Aqueous Solutions Of Sodium Acetate Research Articles

Equilibrium vapor pressure of aqueous sodium acetate and potassium acetate solutions used as working fluids in frost-free air–source heat pumps at 263–328 K

Aqueous solutions of sodium acetate (CH3COONa) and potassium acetate (CH3COOK) are considered effective alternative heat exchange media for frost-free air–source heat pumps (FFASHPs) owing to the low corrosiveness, low viscosity, and low cost. Equilibrium vapor pressure is the most crucial property that characterizes freezing point and latent heat transfer. However, studies on this property, especially in subzero temperature ranges are scarce. This study was conducted to experimentally investigate the equilibrium vapor pressure of CH3COONa and CH3COOK solutions. The developed apparatus and procedures were based on the static method, and validated by evaluating the vapor pressure of distilled water, n-heptane, and calcium chloride (CaCl2) aqueous solution. Their average absolute deviations were within 1.94%. As the temperature increased from 263 to 328 K and solute concentration increased from 9.27 to 33.81 wt%, 124 data points of the vapor pressure of the CH3COONa and CH3COOK solutions were obtained, ranging from 0.2759 to 13.2608 kPa. Modified Antoine equation and ion interaction (Pitzer) model were established for correlation of the experimental data. The average absolute deviations of the CH3COONa and CH3COOK solutions produced by Antoine equation were 2.08 and 2.48%, respectively. Those produced by Pitzer model further decreased to 1.36 and 1.45% due to the import of osmotic coefficient and the accuracy improvement. Furthermore, according to the experimental and calculation results, the vapor pressure of the CH3COONa solution was lower than that of the CH3COOK solution. Therefore, under the same antifreezing conditions, the CH3COONa solution facilitates latent heat absorption from ambient air, while the CH3COOK solution is conducive to achieve regeneration. The results of this study provide foundational data for the vapor pressure of the two solutions and can promote their application in FFASHPs.

Surface tension of aqueous solutions of large organic salts: Tetrabutylammonium acetate solutions

Aqueous solutions of simple ionic salts such as NaCl and NaBr have higher surface tensions compared to that of pure water and the surface tension of the solution increases with the increasing concentration of the salt. In contrast, the aqueous solutions of the ion sodium acetate (NaAc), which has an anion with both hydrophilic and hydrophobic parts, have a surface tension less than that of pure water, with the surface tension decreasing with salt concentration. The presence of large cations in the salt may change these trends. In this work, the interfacial tension of aqueous solutions of the organic ionic salt tetrabutylammonium acetate (TBAAc) is measured and compared with that of tetrabutylammonium bromide (TBAB). The surface tension of TBAAc aqueous solutions with mole fractions ranging from 0.00417 to 0.04191 were measured for temperatures ranging from 288.2 to 308.2 K and compared with the surface tension of TBAB solutions at similar concentrations. The experimental results showed that the interfacial tensions of TBAAc and TBAB aqueous solutions decreased with increasing concentration, leveling at around 0.04 mol fraction. At each concentration, the interfacial tensions of the TBAAc solutions were larger than those of the TBAB solutions. For the TBAAc and TBAB solutions, the surface excess concentrations of the salts in the solutions are calculated. The impact of these results structures and properties of these solutions are discussed.

Electrochemical Impedance Spectroscopy for Electrode Process Evaluation: Lithium Titanium Phosphate in Concentrated Aqueous Electrolyte

AbstractAqueous electrolytes in the form of highly concentrated solutions stand as a viable alternative to the organic counterpart as battery electrolytes thanks to the low flammability, toxicity, cost and large availability, while keeping good potential windows. In this work, a half‐cell constituted of lithium titanium phosphate in a binary aqueous solution of sodium acetate (7 mol kg−1) and potassium acetate (20 mol kg−1) as a promising anode for sodium‐ion batteries is characterized with constant current, static and dynamic electrochemical impedance spectroscopy to reveal its thermodynamic and kinetic properties. The experiments permit to withdraw some information on the thermodynamics (activation energy of processes) and kinetics (processes’ parameters evolution) of the system. Physical information was extracted from impedance spectra with mathematical regression of a porous electrode intercalation model available in literature using an innovative procedure of batch‐fitting of a complete set of spectra at once. The advantage and shortcoming on using impedance in battery‐development is discussed.

