Destruction of Pollutants by Active Oxygen

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Destruction of Pollutants by Active Oxygen
Presentation to Mark Durcan, Micron January 8,
2003
Frank Cheng Department of Chemistry University of
Idaho Moscow, Idaho 83844-2343 208-885-6387 ifchen
g_at_uidaho.edu
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Priority Pollutants
PCB
TCE
DDT
Perc
PCP
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Military Focus
Explosives/Propellants
Nerve Agents
Nitrated Organics
Organophosphorous Cpds.
TNT
VX
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Present Methods of Destruction
- Incineration gt 1200 0C - CxHyClz O2 CO2
H2O HCl (unbalanced)
Problems - Costs (incineration and
transport) - PCDFs PCDs - NIMBY - Nerve
agents, Gulf War Syndrome?
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Ideal Characteristics for Organic Pollutant
Destruction

• Inexpensive
• Abundant reagents
• Mild Reaction Conditions, Room Temperature
• and Atmospheric Pressure
• Simple Reactor Design
• Field Portable, on site or in situ destruction
• Robust with respect to the presence of water air

-Acceptable to NIMBY
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Active Oxygen
-Oxidations by O2 from air -CxHyClz O2 CO2
H2O HCl (unbalanced) ?Glt0
-Room temperature oxidations by air are
kinetically slow -enzymatic or enzyme-mimics
-Partially reduced O2 (active oxygen)
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Partially Reduced Oxygen
E0reduction
O2 e- O2.- -0.45 volts
O2 2H 2e- H2O2 0.30 volts
O2 4H 4e- H2O 1.23 volts
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Fenton Reaction
-Reduction of HO-OH H2O2 FeII FeIII HO-
HO. HO. e- HO- Eo 1.8 volts
-HO. reacts with organics with diffusion limited
kinetics
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Active Oxygen
O2 reducing agents -Zero-valent iron,
Fe(0) Inexpensive Spent agent, Fe2/Fe3
environmentally benign. Chelated forms, capable
oxidizing agents
Fe(0) O2 2H gt Fe2 H2O2
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Active Oxygen
-Fe2 chelation agent - EDTA
FeIIETDA HOOH gt FeIIIEDTA HO- HO.

• Inexpensive
• Efficient Binding Agent for Fe2/3
• FeIIEDTA highly effective Fenton Reaction reagent

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Proposed Overall Scheme
Fe(0) O2(aq) 2H(aq) ? Fe2(aq)
HOOH(aq) Fe2(aq) EDTA ? FeIIEDTA FeIIEDTA
HOOH ? FeIIIEDTA HO- HO Regeneration 2FeII
IEDTA Fe(0) ? Fe2(aq) 2FeIIEDTA
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Pollutant Destruction
H2O2
O2 2H

EDTA
Iron particles 0.1-1 mm
FeIIEDTA
Fe2
FeIIIEDTA HO- HO.
Aqueous pollutant
CO2 H2O
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Aero-Fenton Reaction

• 0.5 g of 40-70 mesh Fe(0)
• 10 mL of solution
• 0.32 mM EDTA
• 140 ppm 4-chlorophenol
• 4 hour reaction time
• GC and LC-MS

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Destruction of other pollutants
100 removal (GC-FID)
VX surrogate - malathion
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Technical Summary
Ability to degrade organic pollutants Under
room temperature, atmospheric pressure
conditions Inexpensive Reagents Iron
particles, water, air EDTA Unspecialized
reactors Process is easily transportable, iron
particles EDTA Strong possibility of scale-up
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Scientific Summary
First example of abiotic RTP activation of O2
able to oxidize destructively organics Control
experiments indicate process is dependent on
Fe(0), EDTA, air, and water
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Future Investigations
Mechanisms Understanding the process Kinetics
Speeding up the process Survey of Pollutants
oxidizable and nonoxidizable functional
groups Application Scale-up