KAGAKU KOGAKU RONBUNSHU, Vol.35, No.3, 287-292, 2009
Effect of Light Intensity on Inactivation of Microorganism in Solution Discharged from Soaking Germination Process by a Laminated Photocatalyst
Effect of light intensity was kinetically investigated on the catalytic inactivation of aerobic bacteria, with a laminated photocatalyst prepared by drying a commercial titanium-dioxide emulsion on the stainless-steel plate, in the solution discharged and filtered with diatomite filter-aids from a soaking process of brown rice germination under the blacklight-lamp irradiation. The inactivation under 352 nm light irradiation was enhanced with shorter induction periods as the number of lamps increased. In terms of effective light intensity I(eff) and microorganism concentration C which could control the process, the inactivation rate was successfully represented by the following equation with a shorter induction period, -dC/dt = k . I(eff) . C where I(eff) was defined the light intensity effective to the inactivation of microorganism through active species produced on the photocatalyst surface under illuminated light intensity I. The absolute value of I(eff) was considered a function of radiant light intensity I(0) (r(2)), solution thickness l, and light absorptivity of solution m; the reference value was selected to be the illuminated light intensity I calculated with a set of minimum values of r(2) and l: r(2) = 2.5 x 10(-3) m, l = 1.0 x 10(-3) m under the defined number of lamps. With increasing the radiant light intensity I(0), the absolute value of effective light intensity I(eff) got larger and the ratio of effective light intensity to illuminated light intensity I(eff)/I was nearly the same.
Keywords:Laminated Photocatalyst;Microorganism;Effective Light Intensity;Radiant Light Intensity;Illuminated Light Intensity