Aqueous Calcium Chloride Research Articles

Features of Thermodynamic Conditions of the Formation and the Gas Composition in Natural Gas Hydrates Obtained in a Dispersed Medium with Aqueous Calcium Chloride

Features of Thermodynamic Conditions of the Formation and the Gas Composition in Natural Gas Hydrates Obtained in a Dispersed Medium with Aqueous Calcium Chloride

Sustainable, Low‐Cost Sorbents Based on Calcium Chloride‐Loaded Polyacrylamide Hydrogels

AbstractSorbents are promising materials for applications in atmospheric water harvesting, thermal energy storage, and passive cooling, thereby addressing central challenges related to water scarcity and the global energy transition. Recently, hygroscopic hydrogel composites have emerged as high‐performance sorbents. However, many of these systems are fabricated with unsustainable and costly sorbent materials, which hinders their wide deployment. Here, the synthesis of high‐performance, cost‐efficient polyacrylamide hydrogels loaded with unprecedented amounts of calcium chloride is demonstrated. To this end, the swelling procedure of polyacrylamide hydrogels in aqueous calcium chloride solutions is optimized. The achievable salt loading in the hydrogel is characterized as a function of temperature, calcium chloride concentration in the swelling solution, and the hydrogel preparation conditions. The obtained hydrogel‐salt composites are shown to be stable under repeated sorption‐desorption cycling and enable water uptakes of 0.92 and 2.38 grams of water per gram of dry materials at 30% and 70% relative humidity, respectively. The resulting cost‐performance ratio substantially exceeds lithium chloride‐based systems. Further, the mechanistic insights on hydrogel salt interactions can guide the design of sustainable and low‐cost sorbent materials for future applications in water and energy.

Structural, magnetic, and metal-carboxylate interactions investigations in alginate-encapsulated MFe2O4 (M = Co, Ni, Zn)

Magnetic ferrites nanoparticles (MFNs) MFe2O4 (M = Co, Ni, Zn) were synthesized via coprecipitation method and then encapsulated by Alginate polymer through cross-linking in aqueous calcium chloride solution. The obtained products were characterized by XRD, SEM, FTIR spectroscopy, TGA, and VSM. X-ray diffraction results indicate a decrease in diffractions picks intensities after encapsulating the MFNs with Alginate. Furthermore, cation distribution among interstitial sites was determined and it indicates an average inversion degree of 0.017, 0.142, and 0.8 for CoFe2O4, NiFe2O4, and ZnFe2O4 respectively, these values are in good agreement with the Rietveld refinement of X-ray diffraction patterns. The interaction of MFNs surface and the carboxylic group of alginates was investigated in detail for the first time, FTIR spectroscopy and VSM were used for this purpose. Therefore, from the wavenumber separation Δ values, between the frequencies of the characteristic peaks for asymmetric and COO− stretching vibration and symmetric COO− stretching vibration, we found 185.16 for Na-Alginate, 177.45 cm−1 for Alg@CoFe and Alg@Ni, while Alg@Zn have a wavenumber separation of 192.88 cm−1, which is characteristic to bidentate chelating coordination. The study of magnetic properties reveals a decrease of saturation magnetization after the encapsulation of nanoparticles, from 80.86, 47.17, and 4.36 emu/g for CoFe2O4, NiFe2O4 and ZnFe2O4 respectively to reach 18.43, 13.53, and 0.69 for their corresponding beads. This decrease is explained by the interaction between COO− and the surface of the nanoparticles.

Examining the Hydration Behavior of Aqueous Calcium Chloride (CaCl2) Solution via Atomistic Simulations

Equilibrium molecular dynamics simulations are performed to examine the hydration behavior of Ca2+ and Cl− across a wide range of salt concentrations (from 1 wt.% to 60 wt.% CaCl2) in an aqueous solution. The predicted radial distribution functions (RDFs) and coordination numbers (CNs) of Ca2+–water, Cl−–water, and Ca2+–Cl− agree with the previous studies conducted at concentrations below the solubility limit at room temperature. The hydration limit of aqueous calcium chloride solution is identified at 10 wt.% CaCl2 as the CNs remain constant below it. Beyond the bulk solubility limit ~44.7 wt.% CaCl2, a noticeable decrease in the CN of Cl− and water is recorded, implying the saturation of the solution. The solvating water molecules decrease with increasing salt concentration, which can be attributed to the growth in the number of ion pairs.

