Partial Hydration Research Articles

Ion Association and Hydration of Some Heavy-Metal Nitrate Salts in Aqueous Solution.

Aqueous solutions of four heavy-metal nitrate salts (AgNO3, TlNO3, Cd(NO3)2 and Pb(NO3)2) have been studied at 25 °C using broadband dielectric relaxation spectroscopy (DRS) at frequencies 0.27 ≤ ν/GHz ≤ 115 over the approximate concentration range 0.2 ≲ c/mol L-1 ≲ 2.0 (0.08 ≲ c/mol L-1 ≲ 0.4 for the less-soluble TlNO3). The spectra for AgNO3, TlNO3, and Pb(NO3)2 were best described by assuming the presence of three relaxation processes. These consisted of one solute-related Debye mode centered at ∼2 GHz and two higher-frequency solvent-related modes: one an intense Cole-Cole mode centered at ∼18 GHz and the other a small-amplitude Debye mode at ∼500 GHz. These modes can be assigned, respectively, to the rotational diffusion of contact ion pairs (CIPs), the cooperative relaxation of solvent water molecules, and its preceding fast H-bond flip. For Cd(NO3)2 solutions an additional solute-related Debye mode of small-amplitude, centered at ∼0.5 GHz, was required to adequately fit the spectra. This mode was consistent with the presence of small amounts of solvent-shared ion pairs. Detailed analysis of the solvent modes indicated that all the cations are strongly solvated with, at infinite dilution, effective total hydration numbers (Zt0 values) of irrotationally bound water molecules of ∼5 for both Ag+ and Tl+, ∼10 for Pb2+, and ∼20 for Cd2+. These results clearly indicate the presence of a partial second hydration shell for Pb2+(aq) and an almost complete second shell for Cd2+(aq). However, the hydration numbers decline considerably with increasing solute concentration due to ion-ion interactions. Association constants for the formation of contact ion pairs indicated weak complexation that varies in the order: Tl+ < Ag+ < Pb2+ < Cd2+, consistent with the charge/radius ratios of the cations and their Gibbs energies of hydration. Where comparisons were possible the present constants mostly agreed well with the rather uncertain literature values.

The manufacture of natural hydraulic limes: Influence of raw materials' composition, calcination and slaking in the crystal-chemical properties of binders

This study aims to achieve an in-depth understanding of the manufacturing process of natural hydraulic lime (NHL) by assessing the influence of raw materials' chemical- mineralogical composition and the effect of the slaking process. NHLs with variable hydraulicity were manufactured using 56 raw materials from carbonate outcrops in Andalusia (Spain). This study shows that siliceous limestones with microcrystalline quartz generate hydraulic phases after calcination. However, when the amount of this reactive silica exceeds 18% by weight, CaO is not formed, and only calcium silicates appear. It was also found that slaking of NHL leads to partial hydration of the most reactive calcium silicates, reducing the expected reactivity of the lime. Instead, exposure of NHL quicklimes to environmental relative humidity promotes the formation of disordered portlandite and reduces the partial hydration of hydraulic phases. Our findings demonstrate that standard slaking can be replaced by alternative methods for the studied binders.

Contrasting Views of the Electric Double Layer in Electrochemical CO2 Reduction: Continuum Models vs Molecular Dynamics.

