Researchers at the University of Texas at Arlington have a bright idea for cleaning and disinfecting water: use the sun. Their process, called solar-assisted disinfection, destroys bacteria and contaminants by exploiting a chemical reaction between ultraviolet light and titanium dioxide, a white pigment found in everything from paint to sunscreen.
Added to the water, titanium dioxide acts as a photo catalyst, splitting beams of ultraviolet light into wavelengths that destroy bacteria and chemicals by oxidation. Minutes later, the titanium dioxide is filtered out and reused. Currently, the technique could be used by campers or the military in remote sites. But chemists Krishnan Rajeshwar, Sanjay Basak, and their colleagues see broader applications. They hope to use the process to destroy tough targets like algae, Giardia lambia, or Cryptosporidium, the protozoa that recently plagued Milwaukee's water supply.