Aqueous NaNO3 Research Articles

Characterization of Silicate Complexes in Aqueous Sodium Sulfate Solutions by FAB-MS

When the sodium ion (Na+) concentration is increased above 0.5 mol-dm−3 (M), the concentrations of dissolved silica in aqueous sodium chloride (NaCl) and sodium nitrate (NaNO3) solutions decrease because of the salting out effect. On the other hand, the concentration of the dissolved silica in aqueous sodium sulfate (Na2SO4) solutions increases monotonously as the concentration of Na+ is increased above 0.5 M. The purpose of this study is to determine the reasons why the salting-out effect is not observed in Na2SO4 solutions. FAB-MS (Fast Atom Bombardment Mass Spectrometry) was used to sample directly the silica species dissolved in aqueous Na2SO4, NaCl, and NaNO3 solutions. In the FAB-MS spectra of these solutions, the peak intensity ratios of the linear tetramer to the cyclic tetramer largely increased for Na+ concentrations between (0.1 and 1) M. This shows that some characteristics of the Na2SO4 solutions are similar to those of the NaCl and NaNO3 solutions. In Na2SO4 solutions, however, when the concentration of Na+ is higher than 1 M, the peak intensity of the dimer is much higher than those of the other silicate complexes. In Na2SO4 solutions, the SO42− ion undergoes partial hydrolysis to form HSO−4 and OH− is produced. In particular, in the range where the concentration of SO42− is high, the pH of the solution increases slightly. This higher pH yields more dimers from the hydrolysis of silicate complexes. This increase in dimer production agrees with the observation that silica dissolves in sodium hydroxide (NaOH) solutions mainly as a dimer when the concentration of NaOH is less than 0.1 M. In Na2SO4 solutions at high concentrations, a salting-out effect is not observed for silica. This is due to the increase in the concentration of OH−, which accelerates the hydrolysis of silica and results in dimer formation.

Densities, Apparent Molar Volumes and Viscosities of Concentrated Aqueous NaNO3 Solutions at Temperatures from 298 to 607 K and at Pressures up to 30 MPa

Densities of four (2.124, 2.953, 5.015 and 6.271 mol-kg−1) and viscosities of eight (0.265, 0.503, 0.665, 1.412, 2.106, 2.977, 5.015 and 6.271 mol-kg−1) NaNO3(aq) solutions have been measured with a constant-volume piezometer immersed in a precision liquid thermostat and using capillary flow techniques, respectively. Measurements were made at pressures up to 30 MPa. The temperature range was 298–607 K for the density measurements and 298–576 K for the viscosity measurements. The total uncertainty of density, viscosity, pressure, temperature and composition measurements were estimated to be less than 0.06%, 1.6%, 0.05%, 15 mK and 0.02%, respectively. The temperature, pressure and concentration dependence of density and viscosity of NaNO3(aq) solutions were studied. The measured values of density and viscosity of NaNO3(aq) were compared with data and correlations reported in the literature. Apparent molar volumes were derived using the measured density values. The viscosity data have been interpreted in terms of the extended Jones–Dole equation for strong electrolytes. The values of the viscosity A-, B-, D- and F-coefficients of the extended Jones–Dole equation for the relative viscosity (η/η0) of NaNO3(aq) solutions were evaluated as a function of temperature. The derived values of the viscosity A- and B-coefficients were compared with the results predicted by Falkenhagen–Dole theory of electrolyte solutions and calculated with the ionic B-coefficient data.

Synthesis, Branched Structure, and Solution Property of Hyperbranched d-Glucan and d-Galactan

