title: Free radical chemistry of disinfection byproducts. 2. Rate constants and degradation mechanisms of trichloronitromethane (chloropicrin).
abstract: Absolute rate constants for the free-radical-induced degradation of trichloronitromethane (TCNM, chloropicrin) were determined using electron pulse radiolysis and transient absorption spectroscopy. Rate constants for hydroxyl radical, *OH, and hydrated electron, e(aq)-, reactions were (4.97 +/- 0.28) x 10(7) M(-1) s(-1) and (2.13 +/- 0.03) x 10(10) M(-1) s(-1), respectively. It appears that the *OH adds to the nitro-group, while the e(aq)- reacts via dissociative electron attachment to give two carbon centered radicals. The mechanisms of these free radical reactions with TCNM were investigated, using 60Co gamma irradiation at various absorbed doses, measuring the disappearance of TCNM and the appearance of the product nitrate and chloride ions. The rate constants and mechanistic data were combined in a kinetic computer model that was used to describe the major free radical pathways for the destruction of TCNM in solution. These data are applicable to other advanced oxidation/reduction processes.
authors.affiliation: Civil and Environmental Engineering Department, Old Dominion University, Kaufman Hall, Norfolk, Virginia 23529, USA.
authors.forename: S Kirkham
authors.initials: SK
authors.lastname: Cole
authors.forename: William J
authors.initials: WJ
authors.lastname: Cooper
authors.forename: Robert V
authors.initials: RV
authors.lastname: Fox
authors.forename: Piero R
authors.initials: PR
authors.lastname: Gardinali
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Mezyk
authors.forename: Bruce J
authors.initials: BJ
authors.lastname: Mincher
authors.forename: Kevin E
authors.initials: KE
authors.lastname: O'Shea
mesh_terms: D002712:Chlorides / Q000032:analysis / Q000737:chemistry; D003037:Cobalt Radioisotopes; D004203:Disinfection; D004307:Dose-Response Relationship, Radiation; D005609:Free Radicals / Q000737:chemistry*; D005720:Gamma Rays; D006843:Hydrocarbons, Chlorinated / Q000737:chemistry*; D007477:Ions; D007700:Kinetics; D008956:Models, Chemical; D009566:Nitrates / Q000032:analysis / Q000737:chemistry; D014865:Waste Disposal, Fluid; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D002712:Chlorides; D003037:Cobalt Radioisotopes; D005609:Free Radicals; D006843:Hydrocarbons, Chlorinated; D007477:Ions; D009566:Nitrates; D014874:Water Pollutants, Chemical; C100187:chloropicrin