Microfluidic dual picoinjection based encapsulation of hemoglobin in alginate microcapsules reinforced by a poly(L-lysine)-g-poly(ethylene glycol).

Hemoglobin (Hb) encapsulation inside polysaccharide hydrogels has been considered a possible red blood cell (RBC) surrogate in transfusiology. Here we report on the microfluidic dual picoinjection assisted synthesis of Hb encapsulated alginate-poly(L-lysine)-g-poly(ethylene glycol) beads. This process is realized by the on-chip injections of blended Hb alginate solutions in emulsified aqueous calcium chloride (CaCl2) droplets followed by a subsequent injection of an aqueous PLL-g-PEG into each emulsified aqueous droplet. The proposed fabrication approach was realized using a flow-focusing and two picoinjection sites in a single PDMS device. Aqueous CaCl2 solution was emulsified and infused with Hb-alginate solution as the squeezed droplet passed through the first picoinjection site. The injection of PLL-g-PEG to reinforce the microgel and minimize the protein leaching was realized in the second picoinjection site located downstream from the first in the same microfluidic channel. In this process, monodisperse Hb-alginate-PLL-g-PEG particles with a diameter around the size of RBCs (9 μm) were obtained with around 80% of the 7.5 mg ml-1 Hb included in the injected aqueous alginate retaining in the obtained microparticles. Microparticles with Hb loading (32.8 pg per bead) and retention (28.8 pg per bead) over a week of storage at 4 °C are in accordance with the average amount of Hb per RBC. The Hb-alginate-PLL-g-PEG microbeads fabricated in the size range of RBCs are significant for further exploration.

Development and performance evaluation of a passive solar liquid desiccant regenerator

Vapour Compression Refrigeration (VCR) cycle that consumes electrical energy dominates airconditioning market today. Production of electrical energy is generally associated with fossil fuel consumption, emission of greenhouse gases and pollution. Air conditioning systems that use waste or renewable energy sources should be investigated as an alternative solution. Liquid desiccant-based air conditioning system (LDAC) is one such a potential candidate. The heat from a solar thermal collector can be supplied to the regeneration process of LDAC systems. A novel solar collector with the goal of no electrical power consumption, simplicity, low cost, and high efficiency was developed in this work for the regeneration of LD (aqueous calcium chloride solution). Condensate output in this device used for water desalination was 3.7 kg/m2, which is comparable with the best in the literature. An area of 7.5 m2 of such a device with no parasitic power would be needed per kW of latent cooling.

Silk-based pressure/temperature sensing bimodal ionotronic skin with stimulus discriminability and low temperature workability

Multi-responsive sensing devices have contributed extensively to health monitoring applications. However, the effects of different stimuli often confuse, and thus cause, signal distortion of the sensor response. In addition, many sensing devices cannot work properly at low temperatures. In the present study, a robust regenerated silk fibroin (RSF)-based hydrogel was fabricated with silver nanowires (AgNWs) embedded in the surface. The microstructure of AgNW-embedded RSF surface was introduced using cotton fabric as a template. Afterwards, the hydrogel was immersed in an aqueous calcium chloride solution to introduce Ca(II) ions into the matrix of the RSF hydrogel. Finally, two pieces of the RSF/AgNW/Ca(II) hydrogel were assembled with AgNW layer face-to-face to form a dual-responsive ionotronic skin that was sensitive to pressure and temperature. The pressure-response of the RSF/AgNW/Ca(II) ionotronic skin showed a high sensitivity, short response time, and good durability. In addition, the temperature-response also showed a high sensitivity and good durability from low temperatures (−30°C) to high temperatures (50°C). As a demonstration of its dual responsiveness, 16 pieces of RSF/AgNW/Ca(II) ionotronic skin were combined to make a 4 × 4 array. It demonstrated high sensitivity without interference between the pressure and temperature signals, achieving a significant dual response. A potential application for the simultaneous detection of body temperature and heartbeat was demonstrated by placing the RSF/AgNW/Ca(II) ionotronic skin on the wrist and further indicated the practicality of such an ionotronic skin because it could distinguish between the percussion wave, tidal wave, and diastolic wave in a single waveforms. Therefore, this RSF/AgNW/Ca(II) ionotronic skin that can discriminated between stimuli and work at low temperatures may have great potential in the field of wearable health monitoring equipment.

