Arsenite, As(III), remains a problematic water contaminate and is more difficult to remove than
arsenate, As(V). This proposal outlines five contributions towards the eventual removal of arsenite
from groundwater (and possibly surface water) in Kentucky: 1) a new dithiol compound (with the
simplified name, AB9) that forms strong As-S covalent bonds to As(III), 2) attachment to silica
derivatized with terminal amine groups through pendant carboxylate groups on AB9 3) attachment
of AB9 to the silica surface of a magnetic nanoparticle (MNP) to create a new composite material,
AB9-SiO2-Fe3O4, 4) covalent capture of arsenite from water to form, As(III)-AB9-SiO2-Fe3O4
(simplified to As(III)-AB9@MNP, and 5) magnetic separation of As(III)-AB9@MNP, from water.
The arsenite-containing composite material is shown in the figure below left with the figure below
right showing AB9@MNP (without As(III)) as a dark suspension in water and the immediate
attraction of this material to an external magnet.
This project will entail the synthesis, characterization, and larger-scale preparation of
AB9@MNP generally following the procedures developed in a previously-funded KWRRI project
with former graduate student Dr. John Walrod, now employed by the Department of Energy
(DOE) at Sandia National Laboratories. The current proposal, with fourth-year graduate student
Shashika Bandara, who wrote the first draft and first revision of this proposal, will determine the
effectiveness of arsenite removal with AB9@MNP under laboratory conditions and in the presence
of potential competing ions commonly found in drinking water such as chloride, phosphate,
silicate, and bicarbonate. The ultimate goal of this project is to demonstrate arsenite removal from
water samples obtained from sources in Kentucky. The outcomes from this research will be
relevant to the removal of other elemental aqueous contaminants, particularly divalent heavy
metals such as Cd, Hg, and possibly other metals like Co, Ni, and Mn.