To achieve a more sustainable future, the world needs to shift from a take-make-waste economy to a circular one focused on reuse, repair and recycling. Indeed, as Inger Andersen, executive director of the UN environment programme, said at the recent COP29 in Baku, Azerbaijan, “many more nations must take up the circularity baton in their new climate pledges” if we’re to have a chance of limiting global warming to 1.5C.
In Belfast, the QUILL research centre (Queen’s University Ionic Liquid Laboratories) is pioneering technologies that could accelerate this much-needed shift. It’s based at Queen’s University Belfast, which is known for its cutting-edge research in the fields of green chemistry and renewable energy, and its commitment to sustainability and environmental leadership.
QUILL’s work centres on the transformative potential of ionic liquids. These are essentially chemical compounds with unique properties that stem from their complex molecular structure. One important property is that they remain liquid at a wide range of temperatures, so can be used as solvents and catalysts in many processes.
“Ionic liquids have the ability to be designed for a particular purpose – to, for example, separate and extract rare earth metals from end-of-life magnets,” says Peter Nockemann, professor of inorganic and materials chemistry, and director of research in the school of chemistry and chemical engineering at Queen’s.
Recycling rates for magnets used in wind turbines and electric vehicles are low, so the valuable rare earth metals they contain typically go to waste. That’s partly because current recycling methods are costly, ineffective and environmentally damaging – issues Nockemann and his team have worked to solve.
He says that his ionic liquid recycling method doesn’t use harsh acids or environmentally harmful solvents, for instance. “It allows us to create cleaner, more efficient, more targeted processes to recover metals at a very high purity level,” Nockemann says. The high purity (about 99.9%) means the recovered materials “can go straight back into manufacturing new magnets” in a truly circular manner. This ultimately reduces the mining of rare earth metals and the carbon footprint associated with transporting them.
Scaling solutions through industry partnerships
Seren Technologies, a spin-out company co-founded by Nockemann and later acquired by Ionic Rare Earths, has already created a demonstration-scale facility capable of processing about 30 tonnes of spent magnets a year, which produces about 10 tonnes of refined rare earth oxides. QUILL also works closely with other partners in the energy industry, including multinational companies such as Chevron and Petronas, in order to commercialise other aspects of its research.
These companies and other members of QUILL’s industrial advisory board are actively involved in shaping its research strategy, and support its work by participating in grant applications or providing direct research funding. The university’s researchers also tap into the companies’ extensive knowledge, technologies and other resources, and apply them to the development of their circular solutions.
“We work with large companies because we see it as a fast way of integrating circular economy technologies into the market,” says Gosia Swadzba-Kwasny, professor at the school of chemistry and chemical engineering and director at QUILL. “They’re also an important source of feedback on what we do, whether it’s relevant and if it has the potential to actually go anywhere.”
Collaboration between QUILL and Petronas resulted in the development of an ionic-liquid commercial technology for removing mercury from natural gas. Other industry partners have provided support for a project that aims to develop a compact, low-cost redox flow battery, which could be used to store renewable electricity.
Redox flow batteries can store large amounts of renewable energy in their electrolytes and have a lifespan of more than 25 years, offering clear advantages over lithium-ion batteries, which have a lifespan of about five. However, most flow battery technologies use vanadium, an element that is increasingly expensive and scarce, as well as environmentally harmful to extract.
“We’ve designed batteries that use abundant metals like iron, which intrinsically reduces the use of critical metals,” says Nockemann. “The recycling of critical metals is one thing, but if we can avoid using them that is also a good strategy.”
Improving fuel cells and plastic recycling
Another area of research for QUILL is hydrogen fuel cells, which convert hydrogen to electricity, but are resource-hungry and expensive, meaning take-up has been limited.
Hydrogen can be stored as a gas in tanks under high pressure, or in a liquid form, for long periods. When electricity is needed, the hydrogen is fed into a fuel cell, which combines it with oxygen from the air to produce electricity; the only byproduct is water. However, the use of expensive and scarce materials, such as platinum (a catalyst) and specialist membranes, has limited adoption – as has the technology’s low tolerance for fuel impurities.
QUILL researchers are now exploring how the physical and chemical properties of ionic liquids, such as their low volatility and high conductivity, could make them ideal components of membranes and catalyst layers in hydrogen fuel cells, and unlock greater uptake of this electrochemical technology. In addition, they are working on electrochemical hydrogen pumps that could offer better compression capabilities. “The ability to compress hydrogen is a serious engineering issue,” says Swadzba-Kwasny. “Because the molecules are very small, they can permeate things.”
Researchers have also demonstrated how ionic-liquid technology can break down plastic waste at lower temperatures – which could reduce the energy used in the recycling process – and convert it into useful products, such as base oils for lubricants used in the renewable energy industry.
Looking ahead, QUILL plans to apply its magnet recycling technology to the recovery of valuable metals from e-waste. “You have a mix of many different metals in those waste streams, and isolating valuable critical metals is quite a challenge,” says Nockemann. “We hope that ionic liquids can really make a difference.”
Although widespread commercial adoption of such solutions could take years or even decades, QUILL’s interdisciplinary approach and focus on market viability are pushing the shift to a circular economy in the right direction, and helping make a sustainable future more achievable.
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