Darya V. Gryaznova

The paper focuses on a transition from studying synthetic analogs of rare titanosilicate minerals (lintisite, ivanyukite, and zorite) in the powdery state to investigating their new granulated forms. Five different methods for granulating titanosilicate samples are tested: fluidized bed and spray dry granulation, spray bed granulation, screw rotor granulation, and manual pressing of paste through a stainless-steel sieve with a 1 mm mesh size. The results of studying sorption of trace amounts of ¹³⁷Cs and ⁹⁰Sr radionuclides from model solutions of various compositions onto inorganic sorbents in powdered and granulated forms are presented.

In this paper, results of studying the properties of armbrusterite, a natural heterophyllosilicate, are presented. Due to its crystal structure consisting of parallel HOH-type sheets separated by a network of large-diameter (4–6 Å) channels, this mineral is of interest as a prototype for producing novel compounds to be used as sorbents. The studies were conducted by X-ray powder diffraction and X-ray single crystal diffraction analyses, electron microscopy, and IR spectroscopy. The natural sample is shown to be able to selectively extract monovalent cations from the solution of complex composition consisting of mono- and divalent salts. Furthermore, the preliminary results of hydrothermal synthesis of an analog of this mineral are reported. It is demonstrated that the mineral can be produced under milder conditions than the known methods for synthesizing heterophyllosilicates using platinum capsules (Tuttle bombs) at 380–450 °C.

The process of granulation obtained by hydrothermal synthesis of alkaline titanosilicate (Ti-Si) with a structure similar to the mineral ivanyukite is studied. The use of silicate binder with different pH values as a binder during granulation is considered. The sorption and strength properties of the obtained alkaline titanosilicate granules were determined.

Flexible crystal(水晶) structures, which exhibit(展览) single-crystal(水晶)-to-single-crystal(水晶) (SCSC) transformations(转型), are attracting attention(注意) in many applied aspects: magnetic(磁) switches, catalysis, ferroelectrics and sorption. Acid treatment(治疗) for titanosilicate material(材料) AM-4 and natural(自然) compounds with the same structures led to SCSC transformation(转型) by loss(损失) Na⁺, Li⁺ and Zn²⁺ cations with large structural(结构) changes (20% of the unit(单位)-cell(细胞) volume(体积)). The conservation(保育) of crystallinity through complex(复杂) transformation(转型) is possible due(由于) to the formation(形成) of a strong hydrogen bonding(债券) system(系统). The mechanism(机制) of transformation(转型) has been characterized using single-crystal(水晶) X-ray(射线) diffraction analysis(分析), powder(粉) diffraction, Rietvield refinement, Raman spectroscopy and electron microscopy. The low migration(迁移) energy(能源) of cations in the considered materials(材料) is confirmed using bond(债券)-valence and density(密度) functional(功能) theory(理论) calculations, and the ion conductivity of the AM-4 family’s materials(材料) has been experimentally verified.

Titanosilicates comprise a broad class of materials with promising technological applications. The typical obstacle that restricts their industrial applicability is the high manufacturing cost due to the use of specific organotitanium precursors. We herein report a new approach to the synthesis of titanosilicates using an inexpensive inorganic precursor, ammonium titanyl sulfate (ATS or STA), (NH₄)₂TiO(SO₄)₂∙H₂O. The latter is an intermediate in the processing of titanium-bearing concentrates produced from apatite-nepheline ores. In this paper, the new synthetic approach is exemplified by the microwave-assisted synthesis of IONSIVE-911, one of the most effective Cs-ion scavengers. The method can be modified to synthesize various titanosilicate compounds.