Polyoxometalate-enhanced oxidation of organic compounds by nanoparticulate zero-valent iron and ferrous ion

ENVR 142

Changha Lee, changhalee@berkeley.edu1, Christina R. Keenan, keenan@berkeley.edu2, and David L. Sedlak, sedlak@ce.berkeley.edu1. (1) Department of Civil & Environmental Engineering, University of California, Berkeley, CA 94720, (2) Department of Civil and Environmental Engineering, University of California at Berkeley, 207 O'Brien Hall, Berkeley, CA 94720
In the presence of oxygen, organic compounds can be oxidized by nanoparticulate zero-valent iron (nZVI) or dissolved Fe(II). However, the yield of oxidants is usually low (i.e., typically less than 5% of the Fe is converted into oxidants capable of transforming organic compounds). The addition of polyoxometalate (POM) greatly increases the yields of oxidants in these two systems. The mechanism of POM enhancement depends on solution pH. Under acidic conditions, POM mediated the electron transfer from nZVI or Fe(II) to oxygen to increase the production of hydrogen peroxide, which was subsequently converted to hydroxyl radical through a Fenton reaction. At neutral pH, POM appeared to form soluble iron-complexes. The formation of Fe-POM complexes prevented the precipitation of iron oxides on the nZVI surface. Significant oxidation of 2-propanol and benzoate at pH 7 suggests that POM coordination to iron may alter the mechanism of Fenton reaction converting the active oxidant from ferryl ion (Fe[IV]) to hydroxyl radical.
 

Advances in Abiotic Transformation Processes for Micropollutants in Drinking Water and for Sourcewater Protection
1:30 PM-5:10 PM, Tuesday, April 8, 2008 Morial Convention Center -- Rm. 237, Oral

Division of Environmental Chemistry

The 235th ACS National Meeting, New Orleans, LA, April 6-10, 2008