I wanted to make a difference and 25 years ago I completely embraced the concept of green chemistry. The idea says, “Let’s start from scratch and make chemistry benign by design.”
As chemists, we cannot continue to do the same without considering the environment. Enough is enough. And I think society finally understands. Despite what some politicians tried to tell us a few years ago, climate change is real, it is measurable. We have bushfires and floods. And we have plastics in the environment and in the oceans.
In chemistry, it went from a moral obligation to take this green path to a matter of time before it became a legal obligation.
As chemists, we cannot continue to do the same without considering the environment.
The 12 principles of green chemistry, presented by Paul Anastas and John Warner, say you don’t just change a process to make it cleaner, because you’re not getting far – you’re still going to generate waste if you use the same toxic reagents in your process . Green chemistry is not a band-aid approach. It’s about making sure we don’t create something that negatively impacts the environment and is sustainable. When it was first proposed it was a paradigm shift and as President of the Royal Australian Chemical Institute I helped to involve many people. This ultimately led to the securing of the Australian Research Council’s Center of Excellence in Green Chemistry.
Overall it is now a great movement. These days, if you’re doing any type of chemistry and applying to a funding body, and you don’t integrate the principles of green chemistry, it is very unlikely that you will obtain this funding.
When I started my green chemistry research, I was interested in applying these green concepts to continuous flow processing. It’s a no-brainer: if you do your research and you run liquid through a reactor and it flows and flows, then you can do all the basic science, and guess what? Unlike batch processing, scalability is already taken into account from the start, so the same research device can be your processing device. This way you can speed up production, potentially bypassing the pilot steps you would normally have to do for conventional batch processing.
You’re not just changing a process to make it cleaner, because you’re not going any further.
I was thinking of trying to make nanomaterials under continuous flow, and I wanted to do this by applying clean mechanical energy rather than adding any kind of auxiliary chemical. And that ultimately led to the design of the vortex fluidic device – the VFD. This is the device that won me and my colleagues the Ig Nobel Prize in 2015.
Understanding how fluids flow has been one of the great unsolved questions in science. Now, by understanding how liquids flow through our vortex fluidic device, simply by applying mechanical energy, we are taking a big step forward. The application potential is immense.
We recently published an article in chemical sciences showing how immiscible liquids behave at very small dimensions. Immiscible liquids are those that you wouldn’t normally think of mixing, such as oil and water. But we have shown how the VFD can mix immiscible fluids down to nanometric dimensions. It took more than 100,000 experiments to figure it out, but the consequences are enormous. We make emulsions with implications for everything from drug delivery to salad dressings.
Understanding how fluids flow has been one of the great unsolved questions in science.
We published on this subject recently in Nature: food science. We put fish oil nanoparticles in apple juice. If you use a homogenizer, everyone can taste and smell fish oil. But if you do it at the nanoscale in the VFD, kids can’t tell the difference between drinking apple juice and drinking apple juice with all the good omega 3s in it.
So what is VFD? It’s basically a rotating test tube with a little lip at the top, and you tilt it off axis at 45 degrees. You have liquid in there, and then you introduce rotating mechanical energy into that liquid. Now you have the maximum cross factor gravity pushing down and you have the centrifugal force holding the liquid against the tube.
The device is only 20mm in diameter and about 20cm long, but you can build larger units for high volume processing. That’s all it is. You can have jet feeds delivering reactive liquids inside the tube. And as they swirl around and come out of the tube, they go through all of these changes. This is your continuous flow process.
With this device you get the formation of Faraday waves in the liquid, and you get Coriolis forces from the base of the tube. And all this mechanical energy is transmitted down to less than a micron in the dimensional regimes. Knowing this is the key to all these other wonderful apps.
With the VFD, we can partially deboil an egg, which we do by refolding the proteins.
With the VFD, we can partially deboil an egg, which we do by refolding the proteins. Protein folding is a huge problem for the pharmaceutical industry. We were also able to speed up a variety of enzymatic reactions, which is another big deal.
An article has just come out showing how graphene oxide can be made. There are many applications of graphene oxide, but the way they traditionally make it uses concentrated sulfuric acid and toxic metals. We have developed a process using our VFD with almost zero waste. All you need is aqueous hydrogen peroxide and graphite. We call it GGO – Green Graphene Oxide. It is a registered trademark.
We have also published work on the use of VFD to extract DNA from extinct species that have been preserved in formalin. Some of these species are over 150 years old.
A test that took four hours comes down to four minutes in the VFD.
We use VFD to amplify the detection of biomarkers. Initially, it was focused on COVID-19 – a test that took four hours boils down to four minutes in the VFD. In the future, there will be good applications of VFD in wine processing, because you won’t be adding chemicals. At certain processing parameters, we can cut carbon nanotubes to specific lengths for applications in devices. It’s very big too.
Because we now understand the flow of fluids in the device, it speeds up more and more applications. Even though we have published more than 100 articles on VFD applications, we still haven’t reached the end of the beginning.
My interest in chemistry ‘exploded’ in Year 12 at John Curtin Secondary School in Perth in 1967. My chemistry teacher blew me away. He was very young, a Mr Stockdale. He was teaching in the country, but he came to Curtin – and he had it all figured out.
If you fully understand your chemistry, you understand your environment.
Our school overlooked Fremantle Harbor and at the time they were blasting for a deep water channel. We would look out the classroom window and periodically see these huge plumes of water rising after these explosions. And he was like, “Oh, I can do better than that.
He had then set up some very exciting experiments. But then we would sit down and go through all the chemistry to explain it. It was then that I realized that if you fully understand your chemistry, you understand your environment. I haven’t looked back.
As told to Graem Sims for Cosmos Weekly.
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