The ring-opening multibranching polymerizations of 1,6-anhydro-β-d-glucopyranose (1) and 1,6-anhydro-β-d-galactopyranose (2) have been studied in order to synthesize hyperbranched polysaccharides. The solution polymerization in propylene carbonate and the bulk polymerization of 1 and 2 using a thermally induced cationic initiator proceeded through a ring-opening reaction and a proton transfer reaction to afford highly water-soluble polysaccharides, i.e., poly-1 and poly-2, respectively. For the polymers from 1 and 2 with the same polymerization conditions, the Mw,SLS and yield of poly-1 were higher than those of poly-2. Here, poly-1 and poly-2 were characterized as hyperbranched polysaccharides consisting of α- and β-linked d-hexopyranosyl and d-hexofuranosyl repeating units, hyperbranched d-glucan and d-galactan, respectively. In addition, poly-1 and poly-2 had ca. 30−40 mol % nonreducing d-hexopyranosyl and d-hexofuranosyl terminal units, and the degree of branching was ca. 0.38 for poly-1 and 0.44−0.60 for poly-2. The respective viscosities of poly-1 and poly-2 in aqueous NaNO3(0.2 mol·L-1) solution were very low with the intrinsic viscosity values of 0.023−0.042 dL·g-1. The steady shear flow of poly-1 in aqueous solution exhibited a Newtonian behavior with steady shear viscosities independent of the shear rate, even at high concentrations. The results indicated that the characteristics of the viscosities were attributed to the spherical structure of the hyperbranched polysaccharide in aqueous solution.

Densities and Apparent Molar Volumes of Aqueous NaNO3 Solutions at Temperatures from 292 to 573 K and at Pressures Up to 30 MPa

Densities of four aqueous NaNO3 solutions (0.100, 0.303, 0.580, 0.892 mol-kg−1 H2O) have been measured in the liquid phase with a constant-volume piezometer immersed in a precision liquid thermostat. Measurements were made at ten isotherms between 292 and 573 K. The range of pressure was 0.1–30 MPa. The total uncertainty of density, pressure, temperature, and concentration measurements were estimated to be less than 0.06%, 0.05%, 10 mK, and 0.014%, respectively. Values of saturated densities were determined by extrapolating experimental P-ρ data to the vapor pressure at fixed temperature and composition. Apparent molar volumes were derived using measured values of density for the solutions and for pure water. The apparent molar volumes were extrapolated to zero concentration to yield partial molar volumes at infinite dilution. The temperature, pressure, and concentration dependence of partial and apparent molar volumes were studied. The measured values of density and apparent and partial molar volume were compared with data reported in the literature.

LURGI WINS CONTRACT FOR METHANOL PLANT

In aqueous solution, both nitrate and nitrite are planar, monovalent, and have the same elements but different sizes and charge densities. Comparing the viscosity of NaNO2 and NaNO3 aqueous solutions provides an opportunity to determine the relative importance of anion size versus strength of anion interaction with water. The viscosity of aqueous NaNO2 and NaNO3 were measured over a temperature and concentration range relevant to nuclear waste processing. The viscosity of NaNO2 solutions was consistently larger than NaNO3 under all conditions, even though nitrate is larger than nitrite. This was interpreted in terms of quantum mechanical charge field molecular dynamics calculations that indicate that nitrite forms more and stronger hydrogen bonds with water per oxygen atom than nitrate. These hydrogen bonds inhibit rotational motion required for fluid flow, thus increasing the nitrite solution viscosity relative to that of an equivalent nitrate solution.

Raman Spectroscopy of the Reaction of Sodium Chloride with Nitric Acid: Sodium Nitrate Growth and Effect of Water Exposure

The reaction of powdered NaCl with HNO3 was studied using Raman spectroscopy. NaNO3 growth was monitored as a function of HNO3 exposure in a flow cell. Mode-specific changes in the NO3- vibrational mode intensities with HNO3 exposure suggest a rearrangement of the NaNO3 film with coverage. In the absence of H2O, intensities of NaNO3 bands increase with HNO3 exposure until a capping layer of NaNO3 forms. The capping layer prevents subsequent HNO3 from reacting with the underlying NaCl. H2O exposure of NaNO3-capped NaCl results in hydration of the surface to form an aqueous solution containing NaNO3 and NaCl. Further exposure results in the formation of a thicker surface-adsorbed H2O layer that is consistent with an aqueous NaNO3 and NaCl solution. Upon exposure of hydrated NaCl to HNO3, molecular HNO3 and solid-state NaNO3 are observed in the thin H2O film.

