COMPARATIVE ASSESSMENT OF NUCLEOPHILIC ALKALINE HYDROLYSIS FOR REMEDIATION OF HIGH EXPLOSIVES-CONTAMINATED GROUNDWATER

Hwang, Sangchul; Min, Kyung-Sok; Davis, Jeffrey L.

doi:2004.9.1.13

Environmental Engineering Research 2004;9(1): 13-22. DOI: https://doi.org/10.4491/eer.2004.9.1.013

COMPARATIVE ASSESSMENT OF NUCLEOPHILIC ALKALINE HYDROLYSIS FOR REMEDIATION OF HIGH EXPLOSIVES-CONTAMINATED GROUNDWATER

Sangchul Hwang¹, Kyung-Sok Min²^†, and Jeffrey L. Davis³

¹Dept of Geography & Environmental Engineering, Johns Hopkins University, Baltimore, MD 21218, USA
²Dept of Environmental Engineering, Kyungpook National University, Taegu 702-701, Korea
³EL, US Army Engineer Research and Development Center, Vicksburg, MS 39180, USA

Corresponding Author: Kyung-Sok Min ,Tel: +82-53-950-6581, Fax: +82-53-950-6579, Email: ksmin@knu.ac.kr

Received: August 15, 2003; Accepted: January 15, 2004.

ABSTRACT

This study was conducted to assess the feasibility of nucleophilic alkaline hydrolysis using a continuous flow stirred-tank reactor as an ex-situ remediation technology for groundwater contaminated with high explosives 2,4,6-trinitrotoluene (TNT) and hexahydro-l,3,5-trinitro-l,3,5-triazine (RDX). The reactivity of TNT and RDX had a strong dependence on the reaction pH (11.0 to 11.9) and hydraulic retention time (HRT, 0.5 to 2 days). For the same influent concentration of 1 mg/L, the reaction pH of 11.9 and 2-day HRT, the best nucleophilic alkaline hydrolysis was achieved at 99 and 73% reduction for RDX and TNT, respectively, with the respective half-lives of 0.02 and 0.5 days. Greater and faster removal with less alkaline demand for RDX hydrolysis than TNT hydrolysis was attributed to the structural characteristics and simpler degradation pathway of RDX. Formate and oxalate were produced as the major hydrolysates in alkaline hydrolysis of RDX and TNT, respectively, indicating that alkaline hydrolysis of high explosives occurred through ring cleavage. Therefore, it is concluded that nucleophilic alkaline hydrolysis can be a promising ex-situ treatment technology for remediation of high explosives-, especially RDX-, contaminated groundwater.