Electrosurface and Ion-Selective Properties of Track-Etched Nanofilters: The Effect of Polyvalent Metal Adsorption

The effect of polyvalent metal adsorption on the performance and ion selectivity of poly(ethylene terephthalate) track-etched membranes with pores of 10 nm in diameter was studied. Membrane samples were prepared from the track-etched membranes with pores of 20 nm in diameter by thermal shrinkage. It was shown that an effective pore diameter decreases and selectivity of track-etched membranes increases upon filtration of Al(NO₃)₃ and Cr(NO₃)₃ solutions. The results obtained are explained by ion adsorption leading to the formation of complexes between polyvalent metals and carboxyl groups on the pore surface that is confirmed by IR spectroscopy data. The study of electrosurface properties of modified membranes and the dependence of ion selectivity of track-etched membranes on the concentration of Al³⁺ ions in 10^–2 M KCl solution indicates the decrease of membrane negative surface charge resulted from Al³⁺ adsorption and membrane charge reversal at Al³⁺ concentration in a solution higher than 10^–6 M. The dependences of the ion selectivity on pH and Al³⁺ concentration C _Al in a solution are similar. At pH < 3 and C _Al > 10^–6 M, the _1–2 > _1–1 > _2–1 ion selectivity series characteristic of the initial negatively charged membranes for the 1–1, 1–2, and 2–1 electrolyte solutions is reversed into the _2–1 > _1–1 > _1–2 series characteristic of positively charged membranes.     

Oscillatory variation in EMF developed due to additions of TiO2 pretreated thermally and γ-irradiated to various doses in the concentration cell made up of Ag/Ag+

Several powder samples of TiO₂ are pretreated thermally at 300, 480 and 540°C, subjected to -irradiation and after irradiation added in one of the compartment of the concentration cell made up of Ag/Ag⁺. The adsorbed oxygen species O _2ad ^– , HO _2ad ^– and O _ad ^– on TiO₂ provide negatively charged sites and develop EMF in the cell. The radiation damage, measured in terms of equilibrium EMF, received at lower doses is partially recovered at higher doses. It is proposed that in heating at 480°C, ad species react with Ti³⁺ ions in the surface and produce –O–O– peroxy linkages and block the negatively charged sites while in heating at 540°C Ti₄O₇ phase is produced on the surface which adsorbs O₂ and provide large number of negatively charged sites. During -irradiation peroxy linkages are broken and the Ti₄O₇ phase is destroyed. Observed oscillatory variation in equilibrium EMF is explained on the basis of several reactions mentioned above proceeding at different rates during radiolysis.     

Electromigration of carrier-free radionuclides

The electromigration behaviour of carrier-free²⁴¹Am–Am(III) in inert electrolytes, =0.1 (C10 ₄ ^– ), T=298.1(1) K, was studied. On the basis of the overall ion mobilities of²⁴¹Am–Am(III) on pH between pH 5.5 and 12.9, the stoichiometric hydrolysis constants p ₃ ³ =23.8(9), and pK₁=6.9(2) were obtained. For K₄ a limitation of pK₄14.4(3) was possible, because no formation of anionic hydrolysis products in solutions pH12.9 was registered. The individual ion mobility of the²⁴¹Am–Am³⁺ decrease in the range pH 5.5–3 from +6.85(15) up to +5.50(15)·10^–4 cm²·s^–1·V^–1. Dependences of this effect on overall ionic strength, inert electrolyte anion, and the temperature of the electrolytes were studied in acidic and neutral solutions.     

