Effect of Treatment pH on the End Products of the Alkaline Hydrolysis of TNT and RDX

Abstract

The development of effective treatment options for munitions contaminants is essential for Department of Defense live fire range management and sustainability. The energetic compounds 2,4,6-trinitotoluene (TNT) and hexahydro-13,5-trinitro-1,3,5-triazine (RDX) have been identified in range soil. Alkaline hydrolysis, initiated through treatment with lime, has been shown to effectively destroy these compounds in solution and in well-mixed soil. This study was conducted to evaluate the effect of treatment pH on the end products of the alkaline hydrolysis of TNT and RDX. Titrations were performed at pH 10.5, 11.5 and 12.5 using unlabeled and universally labeled-14C-TNT or RDX. At the completion of the titration, reverse-phase high performance liquid chromatography established that there was no TNT or RDX present in the solutions except for the untreated control. TNT degraded rapidly at pH 12.5 and 11.5. At pH 10.5, the degradation was slow enough to observe many intermediate products, only some of which were identifiable under standard Method 8330 methods. RDX also degraded rapidly at pH 12.5 and 11.5. At pH 10.5, the reaction appeared to proceed by the established pathway, but at a much slower rate. Using gel permeation chromatography, we determined that the end products from the TNT and RDX alkaline hydrolysis were polar, small molecular weight compounds. Hydrolysis byproducts, including nitrate and formate, were determined using ion chromatography.