When Vicki Chen describes her area of expertise as ‘membranes’, it might not mean much to the average person. But membranes, which can be all manner of thin, permeable barriers, could offer solutions to two key challenges that the world will need to overcome with increasing urgency: excess CO2 and dirty water.
Solution #1: Filter water on a global scale
For more than a century, scientists have known that filling the atmosphere with carbon dioxide – a by-product of fossil-fuel consumption – will have dire consequences for the planet. What hasn’t received so much attention, until very recently, is what’s happening to the world’s fresh water supply.
One consequence of climate change is increased droughts, and more severe water shortages. Mismanagement of land, through agricultural and waste run-off, can also cause water pollution and scarcity. These two forces together could mean that two-thirds of the world’s population may face water shortages by 2025, according to the World Wildlife Fund.
Membranes may help, by filtering out contaminants and salt.
“The bulk of my career has been in filtration, for example, filtration for processed liquids, resource recovery, desalination and wastewater treatment,” says Chen, who is a professor of chemical engineering and executive dean of the Faculty of Engineering, Architecture and Information Technology at the University of Queensland.
Having grown up in the US, in a “smallish town in Tennessee,” Chen moved to Boston to complete her undergraduate degree in chemical engineering at MIT, and went on to earn her PhD at the University of Minnesota.
“What I worked in was actually closer to the ‘surface science’ area,” she says, adding that the 1980s was a time when the subject was leaping ahead. Surface science looks at what happens at the meeting points of different materials, such as when rain hits a glass window and forms a droplet structure. Surface scientists concern themselves with processes like lubrication, adhesion, and friction, among others.
“Researchers were starting to understand the molecular interactions that govern what structures get formed. And that allowed them to synthesise really sophisticated architectures in terms of catalysts, or membranes, or many of the things I work in now.”
Chen became interested in water-treatment technologies early in on her career, and she’s since developed a type of membrane that acts as an ultra-thin filter, which can trap impurities and turn wastewater into fresh water.
She’s also been developing filters that can extract minerals from brines (concentrated salt solutions).
The brine water is placed in an evaporation pond, and as it evaporates, it leaves salts and minerals behind. Separating the minerals from the salts is a difficult and time-consuming process using current technologies, so Chen is developing a membrane that can do the separations instead. She’s hoping that this will be a better way to recover the metal lithium, a critical component of batteries, such as those that power electric cars.
She’s also working on ‘novel nanocomposite membranes’, where carbon dioxide is separated from natural gas, leaving purer methane, a cleaner fuel, behind. To achieve this, Chen is developing entirely new materials.
Solution #2: Strain CO2 from power plant emissions
For the past five decades, Chen’s work has focused on ‘nanocomposite materials’. “This basically means combining the best properties of a polymer material with very highly tailored nano materials,” she says.
The result is something like a crystalline structure that’s flexible but also porous. “That’s really the cutting edge if we’re going to make better membranes, or better batteries – to engineer it into an architecture that will work in a practical setting,” says Chen.
At their most basic, these materials can be used as super-fine filters, which can separate things at a molecular level. “If the structure is right, you don’t even have holes anymore,” says Chen. “You can use it for separating carbon dioxide from emissions from power plants, or from natural gas.”
The chemistry is challenging, as the membranes need to survive both pressure and water. But the implications are startling.
Chen says CO2 emissions could be removed from coal-fired plants. “If we were to separate CO2 from the gas and concentrate it to the point that it’s economically viable, then we could either store it or put it in some other chemical process.”
Solution #3: Attract more women to engineering
Chen has spent her career creating all kinds of new types of membranes, but she has another important goal: she wants more women to enter the field of chemical engineering.While programs such as Women in Engineering, an industry-funded initiative that aims to build networks of engineering women across Australia, are important, she says, more work needs to be done.
The issue isn’t a shortage of female students, says Chen, but the fact that talented women have so many options in front of them, from technology to science to medicine. “We have to sell our discipline,” she says. “The students have a lot of choice.”
While the word “engineering” might conjure up an image of a man in a hard hat, flying in and out of remote areas, the truth, says Chen, is that there is a great diversity of career pathways on offer today.
Companies still want technical depth, but they’re also building much more diverse teams,” she says. They need employees who aren’t just technically skilled, but who can articulate what it is they do and why it’s important, says Chen. “You’ve got to be able to get up there are talk about why you did something.”
The engineers of the future are going into a world that has greater uncertainty and complexity, and bigger problems that must be solved, which means they must be able to articulate what they do, clearly and simply. Chen says that when she’s telling her own story, she’ll say, “I’ve worked on everything from potato protein to wastewater to CO2 capture and hydrogen separation.”
As for what she does next, Chen says water remains a priority. “Power plants needs a lot of water,” she says. “We will still suffer droughts. We still have poor quality water.”
But her hope is that by developing new membranes, the world will not only clean up its water, but it will also recover valuable materials – without doing more environmental damage. “It’s about being more efficient in the way we use things,” she adds.
Article by Felicity Carter
Photo Credit: Photo supplied