[en] A framework potassium titanium silicate K₂TiSi₃O₉·H₂O, compound I, was synthesized by the reaction of a titanium-hydrogen peroxide complex and SiO₃ in alkaline media under mild hydrothermal conditions (180 C). This compound was converted to the corresponding sodium phase, Na₂TiSi₃O₉·H₂O (IV) and two proton-containing phases, K_1.26H_0.74TiSi₃O₉·1.8H₂O (II) and K_0.3H_1.7TiSi₃O₉·2.4H₂O (III) by ion exchange. These products were characterized by elemental analysis, TGA, FT-IR, MAS ²⁹Si NMR, and X-ray diffraction. The ion exchange behavior of compound I and III toward alkali, alkaline earth, and some transition metal ions solutions was studied. A high affinity of the protonic form of titanium trisilicate exchanger for cesium and potassium makes it promising for radionuclide-contaminated groundwater treatment and certain analytical separations. The crystal structure of compound I was found to be isomorphous with that of the zirconium analogue and contains a framework enclosing two types of tunnels. The exchange properties were interpreted on the basis of this structure and selectivity of the Zr and Ti phases rationalized on the basis of the tunnel sizes. The structure of II was solved on the basis of a monoclinic cell, whereas the compound I phase is orthorhombic. The relationship of structure II, monoclinic, to the parent orthorhombic structure is described. Phase III yielded a complex X-ray pattern with evidence of disorder and a highly complex ²⁹Si NMR spectrum. On reexchanging with K⁺, the original crystal lattice was restored

[en] Gas-liquid chromatography method has been used to.show that, following γ-radiolysis of naphthalene aqueous solutions under stationary conditions, naphthalene consumption obeys a kinetic equation of the first order with a rate constant k=(6.05+0.05)x10^-3 s^-1. 1- and 2- naphthols; 1.4-, 1.5- and 2.7-dioxynaphthalenes are found in the reaction products. A maximUm yield of the 1- and 2-naphthols does not exceed 10-15% of the reacted naphthalene quantity. Kinetics of the 1-naphthol accumulation in the initial period is describeb by equation of the second order k=(3.54+-0.03)x10^-6 m³xmol^-1xs^-1; the yield of molecules for 100 eV of absorbed energy is G(NphOH)=1.6. The data obtained in the presence of additions are explained by a high reactivity of the naphthols and naphthalene in relation to OH, H and esub(aq) radicals and their competitions in the reactions with the radicals mentioned

[en] The G⁰ value for naphthalene conversion in aqueous solution amounts to the sum of Gsub(OH)+Gsub(eaq)+Gsub(H)+2Gsub(H₂O₂). Using the GLC method, spectroscopy and mass spectrometry, the following naphthalene derivatives were detected or quantitatively determined among the products of radiolysis: α- and β-naphthols, di- and three-hydroxynaphthalenes, naphthoquinones, dihydronaphthalene and some condensation products. The G⁰ value for α- and β-naphthole formation is 2.5 molec./ 100 eV. The naphthols are unstable in radiolysis conditions and undergo further conversions with G⁰-values 1.4 and 0.67 for α- and β-isomers, respectively. The effect of an increase in the amount of the condensed rings in the aromatic molecule upon the reaction rate of OH radicals with polynuclear aromatic hydrocarbons (PAH) was studied. The rate of the radiation induced hydroxylation was found to increase by several orders of magnitude in the sequence: benzene < naphthalene < phenanthrene < chrysene < anthracene < pyrene < perylene < 3,4-benzopyrene < 1,2-benzoanthracene. The logarithms of reaction rate constants for PAH and substituted naphthalenes are linearly dependent upon the atom localization energies and Hammett's constants of substituents, respectively. (author)

[en] 'To expand the authors efforts to provide families of inorganic ion exchangers useful on a global scale. In carrying out this objective, they will synthesize a variety of ion exchange materials, determine their structures and where necessary alter these structures to build in the desired properties. The underlying thermodynamic, kinetic and molecular basis of ion exchange behavior will be elucidated and their suitability for nuclear waste remediation will be assessed. As of September 1, 1996, they have synthesized a number of highly selective inorganic ion exchangers, determined their crystal structures and elucidated the mechanism of exchange for a number of these exchangers.'