Electrochemical contributions: Adolph Wilhelm Hermann Kolbe (1818–1884)

Hermann Kolbe (Figure 1) was a German scientist who greatly contributed to the development of organic chemistry, transforming it to the state as we know it now. Kolbe pioneered organic synthesis from inorganic sources and introduced the term “synthesis” in the meaning how we use it in chemistry now. His name is associated with several synthetic reactions in organic chemistry, e.g., the Kolbe-Schmitt reaction in the preparation of aspirin, the Kolbe nitrile synthesis, etc. His work is particularly remembered in connection to electrolysis of carboxylic acids resulting in the synthesis of various organic compounds, known as the Kolbe reaction. The Kolbe reaction (Figure 2), proceeding as the electrolysis, results in the oxidative decarboxylation of carboxylic acids yielding free radicals, which dimerize producing symmetrical products. For example, the Kolbe electrolysis process can proceed in an aqueous solution of sodium acetate (Figure 2). The acetate ions get decomposed and form methyl radicals. These combine with other free methyl radicals, which leads to the generation of ethane. In general, Kolbe's electrolysis method uses sodium salts of fatty acids to form the corresponding alkanes as products (D. Klüh, W. Waldmüller, M. Gaderer, Clean. Technol. 2021, 3, 1–18). A similar electrochemical synthesis can be used to produce more sophisticated products (Figure 2B). If the initial mixture includes two different acids, the reaction results in three different products from the cross-reaction of two different free radicals. The Kolbe electrolytic decarboxylation of 1,2-dicarboxylic acids results in the formation of double or triple chemical bonds (Figure 3). When carboxylic groups are located at a longer distance in a molecule, the electrolytic decarboxylation may result in the intramolecular radical cyclization of the reaction product. It should be noted that the Kolbe electrolysis reaction may result in the formation of numerous byproducts (Figure 4). The formation of side products depends on the ease of the follow-up oxidation, which leads to carbenium ions, and their subsequent rearrangements. The exact mechanism and kinetics study of the electrochemical Kolbe process have been investigated confirming the complexity of the electrochemical reaction (A.K. Vijh, B.E. Conway, Chem. Rev. 1967, 67, 6, 623-664). The author declares no conflict of interest.

Measurement and correlation of the solubility of sodium acetate in eight pure and binary solvents

• Fresh solubility data of NaAc in eight pure or binary solvents were presented. • The solubility is influenced by the selected solvent and solution temperature. • The modified Apelblat model and Yaws model provide more accurate correlation. • The solubility of NaAc decreases in the order: in H 2 O > acetic acid > TFE > ethanol. • The standard dissolution enthalpy is obtained by van't Hoff analysis. The knowledge of solubility of a salt in either the pure solvent or blend solvent is of great importance for studying or operating the crystallization, extraction, and distillation processes. The solubility of sodium acetate (NaAc) in four pure solvents (water, ethanol, acetic acid and 2,2,2-trifluoroethanol) and four binary solvents (water–ethanol, water-acetic acid, acetic acid–ethanol, and acetic acid-ethyl acetate) were measured by using the laser dynamic method at temperatures from 288.15 K to 338.15 K at 0.1 MPa. The results showed that the solubility of NaAc was influenced by either the solution temperature or solvent composition. The aqueous sodium acetate solution possessed the maximal solubility under the experimental conditions. The solubility of NaAc in 2,2,2-trifluoroethanol was found to be decreased with the increase of the solution temperature. While, the solubilities of NaAc in other seven solvents increased as the solution temperature was elevated. Besides, five correlation models, including the van't Hoff model, modified Apelblat model, Yaws model, λh model, and modified Apelblat-Jouyban-Acree model were used to correlate the solubility data of those sodium acetate solutions with acceptable deviation, respectively. Finally, van't Hoff analysis method was selected to analyze the change law of thermodynamic properties of a salt during the dissolution process.

