Photoreductions in Aqueous Semiconductor Suspensions and Properties of Modified Polyacrylonitrile Films.
Abstract
Particles of the semiconductor titanium dioxide have been shown to heterogeneously catalyze the destruction of chlorofluorocarbons (CFCs) in both air saturated and degassed aqueous suspensions. The photoreduction of CFC-11 or R-11 (CCl3F) in this manner was studied over a range of initial R-11 concentrations, and UV light intensities. Kinetic determinations of the reduction progress were performed via ion-selective electrodes. The reduction takes place via radical chain mechanism which is eventually slowed by product poisoning of the catalyst. Polyacrylonitrile (PAN) materials treated with methoxide ions exhibit properties typical of polymeric semiconductors. PAN-based semiconducting materials were made from textile fibers. The photochemical activity of the modified fibers was tested by attempting the photoreduction of CH3Cl in aqueous degassed suspensions of ground fibers and sodium perchlorate. The photo-experiment was conducted similar to the experiments involving R-11 and TiO2. Unfortunately, a byproduct of the process that forms the semiconducting fibers, OH(-), proved inseparable from the fibers and is a confirmed interference ion to determination of reaction products. Therefore, only qualitative evidence on the phototransformation of CH3Cl and R-11 initiated by the PAN fibers was obtained in this study. If preparation of PAN-based semiconductors is feasible, then thin films of converted PAN could lend themselves for the development of novel small scale electronic devices. In pursuit of this goal, the electrical properties of solvent cast films of solution converted PAN were studied. Preliminary results show the conductivity is in the range of high resistance semiconductors, but further improvements seemed possible by manipulations of the synthetic parameters.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 14, 1998
- Accession Number
- ADA359760
Entities
People
- Robert L. Calhoun Jr
Organizations
- Auburn University