Biochar has been widely used as a sorbent for pollution control. More recent studies have demonstrated that biochar can serve as an electron donor or acceptor through reversible transformation of redox-active functional groups. This feature is termed electron storage capacity (ESC). Insensitive munitions compounds (IMC’s), such as 2,4-dinitroanisole (DNAN) and 3-nitro-1,2,4-triazol-5-one (NTO), have been used by the DOD to replace legacy explosives to prevent unexpected detonations. IMC’s have the potential to be released to groundwater and soil due to military training and other uses. The purpose of this study was to evaluate the effectiveness of biochar to remove DNAN and NTO through sorption and reduction. Reactors were prepared inside an anoxic glovebox using dithionite-reduced biochar as an electron donor for IMC’s reduction, and air-oxidized biochar as a nonreactive control. Both received an initial DNAN and NTO concentration of 400 µM and 110 µM, respectively, in artificial stormwater at pH 6. Results showed that sorption was the predominant mechanism for DNAN removal (56%), and an additional 13% was transformed by reduced biochar. DNAN transformation was supported not only by additional removal beyond sorption, but also by detection of DNAN reduction products including 2-amino-4-nitroanisole and 4-amino-2-nitroanisole in the presence of reduced biochar. For NTO the mass removal due to sorption was significantly lower in comparison to DNAN (28%) considering the high water solubility of NTO and the lower sorption affinity. In contrast, in the presence of reduced biochar, NTO was removed continuously from solution (81% removal) and ATO was produced concomitantly, which indicates that NTO was chemically reduced by the ESC of reduced biochar. Results suggest that biochar’s sorption and electron storage capacities may be useful for remediating munitions polluted sites.

Sorption and reduction of insensitive munitions compounds by wood biochar

ACS Fall 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.