The surprisingly useful liquids that mop up gases like a sponge

HAVE you ever stopped to consider the technological marvel that is the humble kitchen sponge? Liquids tend to be unruly, sploshy things, but, with a quick swipe, a sponge can soak up and transport them to wherever they are needed. It would all be rather miraculous were it not so familiar.

But here’s a question that is a little more out of the ordinary: could we make a liquid sponge? It would be kind of like the household variety, only it would suck up gases instead of liquids and it could be pumped over vast distances. That would make it incredibly useful. After all, we are in the middle of a climate emergency caused by the emission of greenhouse gases such as carbon dioxide and methane. A liquid sponge could provide a better way of sucking up those gases and preventing them from causing harm.

You might expect the concept of a spongy liquid to be a non-starter. As most of us learned in school, a liquid is something that fills up the bottom of any container it is poured into – no holes or spaces allowed. Yet in labs around the world, chemists are creating a rich assortment of cleverly designed liquid sponges and putting them to the test. We are about to find out just how useful this quirky technology really is.

What are porous liquids?

The story of liquid sponges – sometimes called porous liquids – begins in 2007 when chemist Stuart James began working at Queen’s University Belfast in the UK. He was researching solids known as metal-organic frameworks (MOFs), cage-like compounds made of metal ions and carbon-based molecules. The special thing about …