Environmental photochemistry: Quantitative adsorption and FTIR studies during the TiO2-photocatalyzed degradation of Orange II

The degradation rate of Orange II, taken as a model for recalcitrant ate-dy es, was observed to be a function of the type of TiO2 semiconductor used du ring the process. The surface parameters of the titania material used seem to be a controlling factor in the photosensitized charge-transfer process. The dye abatement was monitored by diffuse reflectance FTIR. When H2O2 was initially added as an oxidant to the photodegradation process, the rate of dye removal from soluton was accelerated significantly. The pore and partic le size distribution of the anatase, mixed anatase-rutile (Degussa P-25), a nd rutile was quantified by gas adsorption and mercury porosimetry. The deg radation on rutile and anatase was observed to follow pseudo-first-order ki netics during the initial stages of the reaction. The photodegradation of O range II was seen to proceed more readily in the case of anatase than in th at of rutile, The rate was seen to increase with the surface area and the m onolayer volume of the titania variety used.