrophilicity or hydrophobicity of the sediments and the presence of salt ions. The formation mechanism of CO 2 hydrates on hydrophilic and hydrophobic kaolinite surfaces in saline solution was investigated through microsecond molecular dynamics simulations. The results demonstrated that both the kaolinite surface and salt ions impacted the formation of CO 2 hydrates. On hydrophilic surfaces, a noticeable enhancement in the formation of hydrates was observed. This can be attributed primarily to the substantial adsorption of water molecules and salt ions by the kaolinite, resulting in a decrease in the amount of free water in the system and a subsequent elevation of CO 2 concentration, thereby facilitating the formation of CO 2 hydrates. Simultaneously, the adsorption of salt ions on hydrophilic kaolinite surfaces led to a reduction in salinity within the free water, contributing to a weakened inhibitory effect. Conversely, the formation of CO 2 hydrates was inhibited on hydrophobic surfaces. The hydrophobic property of the kaolinite surface led to the strong adsorption of CO 2 molecules, reducing the concentration of CO 2 in free water. These findings provide insights to understand the formation mechanism of CO 2 hydrates in marine sediments and value information for geological sequestration of CO 2. [Display omitted] • Effect of kaolin surfaces and salt ions on the formation of CO 2 hydrates was revealed. • The adsorption trends of different kaolin surface affected the formation of CO 2 hydrates. • Hydrophilic kaolin surface absorbed ions and weakened the inhibition of ions. • Hydrophobic kaolin surface absorbed CO 2 to reduce the CO 2 concentration in water. [ABSTRACT FROM AUTHOR]

[Display omitted] • Proposed a cold energy-integrated hydrate cycle for carbon capture using water. • Constructed a two-stage thermodynamic cycle for hydrate process modeling. • Optimized separation performance & power consumption from 1296 operating conditions. • Enriched CO 2 purity from 20 mol% up to 97.6 mol% • Minimized power consumption down to 0.119 kWh/kg CO 2 , i.e., 12.2 % energy penalty. Carbon capture is a crucial part of global warming mitigation. Carbon capture via clathrate hydrate is an attractive approach due to its high capture capacity, high carbon dioxide purity, water-based benign process, ease of recycling, and robustness to contaminants. In this work, we propose a two-stage hydrate-based carbon dioxide separation system integrated with cold energy for carbon capture from flue gases. A thermodynamic cycle consisting of two sub-cycles was constructed to simulate the process. Operating conditions were optimized within the range of 274.15–282.15 K and 0.1–28.04 MPa, resulting in the lowest electricity consumption of 2.22 MJ/kg CO 2 with 95.24 mol% CO 2 purity and 65.97 % CO 2 recovery. A higher CO 2 recovery rate can be achieved by recycling the residual gas of Sub-cycle 2. Gas compression to the high operating pressure (16.01 MPa) is the major contributor to electricity consumption. By incorporating 100 % expansion work recovery from the high-pressure gases, the electricity consumption can be reduced to 0.43 MJ/kg CO 2 (i.e., 0.119 kWh/kg CO 2). A more realistic scenario assuming 80 % compression/pumping efficiency and 90 % expansion work recovery gives an electricity consumption of 1.16 MJ/kg CO 2 (i.e., 0.322 kWh/kg CO 2), representing an energy penalty of 33.1 % for a coal-fired power plant. Future direction for further improvement could be a paradigm shift to hydrate process with thermodynamic promoters, which can potentially reduce the operation pressure by over 90 % and thus cut down the energy consumption dramatically. This work established a framework to simulate the hydrate-based carbon capture process, evaluated its minimum energy consumption and examined how operating conditions affect the separation performance. The results could offer valuable guidelines for the design and optimization of real hydrate-based carbon capture systems. [ABSTRACT FROM AUTHOR]

It can be foreseen that the global demand for natural gas (NG) will show an increase trend in the upcoming decades. Solidified Natural Gas (SNG) having a high energy density provides an alternative solution for the storage and transportation of NG. In this study, our focus lies on investigating the impact of 1,3-dioxane and L-tryptophan on mixed CH 4 /dioxane hydrate formation from multiple perspectives including thermodynamic, Raman spectra, and kinetics. The thermodynamic experimental results confirmed that the mixed CH 4 /dioxane hydrate can form at a moderate conditions and shows high dissociation enthalpies. A thermodynamic model based on van der Waals and Platteeuw model was applied for predicting equilibrium conditions of the Hydrate–Liquid–Vapor system, yielding an average absolute deviation ranging from 1.7% to 3.9%. Raman spectra results re v ealed that there is a two–stage growth mechanism for mixed CH 4 /dioxane hydrates. Kinetic results demonstrated that the system of CH 4 /5.56 mol% dioxane/water shows the highest gas uptake of 91.1 (±0.5) v /v at 287.15 K and 10.0 MPa, compared to other systems. Moreover, the addition of 1000 ppm L-tryptophan can reduce the time to reach 90% uptake (t 90), showing a value of 19.9 (±1.8) minutes. The findings derived from this research are instrumental in developing the SNG technology. [Display omitted] • Methane storage via mixed CH 4 /dioxane hydrates was investigated. • A thermodynamic model for mixed CH 4 /dioxane hydrate was developed. • In-situ Raman spectra analysis of hydrate formation was conducted. • The effects of L-tryptophan on hydrate formation kinetics were studied. • Up to 91.1 v /v of methane uptake is achieved at moderate conditions. [ABSTRACT FROM AUTHOR]