MOLECULAR MECHANISM OF RELAXATION ABSORPTION OF ULTRASONIC WAVES IN AN AQUEOUS SOLUTION OF CALCIUM ACETATE

The absorption of ultrasonic waves in the frequency range from 6 to 146 MHz in aqueous solutions of sodium acetate, sodium chloride and calcium has been studied. It was found that only in solutions of calcium cations and acetate anion present simultaneously, relaxation absorption of ultrasonic waves is observed. The experimental data obtained indicate that the observed relaxation absorption of ultrasound in the studied frequency range by an aqueous solution of calcium acetate is associated with the interaction of the acetate anion with the calcium cation in the solution.

Polymer Composites Containing Phase‐Change Microcapsules Displaying Deep Undercooling Exhibit Thermal History‐Dependent Mechanical Properties

AbstractMicroencapsulated materials are receiving broad attention for applications as diverse as energy storage and conversion, biomedicine, self‐healing materials, and electronics. Here, a general microfluidic approach is presented to prepare phase‐change material‐infilled microcapsules with unique thermal and mechanical properties. Aqueous sodium acetate solutions are encapsulated by an acrylate‐based shell via a microfluidic method. To understand and optimize microcapsule formation, flow behavior during the encapsulation is numerically simulated. When the microcapsules are embedded in an acrylate matrix (same composition as the shell wall material), the microcapsules exhibit a significant 46.6 ºC difference between the crystallization and melting temperatures as determined by differential scanning calorimetry at a rate of 10 ºC per min. Variable temperature dynamic mechanical analysis over the range of 50 to ‐90 ºC reveals up to a 50% change in the composite's elastic modulus at a given temperature, depending on if the sample is being cooled or heated, due to significant undercooling of the core material crystallization as shown by X‐ray diffraction.

Structure of aqueous sodium acetate solutions by X-Ray scattering and density functional theory

Abstract The structure of aq. sodium acetate solution (CH3COONa, NaOAc) was studied by X-ray scattering and density function theory (DFT). For the first hydrated layer of Na+, coordination number (CN) between Na+ and O(W, I) decreases from 5.02 ± 0.85 at 0.976 mol/L to 3.62 ± 1.21 at 4.453 mol/L. The hydration of carbonyl oxygen (OC) and hydroxyl oxygen (OOC) of CH3COO− were investigated separately and the OC shows a stronger hydration bonds comparing with OOC. With concentrations increasing, the hydration shell structures of CH3COO− are not affected by the presence of large number of ions, each CH3COO− group binds about 6.23 ± 2.01 to 7.35 ± 1.73 water molecules, which indicates a relatively strong interaction between CH3COO− and water molecules. The larger uncertainty of the CN of Na+ and OC(OOC) reflects the relative looseness of Na-OC and Na-OOC ion pairs in aq. NaOAc solutions, even at the highest concentration (4.453 mol/L), suggesting the lack of contact ion pair (CIP) formation. In aq. NaOAc solutions, the so called “structure breaking” property of Na+ and CH3COO− become effective only for the second hydration sphere of bulk water. The DFT calculations of CH3COONa (H2O)n=5–7 clusters suggest that the solvent-shared ion pair (SIP) structures appear at n = 6 and become dominant at n = 7, which is well consistent with the result from X-ray scattering.

