ENVR 131 |
| In this study, as-produced (AP) HiPco (high pressure CO conversion synthesis) SWNTs were pretreated and etched by peroxone (ozone/hydrogen peroxide) AOP in the liquid phase, generating hydroxyl radicals (•OH) and then the characteristics of these modified SWNTs and phenanthrene uptake were investigated. The impact of NOM uptake by pretreated SWNTs prior to subsequent phenanthrene uptake was also studied. Nitrogen (N2) isotherms at 77K and NLDFT (non-linear density functional theory) analysis indicated that the pretreatment using air oxidation at 300°C and HCl (18 wt%) soaking increases micro pore volume (MPV) and BET specific surface area (SSA) and decreases average pore width (APW). One explanation is that SWNT end caps were cut, opening internal surface area. Subsequent peroxone AOP etching decreased MPV and SSA and increased APW, implying that SWNT walls were etched. Preloading of NOM collected from a surface water reservoir (Tomhannock, Troy, NY) significantly decreased MPV and SSA and increased APW. Phenanthrene uptake results were consistent with N2 isotherm analysis. Phenanthrene uptake by heat (air oxidation at 300°C) and acid (HCl)-treated (H/A) SWNT was higher than AP SWNT and AOP-etched H/A SWNT and NOM-preloaded H/A SWNT showed lower phenanthrene uptake than H/A SWNT. Raman spectroscopy analysis results indicated that oxygen heteroatoms generated by AOP etching could also contribute to a decrease in phenanthrene uptake by the HiPco SWNTs. |
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General Papers
6:00 PM-8:00 PM, Wednesday, August 22, 2007 BCEC -- Exhibit Hall - B2, Poster
Division of Environmental Chemistry |