NMR study of the interaction between water and tributyl phosphate in the TBP-CCl4-H2O system

Hydrogen bonding between water and tributyl phosphate (TBP) in TBP? CCl₄? H₂O system has been studied by ¹H NMR. A new model and an empirical equation have been established on the basis of Li's model and the parameters of hydrogen bond between water and TBP are determined by nonlinear optimization method. In TBP? CCl₄? H₂O system change of ¹H chemical shift of water can be satisfactorily explained by the new model and the empirical equation in the whole concentration range. When the concentration of water in the organic phase is very low, the main existing forms of water are H₂O · TBP and H₂O · 2TBP. When the concentration of water reaches saturation, the main existing form is associated water, but there are still about 20% of water existing in the forms of H₂O · TBP and H₂O · 2TBP.     

LiNO_3-KNO_3-H_2O三元体系相平衡研究

本文采用等温法分别测定了KNO3-H2O体系的溶解度相图以及LiNO3-KNO3-H2O体系在273.15和298.15K的等温溶解度相图。结果表明在273.15K时LiNO3-KNO3-H2O体系的溶解度等温线有2条分支,对应的固相分别为KNO3和LiNO3·3H2O,共饱点组成为31.55wt%LiNO3和7.07wt%KNO3。该体系在298.15K的等温线有3条分支,对应的固相分别为KNO3,LiNO3和LiNO3·3H2O,2个共饱点组成分别为50.42wt%LiNO3,22.18wt%KNO3,和55.74wt%LiNO3,10.9wt%KNO3。     

Preparation of muscovite with ultrahigh specific surface area by chemical cleavage

The specific surface area of a muscovite sample increases drastically after exposure to a LiNO₃ solution, e.g., from 3.4 m²/g, corresponding to platelets of ca. 200 silicate layers, to 295 m²/g (platelets of ca. 2–3 silicate layers) after treatment at 180°C under atmospheric pressure for 46 h. The efficiency of the cleavage process decreases with decreasing temperature (down to 50°C). The LiNO₃/H₂O weight ratio is also very important: at 130°C and a reaction time of 46 h, for instance, a value in the range of 1.7–1.8 leads to the highest specific surfaces. The cleaved products have the form of strong papers that disperse readily in water. During the cleaving procedure, not only the particle thickness, but also the diameter decreases. There is no evidence of damage or partial dissolution of the silicate structure after cleavage, by IR spectroscopy and yield. The use of LiCl also leads to an increase in specific surface area, but the effect is weaker than in the case of LiNO₃. Treatment with some other alkaline and alkaline earth nitrates and chlorides did not increase the specific surface area of muscovite significantly.     

An octanol hinge opens the door to water transport

Despite their prevalent use as a surrogate for partitioning of pharmacologically active solutes across lipid membranes, the mechanism of transport across water/octanol phase boundaries has remained unexplored. Using molecular dynamics, graph theoretical, cluster analysis, and Langevin dynamics, we reveal an elegant mechanism for the simplest solute, water. Self-assembled octanol at the interface reversibly binds water and swings like the hinge of a door to bring water into a semi-organized second interfacial layer (a “bilayer island”). This mechanism is distinct from well-known lipid flipping and water transport processes in protein-free membranes, highlighting important limitations in the water/octanol proxy. Interestingly, the collective and reversible behavior is well-described by a double well potential energy function, with the two stable states being the water bound to the hinge on either side of the interface. The function of the hinge for transport, coupled with the underlying double well energy landscape, is akin to a molecular switch or shuttle that functions under equilibrium and is driven by the differential free energies of solvation of H₂O across the interface. This example successfully operates within the dynamic motion of instantaneous surface fluctuations, a feature that expands upon traditional approaches toward controlled solute transport that act to avoid or circumvent the dynamic nature of the interface.

Despite their pharmacological relevance, the mechanism of transport across water/octanol phase boundaries has remained unexplored. Octanol molecular assemblies are demonstrated to reversibly bind water and swing like the hinge of a door.     

