Journal article
Hydroxyl Radical Formation during Ozonation of Multiwalled Carbon Nanotubes: Performance Optimization and Demonstration of a Reactive CNT Filter
Environmental science & technology, Vol.49(6), pp.3687-3697
03/17/2015
DOI: 10.1021/es505430v
PMID: 25730285
Abstract
We explored factors influencing hydroxyl radical (•OH) formation during ozonation of multiwalled carbon nanotubes (MWCNTs) and assessed this system’s viability as a next-generation advanced oxidation process (AOP). Using standard reactivity metrics for ozone-based AOPs (R CT values), MWCNTs promoted •OH formation during ozonation to levels exceeding ozone (both alone and with activated carbon) and equivalent to ozone with hydrogen peroxide. MWCNTs oxidized with nitric acid exhibited vastly greater rates of ozone consumption and •OH formation relative to as-received MWCNTs. While some of this enhancement reflects their greater suspension stability, a strong correlation between R CT values and surface oxygen concentrations from X-ray photoelectron spectroscopy suggests that surface sites generated during MWCNT oxidation promote •OH exposure. Removal of several ozone-recalcitrant species [para-chlorobenzoic acid (p-CBA), atrazine, DEET, and ibuprofen] was not significantly inhibited in the presence of radical scavengers (humic acid, carbonate), in complex aquatic matrices (Iowa River water) and after 12 h of continuous exposure of MWCNTs to concentrated ozone solutions. As a proof-of-concept, oxidized MWCNTs deposited on a ceramic membrane chemically oxidized p-CBA in a flow through system, with removal increasing with influent ozone concentration and mass of deposited MWCNTs (in mg/cm2). This hybrid membrane platform, which integrates adsorption, oxidation, and filtration via an immobilized MWCNT layer, may serve as the basis for future novel nanomaterial-enabled technologies, although long-term performance trials under representative treatment scenarios remain necessary.
Details
- Title: Subtitle
- Hydroxyl Radical Formation during Ozonation of Multiwalled Carbon Nanotubes: Performance Optimization and Demonstration of a Reactive CNT Filter
- Creators
- Rebekah Oulton - University of IowaJason P Haase - University of IowaSara Kaalberg - University of IowaConnor T Redmond - University of IowaMichael J Nalbandian - University of California, RiversideDavid M Cwiertny - University of Iowa
- Resource Type
- Journal article
- Publication Details
- Environmental science & technology, Vol.49(6), pp.3687-3697
- Publisher
- American Chemical Society
- DOI
- 10.1021/es505430v
- PMID
- 25730285
- ISSN
- 0013-936X
- eISSN
- 1520-5851
- Grant note
- DOI: 10.13039/100000146, name: Division of Chemical, Bioengineering, Environmental, and Transport Systems, award: 0954645; DOI: 10.13039/100000139, name: U.S. Environmental Protection Agency, award: 91710301
- Language
- English
- Date published
- 03/17/2015
- Academic Unit
- Center for Health Effects of Environmental Contamination; Civil and Environmental Engineering; Public Policy Center (Archive); Chemistry; Chemical and Biochemical Engineering
- Record Identifier
- 9984197103102771
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