Sorption of Arsenic from Drinking Water to Mg(OH)2 Sorrel's Cements, and Zirconium Doped Materials Page: 3 of 26
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Printed November 2002
Sorption of Arsenic from Drinking Water to Mg(OH)2, Sorrel's Cements, and Zirconium
Robert C. Moore, Kathleen Holt, Hongting Zhao,
Fred Salas, Ahmed Hasan, and Dan Lucero
Environmental Decisions and Program Development
Sandia National Laboratories
PO Box 5800
Albuquerque, NM 87185-0779
It was discovered that MgO or Mg(OH)2 when it reacts with water is a very strong
sorbent for arsenic. Distribution constants, or Kd values, are as high as 1 x 106 IJmole. In this
work, Mg(OH)2 and other compounds have been investigated as sorbents for arsenic and other
contaminants. This work has resulted in several major accomplishments including: 1) design,
construction, and testing of a pressure sand filter to remove Mg(OH)2 after it has sorbed arsenic
from water, 2) stabilization of Mg(OH)2 as a Sorrel's cement against reaction with carbonate that
results in MgCO3 formation decreasing the efficiency of Mg(OH)2 to sorb arsenic, and 3) the
development of a new, very promising sorbent for arsenic based on zirconium. Zirconium is an
environmentally benign material found in many common products such as toothpaste. It is
currently used in water treatment and is very inexpensive. In this work, zirconium has been
bonded to activated carbon, zeolites, sand and montmorillonite. Because of its high charge in
ionic form (+6), zirconium is a strong sorbent for many anions including arsenic. In equilibrium
experiments arsenic concentrations in water were reduced from 200 ppb to less than I ppb in less
than 1 minute of contact time. Additionally, analytical methods for detecting arsenic in water
have also been investigated. Various analytical techniques including HPLC, AA and ICP-MS
are used for quantification of arsenic. Due to large matrix interferences HPLC and AA
techniques are not very selective and are time consuming. ICP-MS is highly efficient, requires a
low sample volume and has a high tolerance for interferences. All these techniques are costly
and require trained staff, and with the exception of ICP-MS, these methods cannot be used at low
ppb arsenic concentration without using a pre-concentration step. An alternative to these
traditional techniques is to use a colorimetric method based on leucocrystal violet dye interaction
with iodine. This method has been adapted in our facility for quantifying arsenic concentrations
down to 14 ppb.
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MOORE, ROBERT C.; ZHAO, HONGTING; SANCHEZ, CHARLES ANTHONY; HOLT, KATHLEEN C.; SALAS, FRED; HASAN, AHMED ALI MOHAMED et al. Sorption of Arsenic from Drinking Water to Mg(OH)2 Sorrel's Cements, and Zirconium Doped Materials, report, November 1, 2002; Albuquerque, New Mexico. (digital.library.unt.edu/ark:/67531/metadc737595/m1/3/?rotate=90: accessed September 21, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.