Sorption of 2,4,6-Trinitrotoluene to Natural Soils Before and After Hydrogen Peroxide Application

Abstract

Laboratory batch sorption experiments were conducted to investigate the impact of hydrogen peroxide (H₂O₂) pre-application on post-sorptive behavior of 2,4,6-trinitrotoluene (TNT) in different natural soils (average soil, high Fe soil, and high pH soil). After H₂O₂ application, the values of Freundlich coefficient K_f were increased by ∼ 160% for the average and high pH soils and by ∼ 120% for the high Fe soil, showing that the soils became more favorable for TNT sorption after H₂O₂ application. Nonlinearity in terms of the Freundlich exponent n was increased by ∼ 40% for the average and high pH soils and by ∼ 30% for the high Fe soil, showing greater sorption affinity of TNT for the oxidized soils at lower TNT concentrations and also implying greater TNT availability for transport at high concentrations. The increase in sorption extent for the H₂O₂-oxidized soils was presumably attributed to the oxygen-induced enhancement in the sorption capacity of the soils and the more dominant contribution of clay minerals to sorption. Therefore, enhanced sorption following H₂O₂ application may inhibit the subsequent formation of a TNT plume after either source zone remediation or plume remediation using H₂O₂ such as Fenton oxidation.

Keywords:

• Hydrogen peroxide
• Isotherms
• Sorption
• 2,4,6-trinitrotoluene

ACKNOWLEDGMENTS

This research was performed while the author (S. Hwang) worked at the U.S. Army Corps of Engineers, Engineer Research and Development Center, Vicksburg, Mississippi, as a Postdoctoral Fellow of Johns Hopkins University, Baltimore, Maryland. The authors thank the Strategic Environmental Research and Development Program (SERDP) for the financial support.