From drug delivery to carbon capture: the exciting potential of liquid marbles

What will carbon capture look like in a decade? Research in a range of different fields racing to find the technology that can keep CO₂ out of the air at an industrial scale. One possible candidate – liquid marbles – has just cleared another hurdle, with a team of Australian and UK researchers bringing greater understanding to these mysterious particles.

Liquid marbles are millimetre-sized drops of liquid, coated with a shell of nanometre-sized particles. This nanoparticle coating is normally hydrophobic (water-repelling), meaning that the droplet doesn’t get moisture on nearby surfaces.

The droplet “has some really interesting properties”, according to Dr Charith Rathnayaka, a lecturer in mechanical engineering at the University of the Sunshine Coast.

“It can float on liquids, it can roll smoothly, and it can be stacked upon another [droplet]. It can select what it’s going to react with.”

The way these marbles react is also unusual – and it gives them some interesting possible applications.

“They can selectively react with some gases, they can be activated at certain temperatures, and they can be sensitive to magnetic fields,” says Rathnayaka.

Carbon dioxide is one of the gases that liquid marbles can react with, meaning they’re a prime candidate for carbon capture and storage technology.

“Due to their very small size, they have higher levels of reactivity with gases,” says Rathnayaka. “And at the same time, you can stack thousands of these in a large reactor as an array or as a network.”

The liquid marbles could eventually sit in large gas reactors, separating CO₂ from the rest of the air. They could also be used as drug delivery vehicles, and possibly have application in other areas as well.

But first, the particles need to be better understood.

“Some of the properties of liquid marbles remain elusive, even though there has been a significant amount of experimental work being done,” says Rathnayaka, who is the lead author on a recent perspective published in Archives of Computational Methods in Engineering that sought to better understand these properties with the help of some advanced computer modelling.

“We use computer programming to set up the models and incorporate relevant physics, mathematics and mechanics with relevant initial and boundary conditions,” he says.

“Then we use supercomputing facilities to do the relevant computations and crunch the numbers leading to simulations and predictions of the behaviour of liquid marbles through these computer models.”

While Rathnayaka and colleagues are helping researchers to get a better idea of how liquid marbles work, he says they’re still a while away from becoming industrial-scale carbon-capture machines – and they’ll only make it if there’s more investment.

“It depends on how much funding we allocate for that, and how many people are actually going to invest their time and effort on these things,” he says.

“I think probably if we have solid research programs focusing on these things, research and development both, we are talking about maybe in half a decade, a decade, we might actually be able to produce some solid, tangible results. But it depends on a number of factors.”