In the field of electrochemical CO2 reduction, both continuum models and molecular dynamics (MD) models have been used to understand the electric double layer (EDL). MD often focuses on the region within a few nm of the electrode, while continuum models can span up to the device level (cm). Still, both methods model the EDL, and for a cohesive picture of the CO2 electrolysis system, the two methods should agree in the regions where they overlap length scales. To this end, we make a direct comparison between state-of-the-art continuum models and classical MD simulations under the conditions of CO2 reduction on a Ag electrode. For continuum modeling, this includes the Poisson-Nernst-Planck formulation with steric (finite ion size) effects, and in MD the electrode is modeled with the constant potential method. The comparison yields numerous differences between the two modeling methods. MD shows cations forming two adsorbed layers, including a fully hydrated outer layer and a partial hydration layer closer to the electrode surface. The strength of the inner adsorbed layer increases with cation size (Li+ < Na+ < K+ < Cs+) and with more negative applied potentials. Continuum models that include steric effects predict CO2 to be mostly excluded within 1 nm of the cathode due to tightly packed cations, yet we find little evidence to support these predictions from the MD results. In fact, MD shows that the concentration of CO2 increases within a few Å of the cathode surface due to interactions with the Ag electrode, a factor not included in continuum models. The EDL capacitance is computed from the MD results, showing values in the range of 7-9 μF cm-2, irrespective of the electrolyte concentration, cation identity, or applied potential. The direct comparison between the two modeling methods is meant to show the areas of agreement and disagreement between the two views of the EDL, so as to improve and better align these models.

Mechanisms for deNOx and deN2O Processes on FAU Zeolite with a Bimetallic Cu-Fe Dimer in the Presence of a Hydroxyl Group-DFT Theoretical Calculations.

In this paper, a detailed mechanism is discussed for two processes: deNOx and deN2O. An FAU catalyst was used for the reaction with Cu-Fe bimetallic adsorbates represented by a dimer with bridged oxygen. Partial hydration of the metal centres in the dimer was considered. Ab initio calculations based on the density functional theory were used. The electron parameters of the structures obtained were also analysed. Visualisation of the orbitals of selected structures and their interpretations are presented. The presented research allowed a closer look at the mechanisms of processes that are very common in the automotive and chemical industries. Based on theoretical modelling, it was possible to propose the most efficient catalyst that could find potential application in industry-this is the FAU catalyst with a Cu-O-Fe bimetallic dimer with a hydrated copper centre. The essential result of our research is the improvement in the energetics of the reaction mechanism by the presence of an OH group, which will influence the way NO and NH3 molecules react with each other in the deNOx process depending on the industrial conditions of the process. Our theoretical results suggest also how to proceed with the dosage of NO and N2O during the industrial process to increase the desired reaction effect.

Modulation of ion transport through nanopores in water desalination: a molecular dynamics study

ABSTRACT A good understanding of ion transport mechanisms through nanopores is an important issue for the development of advanced water desalination technologies. We use the molecular dynamics simulation method to systematically investigate the translation dynamics of ions through nanopores in the water desalination process by designing four kinds of nano-membranes based on carbon nanomaterials. Results indicate that circular-shaped pore exhibits better water permeability, nevertheless, the slit pore has a lower resistance due to the larger pore area; nanochannel membranes increase the residence time of ions. Fluorination induces more ordered ionic hydration structures, and enhances Na + -Cl- ion pair association. -OH groups replace partial ionic hydration water molecules and facilitate ions transport into membranes. The -NH3 +, -COO- groups can strongly adsorb the oppositely charged ions, and substantially slow down ion dynamics. Functionalisation within nanochannel interior can further enhance interfacial friction and transport resistance, even causing pore blocking by charged groups. The fluorinated nanochannel membrane demonstrates complete rejection of ions with a water permeability coefficient of 1.88 × 104 L·m−2·h−1·bar−1, breaking the permeability-selectivity trade-off. This study indicates that ion transport in nanopores could be finely modulated to obtain enhanced performance in water desalination.

Subnanoscale spatially confined heterogeneous Fenton reaction enables mineralization of perfluorooctanoic acid

