(639g) Inactivation of E. coli. Using a Novel  TiO2 Nanotube Electrode

Electrochemical technology has gained increasing interests for water/wastewater treatment in recent years. In particular, it may find applications in decentralized treatment due to its simplicity, amenability to automation, compact instrumentation, and ease of operation. The performance of electrochemical processes highly depends on the material of electrodes. However, the high cost of electrodes, formation of toxic byproducts, and short electrode lifetime have impeded its wide application. Therefore, development of cost-effective anode materials are needed to support future adoption of electrochemical technologies for environmental applications. In our study, a novel TiO₂ nanotube anode has been fabricated in the lab via simple electrochemical anodization using metallic Ti as the substrate followed by electrochemical hydrogenation/cathodic polarization. The one-dimensional nanostructure is shown in FESEM images. The TiO₂ nanotube anodes with stainless steel as the cathodes were tested for inactivation of a model microbial contaminant E. Coli. using a filter-press type cell. Effects of current density applied (0.625 ~ 2.5 mA/cm²), electrolyte concentration (0.3 mM~3 mM NaCl), and different electrolyte (NaCl, Na₂SO₄, Na₂HPO₄, NaNO₃, and NaHCO₃) on E. Coli. inactivation were investigated. Electrochemically generated oxidizing species were measured as free chlorine. Further, production of reactive oxygen species (â?¢OH, O₂â?¢-, SO₄²-â?¢) were examined using probe compounds. In addition, electro-disinfection experiments were conducted in real water matrices, i.e. samples of surface water, treated surface water before disinfection, and secondary effluent before disinfection collected from local water/ wastewater treatment plants. Formation of inorganic (e.g. ClO₃^-) and organic (THMs) disinfection byproducts were also monitored. Our results have demonstrated that the novel TiO₂ nanotube anode can effectively achieve 5~6 log reduction of E. Coli. with low byproducts formation. The low energy consumption also indicates that such disinfection system may be operated using solar energy stored in a DC battery for decentralized treatment or as a point-of-use device.