The manufacturing, usage, and disposal of legacy munitions constituents (MCs) and insensitive high explosives (IHEs) can pose risks to human and ecosystem health upon release to soils and waters. Electrochemical systems are useful in treating both groups of explosives in wastewater or other impacted waters by hosting redox reactions that can be controlled, operated, and optimized easily.  Electrochemically induced removal of RDX, NQ, DNAN, MNA, DNT, HMX, TNT, and NTO from the water was studied within an electrochemical plug flow reactor containing stainless steel (SS) disks as a 41.4-mm long cathode and downstream Ti/MMO anode.  The cathode material was first evaluated by varying different SS and nickel wire meshes. SS grade 316 with mesh size 80 showed the greatest removal extent and the shortest time to steady-state operation for RDX, NQ, and DNAN as test compounds.  A mathematical model was then developed for the description of kinetic performance on the removal of all eight explosives under plug flow within the cathode considering reduction by electron transfer at cathode surfaces and alkaline hydrolysis caused by cathodic consumption of H<sup>+</sup>. Reduction reaction kinetics were adequately described by the Butler-Volmer kinetic model.  A kinetic model for alkaline hydrolysis was determined in separate batch reactors for RDX, NQ, DNAN, HMX, and TNT and applied to plug flow pH conditions (11). For MNA and NTO, alkaline hydrolysis was not observed at any pH, and for DNT and HMX, alkaline hydrolysis is significant only at pH 14. Intrinsic reaction rate coefficients for cathodic reduction were derived for all eight explosives, and the order of reactivity on SS316 cathodes was found to be TNT&gt;DNAN&gt;NQ&gt;NTO&gt;DNT&gt;HMX&gt;RDX&gt;MNA. Experimentally-derived coefficients can be used as design parameters for the scaled-up treatment of explosives-laden wastewaters using SS cathodes.

Degradation of dissolved explosives in an electrochemical flow-through reactor: Cathode optimization and reaction kinetics

ACS Spring 2022

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