Molecular state of hydrochloric acid in its tributyl phosphate extracts

Using IR spectroscopy we have shown that at digerent equilibrium concentrations of HCl in aqueous phases, its tributyl phosphate @acts contain: 1) at C_Hcl ^a < 2.3 M, micelle-like associates H₅O₂ ⁺(H₂O)_n–2(TBP)_mCl^–·(H₂0·TBP)₂ (n 26 and m 13), the structure of micelles is discussed 2) at 2.3 M < C_HCl ^a < 5.6 M, dimer associates [H₅O₂ ⁺(H₂O)₂Cl^–(H₂O·TBP)₂]₂; 3) at 5.6 M < C_HCl ^a < 8.5 M, H-bonded molecular fragments H₅O₂ ⁺(TBP)_2/3Cl^–(A); and 4) at C_HCl ^a > 8.5 M, considerable amounts of the H₃O⁺ tisolvate start to form in molecular fragments H₃O⁺(TBP)_1/3Cl ^–(B) H-bonded with the nearest neighbors. At C_Hcl ^a > 5.6 M, almost no free TBP molecules occur in the extracts and a structured liquid forms from the A fragments; and at C_Hcl ^a > 8.5 M, from the B fragments.Institute of Catalysis, Siberian Branch, Russian Academy of Sciences. Translated fromZhurnal Strukturmoi Khimii, Vol. 34, No. 5, pp. 72–79, September–October, 1993.Translated by K. Shaposhnikova     

Electric field gradients from single-crystal X-ray diffraction data

Deuterium quadrupole coupling tensors have been calculated from diffraction determined charge distributions in crystalline LiOH · H₂O, LiNO₃ · 3H₂O and NaHC₂O₄ · H₂O. The sign, orientation, asymmetry and magnitude of these coupling tensors show good agreement with spectroscopic results.     

Enthalpies of solution and of crystallization of lithium nitrate and of lithium nitrate trihydrate in water at 25°C

The enthalpies of crystallization of LiNO₃ and LiNO₃–3H₂O from aqueous solutions at 25°C, measured by a calorimetric method and determined from the previously published data on the concentration dependence of the enthalpy of solution, are reported. The results are compared with the values obtained from the concentration dependences of the activity coefficients and from the temperature dependences of the solubilities. The enthalpy of solution at infinite dilution and the enthalpy of hydration are given.     

Extraction of micro- and macroconcentrations of rare earth ions with the mixture of D2EHPA and TBP in n-hexane and cyclohexane

The synergistic solvent extraction of Eu(III) and some other rare earth elements from nitrate solutions (HNO₃+LiNO₃) by a mixture of (TBP+D2EHPA) in n-hexane and cyclohexane has been investigated at 22 °C. Antagonism found in europium extraction from 0.1M HNO₃ transforms into a synergistic effect. The synergistic effects existing for all investigated metals in extraction from 0.1M HNO₃+3M LiNO₃ were caused by formation of mixed complexes of the type Ln(D2EHPA)_2nH_2n–3+1(NO₃)₁TBP_m, where 1=1 or 2. The selectivity of the extraction in a synergistic system is lower for the La–Yb pair than in the case of D2EHPA extraction under the same conditions. On the other hand, the application of the synergistic mixture is more suitable for Eu–Ho separation. Thus the synergistic effect can be used for the separation or refining of some lanthanides.     

