Bringing Back the CD for Water Treatment
Due to digital downloads and portable media players, CDs have been getting less and less attention of late. There is a good chance that some of us have a collection of discs that we rarely touch, if ever, because our media players are always at hand, so what can we do with the discs? Thanks to researchers in Taiwan, as reported by the Optical Society, we can use them to clean water.
While that small plastic disc may not seem like anything special now, it had to be engineered to survive the rapid spinning of an optical drive. That engineering is key to the researchers' water cleaning system. Zinc oxide is a cheap semiconductor that can break down organic molecules when exposed to UV light. By growing zinc oxide nanorods on the surface of a CD, the researchers had a device to clean water. Spinning the CD accelerates the process as it causes water drops to spread into thin film that light can easily penetrate, and increases the surface area exposed to the nanorods.
When tested, the researchers determined this system could clean 150 mL of waste water a minute. Considering the small size and low power requirement of this system, it could see use in small scale situations. Naturally the researchers are exploring ways to increase the system's efficiency so it can work even faster.
Source: The Optical Society