Doctor of Philosophy (PhD)



Document Type



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.



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Committee Chair

McCarley, Robin

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Chemistry Commons