Surrey makes history with two pinches of salt
19 Feb 2024
Scientists at the University of Surrey are claiming a first with their observations on the effects of electrical current caused by combining different salts in liquid.
Charged particles drift through liquid when a single type of salt is dissolved into it, moving from the most to the least concentrated areas. However, adding a second kind of salt can give instant rise to an electrical current throughout the liquid.
Until now, the process, known as non-local diffusiophoresis, has never previously been observed, said Dr Richard Sear, from the university's School of Mathematics and Physics:
"This is a truly exciting discovery – the first time we've ever seen remote diffusiophoresis. Our research is at a very early stage, and we don't yet know how strong these currents could ultimately become. But the possibilities are tantalising."
The team explained in Physical Review Fluids that they had modelled how they expected types of salts to respond in water, taking turns to dissolve different pairs.
As they were aware the local effects of the concentrations would cancel each other out, any movement had to be explained by non-local diffusiophoresis, they judged.
Of the different combinations, the biggest impact occurred when dissolving sodium chloride with potassium acetate.
"This process could one day be used to sort and separate substances within a liquid. Think how useful that could be for desalinating drinking water from the sea or separating solutions in industrial processes” said Sear.
https://journals.aps.org/prfluids/abstract/10.1103/PhysRevFluids.9.014201