Hyoscyamine and Scopolamine in Honey by HILIC–ESI-MS/MS

A simple but effective method was developed for the ultra-trace determination of two tropane alkaloid residues, hyoscyamine and scopolamine, in honey. Honey samples were dissolved in a concentrated aqueous solution of sodium acetate from which the alkaloids were subsequently extracted using acetonitrile. The resulting extract was analyzed using HILIC–ESI-MS/MS without any additional extract cleanup or enrichment steps. Enhanced sensitivity associated with the combination of HILIC and ESI-MS/MS techniques permitted the quantitation of the two tropane alkaloids at concentrations as low as 0.01 µg kg−1. The use of isotopically labelled analogs permitted accuracies ranging from 86.9 to 106.1% for honey samples fortified at 0.02, 0.2 and 2 µg kg−1 with precisions ranging from 0.8 to 6.2%. The estimated method detection limits for hyoscyamine and scopolamine were 0.002 and 0.003 µg kg−1, respectively. Twenty-three samples of honey were analyzed and only two samples were found to contain residues of the tropane alkaloids at concentrations above the limit of quantitation of 0.01 µg kg−1. Hyoscyamine was detected at 0.012 µg kg−1 in two honey samples, one of which also contained 0.012 µg kg−1 of scopolamine.

Effect of embedding sodium acetate trihydrate on the Ag anode in an electrical nucleation cell of a supercooled latent heat storage material

Electrical nucleation was investigated by using a Ag anode with sodium acetate trihydrate crystals embedded on the surface in a supercooled aqueous solution of sodium acetate (45–54 wt%) as a latent heat storage device. Rapid electrical nucleation was achieved by applying a direct-current voltage of greater than 1.4 V. When the voltage was set to greater than 1.8 V, the induction time of the electrical nucleation increased as the number of operations increased. The Ag anode life increased when the voltage was less than 1.8 V. When the voltage was 2.0 V, the anode resistance increased as the number of operations increased, with the anode surface deteriorating and forming silver oxide. The repeat life of electrical nucleation at voltages less than 1.8 V was about two times longer than that at voltages greater than 1.8 V. The repeat performance of electrical nucleation and the stability of the supercooled solution were found to depend on the surface roughness, Ra, of the Ag anode. The Ra value was optimized to be in the range 0.6 ≤ Ra ≤ 1.0 µm.

Molecular and associative properties of N-vinylpyrrolidone copolymers with N-crotonoylaminocaproic acid in dilute solutions

The random copolymers of N-vinylpyrrolidone and N-crotonoylaminocaproic acid attractive for the modification of drugs are studied by static and dynamic light scattering, viscometry, and sedimentation-diffusion analysis. The content of functional groups in the copolymers is 14.1–27.0 mol %. Analysis is performed in 0.1 N aqueous solutions of sodium acetate and dimethylformamide. The molecular characteristics of the copolymers with various composition are determined. It is shown that supramolecular structures are present in copolymer solutions and their amount depends on copolymer composition; the effect of solvent on the formation of these structures is ascertained.

Unprecedented Property of 4,6-Di(substituted)amino-1,2-dihydro-1,3,5-triazines: Formation of Acid Salts by Simple Treatment with Alkali Metal Salts of Protic Acids

Abstract Treatment of 4,6-di(substituted)amino-1,2-dihydro-1,3,5-triazine derivative (5) with sodium chloride in a bilayer system consisting of toluene and water gave its hydrochloride (6) in the toluene layer and sodium hydroxide in the aqueous layer. Similarly, treatment of 5, 8 and 9 with an aqueous sodium acetate solution in organic solvents resulted in the formation of their corresponding acetates, 7, 12 and 13, respectively.

Cyclosulfenylation of 3-allylthiohydantoin

New fused derivatives – 2-(arylsulfanylmethyl)-2,3,5,6-tetrahydroimidazo[2,1-b][1,3]thiazol-7-onium perchlorates have been synthesized by the cyclosulfenylation reaction of 3-allylthiohydantoin in highly polar nitromethane in the presence of an equimolar amount of lithium perchlorate as “doping-additive”. Their structures have been reliably proven by spectral characteristics. In particular, annelation of the tetrahydrothiazolonium cycle is confirmed by multiplet signals of diastereotopic protons of the CH2-group in position C3 at 3.87-4.04 ppm and the CH-group in position C2 at 4.67-4.77 ppm in 1H NMR-spectra. Thethiazolonium salts obtained were converted to the corresponding free bases – 2-(arylsulfanylmethyl)-2,3-dihydroimidazo[2,1-b] [1,3]thiazole-5(6H)-ones by the interaction with the aqueous solution of sodium acetate at the room temperature. According in their 1H NMR spectra, protons of CH-group in position 2 resonates in a stronger field (0.4-0.5 ppm) compared to the original substrates. Imidazothiazolonium perchlorates are labile to HN-nucleophiles, and under the action of the excess of the secondary amine (morpholine or piperidine) there is the disclosure of an amide bond in the imidazolidine cycle. It leads to formation of thiazolidine derivatives with arylsulfanyl fragments. Preservation of the thiazolidine nucleus in the process of opening the imidazole cycle has been confirmed by spectral characteristics of the compounds obtained.