Superoxide radical (•O2−) is capable of degrading perfluorinated compounds that are persistent in nature and cannot be removed by biological or advanced oxidation treatments, but the inherent drawback is the negligible reactivity of •O2−in aqueous phases due to the hydration effect. Here, we explored an innovative way to make use of •O2− by modulating a partial hydration state through spatial confinement control. We demonstrated this idea by conducting heterogeneous Fenton reaction with layered iron oxychloride (FeOCl) catalyst, wherein •O2−radicals produced and confined within the catalyst structure (interlayer spacing of 7.92 Å) showed defluorination effect dealing with perfluorooctanoic acid (PFOA) as model compound. The defluorination combined with advanced oxidation achieved mineralization. Mechanism study revealed that the confinement frustrated the hydration shell of •O2−with coordination number reduced from 3.3 (for bulk phase) to 1.89, and thereby changed its orbital electron properties and enhanced the nucleophilic ability. We further demonstrated a compact FeOCl membrane reactor with highly efficient degradation of PFOA (kobs up to 1.2 min−1) and cost-effective mineralization (2 × 10−6 $ per mgC), operated under ultrafiltration reaction mode. Our findings highlight the great interest of developing spatial confinement technology to modulate •O2−-based reactions, as well as the feasibility of combining confinement catalyst structures with heterogeneous Fenton reaction to achieve the mineralization treatment goal.

Thermoresponsive Poly(N,N'-dimethylacrylamide)-Based Diblock Copolymer Worm Gels via RAFT Solution Polymerization: Synthesis, Characterization, and Cell Biology Applications.

RAFT solution polymerization is used to polymerize 2-hydroxypropyl methacrylate (HPMA). The resulting PHPMA precursor is then chain-extended using N,N'-dimethylacrylamide (DMAC) to produce a series of thermoresponsive PHPMA-PDMAC diblock copolymers. Such amphiphilic copolymers can be directly dispersed in ice-cold water and self-assembled at 20 °C to form spheres, worms, or vesicles depending on their copolymer composition. Construction of a pseudo-phase diagram is required to identify the pure worm phase, which corresponds to a rather narrow range of PDMAC DPs. Such worms form soft, free-standing gels in aqueous solution at around ambient temperature. Rheology studies confirm the thermoresponsive nature of such worms, which undergo a reversible worm-to-sphere on cooling below ambient temperature. This morphological transition leads to in situ degelation, and variable temperature 1H NMR studies indicate a higher degree of (partial) hydration for the weakly hydrophobic PHPMA chains at lower temperatures. The trithiocarbonate end-group located at the end of each PDMAC chain can be removed by treatment with excess hydrazine. The resulting terminal secondary thiol group can form disulfide bonds via coupling, which produces PHPMA-PDMAC-PHPMA triblock copolymer chains. Alternatively, this reactive thiol group can be used for conjugation reactions. A PHPMA141-PDMAC36 worm gel was used to store human mesenchymal stem cells (MSCs) for up to three weeks at 37 °C. MSCs retrieved from this gel subsequently underwent proliferation and maintained their ability to differentiate into osteoblastic cells.

Study of water resistance of silica protective coatings based on liquid glass

The water resistance of cotton textile materials impregnated with SiO2 sols obtained on the basis of liquid glass was studied. Experimental coatings on fabrics were prepared by the bath method. After applying each coating layer and removing excess ash, the experimental samples were dried at (60–80) ºС. Fabric samples impregnated with sol SiO2 were immersed in containers with distilled water maintaining the same sample/water ratio. The fire-retardant properties of the coatings were determined after standing in water for 2–72 hours. The degree of destruction of coatings during hydrolysis was studied by determining the optical density of the hydrolyzate above the surface of the samples using the spectrophotometric (KFK-2) method. Fire-resistant properties were determined at a laboratory installation for fire tests. Under the influence of water, partial hydration of the surface of the silica coating occurs, which does not lead to its destruction. The presence of a layer of adsorbed water molecules on the surface of the coating is the reason for an additional increase in the fire-retardant properties of the samples. It is shown that the degree of homogeneity of the SiO2 sol affects the resistance to hydrolysis of the gel coatings. Low-concentration SiO2 sols (8 %), which are characterized by high fluidity and have a long service life, have a predominant effect. The long-term effect of water provides an increase in the fire-retardant properties of impregnated samples in comparison with non-impregnated fabric samples. The concentration and degree of homogeneity of the SiO2 sol have a predominant effect on the flame retardant properties. The surface layer of flame-retardants prevents the final burning and smoldering of the samples after removing the fire source, but does not significantly affect values of flame-retardant properties.

