Identifier

etd-08172014-190037

Degree

Doctor of Philosophy (PhD)

Department

Chemistry

Document Type

Dissertation

Abstract

Transition metal oxide nanoparticles contained in fly ash are known to catalyze the formation of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) during the waste incineration process. The potential catalytic activity of silica-supported NiO, CuO, and NiO-CuO nanoparticles for the formation of PCDD/Fs will be discussed in this dissertation. The successful synthesis of silica-supported NiO, CuO, and NiO-CuO nanoparticles as surrogates of combustion-generated nanoparticles was important to this study. The synthesis was followed by the characterization of the nanoparticle surrogates by X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDS). Finally, the catalytic activity of these nanoparticle surrogates for the formation of PCDD/Fs was investigated. Silica-supported metal oxide nanoparticles were prepared by wetness impregnation of metal ionƒ{dendrimer complexes (WI-D) and wetness impregnation of metal ion solutions (WI-M), both followed by oxidative thermal treatment (calcination). NiO nanoparticles with low size dispersity (14%) and an average diameter of 3.6 ¡Ó 0.5 nm were formed by the WI-D method followed by calcination at 500 „aC for 5 h. NiO nanoparticles prepared by the WI-M method showed of low size dispersity (14%) and an average diameter 2.9 ¡Ó 0.4 nm followed by calcination at 500 „aC for 5 h. For the first time, mixed NiO-CuO nanoparticles were synthesized with the ability to control their Ni:Cu (1:1, 1:3, 1:10, 10:1, and 3:1) molar composition by altering the amounts of metal ions in the starting solutions. Catalytic activity of NiO, CuO, and NiO-CuO nanoparticles was investigated by reacting 2-monochlorophenol (2-MCP)ƒ{a known PCDD/Fs precursorƒ{on their surface at cool-zone temperatures of waste incinerators (300¡V500 „aC with 50 „aC intervals). Results indicated nearly 85% of the 2-MCP was reacted at 300 „aC, while close to 100% conversion was achieved for 2-MCP at temperatures above 450 „aC. It is proposed that the reactions associated with PCDD/Fs formation were initiated by binding of 2-MCP to the metal-oxide sites on the silica support, followed by formation of surface-bound chlorinated phenol molecule. PCDD/Fs yields as a function of reaction temperature and the nature of the catalyst (NiO, CuO and NiO-CuO) will be discussed.

Date

2014

Document Availability at the Time of Submission

Secure the entire work for patent and/or proprietary purposes for a period of one year. Student has submitted appropriate documentation which states: During this period the copyright owner also agrees not to exercise her/his ownership rights, including public use in works, without prior authorization from LSU. At the end of the one year period, either we or LSU may request an automatic extension for one additional year. At the end of the one year secure period (or its extension, if such is requested), the work will be released for access worldwide.

Committee Chair

McCarley, Robin

Included in

Chemistry Commons

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