[en] To develop successfully the radiation methods of disinfecting the waste waters and sludges from polyaromatic hydrocarbons (PAH), it is necessary to elucidate the mechanism of their radiolysis in aqueous solutions. The present paper deals with radiation chemical conversions in aqueous naphthalene solutions, the simplest condensed system and convenient model in studying the mechanism of oxidation and kinetic regularities of the radiation oxidation of PAH. The reactivity of a series of PAH with OH radicals under radiolysis was also determined. (author)

[en] Using the method of competing reactions and chromatographic analysis of the reaction products the influence of annelation degree on the rate of OH radical reaction with polycyclic aromatic compounds in aqueous solutions is studied. The influence of substituent nature on naphthalene reactivity in the reaction of gamma-radiation hydroxylation is investigated. A supposition is made that when passing from benzene to polycyclic aromatic compounds a change in formation mechanism of oxycyclodienyl radicals takes place

[en] The mechanism of γ-radiolysis of aqueous solutions of substituted naphthalene NphX, where X-α-CH₃, α-NH₂, α-NO₂, β-OCH₃, β-CH₃, β-Cl has been investigated. The concentration of substituted naphthalene before and after irradiation as well as concentration of formed mononaphthols has been determined chromatographically. Preliminarily by means of mass-spectrometry the process of naphthalene oxidation by Fenton reagent (H₂O₂+Fe⁺⁺) in H₂¹⁸O is studied. It is shown that naphthalene oxidation by hydroxyl radicals generated by the H₂O₂+Fe⁺⁺ system occurs according to the mechanism comprising acid fragmentation with transition into dihydroxynaphthalene only of oxygen from water as well as entering into the formed compound of the second light hydroxyl group from the oxidizer. It has been found that radiation chemical yields of substituted napthalene consumption are considerably higher than the yields of α and β mononaphthols formation and the yields of α naphthols are higher than those of β-naphthols. Low mononaphthol yields are due to their fast oxidation up to trihydroxynaphthalenes and other radiolysis products

[en] The ion exchange properties of crystalline and amorphous phases of a sodium titanosilicate towards alkali and alkaline earth cations has been examined. Potentiometric titration of the crystalline phase in the proton form, H₂Ti₂O₃(SiO₄), showed that 80% of the sodium ion sites could be occupied to pH=12 and only 25% of the exchange sites could be filled by Cs⁺. However, when an equal concentration of Na⁺ was present in the Cs⁺ solution, the cesium loading was reduced to 5.6% (0.47meq/g) of the theoretical IEC. This loading is further reduced to less than 0.1 meq/g in solutions approximating the sodium content of nuclear waste solutions, i.e., 5-6 M NaNO₃, 1-3 M NaOH. This low capacity limits the usefulness of this exchanger to waste solutions less than 10^-5-10^-6 M in Cs⁺. The amorphous phase exhibits a very high affinity for Sr²⁺ but also for Ba²⁺ and Ca²⁺ in alkaline solution. These ions could serve as interferences for selective Sr²⁺ removal from nuclear waste solutions. Sodium titanium silicate has a tunnel structure. The low capacity of the exchanger for Cs⁺ stems form the fact that only a few of the exchange sites can be filled with Cs⁺ in the presence of Na⁺ and still maintain charge balance. 12 refs., 7 figs., 2 tabs

[en] A novel layered sodium titanium silicate Na₂TiSi₂O₇·2H₂O has been synthesized by the reaction of a titanium-hydrogen peroxide complex and silicic acid in alkaline media under mild hydrothermal conditions (200 degree C). The product was characterized by elemental analysis, TGA, FT-IR, MAS ²⁹Si and ²³Na NMR and X-ray spectroscopy. The intercalation reaction of n-alkylamines from the gaseous phase and the ion exchange behavior of Na₂TiSi₂O₇·2H₂O towards alkali, alkaline earth and some transition metal ions in model individual and complex solutions were studied. It was found that the layered sodium titanium silicate contains acidic hydroxyl functional groups, which results in cation uptake at pH>1.5. The high affinity of the exchanger for cesium in weakly acid and neutral solutions makes it a promising material for the treatment of some types of nuclear wastes, contaminated ground water and different biological liquors. 20 refs., 10 figs., 6 tabs

[en] The ion exchange behavior of three sodium micas (phlogopite, Ward's Sci.; phlogopite, Suzorite Inc., biotite, Ward's Sci.) towards Li⁺, K⁺, Rb⁺, Cs⁺, Mg²⁺, Ca²⁺, Sr²⁺, Ba²⁺, Pb²⁺, Hg²⁺, Co²⁺, Cu²⁺, Cd²⁺ and Zn²⁺ ions has been studied. The ion exchange isotherms of alkali, alkaline earth and some other divalent cations were determined and concentration equilibrium constants as a function of metal loading and temperature were analyzed. Sodium micas exhibit high affinity for heavy alkali metals with the selectivity order Rb⁺ > Cs⁺ > K⁺. By studying the cesium uptake in the presence of NaNO₃, CaCl₂, NaOH, NaOH + KOH, HNO₃ electrolytes (in the range of 0.01--6 M) it was found that sodium micas could remove cesium efficiently in neutral and alkaline media, which make them promising for certain types of nuclear waste treatment