Apparent molar volumes of aqueous solutions of sodium acetate and sodium benzoate at temperatures from 323 K to 573 K and pressure 10 MPa

Densities of aqueous solutions of sodium acetate and sodium benzoate have been measured at 50K intervals in the temperature range 323.15–573.15K at constant pressure p=10.0MPa by vibrating tube densimetry. The solute molalities ranged from 0.05 to 4.0mol·kg−1 (for sodium acetate) or 1.0mol·kg−1 (for sodium benzoate). The observed densities were used to calculate apparent molar volumes, which were fitted with an extended Redlich-Rosenfeld-Meyer-type equation to yield standard partial molar volumes of the solutes at infinite dilution. No direct comparisons with literature data were possible but the present results are broadly consistent with previous studies. This work greatly expands the database for the volumetric behaviour of both solutes at high temperatures. Despite the probable presence of anion hydrolysis the volumes of both salts show the steep decrease at high temperatures typical of simple 1:1 electrolytes. As expected, the acetate ion has a smaller volume than benzoate, with the difference increasing markedly with temperature, possibly reflecting the greater hydrophobicity of the benzoate ion. Combination of the present results with appropriate literature data enabled calculation of the volume change for the neutralization reaction: HX(aq)+NaOH(aq)→NaX(aq)+H2O. The values were similar for the two solutes and show a complex dependence on temperature.

Long-term effects of perinatal exposure to low doses of cadmium on the prostate of adult male rats.

Developmental toxicity caused by environmental exposure to heavy metals during the perinatal period has raised questions about offspring health. Cadmium (Cd) is an endocrine-disrupting chemical with the potential to interfere with morphogenesis and susceptibility to diseases in reproductive organs. Taking into account that in the rat prostate morphogenesis occurs during the perinatal period, and that pregnant females absorb and retain more dietary Cd than their non-pregnant counterparts, it is important to understand the effects of perinatal Cd exposure on the adult rat prostate. Therefore this study investigated the effects of gestational and lactational Cd exposure on adult offspring rat prostate histopathology. Pregnant rats (n=20) were divided into two groups: Control (treated with aqueous solution of sodium acetate 10mg/l) and treated (treated with aqueous solution of cadmium acetate 10mg/l) administered in the drinking water. After weaning, male offspring from different litters (n=10) received food and water 'adlibitum'. The animals were euthanized at postnatal day 90 (PND90), the ventral prostates (VPs) were removed, weighed and examined histopathologically. Blood was collected for the measurement of testosterone (T) levels. Immunohistochemistry for androgen receptor (AR) and Ki67, and a TUNEL assay were performed. There were no differences in T levels, cell proliferation and apoptosis indexes, or AR immunostaining between the experimental groups. Stromal inflammatory foci and multifocal inflammation increased significantly in the treated group. These changes were associated with inflammatory reactive epithelial atypia and stromal fibrillar rearrangement. In conclusion, VP was permanently affected by perinatal Cd exposition, with increased incidence of inflammatory disorders with ageing.

Dexterous Creation of Soccer-Ball Pattern by Using Urethane Rubber

It is important to establish new approaches to create value-added products, such as craftwork or artistic goods, that are different from traditional methods of realizing high-quality and low-cost products. Such a production technology is commonly called “dexterous machining.” This study addresses the creation of artistic products by using soft materials with complicated shapes by employing an aqueous solution of sodium acetate to fix a workpiece and to suppress the deformation. Experimental results show that the use of an aqueous solution of sodium acetate has the potential to realize the “dexterous machining” of soft objects.

