The Bioeconomy looks to the natural world for products and services. One approach is to mine waste substances of potential value, such as filtering food waste to capture chemicals or gases. But what can we use to filter waste efficiently?

Professor Yurii Gun'ko is leading research at BiOrbic Bioeconomy SFI Research Centre on developing new membrane technology that can act as a sieve, separating out valuable chemicals or gases from biomass and agri-food waste.

“Normally waste biomass from agriculture and the food industry is not used, and in BiOrbic one of our major targets is to utilise this waste,” explains Professor Gun’ko, Professor of Inorganic Chemistry at Trinity College Dublin School of Chemistry. 

“That might mean separating something useful out as a side-product of waste from milk products processing or mushroom farming, for instance, and then using those materials for high-tech applications.”

Those side products include gases such as methane which could be used for fuel, or chemicals such as lactic acid or sugars that could be used by food industry. The filters or membranes needed to separate these gases and valuable substances need to have tiny pores, and the issue is that they can clog up easily, notes Professor Gun’ko. 

“When these membranes get blocked, you need to dismantle the entire set up and clean them – often with aggressive chemicals – and then put everything back together,” he explains.

His group is coming up with a more practical solution: a membrane that can be easily cleaned by heating it. “We are using induction heating, like you often see in cooking hobs, to rapidly heat the membranes and this cleans them in situ, you don’t have to take the membrane components apart,” he says.

The research is using a new, ultra-thin material called boron nitride to make the membranes, and testing them as fast-cleaning filters. “The choice of material is really important here, because you can’t use a polymer if you are going to heat it to these levels,” he says. “The induction heating can raise the temperature of the material to more than 100 degrees Celsius within one second, so the material we use needs to be robust and not melt at those temperatures.”

Professor Gun’ko is a pioneer in boron nitride – previously he worked in collaboration with Trinity colleague Professor Johnny Coleman to produce the two-dimensional functionalised material in the lab, and now he is applying the technology to make new membranes for the Bioeconomy. “Boron nitride is cheap and it can sustain temperatures up to 900 degrees,” says Professor Gun’ko. “And because it is white, you can see relatively easily what is happening to the membrane as it changes colour.”

The aim is to produce easy-to-clean membranes that have a long life for filtering waste, and that can be scaled up easily to industrial scales. This is where the structure of BiOrbic Bioeconomy Research Centre and its partnership with industry will help to bring the science to the next level, says Professor Gun’ko. “Industry is interested in making more from biomass waste,” he explains. “So we see our research having a very practical application.”