Dynamic and equilibrium studies of the RDX removal from soil using CMC-coated zerovalent iron nanoparticles
; Naja, Ghinwa
; Apiratikul, Ronbanchob
; Pavasant, Prasert
; Volesky, Bohumil
National Research Council Canada; NRC Biotechnology Research Institute
nanoiron; RDX-contaminated soil; dynamic study; flow-through short column
Rapid chemical degradation of toxic RDX explosive in soil can be accomplished using zerovalent nanoiron suspension stabilized in dilute carboxymethyl cellulose solution (CMC-ZVINs). The effect of operating conditions (redox-potential, Fe/RDX molar ratio) was studied on batchwise removal of RDX in contaminated soil. While anaerobic conditions resulted in 98% RDX removal in 3 h, only slightly over 60% RDX removal could be attained under aerobic conditions. The molar ratio did not have any influence on the intermediate and final RDX degradation products (methylenedinitramine, nitroso derivative, N₂, N₂O, NO₂−), however, their distribution changed. Dynamic studies were conducted using a flow-through short column packed with RDX-contaminated soil and fed with CMC-ZVINs. The column was operated at two interstitial velocities (2.2 and 1.6 cm min⁻¹), resulting in the 76.6% and 95% removal of the initial RDX soil contamination load (60 mg kg⁻¹), respectively. While the column operating conditions could be further optimized, 95% of the RDX initially present in the contaminated soil packed in the column was degraded when flushed with a CMC-ZVINs suspension in this work.