Evolution of the morphological, structural, and molecular properties of gluten protein in dough with different hydration levels during mixing.

To understand the formation process of dough with different hydration levels upon mixing and the response of dough rheology, the dynamic evolution of gluten protein was tracked and quantified at morphological, structural, and molecular levels. Both macroscopical and microscopic distribution images showed that partial and full hydration induced quick formation of a more compact gluten network compared with limited hydration. Gluten network in highly hydrated samples was more susceptible to the formation and collapse induced by mechanical force. SE-HPLC results indicated significant depolymerization of glutenin macropolymer (GMP) in fully and partially hydrated samples. Sufficient mixing was accompanied by the increase of ionic and hydrogen bonds, while excessive mixing increased exposure of free -SH. Higher hydration level induced more ordered secondary structure. Correlation and principal component analysis revealed the patterns and dynamics of gluten evolution during dough formation with different hydration levels, and their contribution to the changes in dough modulus.

Study on the interactions of tetradecylpyridinium dl-mandelic acid and cetylpyridinium dl-mandelic acid with some small biomolecules in aqueous solution

Interactions of two active pharmaceutical ingredient ionic liquids (API-ILs) tetradecylpyridinium dl-mandelic acid ([TetPy][MAN]) and cetylpyridinium dl-mandelic acid ([CetPy][MAN]) with some small biomolecules have been studied by using conductometric, density and UV–vis spectroscopic techniques. The chosen small biomolecules are glycine, l-alanine, l-valine, l-leucine and glycylglycine (AAGG). The critical micelle concentration (cmc) of [TetPy][MAN] and [CetPy][MAN] in aqueous AAGG solution is calculated from the measured conductance values, thus yielding some thermodynamic parameters of the micellization, such as the standard Gibbs energy change (ΔGm0), the standard enthalpy change (ΔHm0) and the standard entropy change (ΔSm0). On the basis of the experimental densities of ternary solutions of (AAGG + API-ILs + water), apparent molar volume at infinite dilution (V2,φ0), apparent molar expansibility at infinite dilution (Eφ0), transfer partial molar volume (ΔtV0) and hydration number (nH) of AAGG in aqueous API-ILs solution were calculated. The dominant hydrophobic-hydrophilic and hydrophobic-hydrophobic interactions were involved in the investigated systems. The binding constant (Kb) between AAGG and API-ILs has been calculated from UV–vis spectroscopic data. Effect of some factors including concentration, temperature, molecular structure, etc. on the aforementioned parameters and the existing solvent–solute interaction has been discussed.

Production and Characterization of Bacterial Cellulose Separators for Nickel-Zinc Batteries

The need for energy-storing technologies with lower environmental impact than Li-ion batteries but similar power metrics has revived research in Zn-based battery chemistries. The application of bio-based materials as a replacement for current components can additionally contribute to an improved sustainability of Zn battery systems. For that reason, bacterial cellulose (BC) was investigated as separator material in Ni-Zn batteries. Following the biotechnological production of BC, the biopolymer was purified, and differently shaped separators were generated while surveying the alterations of its crystalline structure via X-ray diffraction measurements during the whole manufacturing process. A decrease in crystallinity and a partial change of the BC crystal allomorph type Iα to II was determined upon soaking in electrolyte. Electrolyte uptake was found to be accompanied by dimensional shrinkage and swelling, which was associated with partial decrystallization and hydration of the amorphous content. The separator selectivity for hydroxide and zincate ions was higher for BC-based separators compared to commercial glass-fiber (GF) or polyolefin separators as estimated from the obtained diffusion coefficients. Electrochemical cycling showed good C-rate capability of cells based on BC and GF separators, whereas cell aging was pronounced in both cases due to Zn migration and anode passivation. Lower electrolyte retention was concluded as major reason for faster capacity fading due to zincate supersaturation within the BC separator. However, combining a dense BC separator with low zincate permeability with a porous one as electrolyte reservoir reduced ZnO accumulation within the separator and improved cycling stability, hence showing potentials for separator adjustment.