• The slow growth phase disappeared with increasing oil–water ratio. • DIOX promotes the bidirectional growth of hydrate on the droplet surface. • The combination of DIOX with oil–water emulsions has better separation. • Lipophilic surfactant systems have fewer hydrate aggregates. The gas separation technology based on hydrate method offers several advantages, including a short process flow, simple equipment, no pollution, less corrosion, and lower energy consumption. It has a broad application prospect in the acid gas purification, biogas purification and CO 2 sequestration., etc. However, demanding hydrate formation conditions and lower gas separation effects constrain its application. Oil-water emulsion shows promise in improving mass and heat transfer efficiency, enhancing hydrate slurry fluidity, and reducing hydrate aggregates. Thus, this study investigates the effects of different oil–water ratios, promoter concentrations, and surfactants on hydrate formation and separation efficiency in an oil–water emulsion system. At an oil–water ratio of 1:1, the purification rate increased to 6.06, five times higher than in a pure water system. The addition of 1,3-Dioxolane (DIOX) facilitated bidirectional growth properties of hydrate formation on droplet surfaces, enhancing hydrate nucleation and formation, leading to a CO2 recovery increase to 87% with 1.5 wt% DIOX. Furthermore, lipophilic surfactants were more likely to promote hydrate slurry fluidization. The addition of Span80 reduced hydrate agglomeration and increased the rate of hydrate formation as concentration rose. The results suggest that adding DIOX and increasing the concentration of Span80 could improve the hydrate method's separation efficiency at an oil–water ratio of 1:1. [ABSTRACT FROM AUTHOR]

Methane hydrates were studied in systems containing aqueous dissolved surfactants in oil emulsions with a volume ratio of 40/60. Two commercial surfactants, named synperonic PE/F127 and cetyltrimethylammonium bromide, were evaluated at 0, 350, 700 and 1500 ppm. Experiments were made by applying the cooling–heating path in an isochoric high-pressure cell at different initial pressures of 5.5, 8.0, 10.0 and 12.0 MPa. The obtained parameters were induction time, temperature onset, pressure drop, and dissociation conditions. The results revealed that the dissociation curve for methane in water-in-oil emulsions was not modified by the surfactants. The crystallization (onset) temperature was higher using synperonic PE/F127 in comparison with zero composition, while the opposite occurred with cetyltrimethylammonium bromide. Both surfactants induced a delaying effect on the induction time and a lesser pressure drop. [ABSTRACT FROM AUTHOR]

This paper examines the application of surface drilling parameters and drilling optimization techniques, such as mechanical specific energy (MSE) and equivalent strength (EST), in detecting hydrate gas-bearing sediments during drilling operations. Gas hydrates are usually detected from 3D seismic imaging and later confirmed with Measurement-While-Drilling (MWD)/Logging-While-Drilling (LWD) data and collected core samples. Here, we describe an analysis of the time-based surface drilling parameters recorded from two wells drilled during the International Ocean Discovery Program (IODP) Expedition 372A offshore of New Zealand and the Indian National Gas Hydrate Program Expedition 02 (NGHP-02) offshore of India. The investigation revealed that drilling parameters, as well as MSE/EST methods, can and should be used to monitor and optimize the drilling process and to detect lithological/tectonic (fractures, fault zones, rock hardness, etc.) changes in the drilled substrata and signs of the dynamic changes in the downhole environment (tool vibration, washouts, pack-offs, etc.). However, surface drilling parameters with MSE models cannot explicitly determine the hydrate gas-bearing sediments. This qualitative analysis of whether the gas-bearing sediments consist of hydrates can only be accomplished with the use of the MWD/LWD suite, preferably located as close as possible to the bit. [ABSTRACT FROM AUTHOR]

Novel di- and tetra-substituted calix[4]arene derivatives bearing diacetylene moieties at the lower rim of macrocycle were synthesized via the Mitsunobu and Williamson reactions. The dealkylation of diacetylene moieties of calix[4]arene was for the first time discovered in the DMSO—hydrazine hydrate system. An important role in the dealkylation of diacetylene moieties is played by neighboring unsubstituted OH groups at the macrocycle. Blocking of OH groups with butyl substituents and elongation of the linker between the butadiynyl fragments and the macrocyclic platform significantly reduce the affinity of macrocycle to reductive cleavage. The unique reactivity of calix[4]arene in its reaction with hydrazine hydrate was demonstrated in comparison with a model conjugate of diacetylene with 4-tert-butylphenol. The reductive cleavage may proceed via the formation of pyrazole derivative of calix[4]arene. Pyrazole derivatives were the most reactive ones in the reaction with hydrazine hydrate among the studied isostructural calixarenes containing an active α-arylmethyleneoxy moiety. Results of performed quantum chemical calculations allowed us to propose a scheme for the reductive cleavage of oxymethylene derivatives of pyrazole with hydrazine hydrate. [ABSTRACT FROM AUTHOR]

