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Destruction of Pollutants by Active Oxygen

This presentation discusses the use of active oxygen for the destruction of various pollutants. Topics covered include the use of partially reduced oxygen, the Fenton reaction, zero-valent iron as an oxidizing agent, and the proposed overall scheme for pollutant destruction. The presentation also discusses the Aero-Fenton reaction and the ability to degrade other pollutants under room temperature and atmospheric pressure conditions. Future investigations and applications are also highlighted.

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Destruction of Pollutants by Active Oxygen

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  1. 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 ifcheng@uidaho.edu Presentation to Mark Durcan, Micron

  2. Priority Pollutants PCB TCE DDT Perc PCP Presentation to Mark Durcan, Micron

  3. Military Focus Explosives/Propellants Nerve Agents Nitrated Organics Organophosphorous Cpds. TNT VX Presentation to Mark Durcan, Micron

  4. Present Methods of Destruction - Incineration > 1200 0C - CxHyClz + O2 = CO2 + H2O + HCl (unbalanced) Problems: - Costs (incineration and transport) - PCDFs PCDs - NIMBY - Nerve agents, Gulf War Syndrome? Presentation to Mark Durcan, Micron

  5. 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 Presentation to Mark Durcan, Micron

  6. Active Oxygen -Oxidations by O2 from air -CxHyClz + O2 = CO2 + H2O + HCl (unbalanced) G<0 -Room temperature oxidations by air are kinetically slow -enzymatic or enzyme-mimics -Partially reduced O2 (active oxygen) Presentation to Mark Durcan, Micron

  7. Partially Reduced Oxygen Presentation to Mark Durcan, Micron

  8. 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 Presentation to Mark Durcan, Micron

  9. 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+ => Fe2+ + H2O2 Presentation to Mark Durcan, Micron

  10. Active Oxygen -Fe2+ chelation agent - EDTA FeIIETDA + HOOH => FeIIIEDTA + HO- + HO. • Inexpensive • Efficient Binding Agent for Fe2+/3+ • FeIIEDTA highly effective Fenton Reaction reagent Presentation to Mark Durcan, Micron

  11. Proposed Overall Scheme Fe(0) + O2(aq) + 2H+(aq)  Fe2+(aq) + HOOH(aq) Fe2+(aq) + EDTA  FeIIEDTA FeIIEDTA + HOOH  FeIIIEDTA + HO- + HO· Regeneration: 2FeIIIEDTA + Fe(0)  Fe2+(aq) + 2FeIIEDTA Presentation to Mark Durcan, Micron

  12. Pollutant Destruction H2O2 O2 + 2H+ + EDTA Iron particles 0.1-1 mm FeIIEDTA Fe2+ FeIIIEDTA + HO- + HO. Aqueous pollutant CO2 + H2O Presentation to Mark Durcan, Micron

  13. 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 Presentation to Mark Durcan, Micron

  14. Destruction of other pollutants 100% removal (GC-FID) VX surrogate - malathion Presentation to Mark Durcan, Micron

  15. 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 Presentation to Mark Durcan, Micron

  16. 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 Presentation to Mark Durcan, Micron

  17. Future Investigations Mechanisms – Understanding the process Kinetics – Speeding up the process Survey of Pollutants – oxidizable and nonoxidizable functional groups Application & Scale-up Presentation to Mark Durcan, Micron

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