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Title: Templated synthesis of mesoporous titanium phosphates for the sequestration of radionuclides

Abstract

Several mesoporous titanium phosphate phases, with varying pore sizes, were prepared using non-ionic surfactants and easily handled titanium precursors under mild reaction conditions. Preliminary testing reveals that these materials have high affinity for certain radionuclides of environmental concern. Significant amounts of radioactive waste have built up over the last half century as the result of nuclear weapons production and the accumulation of spent nuclear fuel. Ultimately, after processing, this waste is targeted to be buried in a deep geological repository. One plan is to include ''getter materials'' in with this waste in order to sequester any radionuclides that might leak from the wasteforms. Of particular interest in this regard are the long-lived actinide species (e.g. Pu, Am, Np, etc.) and the anions (e.g. pertechnetate, iodide, etc.). These getter materials must be able to survive long-term exposure to elevated temperatures (>150 C) and moderately high radiation fluxes. Due to their frailty towards radiolytic degradation, organic components cannot be used for either structure or function in the final getter material.

Authors:
; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Org.:
USDOE
OSTI Identifier:
885194
Report Number(s):
PNNL-SA-46567
2417; TRN: US200621%%874
DOE Contract Number:
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Inorganic Chemistry Communications, 9(3):293-295
Country of Publication:
United States
Language:
English
Subject:
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS; 12 MANAGEMENT OF RADIOACTIVE WASTES, AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; 45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEFENSE; ACTINIDES; AFFINITY; ANIONS; GETTERS; NUCLEAR FUELS; NUCLEAR WEAPONS; PROCESSING; RADIATIONS; RADIOACTIVE WASTES; RADIOISOTOPES; SURFACTANTS; SYNTHESIS; TESTING; TITANIUM; TITANIUM PHOSPHATES; WASTE FORMS; WASTES; SPENT FUELS; Environmental Molecular Sciences Laboratory

