Arsenic has an affinity to iron oxides.
Rice University’s Center for Biological and Environmental Nanotechnology (CBEN) have announced a pilot test for a revolutionary, low-cost way to remove arsenic from drinking water. CBEN’s arsenic-removing technology is based “nanorust,” which are tiny bits of iron oxide smaller than living cells.
Arsenic chemically binds to nanorust because arsenic has a high affinity toward iron oxides. Laboratory tests have demonstrated that nanorust is very effective at removing arsenic from water
Raw water for the city of Guanajuato contains arsenic. As a result, CBEN scientists have signed an agreement with the University of Guanajuato and the Municipal Water and Sewerage Authority of Guanajuato (Simapag) for a pilot test the use of nanotechnology to clean contaminated water in Guanajuato, Mexico.
The agreement is the first known test of nanoparticles for water treatment in a municipal water treatment plant. The secret to nanorust is the magnetic properties among nano-scale magnetite particles.
Magnetite (Fe3O4) is an iron oxide, much like rust, so the term “nanorust” was coined for magnetite nano-particles. Whereas rust (FeO) only contains iron in +2 oxidation states, Fe3O4 has iron in both +2 and +3 states. Nanorust crystals are so tiny that they are measured in the scale of nanometers (10-9 meters).
Because of its ability to bind to arsenic, nanorust may be a low-cost means of removing arsenic from drinking water supplies. CBEN plans to test nanorust-coated sand in sand filters to treat groundwater from wells.
If all goes as planned, the arsenic in the raw water will be captured by the nanorust-coated sand in the filters. For the time being, water treated with nanorust will not be released for human consumption.
Arsenic is a colorless, odorless, tasteless element, and prolonged exposure to dangerous levels of arsenic can lead to skin discoloration, sickness and cancer. Arsenic-poisoned drinking water is a global problem, affecting tens of millions of people in communities in Asia, Africa, North America, South America and Europe.
