27 September 2016 Decomposition of dioctyl phthalate (DOP) using titanium dioxide photocatalyst in a vacuum
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Abstract
We have focused on photocatalytic materials to solve contamination problem for spacecraft. We have fabricated TiO2 thin films and measured decomposition rates of methyl orange (MO) and dioctyl phthalate (DOP) in vacuum by TiO2 thin films as a photocatalyst. From XRD results, fabricated TiO2 thin films have anatase-type crystal structure, which is known to have stronger decomposition activities than rutile-type TiO2. The TiO2 thin films we made were shown to decompose methylene blue (MB) solution, which means that the TiO2 thin films have general photocatalystic activity in atmosphere. In decomposition of MO in atmosphere and vacuum, TiO2 shows photocatalytic activity even in vacuum although the decomposition rate in vacuum is slower than that in atmosphere. In decomposition of DOP in vacuum, DOP was effused from an effusion cell in vacuum chamber and was deposited on a TiO2 thin film using the in-situ measurement apparatus at Tsukuba Space Center, JAXA. Transmission spectra of DOP on TiO2 thin films after UV irradiation were measured to estimate decomposition rate from absorbance of DOP. The results show that TiO2 thin films can decompose DOP even in vacuum. Moreover, H2O can promote the decomposition of DOP. In order to use photocatalyst materials in vacuum for long time, the studies on the durability of photocatalystic activity of TiO2 in vacuum and the effects of O2 and H2O are necessary in the future.
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N. Shimosako, N. Shimosako, K. Shimazaki, K. Shimazaki, E. Miyazaki, E. Miyazaki, H. Sakama, H. Sakama, } "Decomposition of dioctyl phthalate (DOP) using titanium dioxide photocatalyst in a vacuum", Proc. SPIE 9952, Systems Contamination: Prediction, Control, and Performance 2016, 99520O (27 September 2016); doi: 10.1117/12.2237259; https://doi.org/10.1117/12.2237259
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