| 摘要 |
PROBLEM TO BE SOLVED: To evaluate activity of a photocatalyst thin film formed on a surface of a tile or the like, using a simple method. SOLUTION: When a photcatalyst thin film 2 is irradiated with an ultra-violet ray, oxidation reaction and reduction reaction take place concurrently, and a pH of an alkali halide aqueous solution 3 rises by a hydroxyl ion generated by the reduction reaction. Activity is evaluated thereby by a pH difference between a pH before the ultra-violet ray irradiation and a pH after the ultra- vilolet ray irradiation. For example, since the alkali halide aqueous solution is dropped on a surface of the photocatalyst thin film 2 formed on a surface of a substrate such as a tile, the dropped alkali halide aqueous solution is irradiated with the ultra-violet ray for a prescribed time, and since a level of the activity of the photocatalyst thin film 2 is judged by the pH difference between the pH of the alkali halide aqueous solution before the irradiation and the pH of it after the irradiation, the activity of the photocatalyst thin film 2 is determined easily and quickly compared with a conventional method by a gas chromatograph or a conventional method wherein the number of annihilated bacteria is measured. |
