Kinetics and mechanism of wet-air oxidation of nuclear-fuel-chelating compounds

In this paper, we examine the wet-air oxidation (WAO) of four nuclear-fuel- chelating compounds [diethylenetriaminepentaacetic acid (DTPA), ethylenedia minetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), and thenoyltriflu oroacetone (TTA)]. The study focuses on the kinetics and mechanism of the d egradation process. Identification of the free-radical intermediates was pe rformed via the spin-trapping technique. The reaction of each compound stud ied was found to occur in two steps, with a partial order of one with respe ct to TOC for both steps. Among the compounds studied,TTA shows the most di fficulty when degrading. Hydroxyl, hydroxycarbonyl, and nitrogenous radical s are some of those formed during the degradation process. Schematic reacti on pathways, which can explain the formation of some mineral byproducts, ar e proposed an the basis of these radicals.