Phosphine Oxides, Ferrocene, and Volatile Orangic Compounds Adsorbed on Surfaces: A Solid-State NMR Study.

Abstract

Adsorption processes are very important in everyday life and in academia. They are used in chromatography and to remove pollutants from water sources or even to capture carbon dioxide. Despite the importance of adsorption, additional knowledge about the interactions between the adsorbate and the surface is still needed. In this dissertation new mobility studies were performed in order to gain more insight into the adsorption process and the dynamics of adsorbates on the surface of a support. First, triphenylphosphine oxide was adsorbed on alumina and the disappearance of the chemical shift anisotropy (CSA) of the 31P solid-state NMR signal showed that one of the mobility modes must resemble fast solution-like isotropic reorientation. This principle was further investigated with ferrocene on activated carbon and silica. Again, a complete collapse of the CSA in the 13C solid-state NMR spectra indicated isotropic mobility of the molecules on the surface of a support. In both cases, complete solid-state NMR analysis, including quantifying the enthalpy of adsorption, was performed. Finally, in collaboration with a waste management company a prototype air purification system was designed for the removal of odorous volatile organic compounds (VOCs). The prototype performed well and removed the odor of a typical dumpster during the first four days of use. In future applications of the prototype the longevity will be increased by application of larger amounts of absorber and a different oxidizer.