Hydrothermal synthesis of microporous titanosilicates

Kostov‐Kytin, Vladislav; Ferdov, Stanislav; Kalvachev, Yuri; Mihailova, Boriana; Petrov, O.

doi:10.1016/j.micromeso.2007.03.036

Cited by 36 publications

(15 citation statements)

References 17 publications

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“…Therefore, the xerogel in the preparation of the ETS-10 phase pellets can have a dual function, that of forming or favoring the growth of the phase crystals ETS-10, if the experimental conditions favor it, such as a suitable heat treatment, or to act only as a binder, remaining in a semi-amorphic phase. Kostov-Kytin et al [50] also analyzed the conditions for crystallization of titanosilicate phases, however these authors obtained pure crystals and not self-bonded pellets. Figure 6 shows the XRD-diffraction of the xerogel.…”

Section: Methodsmentioning

confidence: 99%

Preparation of ETS-10 Microporous Phase Pellets with Color Change Properties

Luca

Mastroianni

Siciliano

et al. 2019

Gels

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The main scope of the present work is to synthesize pH-responsive Engelhard titanium silicate (ETS)-10 phase crystalline pellets through the smart modification of a synthetic process which was previously applied to the preparation of other phases. The original preparative method, which envisages the use of the same initial synthesis as a binder for the preparation of pellets, was modified by adding an appropriate pH indicator to a number of systems subject to this investigation. It should be noted that the modified process was never before used to give access to pH-responsive ETS-10 phase pellets, and it is disclosed here for the first time. The study started from the definition of the best experimental conditions, which were optimized by analyzing the effects of temperature and system composition. The addition of the pH indicator did not alter the physicochemical characteristics and reactivity of the system. The pH-responsive ETS-10 phase crystalline pellets were characterized by an adequate mechanical strength and by a high capability to change color. The latter aspect can be particularly useful when this material is used in catalytic processes whose performance is strictly dependent on the pH value. The amount of gel used, as well as the working temperature, were the main critical parameters to be controlled during the preparation of pH-responsive ETS-10 phase crystalline pellets. The pellets were fully characterized by X-ray diffraction in order to investigate and identify the possible phases, and by using a hardness tester to measure the compressive strength. Finally, toning tests were performed.

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Section: Methodsmentioning

confidence: 99%

Preparation of ETS-10 Microporous Phase Pellets with Color Change Properties

Luca

Mastroianni

Siciliano

et al. 2019

Gels

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“…The Na-GTS, Na 4 Ti 4 O 4 (SiO 4 ) 3 ·6H 2 O, was prepared by a hydrothermal method according to the procedure reported by the previous studies (Kostov-Kytin et al, 2007;Fujiwara et al, 2010). The starting materials were special grade reagents of NaOH (FUJIFILM Wako Pure Chemical Co.), amorphous SiO 2 fine powder (Merck KGaA), TiCl 4 aqueous solution (Toho Titanium Co., Ltd), and HCl (FUJIFILM Wako Pure Chemical Co.).…”

Section: Sample Preparationmentioning

confidence: 99%

Preparation and crystal structural properties of Er<sup>3+</sup>–exchanged GTS–type sodium titanosilicate

Fujiwara

Kawata

Nakatsuka

2020

Journal of Mineralogical and Petrological Sciences

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Powder sample of GTS-type sodium titanosilicate (Na-GTS) was prepared using a hydrothermal method. The Er 3+ -exchanged forms [Na 4(1−x) Er 4x/3 Ti 4 O 4 (SiO 4 ) 3 ·nH 2 O] of Na-GTS with the compositions up to x = 0.96 were obtained by shaking the single-phase sample of Na-GTS in the ErCl 3 aqueous solutions (25 mL, 0.01-0.5 M) at 25 and 60°C for 6 h. The Er 3+ -exchange experiments revealed that the Er 3+ -exchange amounts (x) increase with increasing the concentration of ErCl 3 aqueous solutions and the higher treatment temperature more effectively promotes ion-exchange. Thermogravimetry-differential thermal analysis (TG-DTA) measurements showed that the exchange of Na + for Er 3+ decreases the dehydration temperature and the H 2 O content. The simulation of powder X-ray diffraction (XRD) patterns suggests that Er 3+ ions occupy both 4e and 6g sites in the assumed psuedocubic structure.

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“…Synthesis of titanosilicates is typically carried out under mild hydrothermal conditions using such titanium sources as titanium isopropyloxide Ti(OC3H7)4, titanium dioxide TiO2, sodium peroxotitanate Na4TiO6 obtained from Ti(OC3H7)4 or TiOCl2, as well as TiCl4. Common silicon sources are the colloidal silicon (Ludox-AS-40, Ludox-HS-40), pyrogenic silicon dioxide, silica gel, silicon dioxide with various particle sizes (12 to 200 μm) or tetraethyl orthosilicate (C2H5O)4Si [38][39][40][41][42][43][44][45][46]. All these synthesis methods involve the use of expensive reagents, which strongly hinders the utilization of the resulting materials as the adsorbents.…”

Section: Years)mentioning

confidence: 99%

Efficient extraction of multivalent cations from aqueous solutions into sitinakite-based sorbents

Perovskiy

Khramenkova

Pidko

et al. 2018

Chemical Engineering Journal

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A highly selective adsorbent for multivalent cationic species based on a sitinakite-type titanosilicate was prepared from a leucoxene ore enrichment waste. The synthesized material was used as for the selective removal of alkali-earth strontium (II) and barium (II) cations as well as for the cationic species based on the natural isotopes of uranium, radium, and thorium from aqueous solutions. The influence of such parameters as the pH, the initial concentration of the ions, the presence of other electrolytes on the sorption parameters was investigated. The sorption capacity of the synthesized material at ambient conditions is 80 and 110 mg/g for Sr 2+ and Ba 2+ , respectively, and it rises with increasing temperature. Furthermore, the material shows a high selectivity towards radionuclides of radium, uranium, and thorium. By using the current titanosilicate materials, the extracting degree of over 99% could be achieved when extracting these species from their respective standard aqueous solutions. The origin of the high adsorption selectivity for cationic complexes of thorium and uranium is rationalized based on periodic density functional theory calculations. The obtained results indicate that the described materials could be promising and inexpensive sorbents for the selective extraction of radioactive isotopes and particularly those of Sr, Ba and U, Th, Ra.

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Hydrothermal synthesis of microporous titanosilicates

Cited by 36 publications

References 17 publications

Preparation of ETS-10 Microporous Phase Pellets with Color Change Properties

Preparation of ETS-10 Microporous Phase Pellets with Color Change Properties

Preparation and crystal structural properties of Er<sup>3+</sup>–exchanged GTS–type sodium titanosilicate

Efficient extraction of multivalent cations from aqueous solutions into sitinakite-based sorbents

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