Citation Formats

Li, Xiaohong S., Courtney, Andrea R., Yantasee, Wassana, Mattigod, Shas V., and Fryxell, Glen E. Templated synthesis of mesoporous titanium phosphates for the sequestration of radionuclides. United States: N. p., 2006. Web. doi:10.1016/j.inoche.2005.11.014.
Li, Xiaohong S., Courtney, Andrea R., Yantasee, Wassana, Mattigod, Shas V., & Fryxell, Glen E. Templated synthesis of mesoporous titanium phosphates for the sequestration of radionuclides. United States. doi:10.1016/j.inoche.2005.11.014.
Li, Xiaohong S., Courtney, Andrea R., Yantasee, Wassana, Mattigod, Shas V., and Fryxell, Glen E. Wed . "Templated synthesis of mesoporous titanium phosphates for the sequestration of radionuclides". United States. doi:10.1016/j.inoche.2005.11.014.
@article{osti_885194,
title = {Templated synthesis of mesoporous titanium phosphates for the sequestration of radionuclides},
author = {Li, Xiaohong S. and Courtney, Andrea R. and Yantasee, Wassana and Mattigod, Shas V. and Fryxell, Glen E.},
abstractNote = {Several mesoporous titanium phosphate phases, with varying pore sizes, were prepared using non-ionic surfactants and easily handled titanium precursors under mild reaction conditions. Preliminary testing reveals that these materials have high affinity for certain radionuclides of environmental concern. Significant amounts of radioactive waste have built up over the last half century as the result of nuclear weapons production and the accumulation of spent nuclear fuel. Ultimately, after processing, this waste is targeted to be buried in a deep geological repository. One plan is to include ''getter materials'' in with this waste in order to sequester any radionuclides that might leak from the wasteforms. Of particular interest in this regard are the long-lived actinide species (e.g. Pu, Am, Np, etc.) and the anions (e.g. pertechnetate, iodide, etc.). These getter materials must be able to survive long-term exposure to elevated temperatures (>150 C) and moderately high radiation fluxes. Due to their frailty towards radiolytic degradation, organic components cannot be used for either structure or function in the final getter material.},
doi = {10.1016/j.inoche.2005.11.014},
journal = {Inorganic Chemistry Communications, 9(3):293-295},
number = ,
volume = ,
place = {United States},
year = {Wed Mar 01 00:00:00 EST 2006},
month = {Wed Mar 01 00:00:00 EST 2006}
}
  • Several mesoporous titanium phosphate phases, with varying pore sizes, were prepared using non-ionic surfactants and easily handled titanium precursors under mild reaction conditions. Preliminary testing reveals that these materials have high affinity for certain radionuclides of environmental concern.
  • Four scandium phosphate-based structures have been prepared hydrothermally in the presence of the primary diamines ethylenediamine and diaminobutane and the primary amine cyclohexylamine and characterised by single crystal and powder X-ray diffraction, {sup 31}P and {sup 45}Sc solid-state MAS NMR and chemical analysis. Charge balancing protons in the structures are located using bond valence sum calculations and postulated hydrogen bonding networks. Compound 1, [(H{sub 3}NC{sub 2}H{sub 4}NH{sub 3}){sub 3}][Sc{sub 3}(OH){sub 2}(PO{sub 4}){sub 2}(HPO{sub 4}){sub 3}(H{sub 2}PO{sub 4})], P1-bar , a=5.4334(6), b=8.5731(9), c=16.3022(18)A, {alpha}=79.732(4), {beta}=83.544(4), {gamma}=80.891(5){sup o}, Z=2, is built up of scandium phosphate ribbons, based on trimers of ScO{sub 6}more » octahedra linked by OH groups. These trimers are joined through phosphate groups bound through three oxygens, and are decorated by phosphate groups linked by a single oxygen atom. The ribbons are arranged parallel to the a-axis and linked one to another by fully protonated ethylenediammonium ions. Compounds 2, [(H{sub 3}NC{sub 4}H{sub 8}NH{sub 3}){sub 3}][(Sc(OH{sub 2})){sub 6}Sc{sub 2}(HPO{sub 4}){sub 12}(PO{sub 4}){sub 2}], P3-bar , a=13.8724(3), c=9.4351(11)A, Z=1, and 3, [(H{sub 3}NC{sub 4}H{sub 8}NH{sub 3}){sub 2}(H{sub 3}O)][Sc{sub 5}F{sub 4}(HPO{sub 4}){sub 8}], C2/m, a=12.8538(4), b=14.9106(4), c=10.1906(3)A, {beta}=101.17(9){sup o}, Z=2, were prepared using diaminobutane as the organic template in the absence and presence, respectively, of fluoride ions in the gel. Compound 2 has a pillared layered structure, in which ScO{sub 6} octahedra are linked by three vertices of hydrogenphosphate groups into sheets and the sheets pillared by ScO{sub 6} octahedra to give a three-dimensionally connected framework isostructural with a previously reported iron(III) hydrogenphosphate. The protonated diaminobutane molecules occupy cavities between the layers. Compound 3 has a layered structure in which isolated ScO{sub 6} octahedra and tetrameric arrangements of ScO{sub 4}F{sub 2} octahedra, the latter linked in squares through fluoride ions, are connected by phosphate tetrahedra that share two or three oxygens with scandium atoms. In this structure, the protonated diaminobutane molecules connect the layers, the -NH{sub 3}{sup +} groups fitting into recesses in the layers. Compound 4, [(C{sub 6}H{sub 11}NH{sub 3})][ScF(HPO{sub 4})(H{sub 2}PO{sub 4})], Pbca, a=7.650(3), b=12.867(5), c=26.339(11)A, Z=8, the first scandium phosphate to be prepared with a monoamine, is also a layered solid. In this case, the layers contain single chains of ScO{sub 4}F{sub 2} octahedra which share fluoride ions in trans positions. Phosphate tetrahedra bridge across scandiums via two of their four oxygens, both within the same chain and also to neighbouring chains to make up the layer. The protonated amine groups of the cyclohexylamine molecules achieve close contact with phosphates of the layer, while the cyclohexyl moieties, which are in the chair configuration, project into the interlayer space.« less
  • Templated mesoporous carbons designed around the pyridine functionality have been made using the cyclotrimerization of a variety of diethynylpyridines. The substitution pattern of the ethynyl moieties about the pyridine ring system was found to have a significant impact on the structure and properties of the final product. A model is proposed that focuses on the self-assembly of the diethynylpyridine monomer on the silica surface, and the order and orientation of the ethynyl moieties within this monolayer.
  • Monodisperse rhodium (Rh) and platinum (Pt) nanoparticles as small as {approx}1 nm were synthesized within a fourth generation polyaminoamide (PAMAM) dendrimer, a hyperbranched polymer, in aqueous solution and immobilized by depositing onto a high-surface-area SBA-15 mesoporous support. X-ray photoelectron spectroscopy indicated that the as-synthesized Rh and Pt nanoparticles were mostly oxidized. Catalytic activity of the SBA-15 supported Rh and Pt nanoparticles was studied with ethylene hydrogenation at 273 and 293 K in 10 torr of ethylene and 100 torr of H{sub 2} after reduction (76 torr of H{sub 2} mixed with 690 torr of He) at different temperatures. Catalysts weremore » active without removing the dendrimer capping but reached their highest activity after hydrogen reduction at a moderate temperature (423 K). When treated at a higher temperature (473, 573, and 673 K) in hydrogen, catalytic activity decreased. By using the same treatment that led to maximum ethylene hydrogenation activity, catalytic activity was also evaluated for pyrrole hydrogenation.« less