Reduction of 2,4,6-Trinitrotoluene and Hexahydro-1,3,5-trinitro-1,3,5-triazine by Hydroxyl-Complexed Fe(II)

The reduction kinetics of two explosives, 2,4,6-trinitrotoluene (TNT) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), by Fe(II) was investigated in aqueous systems. A dilute ferrous iron solution effectively reduces these nitroaromatic (NAC) and nitramine (NAM) compounds between pH 6.75 and 9.2. Observed reaction rates are first order in monohydroxl and dihydroxyl ferrous iron [FeOH+ or Fe(OH)(2)(0)], and NAC/NAM concentrations. The reaction does not require the presence of a mediating surface. Intrinsic rate constants for TNT and RDX reduction by monohydroxyl ferrous iron are 2.00(+/- 0.17)E+09 and 2.04(+/- 0.24)E+06 M-2 s(-1), respectively. The reduction half-lives at neutral pH were on the order of minutes for TNT and hours for RDX, yielding rates faster than any known natural process or current bioremediation technique. The use of a mobile reductant, such as hydroxyl-complexed Fe(II) or other aqueous Fe(II) complexes, for NAC/NAMs could be an effective remediation technique at contaminated sites.