Roles of partial hydration of mantle transition zone and wadsleyite–olivine phase transition in wet plume development: Origin of Quaternary intraplate volcanoes in Korea

The Quaternary intraplate volcanoes in Korea have a sparser distribution (~330–563 km) than that of Japanese arc volcanoes (~80 km), geochemistry indicating mixing of components from the stagnant slab and mantle transition zone, and a longer elapsed time (~10–20 Myr) of the Quaternary eruption after the stagnation of the Pacific Plate. Although volcanism can be explained by wet plumes originating from the hydrous layer of the stagnant slab, previous numerical studies could not consistently explain the spatiotemporal and geochemical observations because of the neglected partial hydration of the mantle transition zone and wadsleyite–olivine phase transition at the 410-km discontinuity, both of which affect the viscosity and buoyancy structures. Thus, we constructed a series of two-dimensional numerical models by considering the partial hydration of the mantle transition zone and phase transition at the 410-km discontinuity. The results showed that the wet plumes are retarded at the 410-km discontinuity by the phase transition and merge into batches forming hybrid plumes in the asthenosphere, explaining the mixing of components from the hydrous slab and mantle transition zone, evidenced by the geochemical observations. The spacing (~485 km) and elapsed time (~24 Myr) of the hybrid plumes beneath the lithosphere are consistent with the spatiotemporal observations. Furthermore, the degree of mixing of the components from the hydrous slab and mantle transition zone found in the hybrid plumes explains the spatial distribution of water in the mantle transition zone beneath Korea.

Suitability of Oral Rehydration Solution (ORS) for Use in the Cisplatin Short Hydration Method.

Short hydration is a method to change partial intravenous hydration to oral to administer cisplatin (CDDP); however, the most suitable form of oral hydration is unknown. This study aimed to determine whether oral rehydration solution (ORS) affects CDDP-induced nephrotoxicity (CIN) and electrolyte imbalance. Lung cancer patients (n=200) who had received CDDP-including regimens (CDDP dosage ≥75 mg/m2) were retrospectively evaluated. We used logistic analysis to evaluate whether ORS intake could be a preventive factor for CIN (≥grade 2 serum creatinine elevation). Moreover, incidence of CIN and electrolyte imbalance and the variation in serum creatinine and electrolyte levels were compared between ORS and non-ORS (control) patients. CIN occurred in 9.8% of ORS patients, and 7.5% of non-ORS patients (p=0.79). The variation in serum creatinine level was also similar in both groups. Multivariate analysis suggested that ORS intake does not affect CIN, although CIN was associated with the coadministration of non-steroidal anti-inflammatory drugs and the presence of diabetes mellitus. The variations in serum electrolyte levels did not differ, and incidence of hyponatremia, hypokalemia, and hypochloremia was also similar between the groups. Moreover, patients in ORS group experienced significantly more anorexia compared to controls, and approximately 40% of the patients were unable to continue ORS intake. ORS intake in CDDP short hydration regimens does not affect CIN and CDDP-induced electrolyte imbalance; however, its intake is associated with the incidence of anorexia suggesting that ORS should not be used for oral hydration.

Hydration and dehydration induced changes in porosity of starch microspheres

Characterization and tuning of the porosity of amorphous starch materials are important for many applications, including controlled release of encapsulated proteins. The porosities of these materials in dry and hydrated states can have different physicochemical origins and properties. Here, porosities of dry cross-linked starch microspheres and their hydration-induced transformations were characterized by small angle X-ray scattering, scanning electron and optical microscopies, thermogravimetric analysis, sorption calorimetry, nitrogen sorption, and helium-pycnometry. The analyses revealed that dry microspheres consist of porous cores with pore diameters below 100 nm and shells which appeared to be denser but contained wider pores (100–300 nm). The outer crust of the microspheres shell is non-porous, which restricts diffusion of nitrogen, water, and ethanol. Partial hydration triggered an irreversible collapse of dry porosity at 12 wt% water. Further hydration resulted in interfacial changes and promoted wet porosity, related to characteristic distances between polymer chains.

