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Seminar: Advanced Oxidation Processes

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April 8, 2011 @ 1:30 pm - 2:30 pm

Headshot of David Cwiertny.

Advanced Oxidation Processes with Carbon Nanotubes:
Surface-Promoted Formation of Hydroxyl Radical during Ozonation

Presented by:

David Cwiertny
Assistant Professor of Chemical and Environmental Engineering
University of California-Riverside, Bourns College of Engineering

Abstract: Paramount to water sustainability is water reclamation and reuse, with applications including ecosystem restoration, landscape irrigation, and aquifer recharge for indirect potable reuse. While conventional treatment is effective in alleviating most concerns traditionally associated with reuse, a new generation of organic micropollutants in wastewater effluent has increased scrutiny of water recycling. Many of these species, which includes hormones, pharmaceuticals, and endocrine-disrupting compounds, can persist or only be partly degraded during conventional wastewater treatment.

Advanced oxidation processes (AOPs), which utilize hydroxyl radicals (·OH) for treatment, are among the most promising technologies for removing persistent organic micropollutants from water and wastewater, and they are likely to be an integral component of future reuse programs. As an alternative to conventional AOPs (e.g., ozone/hydrogen peroxide or UV light/hydrogen peroxide), here we show that multi-walled carbon nanotubes (MWCNTs) can promote ·OH production from the decomposition of ozone. Experiments with para-chlorobenzoic acid as a ·OH probe reveal that MWCNT suspensions (~1 mg/L) increase hydroxyl radical formation during ozonation to concentrations that exceed those of conventional AOPs. Notably, formation of ·OH is promoted to the greatest extent on MWCNTs functionalized via oxidation with nitric acid. This enhanced reactivity results in part from the greater amount of reactive surface area available in more well-dispersed, functionalized MWCNT systems. However, evidence also suggests that the functional groups (e.g., carboxylic acid moieties) added to the MWCNT surface during oxidation represent new reactive sites for ozone decay and ·OH production. These results provide the first steps in the design, fabrication, and optimization of CNT-based strategies for chemical oxidation of organic micropollutants in water and wastewater.

Details

Date:
April 8, 2011
Time:
1:30 pm - 2:30 pm

Venue

127 SHL
Stanley Hydraulics Laboratory
Iowa City, IA 52242 United States
Phone:
319-335-5253
Posted on April 6th, 2011

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