Researchers at A*STAR’s Institute of Materials Research and Engineering in Singapore have found a way to turn iron hydroxides into a coating that can remove pollutants like dyes and heavy metals from drinking water.
Iron hydroxides are found in rust and are known to form stable chemical bonds with pollutants in water. They are much more efficient than conventional activated carbon absorption for removal of the pollutants. However, the iron hydroxide nanoparticles pose a risk to human health, and removing them from water is difficult.
The team at A*STAR, led by researcher Sing Yam Chiam decided to immobilise iron hydroxide nanoparticles on a solid substrate for easy removal. They used nickel foam as the substrate. Iron hydroxide nanoparticles were deposited onto the surface using electrodeposition, in which the nickel foam is immersed in a solution of the nanoparticles and a small voltage is applied. Tests using a dye called congo red showed that the coated foam removed more than 90% of the dye within half an hour at room temperature.
Scanning electron microscopy showed long, ‘fin-like’ protrusions from the surface of the coatings, which they believe is responsible for the efficacy of the coating. “Even though these coatings have some of the highest capacities ever reported, they are only operating at a fraction of their theoretical capacity. We are really excited about tapping their potential,” said Chiam.