Seed Hardening: A Way to Tolerate Against Abiotic Stress in Rainfed Areas

Pre-sowing hardening or priming of seeds is one of the best methods for altering the biochemical and physiological process of seeds for favourable condition to induce drought tolerance in emerging seedlings. The recurrent phenomenon in rainfed areas i.e. soil moisture stress immediately after sowing affects seeds germination and their establishment. Under sub-optimal environmental conditions like rainfed farming, poor seed germination followed by poor field establishment is a common phenomenon. Seed hardening enables seedlings to survive this early moisture stress. hydration of seeds for short term before planting greatly benefits stand establishment along with the uses of chemicals like potassium or sodium phosphate would give additional advantage. It is defined as the process of soaking seeds in chemical solution for specified time and then drying to induce tolerance to drought. Various seed priming/hardening techniques have been developed including hydro-priming, halo-priming, osmo-priming and hormonal priming. Micronutrient seed treatments, which include seed priming and seed coating, are an attractive and easy alternative. Seed hardening promotes early establishment provides more strengthen to plant and it became competitive against infections and diseases is related to gene regulation and expression under stress conditions. The discovery of plant hormones in the 1920s underlined the crucial role of these compounds in seed desiccation tolerance, reserve mobilization, as well as cell division and cell elongation occurring during germination. The seed hardening is considered as low cost technology and is the most important requirement for pre-monsoon sowing. Seed hardening offer an attractive option for resource poor farmers. During seed hardening, seeds are subjected to partial hydration followed by dehydration before sowing.

Interaction behavior of sucrose in aqueous tributylmethylammonium chloride solutions at various temperatures: A volumetric, ultrasonic and viscometric study

Physical properties such as density (ρ), sound speed (u) and viscosity (η) for varied compositions of a saccharide (sucrose) in water and mixed aqueous tributylmethylammonium chloride solvent media has been scrutinised at five discrete temperatures ranging (293.15 K - 313.15 K) and under ambient pressure (101.3 kPa). The empirically procured data has been employed to enumerate different volumetric, acoustic and viscometric parameters like apparent molar parameters (Kϕ,s, Vϕ), partial molar parameters (K0ϕ,s, V0ϕ), transfer parameters (K0ϕ,s,tr, V0ϕ,tr, Btr), hydration number, pair and triplet interaction coefficients, solvation number, viscosity B-coefficient etc. The temperature derivative of viscosity B-coefficient i.e. dB/dT values have been utilized to examine structure making ability of the solute. Also, Gibbs free energy of activation for both solute and solvent has been determined and the influence of temperature on the solute-solvent interactions has been addressed. Moreover, the co-sphere overlap model has been employed for better comprehension of various prevalent intermolecular interactions in the considered systems.

Understanding the Water-in-Salt to Salt-in-Water Characteristics across the Zinc Chloride : Water Phase Diagram.

Using a series of time- and temperature-resolved synchrotron diffraction experiments, the relationship between multiple polymorphs of ZnCl2 and its respective hydrates is established. The δ-phase is found to be the pure anhydrous phase, while the α, β, and γ phases result from partial hydration. Diffraction, gravimetric, and calorimetric measurements across the entire ZnCl2·R H2O, 0 > R > ∞ composition range using ultrapure, doubly sublimed ZnCl2 establish the ZnCl2 : H2O phase diagram. The results are consistent with the existence of crystalline hydrates at R = 1.33, 3, and 4.5 and identify a mechanistic pathway for hydration. All water is not removed from hydrated ZnCl2 until the system is heated above its melting point. While hydration/dehydration is reversible in concentrated solutions, dehydration from dilute aqueous solutions can result in loss of HCl, the source of hydroxide impurities commonly found in commercial ZnCl2 preparations. The strong interaction between ZnCl2 and water exerts a significant impact on the solvent water such that the system exhibits a deep eutectic at a composition of about R = 7 (87.5 mol %) and a eutectic temperature below -60 °C.

