scholarly journals Density, pH, and Boron Species in the Ternary System NaBO2–Na2SO4–H2O at 298.15 K and 323.15 K

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Xiaohui Song ◽  
Shuaiqi Sun ◽  
Lingzong Meng ◽  
Rongjian Ying ◽  
Yafei Guo ◽  
...  
Keyword(s):  
Ternary System ◽  
Mole Fraction ◽  
Boron Concentration ◽  
Equilibrium Constants ◽  
Pitzer Model ◽  
Mixed Solution ◽  
Ph Values ◽  
Two Temperatures

The densities and pH values in the system NaBO2–Na2SO4–H2O at 298.15 K and 323.15 K were investigated. Combining the equilibrium constants for different boron species, the distributions of six boron species in the mixed solution were calculated with total boron concentration and pH values. The molar fractions of the six boron species are mainly affected by the total boron concentration and temperature, but rarely affected by the concentration of SO42–. The dominant boron species in the mixed solution at the two temperatures is B(OH)4‒. The mole fraction of B(OH)3, B5O6(OH)4‒, and B3O3(OH)4‒ can be neglected. The polyborate ions are easier to form as the temperature increases. The results of distribution for boron species in this study and those with the Pitzer model can both be used to describe the distribution of boron species in the mixed solution.

Vapor-Liquid Equilibria for the Ternary System Ethyl Acetate-Acetonitrile-1-Octyl-3-Methylimidazolium Tetrafluoroborate

2013 ◽  
Vol 791-793 ◽  
pp. 141-144
Author(s):  
Xiu Min Shi ◽  
Min Wang
Keyword(s):  
Ionic Liquid ◽  
Ternary System ◽  
Ethyl Acetate ◽  
Mole Fraction ◽  
Salt Effect ◽  
Extractive Distillation ◽  
Relative Volatility ◽  
Azeotropic Point ◽  
Vapor Liquid Equilibria ◽  
Vapor Liquid

In order to research the possibility of separating the azeotrope of ethyl acetate + acetonitrile with ionic liquid as the extractant. Isobaric vapor-liquid equilibria for the ternary system ethyl acetate + acetonitrile + 1-octyl-3-methylimidazolium tetrafluoroborate ([OMIBF4) were measured at 101.32 kPa using a recirculation still. The results showed that the VLE of the ternary system was different from that of the binary system. The ionic liquid (IL) studied showed a slight crossover salt effect, which changed the relative volatility of ethyl acetate to acetonitrile and eliminated the azeotropic point when the mole fraction of IL in the liquid phase was greater than 0.05. Therefore, [OMIBF4 can be used as the extractant of extractive distillation for ethyl acetate + acetonitrile system, the suitable mole fraction of [OMIBF4 is about 10%.

scholarly journals Thermodynamic Investigations on the Inclusion Complexation of Piroxicam with Cyclodextrin Derivatives

2005 ◽  
Vol 73 (3) ◽  
pp. 147-161 ◽  
Author(s):  
Charumanee S. ◽  
Weiss-Greiler P. ◽  
Wolschann P. ◽  
Viernstein H. ◽  
Titwan A. ◽  
...  
Keyword(s):  
Ph Value ◽  
Equilibrium Constants ◽  
Inclusion Complexation ◽  
Solubility Diagram ◽  
Phase Solubility ◽  
Cyclodextrin Derivatives ◽  
Ph Values ◽  
Solubility Behavior ◽  
Solubility Method ◽  
Different Temperatures

Thermodynamic studies of piroxicam in aqueous solution complexed with β-cyclodextrin (β-CD), γ-cyclodextrin (γ-CD) and two β-cyclodextrin derivatives, hydroxypropyl-β-cyclodextrin (HP-P-CD) and methyl-β-cyclodextrin (Me-β-CD) were performed at different temperatures and pH values using the phase solubility method. The phase solubility diagrams of β-CD, γ-CD and HP-β-CD is of AL-type behavior, indicating the formation of 1:l complexes. The related stability constants range from β-CD > γ-CD > Me-β-CD > HP-β-CD, respectively. An Ap-type solubility diagram is observed for Me-β-CD, indicating the formation of 1:2 complexes at higher CD concentrations. From the temperature dependence of the equilibrium constants the reaction enthalpies and entropies have been determined. The contributions of the reaction entropies are small and no enthalpy-entropy-compensation is observed, except for γ-CD, where a very small negative reaction entropy could be estimated. Moreover, the influence of the pH value is rather high because the differently charged forms of piroxicam show different solubility behavior in water.