The purpose of the study was to assess the impact of industrial wastewater on the concentration of methanol in the considered section of the Ob River basin, present proposals for the implementation of a new treatment system and analyse the implementation results. On the basis of the results of the analysis of the known methods for reducing the concentration of methanol in water, a new technological scheme for post-treatment of effluents using biological treatment with methylotrophic Methylomonas methanica Dg bacteria was proposed. The calculation of the dilution of treated wastewater using the "NDS Ecolog" program was carried out on the basis of the detailed calculation method of Karaushev, the results of which showed a decrease in the concentration of methanol in the control section to 0.0954 mg⋅dm-3 (permissible concentration is 0.1 mg⋅dm-3). During the period of the flood of the Glukhaya channel, it ceases to be a separate water body and, in fact, becomes part of the flood channel of the Ob River. Certain parts of the flooded areas, due to elevation changes, communicate with the channel only during a short period of time when the water level rises, i.e. 3-5 weeks during the flood period, and in fact remain isolated reservoirs for the rest of the time, potentially acting as zones of accumulation and concentration of pollutants. [ABSTRACT FROM AUTHOR]

Purpose. Creation of binder based on orthophosphoric acid and aluminum sulfate, study on its structure and physicochemical patterns of formation, determination of the properties of structured mixtures for the needs of foundry. Methodology. In the work, X-ray qualitative and quantitative analysis was performed on the Rigaku Ultima IV unit, and differential thermal analysis was performed on the STA 449 C Jupiter synchronous thermal analyzer. Orthophosphoric acid, technical thermal, of 85 % concentration, 18-hydrous sulfate of aluminum Al2(SO4)3.18H2O and quartz sand of brand 3K5O3025 were used. The strength of core mixtures was determined on the US-700 unit on standard cylindrical samples with a diameter and height of 50 mm. The roughness of the cast surfaces was determined on a profilometer model 107622 with computer processing of the obtained data and construction of profilograms. To determine the propensity of the core mixtures to form caking, a hexagon sample was used according to the method by M. Fedorov. Breakability was determined on standard cylindrical samples with a diameter and height of 50 mm according to the original method described in the text of the article. Findings. For the first time, the mechanism of formation of aluminum phosphates with binding properties during the interaction of aluminum hydrate crystal sulfate Al2(OH)3.18H2O with orthophosphoric acid in the temperature range of 100–200 °С has been investigated. The formation is proved of an intermediate phase during heating – aluminum hydroxide Al2(OH)3, which, in contrast to its sulfate, according to the results of thermodynamic analysis is able to interact with acid. Formation of aluminum in the system of ortho- and metaphosphates, which features binding properties and ensures high strength of samples based on quartz filler, has been established. The thermal transformations of the obtained binder, which consists of a combination of aluminum phosphates with its residual sulfate, are studied. Stages of gradual disintegration of crystal hydrates, formation of new aluminum phosphates and thermal decomposition of residual sulfate are recorded. The tendency to burn and knockout of the developed core mixtures was determined. Originality. For the first time, a description has been developed of the mechanism of formation of aluminum phosphates with binding properties during the interaction of its sulfate crystal hydrate Al2(OH)3.18H2O with orthophosphoric acid in the temperature range of 100–200 °С. Practical value. A new inorganic binder from orthophosphoric acid and 18-aqueous aluminum sulfate has been obtained for foundry production. The scheme of its preparation involves preliminary mixing and heating of the specified reagents with the resulting formation of a dry powder material which consists of phosphates and residual aluminum sulfate, and therefore it is called phosphosulfate. The binding has a long shelf life and is introduced into the mixture in a ready-made form while the technology of its production is less energy-intensive and long-lasting compared to the preparation of traditional metal phosphate binding. [ABSTRACT FROM AUTHOR]