Synthesis and Characterization of Chanar Gum Films

New polysaccharides are being intensely studied as sources of edible materials, with potential application in food packaging systems, eco-materials and the pharmaceutical industry. This investigation aimed to develop biopolymer films based on the polysaccharides obtained from chañar (CH) fruit (Geoffrea decorticans). The resulting polysaccharides, from hydrothermal extraction (CHT) and acid extraction (CHA) were hydrodynamically characterized, with density, viscosity, and diffusion coefficient measurements to obtain their properties in an aqueous solution (intrinsic viscosity, shape factor, partial specific volume, hydration value, molecular weight, and hydrodynamic radius). The polysaccharides films (CHTF and CHAF) were characterized with SEM/EDX, DSC, TGA-DTG, FTIR, DRX, mechanical tests, water vapor permeation, colorimetry, antioxidant capacity, and biodegradability, to determine potential applications based on these properties. The results indicated that the extraction method affects the hydrodynamic properties of the obtained polysaccharide. They differ in molecular weight, and RH of CHT was greater than CHA. Both gums were quasi-spherical, and the νa/b value of CHT was more than CHA. The films properties did not present significant differences in most cases. SEM micrographs illustrate that CHAF presents a much rougher surface. The results of the mechanical analysis show that CHTF has better mechanical properties, it has higher elongation at break and tensile strength, with a Young Modulus of 2.8 MPa. Thermal analysis indicates good thermal stability of the films until about 150 °C. The degradation study shows that CH films are biodegradable in a 35 day range. The study of this properties is critical to demonstrate the functionality of biopolymers and their application. The obtained results represent an advantage and evidence that chañar is an interesting source for extract polysaccharides with film forming properties.

The deep Basel-1 geothermal well: an attempt assessing the predrilling hydraulic and hydrochemical conditions in the basement of the Upper Rhine Graben

Hydrogeological properties of fluid reservoirs in the brittle continental crust at 5 km have been deduced from hydraulic and chemical data provided by the Deep Heat Mining well Basel-1 in the south of the Upper Rhine rift valley (central Europe, Switzerland). The investigation was challenging because no direct temperature logs or fluid samples from the undisturbed reservoir exist. However, the properties of the undisturbed reservoir have been reliably reconstructed from short time hydraulic tests and the evolution of outflow water composition. The rock of the open hole sections (4629–5000 m) is predominantly coarse-grained undeformed poorly fractured quartz-monzodiorite. The permeability k = 5.8 × 10–18 m2 is characteristic for plutonic basement at 5 km depth. Fluid flow is restricted to few steeply dipping fracture zones in this section. Outflow water triggered by massive injection of river water contains predominantly NaCl. The total of dissolved solids (TDS) in the pristine reservoir at depth is about 45 g kg−1. The origin of the high salinity is probably fossil seawater. The water has been modified in the reservoir by desiccation reactions related to the partial and local hydration of the igneous reservoir rock. The estimated reservoir temperature of 185 °C using three different calibrations of standard fluid geothermometers is in excellent agreement with measured and extrapolated temperatures in the borehole. The consistent application of different fluid geothermometers confirms the rock control of the fluid composition.

Accessing new polymorphs and solvates through solvothermal recrystallization.

In high-pressure structural chemistry, recrystallization techniques have been shown to be a powerful way of generating new polymorphs and solvates. A recent study by Olejniczak et al. [IUCrJ (2022), 9, 49-54] on the pyridazine-based compound 6-chloro-1,2,3,4-tetrazolo[1,5-b]pyridazine (C4H2N5Cl or CTP) uses these solvothermal techniques to establish the phase behaviour of CTP and the effects of partial hydration.