Electrocatalytic Inactivation of E. coli in Point of Use Drinking Water Applications Using TiO2 Nanotubes

A flow reactor device initiating electroporation was developed for bacterial disinfection in lab-synthesized and natural waters. Complete inactivation of bacterial contaminated waters with flow rates of 50 mL/min was observed. The device consisted of immobilized titanium dioxide nanotube arrays, which applied a bias of up to 5 V without noticeable water splitting. Water chemistry, applied voltage, and bacterial concentration were all found to impact disinfection rates. Complete inactivation of E. coli W3110 (~8 x 10³ CFU/mL) occurred in 15 seconds in the device with an applied voltage of 3 V in a 100 ppm NaCl solution. Inactivation rates varied widely as a function of ionic concentrations. Disinfection in natural water was inhibited by the presence of inorganic ions and other constituents which are commonly found in natural water. A higher voltage of 6 V was required to reach 100% efficiency because of this. An applied bias to the nanotube flow through disinfection chamber shows promise as an effective bacterial disinfection device for E. coli inactivation without the need for solar irradiation.