Nonbrittle Nanocomposite Materials Prepared by Coprecipitation of TEMPO-Oxidized Cellulose Nanofibers and Hydroxyapatite

Organic–inorganic nanocomposites were prepared by crystallization of hydroxyapatite in an aqueous dispersion of cellulose nanofibers. The addition of aqueous calcium chloride to an aqueous dispersi...

Development of hydroxyapatite reinforced alginate–chitosan based printable biomaterial-ink

This study reports synthesis of sodium alginate/ chitosan/ hydroxyapatite (HAp) based biomaterial-ink. An ionic interaction between polyanionic alginate and polycationic chitosan has been observed that forms a physical gel. The dispersion of HAp has been achieved through ultra-sonication, and stability of HAp in the hydrogel system has been achieved through hydrogen bonding with chitosan. Post printing crosslinking has been carried out with a 10 w/v % aqueous calcium chloride (CaCl2) solution. The combinations of biomaterial-ink have been characterized through Attenuated Total Reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), Scanning Electron Microscope (SEM), contact angle measurements. Further, the inks were characterized to estimate the printability and rheological responses. ATR-FTIR study confirms the ionic interaction between alginate and chitosan and identifies the presence of HAp in the biomaterial-ink. SEM morphology depicted the post-printing shape retention ability of the bioprinted constructs and revealed the structure’s rough morphology. All the biomaterial-ink combinations depicted hydrophilic nature as confirmed by the contact angle measurements. Rheological studies of the printable ink with hydroxyapatite revealed shear thinning properties and acceptable viscosity, essential for extrusion during bioprinting. The biomaterial-ink comprised only sodium alginate, and chitosan also displayed shear thinning abilities and showed lower working viscosity resulting in poor printability. The addition of hydroxyapatite to the hydrogel revealed acceptable post-printing structural stability. However, beyond 0.2% by weight of HAp imparts brittleness in the final structure. The linear viscoelastic regime, elastic modulus, and viscous modulus of the inks have been determined through the oscillatory strain sweep test. Creep recovery study, essential for predicting material behaviour immediately after ejection from the nozzle, indicated the material’s viscoelastic behaviour. The power law model has been used to estimate the flow index that predicted shear thinning abilities of the biomaterial-ink, and a correlation between the experimental and theoretical model was established. Herschel–Bulkley empirical model was used to determine yield stress (minimum stress required for extrusion from the nozzle) of the biomaterial-ink. Rheological studies and printability studies indicated Ink 5% 2% 0.1% as a promising combination for tissue engineering applications.

Novel TOCNF reinforced injectable alginate / β-tricalcium phosphate microspheres for bone regeneration

An innovative, moldable and injectable bone substitute material comprised of microspheres of sodium alginate (SA)/TOCNF and β-tricalcium phosphate (β-TCP) as the solid phase and carrier SA as the gel phase was developed. The microspheres were prepared by a droplet extrusion crosslinking technique using an aqueous calcium chloride solution. The purpose of this study was to explore the osteoconductivity of the prepared injectable microspheres by filling critically sized bone defects. The in vitro biocompatibility and cytotoxicity of the microspheres were analyzed in MC3T3-E1 osteoblast-like cells using an MTT (3-(4,5-dimethylthiazol-2-yl)-2,5diphenyltetrazolium bromide) assay. An in vivo investigation in a rabbit model indicated that the prepared SO3T20 microspheres showed significantly better bone formation than the control after two and four weeks of implantation. The outcomes demonstrated that the microspheres delivered support for osteogenic differentiation. These results suggest that this novel injectable bone substitute material may be useful for bone tissue engineering.

Liquid-absorbing system-assisted intersecting jets printing of soft structures from reactive biomaterials

