Advanced polymers help streamline water purification, environmental remediation

   CHICAGO, Jan. 24-- Researchers at the University of Illinois (UI) have developed a device which, by using specialized polymer electrodes, can purify and reduce arsenic in water by over 90 percent while using roughly 10 times less energy than other methods in a single step.
   The device works by integrating the contaminant separation and reaction steps within a single unit with an electro-catalytic cell using redox-active polymers. When the contaminated water enters the device, the first polymer electrode selectively captures the arsenite and sends it to the other polymer electrode, where it is stripped of two of its electrons or oxidized to form arsenate. Pure water then leaves the device, and the arsenate waste is concentrated for further disposal.
   "The process is powered by electrochemical reactions, so the device does not require a lot of electricity to run and allows for the reuse of the electrodes based only on electrochemical potential," said Xiao Su, a chemical and biomolecular engineering professor at UI who directed the study.
   In addition to improved sustainability and energy efficiency, this electrochemical approach has advantages for field deployment, the researchers said. Users can run the device using solar panels in areas where electricity is scarce, like in parts of rural Bangladesh, a country where over 60 percent of the population is affected by arsenic-contaminated water.
   There are challenges to address before the device is ready for real-world implementation. "We need to increase the stability of the electrodes because this process will need to be cycled many times while running," Su said. "We're using very specialized, highly advanced polymer materials for the electrodes. However, we need to make sure we design them to be not only highly selective for arsenic, but also very stable and robust so that they do not need to be replaced constantly. This will require further chemical development to overcome."
   Arsenic is a naturally occurring element that enters aquifers, streams and lakes when water reacts with arsenic-containing rocks and is considered highly toxic. This is a global issue affecting more than 200 million people in 70 countries.
   The findings, posted on UI's website on Tuesday, have been published in the journal Advanced Materials.  Xinhau