1. SEM of Mg/Pd Zero-Valent Bimetals Zero-valent bimetals have been shown to reduce chlorinated compounds Zero-valent substrate provides thermodynamic driving force: –Mg 2+ + 2e -  Mg 0 E o = -2.20 V –Fe 2+ + 2e ‑  Fe 0 E o = -0.44 V Oxidation reaction provides source of molecular hydrogen: –M 0 + ROH  H 2 + M 2+ (R=H, CH 3 ) Mechanically alloyed zero-valent metals are combined with known hydrogenation/reduction catalysts: –Pd and Ni 20 min Emulsified Zero-Valent Metal (EZVM) Combination of emulsified liquid membranes (ELM) and zero-valent bimetal: –emulsion droplet provides protective reaction barrier Emulsion droplet: –organic membrane, water interior, surfactant, and active metal In-situ technology to remediate: –water and soil contamination –wet TATP contamination Summary and Future Directions Bimetals are shown to successfully degrade nitro explosives (TNT and RDX) and TATP EZVM and BTS are continued to be explored and optimized to clean-up both dangerous TATP contamination and environmentally hazardous nitro explosives contamination Further exploration includes: –reaction pathways –final byproducts Field application: –soil and groundwater nitro explosive contamination near industrial production sites –structures/scrap metal and ordnance due to incomplete detonation –clean-up of TATP residue in underground labs Objectives Degradation of TATP, TNT, and RDX using Mechanically Alloyed Bimetals Christian A. Clausen, Cherie L. Geiger, Rebecca Fidler, Michael E. Sigman Department of Chemistry, University of Central Florida Optimize the use of zero-valent metals (ZVM), emulsified zero- valent metal (EZVM) systems, and bimetal treatment systems (BTS) to degrade TATP, TNT, and RDX contamination Develop an in-situ method for degradation of common explosives TATP Triacetone Triperoxide Prepared from common materials: –acetone, hydrogen peroxide, and acid catalyst Sensitive to shock, friction, and heat High vapor pressure (7 Pa) Incidents involving TATP: –Richard Reid “The Shoe Bomber” used PETN with TATP (2001) –London bombings (2005) –Oklahoma University (2005) Kinetics Experiments TNT (2,4,6-Trinitrotoluene) Nitro Explosives Environmentally hazardous: –considered toxic and mutagenic Types of contamination: –soil and groundwater –metal scraps and ordnance RDX (cyclo-1,3,5-trimethylene- 2-4-6-trinitramine) TATP crystal 1 min6 min Micrograph of Emulsion Droplet TATP crystal absorbed into an emulsion Bimetal Treatment System (BTS) Provides an in situ technique for handling explosive contamination on structures and scrap metal Paste consisting of active bimetal, solvent and thickeners Can be applied directly to contaminated structures or scrap metal Application of BTS TATP A=Acetone A=TATP Vial studies performed in methanol/water solution Pseudo-first order rate law: –rate=-k TATP [TATP] Acetone was observed as major byproduct Other byproducts being explored: –CO 2, ethane, O 2, and methane Half-life for TATP degradation = 11.5 min Kinetic data of TATP degradation with MgPd and acetone byproduct production TNT Kinetic data of TNT degradation with various bimetals/metals MgPd Fe FeNi FePd Vial studies performed in water Pseudo-first order rate law: –rate=-k TNT [TNT] Byproducts observed: –2,4-dinitrotoluene (DNT) –2-amino-4,6-dinitrotoluene and 4-amino-2,6-dinitrotoluene (ADNT) Half-life data for TNT degradation: MetalHalf-Life (min) FeNA Mg/Pd25 Fe/Pd3 Fe/Ni51 RDX Kinetic data of RDX degradation with various bimetals/metals Vial studies performed in water Pseudo-first order rate law: –rate=-k RDX [RDX] Common cyclic byproducts are not observed which suggests: –ring cleavage –production of lower molecular weight gases Half-life data for RDX degradation: MetalHalf-Life (min) FeNA Mg/Pd92 Fe/Pd210 Fe/Ni433 Mg/Pd Fe/Pd Fe/Ni Fe TATP crystal 20 min Fe Fe/Pd Fe/Ni Mg/Pd