Traditional three-dimensional (3D) bioprinting techniques of reactive materials usually include a mixing step of reactive agents prior to deposition, leading to potential changes in the rheological and biocompatibility properties of the resulting ink. During intersecting jets printing, reactive materials are dispensed separately, colliding and mixing with each other in air before landing on a previously deposited layer. While this enables reactive material printing using a printing-then-mixing approach, the resulting excess fluid may compromise the printing quality and accuracy. This study aims to improve the performance of intersecting jets–based reactive material printing by introducing a stainless-steel wire mesh and fibrous tissue paper–based liquid-absorbing system, which functions as a method to remove the excess resultant liquid from the printing zone. The proposed stainless-steel wire mesh and tissue paper-based liquid absorbing system effectively absorbs the excess liquid resulted during the printing process which enables higher-resolution and denser depositions of soft structures. By selecting a proper wire mesh, the proposed liquid-absorbing system can absorb up to 65–90 % of the excess liquid (water herein) resulting from printing aqueous reactive sodium alginate and calcium chloride inks, which are selected as model materials in this study. By controlling the tilt angles of intersecting jets, the incident angle of post-collision droplets is desirable to be less than 14° to avoid droplet bouncing on the top of a previously deposited layer during 3D bioprinting. Using the liquid-absorbing system, different 3D structures have been successfully printed using intersecting jets printing. For tubular alginate constructs printed in air from sodium alginate and calcium chloride inks, a 2.5 height-diameter ratio can be achieved. The proposed printing technology does not influence the post-printing cell viability while printing 3T3 cells, demonstrating its promising potential for bioprinting applications.

Ion Hydration and Association in an Aqueous Calcium Chloride Solution in the GPa Range

Neutron diffraction measurements of an aqueous 2 mol dm–3 CaCl2 solutions in D2O have been made at 1 GPa, 298 K as well as 0.1 MPa, 298 K. The experimental structure factors are subjected to Empirical Potential Structure Refinement (EPSR) modeling to reveal the ion hydration and association and solvent water at the atomic level. About seven water molecules surround Ca2+ at the Ca–O and Ca–D distances of 2.44 Å and 3.70 Å, respectively, at both pressures, suggesting no significant pressure effect on the cation hydration. On the other hand, the Cl‐ ion shows a drastic change in water oxygen coordination from ca. 7 at 0.1 MPa to ca. 14 at 1 GPa, accompanied by shortening of Cl–O distance from 3.18 Å to 3.15 Å. However, the number of water hydrogen atoms around Cl– does not change significantly as 6.0–6.7 in spite of shortening Cl–D distance from 2.22 to 2.18 Å on compression. The pressure effect on the solvent water structure is also drastic as an increase in water oxygen atoms of 4.7 at the O–O distance of 2.79 Å at 0.1 MPa to 10.3 at 2.85 Å at 1 GPa. The number of water hydrogen atoms, however, does not change as 1.2 at the O‐D distance of 1.74 Å for both pressures, demonstrating the presence of the O···D hydrogen bonds which are significantly bent at 1 GPa at 298 K. This change of hydrogen bonds in water with pressure probably causes the drastic increase in water oxygen atoms around Cl–.

Conductive Carbon Microfibers Derived from Wet-Spun Lignin/Nanocellulose Hydrogels.

We introduce an eco-friendly process to dramatically simplify carbon microfiber fabrication from biobased materials. The microfibers are first produced by wet-spinning in aqueous calcium chloride solution, which provides rapid coagulation of the hydrogel precursors comprising wood-derived lignin and 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidized cellulose nanofibrils (TOCNF). The thermomechanical performance of the obtained lignin/TOCNF filaments is investigated as a function of cellulose nanofibril orientation (wide angle X-ray scattering (WAXS)), morphology (scanning electron microscopy (SEM)), and density. Following direct carbonization of the filaments at 900 °C, carbon microfibers (CMFs) are obtained with remarkably high yield, up to 41%, at lignin loadings of 70 wt % in the precursor microfibers (compared to 23% yield for those produced in the absence of lignin). Without any thermal stabilization or graphitization steps, the morphology, strength, and flexibility of the CMFs are retained to a large degree compared to those of the respective precursors. The electrical conductivity of the CMFs reach values as high as 103 S cm–1, making them suitable for microelectrodes, fiber-shaped supercapacitors, and wearable electronics. Overall, the cellulose nanofibrils act as structural elements for fast, inexpensive, and environmentally sound wet-spinning while lignin endows CMFs with high carbon yield and electrical conductivity.

Poly(vinylbenzyl chloride-co-divinyl benzene) polyHIPE monolith-supported o-hydroxynaphthaldehyde propylenediamine Schiff base ligand complex of copper(ii) ions as a catalyst for the epoxidation of cyclohexene.