The determination of thermodynamics of oxygen complexes of anions of sulfur dioxide and fluoronitrobenzenes using atmospheric pressure ionization mass spectrometry

The thermodynamic properties of oxygen complexes of the negative ions of 1-fluoro-2,4-dinitrobenzene (FDNB), 1,5-difluoro-2,4-dinitrobenzene (DFDNB), and sulfur dioxide have been determined by measuring the temperature dependence of the pertinent ion ratios by using a mass spectrometer equipped with a⁶³Ni atmospheric pressure ionization source. The values of -H° and -S°are SO ₂ ^–(O₂), 101 ± 2.1 kJ mole¹ and 121 ± 3.8 J/K-mole; FDNB^–(O₂), 51.5 ±3.4 kJ mole^–1 ± 9.2 J/K-mole; and DFDNB^–(O₂), 65.7 ± 0.4 kJ mole^–2 and 110 ± 5.0 J/K-mole.     

The Degradation of the Active Medium of an Argon Fluoride Discharge Lamp with a Noncorrosive Gas Mixture

The results of a spectroscopic study on the degradation of the active medium of an ArF electric-discharge lamp with the He–Ar–SF₆ working mixture (p 100 kPa) and pumped by a transverse space discharge are presented. Plasma radiation spectra were studied over the range 190–780 nm at different stages of degradation of the working mixture, and the dynamics of emission from the inert gases, as well as the products of sulfur hexafluoride degradation in the plasma, were determined. The ArF(B–X) emission band at = 193 nm was observed when the number of discharge pulses was 10³, whereas the quite effective formation of excited sulfur molecules, which decomposed producing emission bands in the spectral region of 260–550 nm, took place at n 10⁴.     

Role of radical ions in the thermally stimulated luminescence of uranium doped BaCO3 system

Electron paramagnetic resonance (EPR) studies of -irradiated uranium doped BaCO₃ have shown the formation of CO₃ ^–, CO₂ ^–, O₃ ^– and O₂ ^– ions. Thermally stimulated luminescence (TSL) glow curves of the -irradiated samples in the 300–600 K range have exhibited an intense peak around 360 K and a weak one around 440 K. The trap parameters for these peaks have been determined from TSL data. Spectral studies of the glow have revealed emission around 566, 583 and 590 nm characteristic of the uranate ion. From studies on the thermal stabilities of the radical ions, it has been inferred that the glow peak around 360 K is associated with the thermal destruction of O₂ ^– ion and the peak around 440 K is associated with the thermal destruction of CO₃ ^– ion.     

The role of water and K ion in the charge transfer between groups of DNA and the lysine and arginine side chains of histone proteins

We have calculated the charge transfer (CT) between the group of DNA and the lysine (Lys) and arginine (Arg) positive side chains of histones in presence of water and K⁺ ions. The calculations were performed at the HF + MP2 level, using the TZVP basis set. The calculations were corrected for basis set superposition error and besides Mulliken’s population analysis we have introduced the – for charged systems more reliable – natural population analysis. The results show that the bare -Lys and the -Arg interactions become weaker, mainly, due to the presence of the K⁺ ion. We have found 0.067e CT for Lys and 0.050e for Arg.     

Mass spectra of negative ions of condensed aromatic hydrocarbons and biphenyl

Conclusions The positions of the maxima of the effective yield of the (M-H)^– ions on the energy scale of the electrons for condensed hydrocarbons and biphenyl coincide with the maximum yield of the (M-H)^– ions for benzene. The existence of a molecular ion M^–, with a life span with respect to autoionization of 21sec, was observed for anthracene.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1885–1886, August, 1973.     

Adsorption of Cl? ions on electrodeposited rhodium black layer (rhodized electrode) at low concentrations

The adsorption of Cl^– ions on rhodium black layer (rhodized electrodes) was studied by radiotracer technique at low Cl^– ion concentrations (c10^–5 mol dm^–3) in 1 mol dm^–3 H₂SO₄ supporting electrolyte. The specific adsorption of Cl^– ions was treated in terms of partition between solution phase and electrodeposited Rh black layer. The potential dependence of the partition coefficient is determined.     