scholarly journals Comparative Extraction of Aluminum Group Metals Using Acetic Acid Derivatives with Three Different-Sized Frameworks for Coordination

Separations ◽  
2021 ◽  
Vol 8 (11) ◽  
pp. 211
Author(s):  
Keisuke Ohto ◽  
Nako Fuchiwaki ◽  
Hiroaki Furugou ◽  
Shintaro Morisada ◽  
Hidetaka Kawakita ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Metal Ions ◽  
Spectroscopic Data ◽  
Equilibrium Constants ◽  
Structural Effects ◽  
Extraction Equilibrium ◽  
Ph Values ◽  
Slope Analysis ◽  
Coordination Sites ◽  
Extraction Properties

We prepared acetic acid derivatives using three different frameworks, calix[4]arene, alkenyltrimethylol, and trihydroxytriphenylmethane, which differ in the number and size of their coordination sites. We further investigated the extraction properties for aluminum group metal ions. All three extraction reagents exhibited increased extraction compared with the corresponding monomeric compounds, owing to structural effects. The extraction reaction and extraction equilibrium constants were determined using a slope analysis. Their extraction abilities, separation efficiencies, and potential coordination modes are discussed using the extraction equilibrium constants, half-pH values, and spectroscopic data. The calix[4]arene and trihydroxytriphenylmethane derivatives demonstrated allosteric co-extraction of indium ions (In3+) with an unexpected stoichiometry of 1:2.

Use of ionic and zwitterionic (Tris/BisTris and HEPES) buffers in studies on hemoglobin function

1992 ◽  
Vol 72 (4) ◽  
pp. 1611-1615 ◽  
Author(s):  
R. E. Weber
Keyword(s):  
Binding Sites ◽  
Ionic Composition ◽  
Oxygen Affinity ◽  
Chloride Concentration ◽  
Anion Binding ◽  
Chloride Binding ◽  
Ph Values ◽  
Two Temperatures ◽  
Ethanesulfonic Acid ◽  
Chloride Concentrations

The functional characteristics of hemoglobin (Hb) depend on oxygenation-linked proton and anion binding and thus on solvent buffer groups and ionic composition. This study compares the oxygenation properties of human Hb in ionic [tris(hydroxymethyl)aminomethane (Tris) and BisTris] buffers with those in zwitterionic N-2-hydroxy-ethylpiperazine-N′-2-ethanesulfonic acid (HEPES) buffer under strictly controlled chloride concentrations at different pH values, two temperatures, and in the absence and presence of the erythrocytic cofactor, 2,3-diphosphoglycerate (DPG). In contrast to earlier studies (carried out at the same or different chloride concentrations) it shows only small buffer effects that are manifested at low chloride concentration and high pH. These observations suggest chloride binding to the Tris buffers, which reduces the interaction with specific chloride binding sites in the Hb. The findings indicate that HEPES allows for more accurate assessment of Hb-oxygen affinity and its anion and temperature sensitivities than ionic buffers and advocates standard use of HEPES in studies on Hb function. Precise oxygen affinities of Hb dissolved in both buffers are defined under standard conditions.

scholarly journals Phase Equilibria and Phase Diagrams for the Ternary Aqueous System Containing Lithium, Sodium, and Pentaborate Ions at 298.15 and 323.15 K and 101.325 kPa

2019 ◽  
Vol 2019 ◽  
pp. 1-7
Author(s):  
Panpan Li ◽  
Kaiyu Zhao ◽  
Shangqing Chen ◽  
Jiayin Hu ◽  
Yafei Guo ◽  
...  
Keyword(s):  
Refractive Index ◽  
Ternary System ◽  
Phase Equilibria ◽  
Phase Diagrams ◽  
Invariant Point ◽  
Aqueous System ◽  
Eutectic Type ◽  
Two Temperatures ◽  
Sodium Pentaborate Pentahydrate ◽  
Experimental Values

