Scientists at Rice University in the U.S. have created tiny spheres that can catch and destroy BisPhenol A (BPA). The micron-sized spheres are a collection of titanium dioxide petals.
BPA is a synthetic chemical used to make plastics that often contaminates water. It is commonly used to coat the insides of food cans, bottle tops and water supply lines. BPA is hydrophobic and naturally attracted to the cavity. Once trapped, Reactive Oxygen Species (ROS) produced by the spheres degrades BPA into harmless chemical.
The researchers determined that 200 mg of the spheres per litre of contaminated water degraded 90% of BPA in an hour, a process that would take more than twice as long with unenhanced titanium dioxide.
BPA is commonly used to coat the insides of food cans, bottle tops and water supply lines, and was once a component of baby bottles. While BPA that seeps into food and drink is considered safe in low doses, prolonged exposure is suspected of affecting the health of children and contributing to high blood pressure.
The micron-sized spheres resemble tiny flower-like collections of titanium dioxide petals.
The supple petals provide plenty of surface area for researchers to anchor cyclodextrin — a benign sugar-based molecule often used in food and drugs. It has a two-faced structure, with a hydrophobic (water-avoiding) cavity and a hydrophilic (water-attracting) outer surface.
BPA is hydrophobic and naturally attracted to the cavity. Once trapped, reactive oxygen species (ROS) produced by the spheres degrades BPA into harmless chemicals.
The size of the particles is less than 100 nanometers. Because of their very small size, they’re very difficult to recover from suspension in water.
While a 100-nanometer particle is 1,000 times smaller than a human hair, the enhanced titanium dioxide is between 3 and 5 microns, only about 20 times smaller than the same hair.