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Title: The Origin of Ion Exchange Selectivity in a Porous Framework Titanium Silicate

Abstract

The use of in-situ X-ray and neutron diffraction has elucidated the differences in the mechanism of ion exchange between a titanium silicate and a phase in which Nb is substituted for Ti at the 25% level both with the sitinakite structure. The area of interest is the very high level of selectivity required of the exchangers for use in nuclear waste systems.

Authors:
;
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL) National Synchrotron Light Source
Sponsoring Org.:
Doe - Office Of Science
OSTI Identifier:
960054
Report Number(s):
BNL-83040-2009-JA
Journal ID: ISSN 0959-9428; JMACEP; TRN: US1005891
DOE Contract Number:
DE-AC02-98CH10886
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Materials Chemistry; Journal Volume: 17; Journal Issue: 46
Country of Publication:
United States
Language:
English
Subject:
12 MANAGEMENT OF RADIOACTIVE WASTES, AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; 36 MATERIALS SCIENCE; 37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ION EXCHANGE; NEUTRON DIFFRACTION; ORIGIN; RADIOACTIVE WASTES; TITANIUM SILICATES; national synchrotron light source

Citation Formats

Celestian,A., and Clearfield, A. The Origin of Ion Exchange Selectivity in a Porous Framework Titanium Silicate. United States: N. p., 2007. Web. doi:10.1039/b708309b.
Celestian,A., & Clearfield, A. The Origin of Ion Exchange Selectivity in a Porous Framework Titanium Silicate. United States. doi:10.1039/b708309b.
Celestian,A., and Clearfield, A. Mon . "The Origin of Ion Exchange Selectivity in a Porous Framework Titanium Silicate". United States. doi:10.1039/b708309b.
@article{osti_960054,
title = {The Origin of Ion Exchange Selectivity in a Porous Framework Titanium Silicate},
author = {Celestian,A. and Clearfield, A.},
abstractNote = {The use of in-situ X-ray and neutron diffraction has elucidated the differences in the mechanism of ion exchange between a titanium silicate and a phase in which Nb is substituted for Ti at the 25% level both with the sitinakite structure. The area of interest is the very high level of selectivity required of the exchangers for use in nuclear waste systems.},
doi = {10.1039/b708309b},
journal = {Journal of Materials Chemistry},
number = 46,
volume = 17,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}
  • A framework potassium titanium silicate K{sub 2}TiSi{sub 3}O{sub 9}{center_dot}H{sub 2}O, compound I, was synthesized by the reaction of a titanium-hydrogen peroxide complex and SiO{sub 3} in alkaline media under mild hydrothermal conditions (180 C). This compound was converted to the corresponding sodium phase, Na{sub 2}TiSi{sub 3}O{sub 9}{center_dot}H{sub 2}O (IV) and two proton-containing phases, K{sub 1.26}H{sub 0.74}TiSi{sub 3}O{sub 9}{center_dot}1.8H{sub 2}O (II) and K{sub 0.3}H{sub 1.7}TiSi{sub 3}O{sub 9}{center_dot}2.4H{sub 2}O (III) by ion exchange. These products were characterized by elemental analysis, TGA, FT-IR, MAS {sup 29}Si NMR, and X-ray diffraction. The ion exchange behavior of compound I and III toward alkali, alkaline earth,more » 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 {sup 29}Si NMR spectrum. On reexchanging with K{sup +}, the original crystal lattice was restored.« less
  • Herein we developed a novel porous Titanium silicate/g-C{sub 3}N{sub 4} (TSCN) hybrid composite with a inorganic-organic heterojunction. The synthesized porous TSCN were well characterized by various analytical techniques for structural and chemical properties evaluation. FESEM results shows the growth of finely distributed porous titanium silicate on the surface of the g-C{sub 3}N{sub 4}. Porous TSCN hybrid nanocomposite has a great influence on the electronic and optical properties.
  • [ThB5O6(OH)6][BO(OH)2]·2.5H2O (Notre Dame Thorium Borate-1, NDTB-1) is an inorganic supertetrahedral cationic framework material that is derived from boric acid flux reactions. NDTB-1 exhibits facile single crystal to single crystal anion exchange with a variety of common anions such as Cl-, Br-, NO3-, IO3-, ClO4-, MnO4-, and CrO42-. More importantly, NDTB-1 is selective for the removal of TcO4- from nuclear waste streams even though there are large excesses of competing anions such as Cl-, NO3-, and NO2-. Competing anion exchange experiments and magic-angle spinning (MAS)-NMR spectroscopy of anion-exchanged NDTB-1 demonstrate that this unprecedented selectivity originates from the ability of NDTB-1 tomore » trap TcO4- within cavities, whereas others remain mobile within channels in the material. The exchange kinetics of TcO4- in NDTB-1 are second-order with the rate constant k2 of 0.059 s-1 M-1. The anion exchange capacity of NDTB-1 for TcO4- is 162.2 mg g-1 (0.5421 mol mol-1) with a maximum distribution coefficient Kd of 1.0534 × 104 mL g-1. Finally, it is demonstrated that the exchange for TcO4- in NDTB-1 is reversible. TcO4- trapped in NDTB-1 can be exchanged out using higher-charged anions with a similar size such as PO43- and SeO42-, and therefore the material can be easily recycled and reused.« less