The use of inorganic salt hydrates for thermochemical energy storage (TCS) applications is widely investigated. One of the drawbacks that researchers face when studying this class of materials is their tendency to undergo deliquescence phenomena. We here proposed and investigated, for the first time, the possibility of using organic salt hydrates as a paradigm for novel TCS materials with low water solubility, that is, more resistance to deliquescence, a tendency to coordinate a high number of water molecules and stability under operating conditions. The organic model compound chosen in this study was calcium; 7-[[2-(2-amino-1,3-thiazol-4-yl)-2-methoxyiminoacetyl]amino]-3-[(2-methyl-5,6-dioxo-1H-1,2,4-triazin-3-yl)sulfanylmethyl]-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylate, known as calcium ceftriaxone, hereafter named CaHS (calcium hydrated salt), a water-insoluble organic salt, which can combine up to seven water molecules. The CaHS was prepared by precipitation from the water-soluble disodium triaxone. The thermal behavior of CaHS, in terms of stability and dehydration–hydration cyclability, was assessed. The material can operate in the temperature range of 30–150 °C, suitable for TCS. No deliquescence phenomena occurred upon exposure to a relative humidity (RH) between 10 and 100%. Its heat storage capacity, so far unknown, was measured to be ~595.2 kJ/kg (or ~278.6 kWh/m3). The observed heat storage capacity, thermal stability, and good reversibility after dehydration–hydration cycles highlight the potential of this class of materials, thus opening new research paths for the development and investigation of innovative organic salt hydrates. [ABSTRACT FROM AUTHOR]

The layered perovskite LaSr3Fe3O10 (LSF) easily hydrates under ambient air. The hydrated LSF transports hydroxides in the middle‐temperature range of 100 °C–250 °C. This study used X‐ray absorption fine structure analysis on normal and hydrated LSF from room temperature to 350 °C to evaluate the relationship between local structures and ion transport characteristics. The H2O molecules are mainly intercalated into rock‐salt interlayers, which are close to the La1 and O3 sites. The generated OH− ions are found at O3 sites, which are closer to Sr ions than La ions. The intercalated H2O molecules and formed OH− ions expand the spaces of the rock‐salt interlayers. The temperature dependence of the local crystal structure was also studied in this study. According to the findings, the presence of OH− ions on the O3 sites, which are closer to Sr ions, plays a significant role in OH− transport in the medium temperature range. [ABSTRACT FROM AUTHOR]

The layered perovskite LaSr3Fe3O10 (LSF) easily hydrates under ambient air. The hydrated LSF transports hydroxides in the middle‐temperature range of 100 °C–250 °C. This study used X‐ray absorption fine structure analysis on normal and hydrated LSF from room temperature to 350 °C to evaluate the relationship between local structures and ion transport characteristics. The H2O molecules are mainly intercalated into rock‐salt interlayers, which are close to the La1 and O3 sites. The generated OH− ions are found at O3 sites, which are closer to Sr ions than La ions. The intercalated H2O molecules and formed OH− ions expand the spaces of the rock‐salt interlayers. The temperature dependence of the local crystal structure was also studied in this study. According to the findings, the presence of OH− ions on the O3 sites, which are closer to Sr ions, plays a significant role in OH− transport in the medium temperature range. [ABSTRACT FROM AUTHOR]

Depressurization combined with brine injection is a potential method for field production of natural gas hydrate, which can significantly improve production efficiency and avoid secondary formation of hydrate. In this work, the experiments of hydrate production using depressurization combined with brine injection from a simulated excess-water hydrate reservoir were performed, and the effects of NaCl concentration on hydrate decomposition, temperature change, and heat transfer in the reservoir were investigated. The experimental results indicate that there is little gas production during depressurization in a excess-water hydrate reservoir, and the gas dissociated from hydrate is trapped in pores of sediments. The high-water production reduces the final gas recovery, which is lower than 70% in the experiments. The increasing NaCl concentration only effectively promotes gas production rate in the early stage. The final cumulative gas production and average gas production rate have little difference in different experiments. The NaCl concentration of the produced water is significantly higher than that which is in contact with hydrate in the sediments because the water produced by hydrate decomposition exists on the surface of undissociated hydrate. The high concentration of NaCl in the produced water from the reactor significantly reduces the promoting effect and efficiency of NaCl solution on hydrate decomposition. The injection of NaCl solution decreases the lowest temperature in sediments during hydrate production, and increases the sensible heat and heat transfer from environment for hydrate decomposition. The changes of temperature and resistance effectively reflect the distribution of the injected NaCl solution in the hydrate reservoir. [ABSTRACT FROM AUTHOR]

We describe the development of a nanosilica‐based oil and gas well cement additive which reduces the risk of casing‐casing annulus (CCA) and sustained casing pressure (SCP) through gas migration mitigation. Nanosilicas added to oil and gas well cement have been shown to accelerate cement hydration and reduce the cement porosity and permeability. While these qualities can potentially reduce the risk of zonal isolation loss, there are known rheological effects associated with adding nanosilicas to cements. It is known that cements loaded with nanosilicas produce gels prematurely, which has the deleterious effect of leading to air entrainment in cement and can also effect the pumpability of the cement slurry. This property can also interfere with gas migration mitigation because it is the formation of the gel that reduces the hydrostatic pressure on the formation. This can, in‐turn, allow for fluid from the formation to invade the cement prior to building enough mechanical strength to resist the fluid influx. The nanosilica product described in this article has been developed to display no gelation effect in the cement and a rapid hydration onset. These performance attributes are due to a specialized functionalization or coating on the nanosilica particle. At temperatures equal to or below 120°F (49°C), this functionalization renders the nanosilica inert from the cement until its timed degradation and thus does not interact with the cement phases responsible for the gelation behaviour observed with other commercially available nanosilicas in the process of cement placement. [ABSTRACT FROM AUTHOR]

