Hydroxyl radical rate constants: comparing UV/H₂O₂ and pulse radiolysis for environmental pollutants

The objective of this study was to measure hydroxyl radical reaction rates using both UV/H₂O₂ and pulse radiolysis techniques for 10 US EPA Contaminant Candidate List compounds (2,6- and 2,4-DNT, EPTC, prometon, linuron, diuron, RDX, molinate, nitrobenzene, and terbacil). The rate constants determined using these techniques were compared to each other and to values reported in the literature. Difference factors between k_OH obtained using UV/H₂O₂ and pulse radiolysis ranged from 1.1 to 4.7. It was shown that even small differences in hydroxyl radical rate constants values can result in fairly large differences (up to 50%) when trying to predict removals of pollutants in an advanced oxidation process.