Photocatalytic inhibition of microbial fouling by anodized Ti6Al4V alloy

Biofouling is one of the major concerns in the use of titanium, an excellent material with respect to corrosion resistance and mechanical properties, for seawater-cooled condensers of power plants. Earlier studies conducted in our laboratory have shown that anodized titanium with a thin film of anatase (TiO₂) inhibits attachment of Pseudomonas sp. of bacteria when illuminated with near-UV light (350–380 nm) from black light blue (BLB) florescent lamps. The following work compares the photocatalytic efficiencies of anodized commercially pure titanium (grade 2) and Ti6Al4V alloy, in order to understand the role of the alloying elements such as Al and V on the photocatalytic activity in relation to inhibition of microbial attachment. The study was carried out by employing both methylene blue (MB) dye degradation as well as microbial adhesion experiments under near-UV light illumination. The results have shown that the anodized Ti6Al4V surfaces showed an order of magnitude increase in photocatalytic activity, as shown by the decrease in microbial attachment compared to titanium grade-2. The oxide film on both the surfaces has been characterized using Glancing Incidence X-ray Diffraction (GIXRD) and Atomic Force Microscopy (AFM). The GIXRD and AFM results showed that the oxide formed on anodized Ti6Al4V surface has higher crystallinity and is composed of particles, which are smaller in size; both these attributes are reported to enhance the photocatalytic activity. Since, vanadium is reported to shift the photo-response of the photoactive anatase thin film into visible range, the photocatalytic activity of anodized Ti6Al4V was also studied under visible light and it was observed that the surfaces showed significant photocatalytic activity even under visible light.