Gas hydrates have been potentially recognized for developing new technologies for CO2 capture and storage; however, the respective industrialization faces difficulties. Hydrate's crystallization is highly exothermic, 1.3 kJ tonne−1 of captured CO2, and it only occurs in a narrow window of temperatures, typically 1–5 °C. Previous works have systematically reported low space–time yields (STY) due to low specific heat and mass transfer rates of the technologies tested. Herein, NetMIX, a novel mixing technology, is used for the continuous production of CO2 hydrates. NetMIX is a structured mixer consisting of a network of unit cells comprising mixing chambers interconnected by channels. The device used here has specific heat transfer rates ranging from 107 to 108W m−3 °C−1. The setup proves to be capable of producing hydrates at a STY of 200 tonne h−1m−3, two orders of magnitude larger than other technologies, resulting in a slurry with more than 20 wt% of CO2 inside the hydrates lattice. The solid is characterized, and a cubic structure I (sI) hydrate structure is detected, with no ice traces. Moreover, results indicate that the process is stable, and no plugging occurs, crucial for industrialization. [ABSTRACT FROM AUTHOR]

The reaction of Mn(NCS)2 with 3‐cyanopyridine in water accidentally leads to the formation of single crystals of Mn(NCS)2(H2O)2 (1). If the synthesis is performed without 3‐cyanopyridine, the known tetrahydrate Mn(NCS)2(H2O)4 is formed. In the crystal structure of the new hydrate, the Mn2+ cations are linked by pairs of μ‐1,3‐bridging anionic ligands to chains, which are further connected via Mn(NCS)2(H2O)4 units into layers, that are additionally stabilized by intralayer hydrogen bonding. These layers are linked by interlayer hydrogen bonding into a 3D network. The structure of 1 shows strong similarities to that of both the tetrahydrate and of Mn(NCS)2. The synthesis from water always leads to the tetrahydrate, which is also obtained, when Mn(NCS)2 is stored in a humid atmosphere. Thermoanalytical measurements on the tetrahydrate show a more complicated behavior, which includes melting at about 46 °C and on cooling sometimes the dihydrate is observed. If the tetrahydrate is stored in vacuum at room temperature, the dihydrate forms before the transformation to the anhydrate is observed. Isothermic water sorption measurements prove, that at low humidity the dihydrate is obtained, which transforms into the tetrahydrate at higher humidities. [ABSTRACT FROM AUTHOR]

The reaction of Mn(NCS)2 with 3‐cyanopyridine in water accidentally leads to the formation of single crystals of Mn(NCS)2(H2O)2 (1). If the synthesis is performed without 3‐cyanopyridine, the known tetrahydrate Mn(NCS)2(H2O)4 is formed. In the crystal structure of the new hydrate, the Mn2+ cations are linked by pairs of μ‐1,3‐bridging anionic ligands to chains, which are further connected via Mn(NCS)2(H2O)4 units into layers, that are additionally stabilized by intralayer hydrogen bonding. These layers are linked by interlayer hydrogen bonding into a 3D network. The structure of 1 shows strong similarities to that of both the tetrahydrate and of Mn(NCS)2. The synthesis from water always leads to the tetrahydrate, which is also obtained, when Mn(NCS)2 is stored in a humid atmosphere. Thermoanalytical measurements on the tetrahydrate show a more complicated behavior, which includes melting at about 46 °C and on cooling sometimes the dihydrate is observed. If the tetrahydrate is stored in vacuum at room temperature, the dihydrate forms before the transformation to the anhydrate is observed. Isothermic water sorption measurements prove, that at low humidity the dihydrate is obtained, which transforms into the tetrahydrate at higher humidities. [ABSTRACT FROM AUTHOR]

Hydrate technology promoted the development of natural gas industry. Nanoparticles showed a broad prospect for hydrate technology because of their excellent mass and heat transfer characteristics. At an experimental temperature of 275.15 K and pressure of 5 MPa, silica nanoparticles and cetyltrimethylammonium bromide (CTAB) were used to investigate the characteristics (pressure drop, gas storage capacity, and formation rate). The experimental results showed that the higher the concentration of silica nanofluid, the shorter the induction time. Among the four silica nanoparticles concentration (0.1, 0.2, 0.3, and 0.5 wt%) tested in this work, the concentration of 0.3 wt% was optimal for the enhancement of CH4 hydrate formation. In the complex system composed of silica nanoparticles and CTAB, the surface of silica nanoparticles was positively charged by hydrolysis. The cationic active groups ionized by surfactants were aggregated to the surface of the particles under the Coulomb force. Methane molecules were gathered to hydrophobic groups by non‐polar adsorption, which was more conducive to hydrate formation. Compared to silica nanofluid, the total time for hydrate formation decreased by 66.2 %. [ABSTRACT FROM AUTHOR]

