Honors Theses
Date of Award
2004
Document Type
Undergraduate Thesis
Department
Chemistry and Biochemistry
First Advisor
Eric Ellison
Relational Format
Dissertation/Thesis
Abstract
Zeolites are microporous aluminosilicates that are used in many capacities as media for ion - exchange, catalysis, and molecular sieving. The internal structure of zeolites consists of silica and alumina tetrahedra arranged in such a way to form two types of cages: sodalite cages and supercages. Polynuclear aromatic hydrocarbons (PAH's) such as pyrene can get into the supercages by means of adsorption from a nonpolar solvent, but cannot be extracted from the supercage by submersion of the zeolite in a polar solvent. In this study the zeolites X and Y (which are synthetic analogs of the naturally occurring zeolite faujacite) were used to observe this effect for a variety of PAH's and to determine under what conditions, if any, PAH's can be removed from zeolites. The results indicate that pyrene and other PAH's are indeed trapped within the supercages of the zeolites and that heating and evacuating the zeolite discs prior to exposure to a polar solvent makes the effect even more obvious. It was also observed that zeolite X retains a higher percentage of PAH's than does the Y form; that the PAH does not become a derivative species while in the zeolite; and that some cages trap molecules while others do not. We conclude from this study that higher ionic content in the zeolite cages caused more PAH to be retained and also caused "trapping cages." Heating and evacuating the zeolite discs caused an increase in molecular movement within the zeolite, which allowed PAH molecules to find trapping sites deep within the zeolite. This phenomenon permitted PAH's that were located on the exterior of the zeolite to become trapped in cages not normally filled by probe. A possible application of this study could be as a separation technique for molecules of different sizes.
Recommended Citation
Levidiotis, Reagan, "Molecular Entrapments in the Nanosized Cavities of Polar-Solvated Zeolites X and Y”" (2004). Honors Theses. 2054.
https://egrove.olemiss.edu/hon_thesis/2054
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