For almost a century nobody wanted to burn their fingers on the Debye-Hückel theory. Now, Maarten Biesheuvel is putting a bomb under it.

‘Teachers don’t find it interesting, nor do students.’ That’s the only way chemical technologist Maarten Biesheuvel (see photo) can explain that a theory about the activity of ions in solution dating from 1923 still holds, even though it rattles all over. But his own theory has recently been published online on arXiv, and it no longer contains a square root of the ion concentration, but a cube root.

For Biesheuvel, who is a researcher at the public-private water technology centre Wetsus in Leeuwarden, it is a spin-off from a textbook on electrochemical processes that he is working on with Wageningen assistant professor Jouke Dykstra. ‘Thanks to the corona crisis, I finally had the time and the motivation.’ While writing, he decided to elaborate on his dormant thoughts about ion activity.