(1) Background: The study systematically investigated the influence of dispersed particles within a topical formulation on the dermal penetration efficacy of active compounds that are dissolved in the water phase of this formulation. The aim was to prove or disprove if particle-assisted dermal penetration can be used for improved dermal drug delivery. (2) Methods: Fluorescein was used as a surrogate for a hydrophilic active ingredient (AI). It was dissolved in the water phase of different formulations with and without particles. Two different types of particles (titanium dioxide and nanostructured lipid carriers (NLC)) were used. The influence of particle size and number of particles and the influence of skin hydrating excipients was also investigated. (3) Results demonstrate that the addition of particles can strongly increase the dermal penetration efficacy of AI. The effect depends on the size of the particles and the number of particles in the formulation, where smaller sizes and higher numbers resulted in higher penetration parameters. Formulations with NLC that contained 20% w/w or 40% w/w particles resulted in an about 2-fold higher amount of penetrated AI and increased the penetration depth about 2.5-fold. The penetration-enhancing effect was highly significant (p < 0.001) and allowed for an efficient delivery of the AI in the viable dermis. In contrast, the penetration-enhancing effect of excipients that increase the skin hydration was found to be very limited and not significant (≤5%, p > 0.05). (4) Conclusions: Based on the results, it can be concluded that particle-assisted dermal penetration can be considered to be a simple but highly efficient and industrially feasible formulation principle for improved and tailor-made dermal drug delivery of active compounds. [ABSTRACT FROM AUTHOR]

The swelling behavior of IPN hydrogel tablets in the shape of cuboid or rectangular parallelepiped tablets in contact with buffer solutions at different pH and temperature conditions were estimated by a three-dimensional multiple-relaxation-time lattice Boltzmann (LB) model. Adsorption isotherms were obtained experimentally for tablets of IPN hydrogel formulation immersed in buffer solution at 298.15 and 310.15 K at pH equal to 4.48, 7.25, and 8.225, and those of copolymer hydrogel formulation at 298.15 K at pH equal to 4.48, 7.25, and 8.225. A computational method based on an LB model is used to simulate the hydrogels swelling, employing dimensionless units of length and mass. The discretization error estimation of the computational simulations was calculated by the grid convergence index method. Excellent correlations were achieved between the computational data and experimental values of mass swelling percentage, achieving coefficients of determination equal to or higher than 0.993 for the finest grids. The equilibrium diffusion coefficient at low pH values is higher than at large pH values. The simulations allowed us to estimate the equilibrium diffusion coefficient for each case; a qualitative property of the polymer, and to observe how the inner regions of a sample are hydrated in the time domain, both of which cannot be done experimentally. [ABSTRACT FROM AUTHOR]

Recently, phase change materials (PCMs) are acquiring much attention for the overall enhancement of photovoltaic (PV) systems' performance, because of their extraordinary property in temperature management. Many researchers have been incorporating PCMs in PV systems. However, the tested materials are principally organic PCMs. In this review, a comprehensive literature of PV systems with utilization of inorganic PCMs is introduced. Salt hydrates are the focus materials. They, in general, have comparative properties as organic PCMs and are better from safety and environmental standpoints. The characterization, properties, and applications of the salt hydrates in PV‐PCM research are discussed in this paper. Indeed, even most research shows promising outcomes, there is still need in data collection for more detailed and accurate system performance evaluation. Therefore, the real‐life application of this type of PV‐PCM system is still a long way from clear due to the discovered challenges. Finally, the possibilities of future research on PV‐PCM systems are highlighted, innovative technologies are to be discovered and addressed to defeat the current issues including system reliability and economic attainability. [ABSTRACT FROM AUTHOR]

Hydrate‐based solidified natural gas (SNG) technology provides a promising approach to store and transport natural gas, but demanding formation conditions and low methane storage capacity limit its application. Here, we presented a novel spiral‐agitated reactor, and hydrate formation in pure water and amino acid systems was evaluated. It is worth to highlight that spiral agitation significantly enhances initial hydrate grow kinetics, and satisfied methane uptake of 134.9 V/V was obtained under a mild condition (4.3 MPa, 275.15 K, and 30 rpm). Impressively, when amino acids were introduced, late hydrate growth was greatly improved because of secondary uptake, and a large methane uptake (145.97 V/V) was obtained under a milder condition (3.8 MPa, 275.15 K, and 60 rpm), which increases by 82.97% comparing to that in pure water systems. These findings provide a new insight (synergistic effect of spiral agitation and amino acids) on enhanced hydrate production under extremely mild conditions. [ABSTRACT FROM AUTHOR]

