抄録
Application of photocatalysis has been demonstrated on the removal of NOx in air over titania coated porous concrete. Sample prepared were compared with each other in NOx oxidation activity using the standard reactor JIS R 1701-1. In addition, two types of titania were used for the test. One of them was prepared by mixing the titania particles into cement powders, and the other was prepared by spray coating of the titania aqueous solution peripherally onto the porous concrete. The porous concrete was improved in the adsorption characteristics by mixing the commercially available zeolite, and was tested for the removal of NOx.
In the adsorption stage, no remarkable change can be observed among the samples, so that it is considered that the NOx adsorption is not improved by adding zeolite. The photocatalytic activity is remarkably improved in the zeolite admixed samples. This means that the admixed zeolite enhanced the reaction rate by affecting the performance of products. The amount of NO2- and NO3-, eluted from the sample, was larger in the zeolite admixed samples compared with that in the porous concrete which does not contain zeolite. From this result, the anion adsorption is considered to be enhanced by zeolite which has strong acidity.
Next, the photocatalytic activity was examined in the samples made with different types of preparation. High activity is observed in the coating type photocatalyst. It is concluded that high activity is achieved by titania being concentrated on the surface of porous concrete, so that the titania can catch the light beam effectively.
