Voltage Asssisted Photocatalytic Flow through Cell for Inactivation of Biological Pathogens Using Titania Nanotube Arrays

Diseases stemming from pathogen contaminated water kills 3.4 million people annually; despite our centralized water treatment facilities in the US, we are not immune to tainted drinking water.   Aging infrastructure and natural disasters can cause limited access to potable water, making point-of-use (POU) disinfection devices critical for survival.

In this work, a POU device using a voltage assisted photocatalytic flow through cell, was designed and built for the disinfection of water under various conditions.  Anodically formed titania nanotube arrays (TNAs) were used as the photocatalytic component of the cell.  The TNAs were characterized via x-ray diffraction, scanning electron microscopy and photoelectrochemical measurements.  Voltage assisted inactivation was examined under different light intensities, water chemistries and applied biases. Complete biocide (a 10-log reduction) of Escherichia coli (E. Coli) W3110, was achieved in 15 s of contact time under 25 mW/cm² insolation and an anodic bais of 3 V. The presence of chloride ions was found to enhance disinfection as chlorine radicals participate in bacterial inactivation; however, sulfate and nitrate ions were found to inhibit inactivation.  It was also determined that TNAs annealed in a reducing atmosphere performed significantly better than those annealed in air.  Overall, this voltage assisted photocatalysis methodology proved to be highly effective in complete inactivation of E. Coli.