Study on Properties of TBP-HNO3 Complex Used for Direct Dissolution of Lanthanide and Actinide Oxides in Supercritical Fluid CO2

The tri-n-butyl phosphate-nitric acid （TBP-HNO3） complex prepared by contacting the pure TBP with the concentrated HNO3 can be used for direct dissolution of lanthanide and actinide oxides in the supercritical fluid carbon dioxide （SCF-CO2）. Properties of the TBP-HNO3 complex have been studied. Experimental results showed that when the initial HNO3/TBP volume ratio was varied from 1 ： 7 to 5 ： 1, the concentration of HNO3 in the TBP-HNO3 complex changed from 1.95 to 5.89 mol/L, the [HNO3]/[TBP] ratio of the TBP-HNO3 complex changed from 0.61 to 2.22, and the content of H20 in the TBP-HNO3 complex changed from 2.02% to 4.19%. All of the density, viscosity and surface tension of the TBP-HNO3 complex changed with the concentration of HNO3 in the complex, and were higher than those of the pure TBE The protons of HNO3 and H2O in the complex underwent rapid exchange to exhibit a singlet resonance peak in nuclear magnetic resonance spectra. When the TBP-HNO3 complex was dissolved in a low dielectric constant solvent, small droplets of HNO3 were formed that can be detected by NMR.     

Extraction liquide-liquide par des esters alkylphosphoriques. II. Extraction des nitrates de béryllium et des autres alcalino-terreux par le tri-n-butylphosphate

The solvent extraction systems Be(NO₃)₂? HNO₃? H₂O? TBP/kerosene and M(NO₃)₂? H₂O? TBP/kerosene (TBP = tri-n-butylphosphate, M = Be, Mg, Ca and Sr) have been studied. The alkaline earths elements are poorly extracted. Only very high acidities allow better extraction of beryllium. The sequence of extraction of the alkaline earths elements by the TBP depends on the concentration of the cations and is Ca > Be > Sr > Mg if the metal concentration is lower than 2 M.     

Viskosimetrische Untersuchung des Systems LiNO3−H2O

Zusammenfassung Die Temperaturabhängigkeit der Viskosität im System LiNO₃–H₂O und im Temperaturbereich 20–70°C wird in der Gleichung =A expB/T=T ₀ zusammengefaßt; aus der so erhaltenen Beziehung werden Rückschlüsse auf die Struktur der Lösungen gezogen.

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Temperature dependence of the viscosity in the system LiNO₃–H₂O is expressed by =A expB/T-T ₀ in the temperature range 20–70°C. Possible relations to structural changes in the solutions are considered.

     

Solubility of Lithium Nitrate in Solutions of Lithium Halides

Solubility isotherms in LiNO₃ – LiX – H₂O (X = Cl, Br, I) systems at 298.15 K were measured for the first time with special regard to the retrograde solubility of lithium nitrate trihydrate. The compositions of solutions used as media in absorption refrigerators and heat pumps were compared with the results and subsequently discussed.     

Solubility of Lithium Nitrate in Solutions of Lithium Halides

Summary. Solubility isotherms in LiNO₃ – LiX – H₂O (X = Cl, Br, I) systems at 298.15 K were measured for the first time with special regard to the retrograde solubility of lithium nitrate trihydrate. The compositions of solutions used as media in absorption refrigerators and heat pumps were compared with the results and subsequently discussed.     

N235萃取HCl体系中TBP消除第三相的作用机理

通过测定萃取有机相的电导率变化研究叔胺N₂₃₅(三烷基胺)萃取盐酸体系中第三相的形成及改性剂消除第三相的作用机理。实验结果表明，无改性剂时萃取体系在各种条件下均出现第三相。第三相组成为R₃NH⁺(H₂O)₃·Cl^-，具有导电性。加改性剂TBP(磷酸三丁酯)后，第三相消失。本文认为改性剂TBP消除第三相的作用机理是TBP能够将萃合物R₃NH+(H₂O)₃·Cl^-拆分为可溶于惰性稀释剂的R₃NH⁺(H₂O)₃·O=P(OC₄H₉)₃大阳离子，Cl^-离子则以抗衡离子分散于稀释剂中。     

Effect of Ethylene Glycol on the Molecular Organization of H2O in Comparison with Methanol and Glycerol: A Calorimetric Study