Ionic Strength Effects of Electrolytes on Solubilized States of Water in AOT Reversed Micelles

The limiting amounts of solubilized aqueous NaCl, NaNO3, MgCl2, and AlCl3 in sodium 1,2-bis-(2-ethylhexyloxycarbonyl)-1-ethanesulfonate (aerosol OT)/isooctane solutions have been measured as a function of the ionic strength of the electrolytes. In any system, the limiting amounts increased up to the optimal ionic strength (Ioopt), and afterward, as ionic strength increased, they decreased and were followed by a constant. These increased and decreased curves of water solubilization below and above Ioopt, called, respectively, salting-in and salting-out curves, could be interpreted, respectively, from the counteracting effects of attractive intermicellar interaction and interfacial bending stress. The effects of electrolytes on the solubilized states of water by micelles were examined using NMR and near-infrared spectroscopic techniques. Consequently, two types of waters, i.e., water bound directly to the ionic head groups of the surfactant in reversed micelles and water interacting with the hydrated head groups in swollen micelles through hydrogen bonds, were almost unaffected by any electrolytes, whereas much greater effects were observed for bulklike water in W/O microemulsions. The order of the degree of lowering of salting-out curves in W/O microemulsion regions in each system was found to agree with the Hofmeister series.

Hydrolysis of methyltin(IV) trichloride in aqueous NaCl and NaNO3 solutions at different ionic strengths and temperatures

Hydrolysis of methyltin(IV) trichloride in aqueous NaCl and NaNO3 solutions at different ionic strengths and temperatures

Hydrolysis of methyltin(IV) trichloride in aqueous NaCl and NaNO3 solutions at different ionic strengths and temperatures

The hydrolysis of methyltin(IV) trichloride (CH 3 SnCl 3 ) has been studied in aqueous NaCl and NaNO 3 solutions (0 < l/mol dm -3 ≤1), at different temperatures (15 ≤ T/°C ≤ 45) by potentiometric measurements (H + -glass electrode). By considering the generic hydrolytic reaction pCH 3 Sn 3+ + qH 2 O = (CH 3 Sn) p (OH) q 3p-q +qH + (logβ pq ), we have the formation of five species and logβ 12 = -3.36, logβ 13 = -8.99, logβ 14 = -20.27 and logβ 25 = -7.61. The first hydrolysis step is measurable only at very low pH values and was not determined: a rough estimate of the hydrolysis constant is logβ 11 = -1.5 (± 0.5). The dependence on ionic strength of logβ pq is quite different in NaNO 3 and NaCl solutions, and the formation at low pH values of the species CH 3 Sn(OH)Cl - has been found with logβ = -1.40. Hydrolysis constants strongly depend on temperature and from the relationships logβ pq = f(T), ΔH o values have been calculated. Speciation problems of CH 3 Sn 3+ in aqueous solution are discussed.

Extraction of uranium(VI) with N,N,N′,N′-tetrabutylmalonamide and N,N,N′,N′-tetrahexylmalonamide

A new diamide N,N,N′,N′-tetrahexylmalonamide (THMA) was synthesized, characterized and used in the extraction of U(VI) from nitric acid solutions. N,N,N′,N′-tetrabutylmalonamide (TBMA) was also studied to test the steric hindrance. Factors affecting this extraction system, the concentration of the extractant, aqueous nitric acid and NaNO3 and the temperature were investigated. The IR spectral study was also made of the extracted species.

Influence of the purity and irradiation stability of Cyanex 301 on the separation of trivalent actinides from lanthanides by solvent extraction

The solvent extraction of trivalent actinides and lanthanides from aqueous IM NaNO3 by the sulfur containing acidic extractant Cyanex 301 was studied. This commercial extractant shows very interesting features for An(III)/Ln(III) separations depending on the purification of its main constituent bis(2,2,4-trimethylpentyl)dithiophosphinic acid. Efficient separations were observed with nonpurified Cyanex 301 for high Ln(III) concentrations, but not for low Ln(III) concentrations. Successful purification of Cyanex 301 was performed by precipitation of the ammonium dithiophosphinate. Very high An(III)/Ln(III) separation factors (higher than 103) were obtained for micro or macro concentrations of Ln(III) at pH 3–4.

