RITE−ATSUGI LABORATORY
in Kurita Water Industries Ltd. 

Studies have been made of treating waste water and simultaniously generating hydrogen using photocatalysis of semiconductor powder. For these purposes, it has been required to optimize the photocatalyst reactor.

In laboratory scale experiment, the effects of the suspended photocatalyst concentration and the reactor radius on the decomposition rate of total organic carbon (TOC) were studied to elucidate the design concept of an internal radiation-type cylindrical photocatalyst reactor. The transmittancy of UV light through the suspension of platinum loaded titanium dioxide powder used as a photocatalyst and the rate of photocatalytic decomposition of TOC within the reactor equipped with a high pressure mercury lamp were measured. The logarithm of the reciprocal of the transmittancy was found to be empirically correlated with the photocatalyst concentration and the square root of the light pass length. The decomposition rate of TOC was independent of its concentration.

By using these obserbed results and assuming that the photocatalytic decomposition rate was proportional to the photocatalyst concentration and the square root of the light intencity, an equation represented as a function of the light pass length and the photocatalyst concentration was proposed to obtain the average decomposition rate within the photocatalyst reactor. Experimental results of TOC decomposition in reactors with different diameters were well correlated with this equation. This result could be useful for the general use of the photocatalyst. We produced a bench-scale photocatalyst reactor based on the above result.

Moreover, the photocatalytic decomposition property of halogenated organic compounds which are generaly regarded as anti-biodegradable and the photocatalytic generation of hydrogen were also studied.

These results are described in the following papers.

1) Matsutani,H and S.Takasaki, Mizuk ankyo-gakkaishi, 19, 236 (1996)

2) Matsutani,H and Y.Miyaji, Tikasuiosen to sono boushitaisaku ni kansuru kenkyushukai dai 2 kai kouenshu, 10 (1992)