Hydroxyl radical, sulfate radical and nitrate radical reactivity towards crown ethers in aqueous solutions

Wan, L. K.*; Peng, J.*; Lin, M.; Muroya, Yusa*; Katsumura, Yosuke*; Fu, H. Y.*

Rate constants of common crown ethers ((CHO), n=4, 5, 6) and their model compound, 1,4-dioxane(6C2) with some important oxidative radicals, OH, SO, and NO were determined in various aqueous solutions using pulse radiolysis and laser photolysis techniques. The rate constants for 6C2 and crown ethers with OH and SO increase with the number of H-atom in the ethers, indicating that H-abstraction is dominant reaction between crown ethers and these two radicals. The presence of cations in solution has negligible effect on the rate constants for OH and SO. However, for NO, the rate constants is not in proportional to H-atom number in crown ethers, and the 12-crown-4 is most reactive compared with the others. For the studied crown ethers, the rate constants of these oxidative radicals have the order: OH SO NO. This is the first report on the kinetic behavior of crown ethers with NO, and it would be helpful for the understanding of stability of crown ethers in the nuclear fuel reprocessing.