Structure of hydroxyapatite powders prepared through dicalcium phosphate dihydrate hydrolysis

We have studied the structure of hydroxyapatite (HA) powders prepared by hydrolyzing dicalcium phosphate dihydrate (DCPD) in an aqueous sodium acetate solution at a temperature of 60°C for 16 h or a longer time. The results demonstrate that the HA in the powders has a distorted structure. The Baur’s distortion index for the PO4 tetrahedra is DI(TO) ≃ 0.03, whereas hydroxyapatite single crystals have DI(TO) ≃ 0.005. The powders are similar in structural parameters to calcium-deficient HAs: they have Ca/P ≃ 1.6 and an imperfect substructure (crystallite size of ≃30 nm) and contain sodium impurities. The structural features of the HA powders are analyzed in the context of their ability to biodegrade (dissolve).

Structural changes during the hydrolysis of dicalcium phosphate dihydrate to octacalcium phosphate and hydroxyapatite

Powders prepared through dicalcium phosphate dihydrate (DCPD) hydrolysis to octacalcium phosphate (OCP) and hydroxyapatite (HA) in an aqueous sodium acetate solution have been characterized by X-ray diffraction. The lattice parameters of the synthesized OCP and HA phases have been determined as functions of holding time at synthesis temperatures of 37 and 60°C. The structure of the HA obtained through hydrolysis at 60°C has been refined, and the distortion of the elements of the crystal lattice of this compound has been assessed in terms of Baur indices. A model has been proposed for the heterogeneous nucleation and growth of the OCP phase on DCPD crystals, in which the structure of these compounds is represented as made up of groups similar in structure to Posner regions.

Volumetric and Solvation Properties of Glycyl-Glycine and Glycyl-l-leucine in Aqueous Acetate Solutions

The densities of glycyl-glycine (diglycine) and glycyl-l-leucine, in water and in aqueous sodium acetate, potassium acetate, magnesium acetate and calcium acetate solutions, were measured at 298.15 K. The apparent molar volumes, V 1, and the partial molar volumes, $$ \bar{V}_{1} $$ , of diglycine and glycyl-l-leucine have been calculated. The solvation number, n S, of diglycine was also calculated. The limiting apparent molar volumes of the studied peptides were also analyzed in terms of the Setschenow relationship. The effect of the acetate salt solutions on the volumetric properties of the studied peptides was also discussed in terms of the Setschenow coefficients, k 1. The results indicate that the limiting apparent molar volume in aqueous acetate solutions is higher than that in water and the values increase with the concentration of the co-solutes (NaA, KA, MgA and CaA). The results indicate that the peptide interactions are stronger with MgA/CaA than NaA/KA. Also the data suggest that the peptide interactions are stronger with NaA than KA and with MgA than CaA. Further, the limiting apparent molar volume values increase from diglycine to glycyl-l-leucine. It was also noted that the solvation numbers for the diglycine in aqueous acetate salt solutions are less than in water and decrease as the concentration of acetate salt increases.

Dexterous Machining of Soft Objects by Means of Flexible Clamper

It is important to establish a new way of creating value-added products, such as craftwork objects or applied arts, different from traditional way of achieving high quality and low price. Such a machining technology that enables (1) extremely complex or small shape generation, (2) machining of hard or soft materials, and (3) machining of difficult-to-grasp or fix workpiece may be called “Dexterous Machining.” Thus, the study deals with the first attempt to create an artistic product shape out of soft objects that have low stiffness and high elasticity. It is generally difficult to machine soft objects precisely because of the deformation caused by not only the cutting force but also the clamping force itself. In order to solve this problem, flexible clamper employing an aqueous solution of sodium acetate is devised to fix a workpiece and to suppress the deformation. The workpiece is placed in a case filled with an aqueous solution of sodiumacetate on a machine tool table. The aqueous solution is crystallized by applying a stimulus, and the solid sodium acetate clamps the workpiece. As a result of experimental machining, it is found that the proposed flexible clamper has the potential of realizing “Dexterous Machining” of soft objects.