Effects of Electrolytes on Solubilized States of Water by Aerosol OT Reversed Micelles

Aqueous NaCl, NaNO3, and MgCl2 solubilized by Aerosol OT reversed micelles in isooctane media were determined as a function of surfactant concentration. Three solubilization regions I, II and III were apparent based on chemical shifts of water at given AOT concentrations. The states of water in these regions were examined based on change in near infrared spectra with Rw (= [H2O] / [AOT]), and were found the same in the absence of electrolytes. Water in reversed micelles was bounded, interacted with polar groups of the surfactant, and in swollen micelles, was metabounded and interacted with hydrated polar groups by hydrogen bonds. Water in W/O microemulsions was bulk-like. Based on minimal solubilized water required for swollen micelle and W/O microemulsion formation, bounded and metabounded water in reversed and swollen micelles respectively were shown not affected by these electolytes, whereas bulk-like water in W/O microemulsions was so. Electrolytes effect intensity followed the order of Cl->NO3- for sodium salts and Na+>Mg2+ for chloride salts.

Static and Kinetic Studies of the Adsorption/Desorption of H+ and OH− Ions on Alumina in Aqueous NaNO3 Solution

The adsorption/desorption of H+ and OH− ions under static conditions on to alumina in aqueous NaNO3 solution was studied at 30°C by potentiometric titration and calculations undertaken using the triple layer model (TLM). Intrinsic dissociation constants and intrinsic complexation constants at 30°C were used to calculate surface charge density, surface potential and surface species as a function of pH and ionic strength (I). Related adsorption/desorption studies of H+ and OH− ions under dynamic conditions on to alumina in aqueous NaNO3 solution were studied by means of the concentration-jump technique. Mechanistic information regarding H+ and OH− ion adsorption/desorption on to alumina was discussed using the experimental data in conjunction with the TLM.

Speciation of aluminium in soil extracts by employing cation-exchange fast protein liquid chromatography–inductively coupled plasma atomic emission spectrometry

A fast protein liquid chromatographic–inductively coupled plasma (ICP) atomic emission spectrometric procedure was developed for the speciation of Al over a wide pH range, from acidic to alkaline regions. Positively charged monomeric Al species in synthetic aqueous solutions were separated from polymeric, neutral and negatively charged species on a cation-exchange fast protein LC column. Linear gradient elution with aqueous NaNO3(8 mol dm–3) at a flow rate of 1.0 cm3 min–1 over 10 min was employed for the separation. The separated Al species were determined ‘off-line’ by ICP atomic emission spectrometry in 0.5 cm3 fractions, which were diluted prior to analysis; yttrium was added as the internal standard. Retention times were found to be 1.5 min for Al(OH)2(H2O)4+[Al(OH)2+], 4.0 min for Al(OH)(H2O)52+[Al(OH)2+] and 4.5 min for Al(H2O)63+[Al3+]. Good reproducibility of measurement (relative standard deviation 1.5%) was obtained in the optimum concentration range. The limit of detection (3s) for the separated Al species was found to be 120 ng cm–3(1.0 cm3 sample). The distribution of Al species over a wide pH range agreed with the reported calculated data and, in general, agreed also with the data from the 8-hydroxyquinoline spectrophotometric method. An investigation of the effect of inorganic and organic complexing ligands on the speciation of Al indicated that positively charged [Al(SO)4+, AlF2+] and negatively charged (oxalate and citrate) Al species co-eluted with Al(OH)2+ and were separated from Al(OH)2+ and Al3+ species, while AlF2+ co-eluted with Al(OH)2+ species. At lower pH values (e.g., 4.0), aluminium citrate was partially co-eluted with Al3+ and Al(OH)2+ species. The same observations were found when soil extracts were analysed.