The formation of hydrates of inorganic compounds is well known and is widely discussed in the contemporary literature. The reasons for the insufficiently detailed characterization of numerous well-known hydrates of organic compounds are analyzed, the main of which is their instability. The CAS numbers assigned to many of these hydrates confirm interest in these hydrates. We found that the reversible formation of the hydrates of various organic compounds can be a reason for anomalous dependences of their retention parameters (t.sub.R) on the concentration of an organic eluent modifier (c) in reversed-phase high-performance liquid chromatography. The recurrent approximation of the retention parameters t.sub.R(c + [DELTA]c) = at.sub.R(c) + b (*), where [DELTA]c = const is a constant step of c, is the most effective way to detect these anomalies. Deviations of dependences like (*) from linearity are observed with compounds in which variations in c and, consequently, in the water content of the eluent (1 - c) affect the equilibrium of the reaction [Formula omitted], Author(s): I. G. Zenkevich [sup.1], D. A. Nikitina [sup.1], A. Deruish [sup.1] Author Affiliations: (1) grid.15447.33, 0000 0001 2289 6897, Institute of Chemistry, St. Petersburg State University, , 198504, St. [...]

In this work, we studied the dehydration process of the glycine‐MgSO4·5H2O complex under Mars‐relevant conditions (99% CO2 and 0.6% H2O under ultra violet (UV) irradiation exposure at 7‐mbar pressure and high vacuum conditions: 8 × 10−5 and 5 × 10−5 mbar) by in situ Raman spectroscopy inside a planetary atmosphere and surface chamber (PASC). This work provides quality Raman spectra taken under simulated planetary conditions (to be integrated in a database), as Raman spectroscopy forms part of the current and upcoming NASA and ESA Mars planetary missions. The results demonstrate that Raman spectroscopy can be used to calculate rates of dehydration of the glycine‐MgSO4·5H2O compound to study the chemical stability with respect to photodecomposition (1) of metal‐bound glycine molecules forming the complex and (2) glycine expelled from the complex, both under Mars‐simulated conditions; finally, Raman spectroscopy can also be used to quantify intermolecular interactions in terms of local pressures. Importantly, advanced detection of water molecules as part of a complex with astrobiological interest under planetary conditions plays a crucial role in planetary missions. [ABSTRACT FROM AUTHOR]

[Display omitted] Clathrate hydrates preferentially form at interfaces; hence, wetting properties play an important role in their formation, growth, and agglomeration. Experimental evidence suggests that the hydrate preparation process can strongly affect contact angle measurements, leading to the different results reported in the literature. These differences hamper technological progress. We hypothesize that changes in hydrate surface morphologies are responsible for the wide variation of contact angles reported in the literature. Experimental testing of our hypothesis is problematic due to the preparation history of hydrates on their surface properties, and the difficulties in advanced surface characterization. Thus, we employ molecular dynamics simulations, which allow us to systematically change the interfacial features and the system composition. Implementing advanced algorithms, we quantify fundamental thermodynamic properties to validate our observations. We achieve excellent agreement with experimental observations for both atomically smooth and rough hydrate surfaces. Our results suggest that contact line pinning forces, enhanced by surface heterogeneity, are accountable for altering water contact angles, thus explaining the differences among reported experimental data. Our analysis and molecular level insights help interpret adhesion force measurements and yield a better understanding of the agglomeration between hydrate particles, providing a microscopic tool for advancing flow assurance applications. [ABSTRACT FROM AUTHOR]

A screening of amorphous, heptahydrate, and tetrahydrate forms of disodium guanosine 5′‐monophosphate is investigated using an antisolvent crystallization process with the aim to selectively produce each solid form. The concentrations of the solution and solid forms are monitored by in situ Raman spectroscopy using a calibration tool. Particle sizes and particle counts are measured with elapsed time by a focal beam reflection measurement. Concentrations of amorphous and hydrates phases are determined using in‐line measurement techniques. The variables studied are temperature, initial concentration, addition rate, and solvent fraction. The results demonstrate that transformation from amorphous to hydrate forms consists of four stages, which are the nucleation of the amorphous form, predissolution of amorphous form, the nucleation of hydrate crystal and dissolution of amorphous solid, and the growth of hydrate crystal. The rate‐controlling step, in this case, is the dissolution of amorphous form. Transformation between heptahydrate to tetrahydrate crystals is a nucleation‐growth‐controlled step. It is possible to obtain selectively the solid forms of disodium guanosine 5′‐monophosphate by referring to the supersaturation and solubility data. [ABSTRACT FROM AUTHOR]

As a group of the most notorious carcinogens, N- nitrosamines (NAs) are highly toxic and usually involved in healthy issue of human daily life. An electrochemical sensor for N-nitrosodiphenylamine ( NDPhA ) detection was constructed based on graphene electrode material. The graphene was facilely obtained by direct reduction of graphene oxide (GO) with hydrazine hydrate, and further coated on the surface of the glassy carbon electrode (GCE) to fabricate the electrochemical sensor for NDPhA analysis in food samples. The present sensor showed excellent sensitivity and selectivity for the electrochemical determination of NDPhA under a reduction manner with the detection limit of 0. 6 μmol / L. It was also successfully used in beer and ham food samples with satisfactory recovery results. [ABSTRACT FROM AUTHOR]

