Post on 12-Jan-2016
description
SEM of Mg/Pd
Zero-Valent Bimetals• Zero-valent bimetals have been shown to
reduce chlorinated compounds• Zero-valent substrate provides thermodynamic
driving force:– Mg2+ + 2e- Mg0 Eo = -2.20 V
– Fe2+ + 2e‑ Fe0 Eo = -0.44 V
• Oxidation reaction provides source of molecular hydrogen:
– M0 + ROH H2 + M2+ (R=H, CH3)
• 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. GeigerChristian A. Clausen, Cherie L. Geiger, , Rebecca FidlerRebecca Fidler, , Michael E. Michael E. SigmanSigman
Department of Chemistry, University of Central FloridaDepartment 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
CH3
NO2
NO2
O2N
O
O
C
C
H3C CH3
O
O
H3C
H3CO
O
C CH3
CH3
N
N
N
NO2O2N
NO2
RDX (cyclo-1,3,5-trimethylene-2-4-6-trinitramine)
TATP crystal
TATP crystal 1 min 6 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=-kTATP[TATP]
• Acetone was observed as major byproduct
• Other byproducts being explored:
– CO2, ethane, O2, 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
FeFeNi
FePd
• Vial studies performed in water
• Pseudo-first order rate law:– rate=-kTNT[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:Metal Half-Life (min)
Fe NA
Mg/Pd 25
Fe/Pd 3
Fe/Ni 51
RDX
Kinetic data of RDX degradation with various bimetals/metals
• Vial studies performed in water
• Pseudo-first order rate law:
– rate=-kRDX[RDX]
• Common cyclic byproducts are not observed which suggests:
– ring cleavage– production of lower
molecular weight gases
• Half-life data for RDX degradation:
Metal Half-Life (min)
Fe NA
Mg/Pd 92
Fe/Pd 210
Fe/Ni 433
Mg/Pd Fe/Pd
Fe/Ni
Fe
TATP crystal
20 min
Fe
Fe/Pd
Fe/Ni
Mg/Pd
0
0.2
0.4
0.6
0.8
1
1.2
0.00 10.00 20.00 30.00 40.00
Time (min)
C/C
o TATP
Acetone