Electrolytic Transformation of Hexahydro-1,3,5-Trinitro-1,3,5-Triazine (RDX) and 2,4,6-Trintrotoluene (TNT) in Aqueous Solutions
Abstract
Electrolytic reactive barriers (e-barriers) consist of closely spaced permeable electrodes installed across a groundwater contaminant plume in a permeable reactive barrier format. Application of sufficient potential to the electrodes results in sequential oxidation and reduction of the target contaminant. The objective of this study was to quantify the mass distribution of compounds produced during sequential electrolytic oxidation and reduction of ordinance related compounds (ORCs) in a laboratory analog to an e-barrier. In this study, a series of column tests were conducted using RDX (hexahydro- 1,3,5-trinitro-1,3,5-triazine) and TNT (2,4,6-trinitrotoluene) as representative ORCs. The experimental setup consisted of a Plexiglass column packed with quart-feldspar sand to simulate aquifer conditions. A single set of porous electrodes consisting of expanded titanium-mixed metal oxide mesh was placed at the midpoint of the soil column as a one-dimensional analog to an e-barrier. Constant current of 20 mA (variable voltage) was applied to the electrode set. Initial studies involved quantification of reaction products using unlabeled RDX and TNT. Approximately 70 percent of the influent concentration was transformed, in one pass, through sequential oxidation-reduction for both contaminants. Following the unlabeled studies, 14C labeled RDX and TNT were introduced to determine the mass balance. An activity balance of up to 96% was achieved for both 14C-RDX and 14C-TNT. For both contaminants, approximately 21% of the influent activity was mineralized to 14CO2. The proportion of the initial activity in the dissolved faction was different for the two contaminants. Approximately 30% of the initial 14C-RDX was recovered as unreacted in the dissolved phase. The balance of the 14C-RDX was recovered as non-volatile, non-nitroso transformation products. None of the 14C-RDX was sorbed to the column sand packing. For 14C-TNT approximately 51% of the initial activity was recovered.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 2005
- Accession Number
- ADA444821
Entities
People
- Altaf H. Wani
- Brenda R. O'neal
- David B. Gent
- David M Gilbert
- Jeffrey L. Davis
Organizations
- Engineer Research and Development Center