The contamination of drinking water with arsenic is a pressing problem in several regions of the world, e.g., Bangladesh, China, and India. This is caused by elevated levels of arsenic compounds in the groundwater. Long-term exposure can lead to adverse health effects, especially skin lesions and cancer. Many of the existing techniques for arsenic removal have problems such as limited effectiveness for arsenic in its +5 oxidation state.

Raffaele Mezzenga, Swiss Federal Institute of Technology (ETH) Zurich, Switzerland, and colleagues have developed an amyloid-carbon hybrid membrane which can efficiently remove both arsenate (oxidation state +5) and arsenite (oxidation state +3) from contaminated groundwater. The team prepared the membranes by mixing a β-lactoglobulin fibril solution with activated carbon and vacuum filtering the resulting solution through cellulose filters. The resulting membranes have a protein fibril content of about 10 %.

The team tested the membranes’ arsenic removal properties in a vacuum filtration setup. They found that the material removed both arsenite and arsenate from water with efficiencies of over 98 %. The team also purified contaminated ground water samples from Romania and Guatemala and were able to reduce the overall arsenic concentration to safe, drinkable levels in one filtration step. The team attributes this effective absorption of arsenic compounds to the protein fibrils contained in the membranes. The material could be reused for several filtration cycles without significant saturation effects.

• Efficient Purification of Water from Arsenic by Amyloid-Carbon Hybrid Membranes,
  Raffaele Mezzenga, Sreenath Bolisetty, Noemi Reinhold, Christophe Zeder, Monica Orozco,
  Chem. Commun. 2017.
  DOI: 10.1039/c7cc00406k