Kinetics of aminodinitrotoluene oxidations with ozone and hydroxyl radical

Aminodinitrotoluenes [2-amino-4,6-dinitrotoluene (2-ADNT) and 4-amino-2,6-d initrotoluene (4-ADNT)] are serious groundwater contaminants commonly found in soils and groundwaters near TNT production facilities. To evaluate the kinetics and pathways for their oxidation in peroxone (ozone and hydrogen p eroxide) oxidizing systems where both hydroxyl (HO) radical and ozone are i mportant oxidants, competition kinetics and modeling experiments were done. ADNTs react rapidly with both ozone and HO radical. From competition kinet ics with resorcinol as a reference, ozone rate constants of 1.45 x 10(5) an d 1.8 x 10(5) M-1 s(-1) were determined for 2- and 4-ADNT, respectively. HO radical rate constants, determined using p-nitroacetophenone (PNAP) as a r eference compound, are 1.6 x 10(9) and 1.9 x 10(9) M-1 s(-1) for 2- and 4-A DNT, respectively. Although rate constants for HO radical oxidations are 4 orders of magnitude larger than those for ozone, modeling shows that ozone is the dominant oxidant for ADNTs in peroxone mixtures, except at ADNTs con centrations below 1 mu M (200 ppb).