In this manuscript, two thiouronium-based ionic liquids (ILs), namely 2-ethylthiouronium bromide [C2th][Br] and 2-(hydroxyethyl)thiouronium bromide [C2OHth][Br], were tested at different concentrations (1 and 10 wt%) for their ability to affect CO2 (sI) and tetrahydrofuran (THF) (sII) hydrate formation and growth. Two different methods were selected to perform a thermodynamic and kinetic screening of the CO2 hydrates using a rocking cell apparatus: (i) an isochoric pressure search method to map the hydrate phase behavior and (ii) a constant ramping method to obtain the hydrate formation and dissociation onset temperatures. A THF hydrate crystal growth method was also used to determine the effectiveness of the ILs in altering the growth of type sII hydrates at atmospheric pressure. Hydrate–liquid–vapor equilibrium measurements revealed that both ILs act as thermodynamic inhibitors at 10 wt% and suppress the CO2 hydrate equilibria ~1.2 °C. The constant ramping methodology provides interesting results and reveals that [C2OHth][Br] suppresses the nucleation onset temperature and delays the decomposition onset temperatures of CO2 hydrates at 1 wt%, whereas suppression by [C2th][Br] was not statistically significant. Normalized pressure plots indicate that the presence of the ILs slowed down the growth as well as the decomposition rates of CO2 hydrates due to the lower quantity of hydrate formed in the presence of 1 wt% ILs. The ILs were also found to be effective in inhibiting the growth of type sII THF hydrates without affecting their morphology. Therefore, the studied thiouronium ILs can be used as potential dual-function hydrate inhibitors. This work also emphasizes the importance of the methods and conditions used to screen an additive for altering hydrate formation and growth. [ABSTRACT FROM AUTHOR]

The thermal decomposition of NiSO4·6H2O, NiCl2·6H2O, and Ni(SO3NH2)2·xH2O was investigated in 50–1200 °C range by simultaneous thermogravimetry (TG) and differential scanning calorimetry (DSC) in flowing air. The solid products of the decomposed salts were identified by X-ray diffraction (XRD) analysis. The nickel salt hydrates first dehydrate in 100–350 °C, followed by decomposition into nickel oxide and gaseous species. The decomposition temperatures of the anhydrous NiSO4, NiCl2, and Ni(SO3NH2)2 are, respectively, 810 °C, 740 °C, 375–797 °C. The enthalpies for decomposition of the anhydrous salts, determined from the DSC curve, are 93.50 kJ·mol−1, 14.55 kJ·mol−1, and 26.67–56.15 kJ·mol−1for NiSO4, NiCl2, and Ni(SO3NH2)2, respectively. [ABSTRACT FROM AUTHOR]

This paper discusses an environmental criterion rarely addressed in the literature for the selection of salt hydrates for use in photovoltaic installations as Phase change materials. The aim of the paper is to assess the possibility of utilization of used salt hydrates from photovoltaic installations according to current Polish legal requirements concerning the environment. The properties of the composition components of hydrated salts were discussed in terms of their safety for the environment before and after the period of exploitation in photovoltaic panels. A method of dealing with used salt hydrates was proposed and a waste code was assigned. It has been established that spent salt hydrates will be allowed to be collected in no-outflow tanks and accepted at liquid waste collection points, which operate at water supply and sewerage companies, and the load of permissible pollutants should not exceed the value for industrial sewage. [ABSTRACT FROM AUTHOR]

Storage hydrogen using hydrates is a promising alternative to other hydrogen storage technologies. In this work, the effects of pressure and temperature on the decomposition kinetics of binary THF-H 2 hydrates was investigated systematically in the pressure range of 0.1 MPa–7 MPa and temperature from 243 K to 273 K. The results showed that the dissociation of THF-H 2 hydrates could be divided into three stages, rapid decomposition, slow decomposition, and stable state. The higher the pressure, the lower the dissociation rate of THF-H 2 hydrates in the final stable stage. It was worth to note that the dissociation rate of THF-H 2 hydrates does not show a simple linear relationship with temperature. The anomalous phenomenon of THF-H 2 hydrates dissociation was observed in the temperature region of 253 K and 268 K under 5 MPa, especially at 268 K, and it was called "similar self-preservation" phenomenon. The dissociation ratio of THF-H 2 hydrates in 80 h was not more than 50 mol% at 268 K and 5 MPa. This study provides practical way for developing clathrate hydrate-based storage hydrogen (transport and application) in the future. [Display omitted] • The "similar self-preservation effect" of THF-H 2 hydrates was discovered. • The self-preservation region of THF-H 2 hydrates was in the range of 253 K and 268 K at 5 MPa. • Less than 50% hydrogen lose from binary THF-H 2 hydrates preserving at 268 K and 5 MPa after 80 h. • Three-stages decomposition mechanism of binary THF-H 2 hydrates was proposed. [ABSTRACT FROM AUTHOR]