Our quest to help make seawater drinkable leads to a scientific discovery we weren’t expecting – salt ions that can change shape
Desalination of seawater remains one of the most challenging and expensive ways to produce drinking water. But as water scarcity forces communities in many parts of the world to find new sources of drinking water, our international research team based in The University of Manchester is committed to making a breakthrough in this critical field using our world-leading expertise in materials science.
This quest has inspired us to develop ambitious experiment. Not only has our Manchester-led team created the smallest possible man-made slits in a bid to perfect the desalination of seawater, our pioneering filter also produced a shocking result – we revealed that large salts with ions considerably bigger than the slits were still able to squeeze through by flattening their shape.
That is because these ions apparently behave like soft balls – for example, like tennis balls which can be squeezed into a different shape – rather than hard balls, such as billiard balls which are very rigid.
Our study began when we succeeded in creating slits that are just several angstroms (Å) – one ten-billionth of a metre or 0.1 nanometre in size – and we investigated how ions pass through such ultra-confined structures.
These slits are the smallest possible man-made holes. They were painstakingly created from various 3D and 2D materials, including graphite, graphene, hexagonal boron nitride (hBN) and molybdenum disulphide (MoS2) and, surprisingly, they allowed ions with diameters larger than the size of the slit to permeate through.