Excess partial molar enthalpies of ethylene glycol, H ^E _EG, in binary ethylene glycol–H₂O, and those of 1-propanol, H ^E _IP, in ternary 1-propanol–ethylene glycol (or methanol)–H₂O were determined at 25°C. From these data, the solute–solute interaction functions, H ^E _EG–EG = N(H ^E _EG/n _EG) and H ^E _1P–1P = N(H ^E _1P/n _1P), were calculated by graphical differentiation without resorting to curve fitting. Using these, together with the partial molar volume data, the effect of ethylene glycol on the molecular organization of H₂O was investigated in comparison with methanol and glycerol. We found that there are three concentration regions, in each of which the mixing scheme is qualitatively different from the other regions. Mixing scheme III operative in the solute-rich region is such that the solute molecules are in a similar situation as in the pure state, most likely in clusters of its own kind. Mixing scheme II, in the intermediate region, consists of two kinds of clusters each rich in solute and in H₂O, respectively. Thus, the bond percolation nature of the hydrogen bond network of liquid H₂O is lost. Mixing scheme I is a progressive modification of liquid H₂O by the solute, but the basic characteristics of liquid H₂O are still retained. In particular, the bond percolation of the hydrogen bond network is still intact. Similar to glycerol, ethylene glycol participates in the hydrogen bond network of H₂O via-OH groups, and reduces the global average of the hydrogen bond probability and the fluctuations inherent in liquid H₂O. In contrast to glycerol, there is also a sign of a weak hydrophobic effect caused by ethylene glycol. However, how these hydrophobic and hydrophilic effects of ethylene glycol work together in modifying the molecular organization of H₂O in mixing scheme I is yet to be elucidated.     

Transport study of V(V), Zn(II) and Be(II) using supported liquid membranes

V(V), Zn(II) and Be(II) have been studied to test oxine and tri-n-butylphosphate (TBP) as carriers for transport through supported liquid membranes in polypropylene film. All the three types of ions can be passed through such membranes using oxine in case of V(V) and TBP in case of Zn(II) and Be(II). Maximum flux of metal ions has been observed from 0.01M H₂SO₄ for V(V) (3.22·10^–6 mol·m^–2·s^–1) and 2M HCl containing 3M CaCl₂ for Zn(II) solution (1.4·10^–6 mol·m^–2·s^–1). Low flux was observed in case of Be(II) since the membrane was affected by sulphocyanide group and did not remain hydrophobic. Mechanism of transport for these metal ions have been proposed separately. Distribution coefficient data for V(V) have also been evaluated to determine theoretical values of the permeability coefficient, and compared with experimental values.     

Thermodynamic study of the system (LiCl + LiNO3 + H2O)

The solubility of the binary system (LiNO₃ + H₂O) from T = 273.15 K to T = 333.15 K and solubility isotherms of the ternary system (LiCl + LiNO₃ + H₂O) were elaborately measured at T = 273.15 K and T = 323.15 K. These solubility data, as well as water activities in the binary systems from the literature, were treated by an empirically modified BET model. The isotherms of the ternary system (LiCl + LiNO₃ + H₂O) were reproduced and a complete phase diagram of the ternary system in the temperature range from 273.15 K to 323.15 K predicted. It is shown that the solubility data for the binary system (LiNO₃ + H₂O) measured in this work are slightly different from the literature data. Simulated results showed that the saturated salt solution of (2.8LiCl + LiNO₃) is in equilibrium with the stable solid phase LiNO₃(s) over the temperature range from 283.15 K to 323.15 K, other than the solid phases LiNO₃ · 3H₂O(s) and LiClH₂O(s) as reported by Iyoki et al. [S. Iwasaki, Y. Kuriyama. T. Uemura, J. Chem. Eng. Data 38 (1993) 396–398].     

