Charged sulfurous polymers sop up metals

Petroleum refining produces millions of metric tons of excess elemental sulfur each year. Seeking to use this material practically, researchers have incorporated sulfur into polymers to enable them to bind heavy metals for cleaning up water. But because they’re made with hydrophobic monomers, these polymers often suffer from poor solubility, and only sulfur on their surface is available for binding. In an effort to make more-soluble sulfur-containing polymers, chemists Courtney L. Jenkins and Cameron B. Call of Idaho State University and M. Logan Eder of Ball State University combined sulfur with charged monomers, including diallyldimethylammonium chloride, in an inverse vulcanization process (ACS Appl. Polym. Mater. 2022, DOI: 10.1021/acsapm.1c01536). The resulting charged polymer captures gold and silver, precipitating into a complex that can be filtered to leave behind clean water. “Using petroleum waste to create polymers for the remediation of industrial waste helps manage two waste streams with one material,” the chemists say in their paper. Solutions of the sulfur-containing polymer also change color in the presence of heavy metals (shown). The chemists say this color-changing property could be used to detect lead contamination without complex equipment.