Poly(vinylbenzyl chloride-co-divinyl benzene)-based polyHIPE monoliths of different porosities were prepared using high-internal-phase emulsions (HIPEs) containing a fixed amount of vinylbenzyl chloride (VBC, 6.0 g, 0.0393 mol) and divinyl benzene (DVB 4.0 g, 0.0308 mol) as the oil phase and different volume ratios of aqueous calcium chloride as the internal phase. Span-80 (2.0 g (4.67 mmol))-stabilized HIPEs were polymerized at 60 °C using potassium persulfate (0.4 g, 1.48 mmol) as the initiator. Upon varying the volume ratio of aqueous calcium chloride from 80 to 90%, the prepared polyHIPE monoliths have shown significant variations in their surface morphology, specific surface area (SA), and pore volumes (Vp) as confirmed by scanning electron microscopy (SEM) and a gas adsorption (BET) method. The prepared polyHIPE monoliths were anchored with o-hydroxynaphthaldehyde propylenediamine Schiff base ligand (HNPn) and then loaded with copper(ii) ions (HNPn–Cu) to act as a catalyst. The structural information of unsupported HNPn–Cu complexes was obtained by recording its FT-IR and UV-visible spectra. The amount of copper(ii) ions loaded onto HNPn ligand-anchored polyHIPE monoliths was determined by atomic absorption spectroscopic analysis. In comparison to unsupported HNPn–Cu catalyst, the polyHIPE monolith-supported HNPn–Cu catalyst has shown high catalytic activity (66.8%), product selectivity for epoxycyclohexane (ECH) (94.8%), high turn over number (0.028 mol mol−1 h−1) and low energy of activation (22.4 kJ mol−1) in the epoxidation of cyclohexene in the presence of hydrogen peroxide (H2O2) as an oxidant at 40 °C. The polyHIPE-supported HNPn–Cu catalyst also shows high reuse applications. Studies show that there is sufficient scope to develop polyHIPE monoliths with various properties for specific applications.

Bioactive characteristics of an implant surface coated with a pH buffering agent: an in vitro study.

PurposeThe purpose of this study was to evaluate the effectiveness of conventional sandblasted, large-grit, acid-etched (SLA) surface coated with a pH buffering solution based on surface wettability, blood protein adhesion, osteoblast affinity, and platelet adhesion and activation.MethodsTitanium discs and implants with conventional SLA surface (SA), SLA surface in an aqueous calcium chloride solution (CA), and SLA surface with a pH buffering agent (SOI) were prepared. The wetting velocity was measured by the number of threads wetted by blood over an interval of time. Serum albumin adsorption was tested using the bicinchoninic acid assay and by measuring fluorescence intensity. Osteoblast activity assays (osteoblast adhesion, proliferation, differentiation, mineralization, and migration) were also performed, and platelet adhesion and activation assays were conducted.ResultsIn both the wetting velocity test and the serum albumin adsorption assay, the SOI surface displayed a significantly higher wetting velocity than the SA surface (P=0.000 and P=0.000, respectively). In the osteoblast adhesion, proliferation, differentiation, and mineralization tests, the mean values for SOI were all higher than those for SA and CA. On the osteoblast migration, platelet adhesion, and activation tests, SOI also showed significantly higher values than SA (P=0.040, P=0.000, and P=0.000, respectively).ConclusionsSOI exhibited higher hydrophilicity and affinity for proteins, cells, and platelets than SA. Within the limits of this study, it may be concluded that coating an implant with a pH buffering agent can induce the attachment of platelets, proteins, and cells to the implant surface. Further studies should be conducted to directly compare SOI with other conventional surfaces with regard to its safety and effectiveness in clinical settings.

Calcium ions in aqueous solutions: Accurate force field description aided by ab initio molecular dynamics and neutron scattering.

We present a combination of force field and ab initio molecular dynamics simulations together with neutron scattering experiments with isotopic substitution that aim at characterizing ion hydration and pairing in aqueous calcium chloride and formate/acetate solutions. Benchmarking against neutron scattering data on concentrated solutions together with ion pairing free energy profiles from ab initio molecular dynamics allows us to develop an accurate calcium force field which accounts in a mean-field way for electronic polarization effects via charge rescaling. This refined calcium parameterization is directly usable for standard molecular dynamics simulations of processes involving this key biological signaling ion.

