Environmentally Persistent Free Radicals (EPFRs). 3. Free versus Bound Hydroxyl Radicals in EPFR Aqueous Solutions

Authors

Lavrent Khachatryan, Department of Chemistry, Louisiana State University, Baton RougeFollow
Cheri A. McFerrin, Department of Natural Sciences and Mathematics, Dominican University of CaliforniaFollow
Randall W. Hall, Department of Natural Sciences and Mathematics, Dominican University of CaliforniaFollow
Barry Dellinger, Department of Chemistry, Louisiana State University, Baton Rouge

Document Type

Article

Source

Environmental Science & Technology

ISSN

0013-936X

Volume

48

Issue

16

First Page

9220

Last Page

9226

Publication Date

6-18-2014

Department

Natural Sciences and Mathematics

Abstract

Additional experimental evidence is presented for in vitro generation of hydroxyl radicals because of redox cycling of environmentally persistent free radicals (EPFRs) produced after adsorption of 2-monochlorophenol at 230 °C (2-MCP-230) on copper oxide supported by silica, 5% Cu(II)O/silica (3.9% Cu). A chemical spin trapping agent, 5,5-dimethyl-1-pyrroline-N-oxide (DMPO), in conjunction with electron paramagnetic resonance (EPR) spectroscopy was employed. Experiments in spiked O¹⁷ water have shown that ∼15% of hydroxyl radicals formed as a result of redox cycling. This amount of hydroxyl radicals arises from an exogenous Fenton reaction and may stay either partially trapped on the surface of particulate matter (physisorbed or chemisorbed) or transferred into solution as free OH. Computational work confirms the highly stable nature of the DMPO–OH adduct, as an intermediate produced by interaction of DMPO with physisorbed/chemisorbed OH (at the interface of solid catalyst/solution). All reaction pathways have been supported by ab initio calculations.

Rights

Copyright © 2014 American Chemical Society. Terms of use.

PubMed ID

25036238