Pressure-tuning flotation method for measurement of specific volume of solid organic compounds under high pressures

An accurate and simple method for the measurement of specific volumes of solid organic compounds under high pressures was proposed. The principle of this method was based on the flotation methods, in which pressure was adjusted to find the floating equilibrium point at isothermal condition. One of the advantages of the proposed method is that the specific volume of solid organic compounds under high pressures can be determined with almost the same accuracy as that of immersion liquids. The specific volumes of naphthalene were measured at 293.15 K and at pressures up to 440 MPa. The immersion liquid used consisted of aqueous NaNO3 solutions. The specific volumes of the aqueous NaNO3 solutions under high pressures were measured with the glass piezometer method proposed in our previous study. Experimental results of the specific volume and also the isothermal compressibility were compared with the literature data. It was found that good agreement was obtained between the present results and the literature data for the volume compressibility.

The ionic product of water in highly concentrated aqueous electrolyte solutions

The ionic product of water, {Mathematical expression}, has been determined in aqueous NaCl (0.5-5.0 M), KCl (3.0 M), NaNO3 (3.0 and 5.0 M), and KNO3 (2.5 M) at 25 °C from high-precision potentiometric titrations carried out in cells with liquid junction using either glass or hydrogen electrodes. Measurements of Kw provide a set of self-consistent data that can be used in the estimation of activity coefficient changes and liquid junction potentials in the study of extremely concentrated electrolyte solutions. Where comparison is possible, results obtained by hydrogen electrode measurements are in excellent agreement (ca ± 0.005 in pKw) with other reliable experimental values and the predictions of the Pitzer activity-coefficient model. The glass electrode results are, as expected, routinely lower (by 0.03-0.05 pKw units), owing to interference by Na+ ions. This effect virtually disappears in solutions of potassium salts. Comparison of the experimental results with the Pitzer predictions shows that knowledge of the ternary interaction parameters is essential to account for specific ionic effects in the concentration dependence of pKw.

Radiolysis of benzene solutions in aqueous NaNO3: A temperature dependence study by HPLC and GC analytical techniques

The radiolysis of aqueous benzene solutions was carried out at 35 °C, 45 °C, 55 °C, and 65 °C. The results, obtained by coupling HPLC and GC separations, showed that the yields of all the radiolysis products increased with temperature. However, the comparison of the results must be limited to those compounds that are formed exclusively in aqueous solutions. It was found that the increase of the relative concentrations of the products with the temperature followed the order: nitrobenzene>phenol>o-nitrophenol >p-nitrophenol.

The kinetics of contact noise of Naβ″ alumina

The kinetics of interfacial chemical reaction noise at sodium amalgam, NaI in propylene carbonate, and aqueous NaNO3 contacts to Naβ″ alumina are examined by determining the time, temperature, and sodium ion concentration dependence of the noise. The rate constant for the reaction noise is smallest for the NaI propylene carbonate contacts, 2.0×10−4 s−1, increases with sodium concentration, and has a thermal activation energy of 0.5 eV. Contact noise is interpreted in terms of ionic shot noise at the interface during the buildup of the electric double layer.

Reduction of nitrate during release of stored energy from γ-irradiated NaCl crystals in aqueous NaNO3 solution

Reduction of nitrate to nitrite takes place when the stored energy in the form of colour centres is released during dissolution of γ-irradiated NaCl crystals in aqueous sodium nitrate solution. Various parameters like dose, amount, storage time and particle size of irradiated NaCl salt which control the yield of nitrite have been studied. Similarly, the effect of concentration of NaNO3 and the role of precipitation on the yields of nitrite in aqueous TlNO3 and AgNO3 have been investigated. The energy transfer parameter has been determined as the ratio of G/NO 2 − / obtained by the addition of irradiated NaCl to that of direct γ-radiolysis. The data permit the evaluation of the concentration of colour centres in the irradiated NaCl crystals on the basis of the mechanism of reduction of nitrate.

Determination of the density dispersion of suspension poly(vinyl chloride) by the method of kinetic density curves

AbstractA new method has been developed for the evaluation and comparison of quality of various types of poly(vinyl chloride) (PVC) powder with respect to their density homogeneity. The method consists in the determination of the dependence of the volume of a specifically heavier fraction of PVC powder on the density or concentration of testing aqueous NaNO3 solutions after a chosen time of contact between the powder and the testing solutions. Compared with the method of determination of density distribution using densitometric titration, the new method simplifies and extends possibilities of comparison of polymers and improves the density characterization.