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  • Author or Editor: A. Puziy x
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Abstract  

Potassium titanium silicate with a semicrystalline framework of the formula K3HTi4O4(SiO4)3·4H2O has been prepared under mild hydrothermal conditions and its protonic form, H4Ti4O4(SiO4)3·8H2O, was obtained by acid treatment of the potassium compound. A comparative ion exchange testing of the H4Ti4O4(SiO4)3·8H2O towards alkali and alkaline earth metals in a broad pH and concentration range was carried out. It was found that potassium titanium silicate is a moderately weak cation exchanger, possessing high ion exchange capacity (up to 4–5 meq/g) and showing preference for heavy alkali and alkaline earth metals uptake. The selectivity of K3HTi4O4(SiO4)3·4H2O towards Cs+ and Sr2+ ions in alkaline and acid media in the presence of competitive inorganic ions and certain organic compounds was also studied. The data obtained suggest that despite the existence of well defined tunnel structure with parameters fitting for cesium ion in the K3HTi4O4(SiO4)3·4H2O, potassium titanium silicate could remove cesium (and strontium) efficiently only under some specific conditions, namely, at pH close to neutral and in the absence of competitive ions and especially of organic complexing agents.

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Abstract  

Peculiarities of carbonization of two styrene/divinylbenzene precursors (one sulfonated, another aminated and phosphorylated) have been investigated by thermogravimetry and differential thermal analysis. It was shown that phosphorus compounds incorporate into carbon structure and cause delayed carbonization. Porous structure and surface properties of synthetic carbons have been investigated by standard (BET, αs method, DA) and advanced (AED, PSD, regularization) methods from benzene and water adsorption isotherms. It was shown that phosphorus-containing carbon is less microporous and shows highly hydrophilic surface.

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Abstract  

Sodium titanium germanate with a semicrystalline framework (STG) of the formula Na3H(TiO)3(GeO)(GeO4)3·7H2O was synthesized under mild hydrothermal conditions and its proton form, H4(TiO)3(GeO)(GeO4)3·8H2O (STG-H), was prepared by acid treatment of the sodium compound. The STG was characterized by elemental analysis, TGA, FT-IR, and X-ray powder diffraction. A comparative ion exchange examination of the STG-H towards alkali and alkaline earth metals in a broad pH and concentration range was carried out. It was found that the STG is a moderately weak cation exchanger, possessing high ion exchange capacity (up to 4.0 meq/g) and showing preference for heavy alkali and alkaline earth metals. The STG selectivity towards Cs+ and Sr2+ ions in the presence of competitive metal ions and certain organic compounds was also studied. The data obtained suggest that the sodium titanium germanate is a more selective exchanger for Sr2+ ion than its titanium silicate analogue, K3H(TiO)4(SiO4)3·4H2O.

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Abstract  

Distribution coefficients, pH dependence, isotherms, kinetics and breakthrough curves of Sr binding have been measured on several types of adsorbents (carbons modified with titanium silicate, crystalline titanium silicate, mixed titanium-manganese oxide, and synthetic zeolites A4 and P) from different water solutions. It is concluded that acid-base properties of the adsorbent is very important for Sr binding. Titanium silicate based adsorbents had reduced chemical stability in an artificial food fluid below pH 2, the mixed titanium manganese oxide below pH 6, zeolite A4 below pH 5 and zeolite P below pH 7. Consideration is given to the feasibility of the adsorbents for food decontamination.

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