AVS 51st International Symposium
    Applied Surface Science Monday Sessions
       Session AS-MoP

Paper AS-MoP20
Importance of Binding Energy Reference Materials for Understanding the Chemistry of Oxidized-Iron Arsenic-Adsorbing Materials

Monday, November 15, 2004, 5:00 pm, Room Exhibit Hall B

Session: Poster Session
Presenter: M.H. Engelhard, Pacific Northwest National Laboratory
Authors: B.M. Sass, Battelle Columbus
M.H. Engelhard, Pacific Northwest National Laboratory
D.R. Baer, Pacific Northwest National Laboratory
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Arsenic as a contaminant in drinking water is a growing problem around the world. Consequently many research and commercial efforts are being made to develop low cost and effective means for producing acceptable quality drinking water. Iron oxide based sorbing minerals are now available commercially. However, the effectiveness, lifetime and ability to recycle these materials are not adequately understood. The extent of arsenic sorption and the chemical nature of the sorbed species are important to understanding the chemistry that take place on the surface and the long term effectiveness. We have used XPS to measure the arsenic coverage on the mineral surfaces and to examine arsenic chemical state. Because of the limited amount of arsenic oxidation state data in general, the variability of binding energies observed in the existing data, and the lack of data for arsenic sorbed onto oxidized iron phases, to interpret our data it was necessary to examine As(III) and As(V) oxides as well as ferric arsenite and ferric arsenate compounds. Based on these references the arsenic sorbed onto the commercial sorbers was found to be mostly As(V) in the conditions examined.