Supersaturation of calcium citrate as a mechanism behind enhanced availability of calcium phosphates by presence of citrate

Dissolution of amorphous calcium phosphate (ACP) in aqueous citrate at varying pH has been studied with perspective of increasing availability of calcium from sidestreams of whey protein, lactose and/or cheese production or on development of new functional foods. ACP formed as an initial precipitate in 0.10 mol L−1 equimolar aqueous calcium chloride, sodium citrate, and sodium hydrogenphosphate was used as model for mineral residues formed during milk processing. Upon acidification of the ACP suspension by hydrochloric acid decreasing pH from 6.5 to 4.5, the transformations of ACP occurred through an 8 h period of supersaturation prior to a slow precipitation of calcium citrate tetrahydrate. This robust supersaturation, which may explain increased availability of calcium phosphates in presence of citrate, presented a degree of supersaturation of 7.1 and was characterized by precipitation rates for 0.10 mol L−1 equimolar aqueous calcium chloride, sodium hydrogencitrate, and sodium hydrogenphosphate with pH 5.5, and for 0.10 mol L−1 equimolar aqueous calcium chloride, sodium hydrogencitrate, and sodium dihydrogenphosphate with pH 4.1, with a degree of supersaturation of 2.7. The crystallization processes were similar according to Avrami's model with a half-life for precipitation of approximately 5 h independent of the degree of supersaturation. Ion speciation based on measurement of pH, and total concentrations of calcium, phosphate and citrate, and of conductivity and calcium ion activity during precipitation indicates a low driving force for precipitation with calcium citrate complex dominating at pH 5.5 and calcium hydrogencitrate complex dominating at pH 4.1. Calcium hydrogencitrate is suggested to be the species involved in the crystal growth followed by solid state transformation to calcium citrate tetrahydrate.

A novel method for the production of core-shell microparticles by inverse gelation optimized with artificial intelligent tools

Numerous studies have been focused on hydrophobic compounds encapsulation as oils. In fact, oils can provide numerous health benefits as synergic ingredient combined with other hydrophobic active ingredients. However, stable microparticles for pharmaceutical purposes are difficult to achieve when commonly techniques are used. In this work, sunflower oil was encapsulated in calcium-alginate capsules by prilling technique in co-axial configuration. Core-shell beads were produced by inverse gelation directly at the nozzle using a w/o emulsion containing aqueous calcium chloride solution in sunflower oil pumped through the inner nozzle while an aqueous alginate solution, coming out from the annular nozzle, produced the beads shell. To optimize process parameters artificial intelligence tools were proposed to optimize the numerous prilling process variables. Homogeneous and spherical microcapsules with narrow size distribution and a thin alginate shell were obtained when the parameters as w/o constituents, polymer concentrations, flow rates and frequency of vibration were optimized by two commercial software, FormRules® and INForm®, which implement neurofuzzy logic and Artificial Neural Networks together with genetic algorithms, respectively. This technique constitutes an innovative approach for hydrophobic compounds microencapsulation.

Effect of eco-safe compounds on postharvest quality preservation of papaya (Carica papaya L.)

Early ripening and susceptibility to microbial infection are major postharvest problems in papaya fruits. Being a tropical climacteric fruit, low-temperature storage is not successful in papaya. In this study, we demonstrate the effect of aqueous salicylic acid (1 and 2 mM), nitric oxide (1 and 2 mM), and calcium chloride (1 and 2%) to enhance the papaya shelf life at the ambient conditions with reduced disease incidence. Calcium chloride 2% was the most effective for maintaining postharvest quality. The fruits had good firmness and maintained TSS, acidity, total chlorophyll, free radical scavenging activity and ascorbic acid on the 6th day during ambient storage. Moreover, the weight loss, yellow color development and disease incidence were minimum in calcium chloride 2%, followed by 1% solution of calcium chloride. The nitric oxide (2 mM) maintained higher antioxidant capacity and total phenol content in fruits that was followed by 1 mM salicylic acid during storage. The result suggests that application of calcium chloride 2% could be an easy and effective technique for extending the shelf life without impairing fruit quality during storage.

Dependences of the osmotic coefficients of aqueous calcium chloride solutions on concentration at different temperatures

A model that considers the contributions from hydration, ion association, and electrostatic interactions to the nonideality of 2‒1 electrolyte solutions is substantiated. The parameters of the model’s equations are the mean ion hydration number, the spread of the distribution of hydrated ion stoichiometric coefficients in the standard state, and the number of association. The model is successfully used to describe literature experimental data on the concentration dependence of osmotic coefficients of aqueous CaCl2 solutions at temperatures ranging from 0 to 100°C. The modeling of the above systems shows that as the temperature rises, the hydration number falls slightly, the distribution of the hydration number broadens, and the ion paring of the salt rises by the first degree.