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Title: Compositional and Structural Control on Anion Sorption Capability of Layered Double Hydroxides (LDHS)

Abstract

Layered double hydroxides (LDHs) have shown great promise as anion getters. In this paper, we demonstrate that the sorption capability of a LDH for a specific oxyanion can be greatly increased by appropriately manipulating material composition and structure. A large set of LDH materials have been synthesized with various combinations of metal cations, interlayer anions, and the molar ratios of divalent cation M(II) to trivalent cation M(III). The synthesized materials have then been tested systematically for their sorption capabilities for pertechnetate (TcO{sub 4}{sup -}). It is discovered that for a given interlayer anion (either CO{sub 3}{sup 2-} or NO{sub 3}{sup -}) the Ni-Al LDH with a Ni/Al ratio of 3:1 exhibits the highest sorption capability among all the materials tested. The distribution coefficient (K{sub d}) is determined to be as high as 307 mL/g for Ni{sub 6}Al{sub 2}(0H){sub 16}CO{sub 3}nH{sub 2}O and 1390 mL/g for Ni{sub 6}Al{sub 2}(OH){sub 16}NO{sub 3}nH{sub 2}O at a pH of 8. The sorption of TcO{sub 4}{sup -} on M(II)-M(III)-CO{sub 3} LDHs is dominated by the edge sites of LDH layers and strongly correlated with the basal spacing d{sub 003} of the materials, which increases with the decreasing radii of both divalent and trivalent cations. Themore » sorption reaches its maximum when the layer spacing is just large enough for a pertechnetate anion to fit into a cage space between two neighboring octahedra of metal hydroxides at the edge. Furthermore, the sorption is found to increase with the crystallinity of the materials. For a given combination of metal cations and an interlayer anion, a best crystalline LDH material is obtained generally with a M(II)/M(III) ratio of 3:1. Replacement of interlayer carbonate with readily exchangeable nitrate greatly increases the sorption capability of a LDH material for pertechnetate, due to the enhanced adsorption on edge sites and the possible contribution from interlayer anion exchanges. The work reported here will help to establish a general structure-property relationship for the related layered materials.« less

Authors:
;
Publication Date:
Research Org.:
Yucca Mountain Project, Las Vegas, Nevada
Sponsoring Org.:
USDOE
OSTI Identifier:
894051
Report Number(s):
NA
MOL.20060831.0129, DC# 47416; TRN: US0700051
DOE Contract Number:  
NA
Resource Type:
Journal Article
Country of Publication:
United States
Language:
English
Subject:
38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY; ANIONS; CARBONATES; GETTERS; HYDROXIDES; NITRATES; PERTECHNETATES; SORPTION; CHEMICAL COMPOSITION; MORPHOLOGY; ADSORBENTS; SORPTIVE PROPERTIES

Citation Formats

Y. Wang, and H. Gao. Compositional and Structural Control on Anion Sorption Capability of Layered Double Hydroxides (LDHS). United States: N. p., 2006. Web. doi:10.1016/j.jcis.2006.04.061.
Y. Wang, & H. Gao. Compositional and Structural Control on Anion Sorption Capability of Layered Double Hydroxides (LDHS). United States. doi:10.1016/j.jcis.2006.04.061.
Y. Wang, and H. Gao. Thu . "Compositional and Structural Control on Anion Sorption Capability of Layered Double Hydroxides (LDHS)". United States. doi:10.1016/j.jcis.2006.04.061. https://www.osti.gov/servlets/purl/894051.
@article{osti_894051,
title = {Compositional and Structural Control on Anion Sorption Capability of Layered Double Hydroxides (LDHS)},
author = {Y. Wang and H. Gao},
abstractNote = {Layered double hydroxides (LDHs) have shown great promise as anion getters. In this paper, we demonstrate that the sorption capability of a LDH for a specific oxyanion can be greatly increased by appropriately manipulating material composition and structure. A large set of LDH materials have been synthesized with various combinations of metal cations, interlayer anions, and the molar ratios of divalent cation M(II) to trivalent cation M(III). The synthesized materials have then been tested systematically for their sorption capabilities for pertechnetate (TcO{sub 4}{sup -}). It is discovered that for a given interlayer anion (either CO{sub 3}{sup 2-} or NO{sub 3}{sup -}) the Ni-Al LDH with a Ni/Al ratio of 3:1 exhibits the highest sorption capability among all the materials tested. The distribution coefficient (K{sub d}) is determined to be as high as 307 mL/g for Ni{sub 6}Al{sub 2}(0H){sub 16}CO{sub 3}nH{sub 2}O and 1390 mL/g for Ni{sub 6}Al{sub 2}(OH){sub 16}NO{sub 3}nH{sub 2}O at a pH of 8. The sorption of TcO{sub 4}{sup -} on M(II)-M(III)-CO{sub 3} LDHs is dominated by the edge sites of LDH layers and strongly correlated with the basal spacing d{sub 003} of the materials, which increases with the decreasing radii of both divalent and trivalent cations. The sorption reaches its maximum when the layer spacing is just large enough for a pertechnetate anion to fit into a cage space between two neighboring octahedra of metal hydroxides at the edge. Furthermore, the sorption is found to increase with the crystallinity of the materials. For a given combination of metal cations and an interlayer anion, a best crystalline LDH material is obtained generally with a M(II)/M(III) ratio of 3:1. Replacement of interlayer carbonate with readily exchangeable nitrate greatly increases the sorption capability of a LDH material for pertechnetate, due to the enhanced adsorption on edge sites and the possible contribution from interlayer anion exchanges. The work reported here will help to establish a general structure-property relationship for the related layered materials.},
doi = {10.1016/j.jcis.2006.04.061},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Thu Mar 16 00:00:00 EST 2006},
month = {Thu Mar 16 00:00:00 EST 2006}
}