Phase equilibria and phase diagrams for the ternary aqueous system containing lithium, sodium, and pentaborate ions at 298.15 and 323.15 K and 101.325 kPa were investigated by the methods of isothermal dissolution equilibrium. From the experimental data, the phase diagrams and the diagrams of physicochemical properties versus composition of lithium pentaborate in the equilibrium systems were plotted, respectively. The phase diagrams of the ternary system LiB5O8 + NaB5O8 + H2O at two temperatures contain one invariant point, two univariant curves, and two crystallization regions corresponding to sodium pentaborate pentahydrate (NaB5O8·5H2O) and lithium pentaborate pentahydrate (LiB5O8·5H2O). Due to the different dissolution behaviors of pentaborate salts in the aqueous systems, the component of LiB5O8 has a relatively strong effect on the solubility of NaB5O8. It was found that this system belongs to a simple eutectic type at two temperatures, and neither double salts nor solid solutions were formed. The densities and refractive indices in the ternary system at 298.15 and 323.15 K are as similar as changing regularly with the increase of LiB5O8 concentration. On the basis of empirical equations of the density and refractive index in electrolytes, the calculated values of density and refractive index agreed well with the experimental values at two temperatures.

Ligand Redistribution Equilibria in Aqueous Fluoroberyllate Solutions

1998 ◽  
Vol 53 (11) ◽  
pp. 1294-1300 ◽  
Author(s):  
Michael Schmidt ◽  
Hubert Schmidbaur
Keyword(s):  
Experimental Data ◽  
Ligand Exchange ◽  
Room Temperature ◽  
Chemical Shifts ◽  
Equilibrium Constants ◽  
Individual Species ◽  
Ph Values ◽  
Exchange Processes ◽  
The Individual ◽  
Good Agreement

The composition of aqueous fluoroberyllate solutions has been studied by 9Be and 19F NMR spectroscopy for various ratios of the beryllium and fluorine concentrations, and at different pH values. The equilibrium constants have been determined for the ligand exchange processes, which involve the species [Be(OH2)4]2+, [BeF(OH2)3]+, [BeF2(OH2)2], [BeF3(OH2)]- , and [BeF4]2-. These equilibria are shifted towards [BeF4]2- at high pH. No polynuclear fluoroberyllates have been detected. The fluoride exchange between the individual species is slow on the NMR time scale at room temperature, and separate sharp signals with the expected multiplicity are therefore recorded. Calculated 9Be chemical shifts are in good agreement with experimental data.

109Ag NMR-Study of the Selective Solvation of the Ag+ Ion in Solvent Mixtures of Water and the Organic Solvents: Pyridine, Acetonitrile, and Dimethyl Sulfoxide

1984 ◽  
Vol 39 (1) ◽  
pp. 83-94 ◽  
Author(s):  
L. Guinand. K. L. Hobt. E. Mittermaier ◽  
E. Rößler ◽  
A. Schwenk ◽  
H. Schneider
Keyword(s):  
Chemical Shift ◽  
Dimethyl Sulfoxide ◽  
Organic Solvents ◽  
Mole Fraction ◽  
Chemical Exchange ◽  
Chemical Shifts ◽  
Equilibrium Constants ◽  
Solvent Mixtures ◽  
Nmr Study ◽  
Solvent Molecules

In mixtures of water (W) and one of the organic solvents pyridine, acetonitrile, and dimethyl sulfoxide (O), the silver ion forms the following solvate complexes: AgW2, AgWO, and Ag02. The chemical shift of 109Ag is strongly affected by the ligating solvent molecules, and replacing the ligand W by one of the three organic ligands yields a higher Larmor frequency. In solvent mixtures, only a single resonance line has been observed because of rapid chemical exchange. The measured chemical shifts in the range up to 400 ppm are mean values of the chemical shifts of the different solvate species in a given mixture, weighted with their relative concentrations. The 109Ag chemical shifts were determined for 0.05 to 0.15 molal solutions of AgNO3, as functions of the mole fractions of the solvent components. Using a Gaussian least squares fitting routine, the individual chemical shifts of the Ag+ solvate complexes and the corresponding equilibrium constants were determined. This fit was successful for the whole mole fraction range of DMSO, while in the solvent systems with acetonitrile and with pyridine at higher concentrations of the organic component the chemical shift is influenced by more than two solvent molecules. In these cases equilibrium constants were calculated from chemical shift data for solutions of low mole fraction of acetonitrile and pyridine.

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