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Nature and reactivity of layered double hydroxides formed by coprecipitating Mg, Al and As(V): Effect of arsenic concentration, pH, and aging

Sommella, A. and Caporale, A.G. and Denecke, M.A. and Mangold, S. and Pigna, M. and Santoro, A. and Terzano, R. and Violante, A. (2015) Nature and reactivity of layered double hydroxides formed by coprecipitating Mg, Al and As(V): Effect of arsenic concentration, pH, and aging. Journal of Hazardous Materials, 300. pp. 504-512. DOI: 10.1016/j.jhazmat.2015.07.046

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Abstract

Arsenic (As) co-precipitation is one of the major processes controlling As solubility in soils and waters. When As is co-precipitated with Al and Mg, the possible formation of layered double hydroxides (LDHs) and other nanocomposites can stabilize As in their structures thus making this toxic element less available. We investigated the nature and reactivity of Mg�Al�arsenate [As(V)] co-precipitated LDHs formed in solution affected by As concentration, pH, and aging. At the beginning of the co-precipitation process, poorly crystalline LDH and non-crystalline Al(Mg)-oxides form. Prolonged aging of the samples promotes crystallization of LDHs, evidenced by an increase in As K XANES intensities and XRD peak intensities. During aging Al- and/or Mg-oxides are likely transformed by dissolution/re-precipitation processes into more crystalline but still defective LDHs. Surface area, chemical composition, reactivity of the precipitates, and anion exchange properties of As(V) in the co-precipitates are influenced by pH, aging, and As concentration. This study demonstrates that (i) As(V) retards or inhibits the formation and transformation of LDHs and (ii) more As(V) is removed from solution if co-precipitated with Mg and Al than by sorption onto well crystallized LDHs.

Item Type: Article
Subjects: Research Publications
Departments: College of Physical and Applied Sciences > School of Chemistry
Date Deposited: 19 Jan 2016 03:20
Last Modified: 19 Jan 2016 03:20
ISSN: 0304-3894
URI: http://e.bangor.ac.uk/id/eprint/6090
Identification Number: DOI: 10.1016/j.jhazmat.2015.07.046
Publisher: Elsevier
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