Date of Award

2020

Document Type

Campus Access Dissertation

Degree Name

Doctor of Philosophy in Materials Science and Engineering (PhD)

Administrative Home Department

Department of Materials Science and Engineering

Advisor 1

Bowen Li

Committee Member 1

Stanley J. Vitton

Committee Member 2

Bruce Lee

Committee Member 3

Rupali Datta

Abstract

In the United States, the Amargosa Valley of Nevada has the exclusively exploitable and commercial deposit of sepiolite. However, the current sepiolite products are mainly low-value products. Hence, developing advanced and value-added sepiolite nanocomposites products has a promising future.

In this study, the structure and morphology changes of sepiolite samples were investigated under thermal treatment from 200 to 1000ºC. The results revealed the dehydration law, structure folding process, and the morphology change of sepiolite. Then the effect of the differently acidic attack on the structural characteristics of sepiolite was also studied. The results showed the effect of HNO3, H2SO4 and HCl attack on the purification, the structure change and functional group change of sepiolite.

Then the Cu/sepiolite, Ni/sepiolite, NiO/sepiolite, ZnO/sepiolite, and Cu@ZnO/sepiolite nanocomposites were prepared by a simple sorption-reduction or sorption-oxidation process. (1) For Cu/sepiolite nanocomposites, the reaction conditions, such as Cu concentration, reduction temperature, and reduction time have a significant effect on the size of copper nanoparticles. (2) For Ni/sepiolite nanocomposites, the diverse characterization results revealed that the Ni nanoparticles with a mean diameter of about 12 nm mono dispersedly resided on the surface of the sepiolite fibers. (3) For NiO/sepiolite nanocomposites, the size of the nanoparticles obtained increased with the heating temperature increasing. (4) For ZnO/sepiolite nanocomposites, the ZnO nanoparticles with a mean diameter of about 50 nm preferentially resided on the surface of sepiolite. (5) For Cu@ZnO/sepiolite nanocomposites, the nanoparticles obtained in this study had a core/shell structure, which is made up of a copper core and zinc oxide shell.

Finally, the antibacterial applications of these nanocomposites were studied, which showed good antibacterial properties against E. coli and S. aureus.

Available for download on Tuesday, December 01, 2020

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