Photolytic and Radiolytic Oxidation of Humic Acid

Abstract

The reactions of Br2.-), Br., HO. and N3.- with Aldrich humic acid (AHA) were investigated. The Br ⁄ Br2.-) radicals were obtained in flash-photolysis experiments (lambda exc = 266 nm) performed with NaS2O8 solutions in the presence of bromide ions. HO.and N3.- radicals were generated by pulse radiolysis of N2Osaturated solutions. From the combination of a bilinear analysis and computer simulations of the absorbance traces, it was possible to obtain information on the rate constants for the reactions of Br2Æ), BrÆ, HOÆ and N3Æ with AHA and on the intermediate species involved in the mechanism. Evidence for the participation of phenoxyl radicals (kmax = 410 nm) is given.