Coordinating zincophilic sites and a solvation shell for a dendrite-free Zn anode under the synergistic effects of polyacrylonitrile and dimethyl sulfoxide

The advantages of aqueous zinc-ion batteries (AZIBs) are largely offset by the dendrite growth on the Zn anode, which is induced by the heterogeneous electrical field and limited ion transport of the Zn anode–electrolyte interface during plating and stripping. Here, we propose a dimethyl sulfoxide (DMSO)–H₂O hybrid electrolyte containing polyacrylonitrile (PAN) additives (PAN–DMSO–H₂O) to improve the electrical field and ion transport of the Zn anode, which can thus effectively inhibit dendrite growth. Experimental characterization and theoretical calculations show that PAN preferentially adsorbs on the Zn anode surface and provides abundant zincophilic sites after its solubilization by the DMSO, enabling a balanced electric field and lateral Zn plating. DMSO regulates the solvation structure of the Zn²⁺ ions and strongly bonds to H₂O, which concurrently reduces side reactions and enhances the ion transport. Thanks to the synergistic effects of PAN and DMSO, the Zn anode presents a dendrite-free surface during plating/stripping. Moreover, Zn–Zn symmetric and Zn–NaV₃O₈·1.5H₂O full batteries with this PAN–DMSO–H₂O electrolyte achieve enhanced coulombic efficiency and cycling stability compared to those with a pristine aqueous electrolyte. The results reported herein will inspire other electrolyte designs for high-performance AZIBs.

In order to improve the critical issues of Zn dendritic in zinc-ion batterie, we investigate herein a hybrid electrolyte with PAN-DMSO-H₂O. With the synergistic effects of PAN and DMSO, a uniform, smooth and dendrite-free Zn anode could be obtained.     

Extraction chemistry of uranyl nitrate and nitric acid in high concentration systems

HNO₃ is extracted in significant quantities by uranyl nitrate solvates with different extractants: TBP (tributyl phosphate), TOPO (trioctyl phosphine oxide) and TDA (tetradecyl ammonium). The effect of diluent nature is not observed on extracting HNO₃ and TBP saturated by uranium at equilibrium with its salt using the diluents (CCl₄, C₆H₅Cl, C₁₂H₂₆, CHCl₃) which are less polar than UO₂(NO₃)₂(TBP)₂. HNO₃ occurs in organic phase as undissociated form and its state is similar to pure anhydrous HNO₃. Solvates of TBP and TDA with uranyl nitrate dissolve HNO₃ without displacement of uranium from organic phase.     

A Density Functional Theory and Microkinetic Study of Acetylene Partial Oxidation on the Perfect and Defective Cu2O (111) Surface Models

The catalytic removal of C₂H₂ by Cu₂O was studied by investigating the adsorption and partial oxidation mechanism of C₂H₂ on both perfect (stoichiometric) and Cu_CUS-defective Cu₂O (111) surface models using density functional theory calculations. The chemisorption of C₂H₂ on perfect and defective surface models needs to overcome the energy barrier of 0.70 and 0.81 eV at 0 K. The direct decomposition of C₂H₂ on both surface models is energy demanding with the energy barrier of 1.92 and 1.62 eV for the perfect and defective surface models, respectively. The H-abstractions of the chemisorbed C₂H₂ by a series of radicals including H, OH, HO₂, CH₃, O, and O₂ following the Langmuir–Hinshelwood mechanism have been compared. On the perfect Cu₂O (111) surface model, the activity order of the adsorbed radicals toward H-abstraction of C₂H₂ is: OH > O₂ > HO₂ > O > CH₃ > H, while on the defective Cu₂O (111) surface model, the activity follows the sequence: O > OH > O₂ > HO₂ > H > CH₃. The Cu_CUS defect could remarkably facilitate the H-abstraction of C₂H₂ by O₂. The partial oxidation of C₂H₂ on the Cu₂O (111) surface model tends to proceed with the chemisorption process and the following H-abstraction process rather than the direct decomposition process. The reaction of C₂H₂ H-abstraction by O₂ dictates the C₂H₂ overall reaction rate on the perfect Cu₂O (111) surface model and the chemisorption of C₂H₂ is the rate-determining step on the defective Cu₂O (111) surface model. The results of this work could benefit the understanding of the C₂H₂ reaction on the Cu₂O (111) surface and future heterogeneous modeling.