Radiolytic Gas Formation in Aqueous Alkali–Nitrate and Alkali–Nitrate–Aluminate Solutions Simulating Liquid Intermediate-Level Wastes

Radiolytic gas formation was measured in aqueous alkali–nitrate and alkali–nitrate–aluminate solutions simulating liquid intermediate-level wastes. The radiation-chemical yields of the gas mixture and its individual components depending on solution composition and irradiation temperature (up to 60°C) were determined. It was noted that oxygen was formed in comparatively high yields (up to 0.4 and 0.6 molecule/100 eV in alkali–nitrate–aluminate solutions at 30 and 60°C, respectively). This fact was explained by the decomposition of hydrogen peroxide, which is formed as a primary product of water radiolysis and in the combination of O^– radical ions, and by the catalytic effect of aluminate ions.     

Untersuchung der Ionengleichgewichte in Tetrahydrofuranlösungen des 2-Naphthonitril-Natriums

With the aid of conductometric measurements the ion equilibria inTHF solutions of 2-naphthonitrile sodium were studied. It was established that in the concentration interval of 10^–4–10^–5 mol/l the equilibrium ion pairs—free ions is predominant . The ion pairs are contact (average interion distance about 4.1 Å). In the temperature interval of 25 to 40° the heat of dissociation –H=3.1 kcal/mol, whereas between –40 and –70°–H is 1.26 kcal/mol. At higher concentrations (10^–2–10^–3 mol/l) triple ion formation is observed.     

Spectrophotometric determination of nitrogen dioxide in air

Summary A sensitive spectrophotometric method for the determination of trace amounts of nitrogen dioxide, after fixing it as nitrite in alkaline sodium arsenite solution, is described. The reaction is based on the diazo-coupling of p-nitroaniline with chromotrophic acid in acetate medium (pH 6±0.5). The azo dye formed has its absorption maximum at 515 nm, with a molar absorptivity of 3.7×10⁴ l mol^–1 cm^–1. Beer's law is obeyed over the range 0–20 g of nitrite. The relative standard deviation is 2.5% for ten determinations of 10 g of nitrite. The effect of interfering gases and ions on the determination is discussed. The method has been applied to the determination of residual nitrogen dioxide in a laboratory fume cupboard and the results are compared with those obtained by the widely used sulphanilamide — NEDA method. Down to 0.5 g of nitrite can be determined.     

Influencing of the migration time in CZE

For selective influencing of the ion mobility in CZE several electrolyte additives were used. With acetone as organic solvent the migration times of inorganic cations are changed. The separation of Cl^– and I^– is optimized by adding -cyclodextrin to the electrolyte. By adding 18-crown-6 it is possible to slow down the mobility of K⁺. In this way the disturbing effect of matrix ions can be prevented.     

Effect of gamma-rays on the formation of color centers in copper-containing lead borate glasses

Absorption bands in the range of 350–950 nm, induced in copper-containing lead borate glasses by -rays were identified and characterized. The effect of irradiation dose, copper oxide and lead oxide contents on the intensity and position of the induced absorption bands were also considered. Several induced absorption bands were observed. At least two bands in the ranges of 740–780 and 850–870 nm could be identified. They are suggested to be associated with induced Cu⁽²⁺⁾ ions. The band in the 800–830 nm (1.6 eV) range is ascribed to the Pb⁽³⁺⁾ ion, whereas others in the ranges of 600–630 and 650–730 nm are associated with the intrinsic defects formed in the base glass.     

Electroconduction,Association, and Ion–Molecular Interactions in Nickel Chloride Solutions in Methanol at 5–55°C

Results of a conductimetric investigation of nickel chloride in methanol at 5–55°C and electrolyte concentrations of 0.1–5 mM are presented. Limiting equivalent conductivities by Ni²⁺ and Cl^– and constants of ionic association in the first step with the formation of ionic pair NiCl⁺ are determined for asymmetric electrolytes using an extended Lee–Wheaton equation. In dilute nickel chloride solutions in methanol the association of ions in the second step is inessential. The size of dynamic solvation sheaths of the ions and the short-range non-coulombic interion potential suggest that the Ni²⁺ ion forms a kinetically and energetically stable solvated complex with the nearest solvation layer being 400 pm thick and virtually temperature-independent. The nearest kinetically stable solvation sheath of the Cl^– ion comprises mostly hydroxyl groups of methanol molecules and its stability is severely dependent on temperature.     

