Electrolysis can solve one of our biggest contamination problems

Summary

They were once considered miracle workers – insecticides such as lindane or DDT were produced and used millions of times during the 20th century. But what was hailed as progress led to a global environmental catastrophe: persistent organic pollutants (POPs) are so chemically stable that they remain in soil, water and organisms for decades. They accumulate in the fatty tissue of animals and thus enter the human food chain. Many of these substances were banned long ago, but their traces can still be found today – even in human blood. How to remediate such contaminated sites, be they soils, bodies of water or landfills, is one of the major unresolved questions of environmental protection. How can highly stable poisons be rendered harmless without creating new problems? Researchers at ETH Zurich, led by Bill Morandi, Professor of Synthetic Organic Chemistry, have now found a promising approach. Using an innovative electrochemical method, they are not only able to break down these long-lived pollutants but also to convert them into valuable raw materials for the chemical industry. Converting pollutants into raw materials A key distinction between this and previous work is that the carbon skeleton of the pollutants is recycled and made reusable, while the halide component is sequestered as a harmless inorganic salt. “The previous methods were also energetically inefficient,” says Patrick Domke, a doctoral student in Morandi’s group. He explains: “The processes were expensive and still led to outcomes that were harmful to the environment.” Together with electrochemistry specialist Alberto Garrido-Castro, a former postdoc in this group, Domke developed a process that renders the pollutants in question completely harmless. During this project, the two researchers were able to draw on the many years of experience of ETH professor Morandi, who has been working on the transformation of such compounds for years. “The key advance of this new technology is the use of alternating c...