Photocatalytic Evaluation of TiO[sub.x] Films Produced by Cathodic Arc-PVD with Silver Addition by UVC Photo-Reduction Method

A titanium (Ti) commercial cathode material and high purity Ar and O[sub.2] were used in the cathodic arc physical vapor deposition (arc-PVD) process. The TiO[sub.x] coating was deposited on the three sets of Raschig rings using decreasing ratios of Ar/O[sub.2] :440/60, 400/100 and 300/100. The cross sections of the TiO[sub.x] PVD coating were analyzed using field emission scanning electron microscopy (FE-SEM), X-ray energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD). A homogeneous layer of Ti with small O content was observed, and the data suggest that a thin TiO[sub.x] oxide film was deposited. For this reason, a thermal treatment was applied to the coating to oxidize it and form the rutile phase of TiO[sub.2] in the coating, which was demonstrated by grazing incidence XRD. In addition, the TiO[sub.x] coatings absorb radiation, which was observed by diffuse reflectance band gap energy measurement. Silver (Ag) was added by the photo-reduction method, using UVC light to activate the TiO[sub.2] coating, and the band gap energy was analyzed by diffuse reflectance. The photocatalytic activities of the films were evaluated by degradation of the model dye rhodamine B and in the removal of fecal coliforms using two matrices, water from a secondary treatment effluent, and synthetic water.