Water Purification Chemical Uses Visible, Not UV, Light To Kill Bacteria

Shang, et al. University of Illinois at Urbana-Champaign, via Technology Review

The World Health Organization estimates that around one sixth of the world lacks access to clean drinking water. Since those billion people are also the poorest people in the world, water purification techniques need to be cheap to help those most in need. Since it activates under plain visible light, this new water-purifying photocatalyst may help bring purer water to the world’s neediest people.

The water-purifying chemical consists of nitrogen-doped titanium oxide enhanced with palladium nanoparticles. When exposed to visible light, the titanium oxide produces bacteria-killing free radicals, while the palladium nanoparticles absorb electrons that would shut that reaction down. Once activated, the material reduces the bacteria levels from 40 million cells per gallon to just one cell per 2,500 gallons.

Even more impressive, the palladium nanoparticles perpetuate the reaction so efficiently that the titanium oxide continues to purify the water even after the light is shut off. For countries with limited lighting infrastructure, or places prone to blackout, that greatly extends the purification power of the material.

Technology Review