A new method for quantitative mass-spectrometric analysis of solutions

Summary The mass-spectrometric method for the analysis of inorganic solutions is not only a very sensitive technique but also one of broad applicability. The study of the behaviour of solutions of mineral acids chilled to –70°C under a r.f. voltage from 7 to 15 kV indicated that solutions of hydrochloric acids containing 20–32% of hydrogen chloride allow to obtain stable ion currents. The equipment for the analysis of solutions on the spark source mass-spectrometer is designed and the procedure of analysis is described. The detection limits of 47 elements are in the range from 10^–7 to 10^–11 g. The accuracy of the determinations was established by the added-found method. The reproducibility is 0.1–0.34 for content levels of 10^–7–10^–9 g. The analytical possibilities of different spark source mass-spectroscopic methods for the analysis of solutions are compared.     

Synthesis and Crystal Structures of [(Nicotinic Acid)2H]+I-, [(2-Amino-6-methylpyridine)H]+(NO3)-, and the 1:1 Complex Between 1-Isoquinoline Carboxylic Acid (Zwitter Ion) and L-Ascorbic Acid Assembled via Hydrogen Bonds

Summary. Three new complexes, namely [(nicotinic acid)₂H]⁺I^–, [(2-amino-6-methylpyridine)H]⁺ (NO₃)^–, and the 1:1 complex between 1-isoquinoline carboxylic acid (zwitter ion form) and L-ascorbic acid were synthesized. The IR spectra revealed different types of hydrogen bonds in these compounds. The X-ray structure determination has shown the first compound to consist of a packing of [(nicotinic acid)₂H]⁺ cations and I^– anions. In the dimeric cation the two nicotinic acid molecules (zwitter ions) are connected through hydrogen bonds (O–HO). Each dimer is further engaged in other hydrogen bonds with adjacent dimers giving 2D layers. The I^– ion is located at the inversion center. In the second compound the cation and anion are connected via hydrogen bonds formed between oxygen atoms of the NO₃ ^– anion and NH and NH₂ of the cation generating a layer structure. All atoms are coplanar on mirror planes. In the 1:1 complex the two molecules are connected through hydrogen bonds formed between the two oxygen atoms of the carboxylate group of 1-isoquinoline carboxylic acid (zwitter ion) and the oxygen atoms of the two adjacent hydrogen groups of the L-ascorbic acid molecule. These complex molecules are engaged in other hydrogen bonds with each other forming a 2D system normal to the long b-axis of the unit cell.     

Kinetics and mechanism of base hydrolysis of Reinecke's salt revisited – specific salt effects

The kinetics of base hydrolysis of the trans-[Cr(NH₃)₂(NCS)₄]^– anion follows the rate law: -d[complex]/dt = k ₀ + k ₁[OH^–] (50–70 °C, [OH^–] = 0.1–1.9 M and = 2.0 M). The specific salt effect has been investigated for eight aqueous media: NaCl, NaBr, NaI, NaClO₄, KCl, KBr, CsCl and CsBr. The alkali-independent path (k ₀) does not show any specific effect of inert electrolyte ions, the activation parameters: H = 113.5 ± 0.4 kJ mol^–1 and S = 24.1 ± 1.3 J mol^–1 K^–1 are interpreted in the frame of a dissociative interchange mechanism (I _d). For the alkali-dependent path (k ₁) the specific salt effect is observed for cations of the inert electrolyte, showing an important role for ion-pair formation between the cations and reagent complex anion in the activation process. A linear correlation between lnk ₁ and lnK ₀ (K ₀ – ion-pair formation constant) has been found for the cations studied. The dissociative, via conjugate base, mechanism (D _CB) has been proposed for the alkali-dependent path.