by I he wanted to make a difference and 25 years ago I fully embraced the concept of Green Chemistry. The idea goes, “Let’s start over and make chemistry ‘good by design.’
As chemists, we can’t just keep making more of the same without considering the environment. That’s enough. And I think society is finally getting it. Despite what some politicians tried to tell us a few years ago, climate change is real, it is measurable. We have fires and floods. And we have plastics in the environment and in the oceans.
In chemistry, it has become almost a moral obligation to follow this green road in a matter of time before it becomes a legal obligation.
As chemists, we can’t just keep making more of the same without considering the environment.
The 12 Principles of Green Chemistry, formulated by Paul Anastas and John Warner, say that you don’t just tweak a process to make it cleaner because you only get so far—you’ll still be creating waste if you use the same toxic reagents in your process. Green Chemistry is not a band-aid approach. We make sure not to create anything that has a negative impact on the environment and is sustainable. When it was first proposed, it was a paradigm shift, and as president of the Royal Australian Institute of Chemistry, I helped get a lot of people involved. This ultimately led to securing the Australian Research Council Center of Excellence in Green Chemistry.
Globally, it is now a big movement. These days, if you’re doing any kind of chemistry and applying to a finance company, you too no consider the principles of Green Chemistry, it is highly unlikely that you will get this funding.
At the beginning of my Green Chemistry research I was interested in applying these green concepts to continuous flow processing. It’s not unreasonable: if you do your research and you run some liquid through a reactor and it flows in and flows out, then you can do all the fundamental science and guess what? Unlike batch processing, scalability is already taken into account from the start, so that the same survey device can be your processing device. This way you can speed up production, potentially skipping the pilot stages you would normally have to do for conventional batch processing.
You don’t just tweak a process to make it cleaner, because you only go so far.
I was thinking of trying to make nanomaterials under continuous flow and wanted to do it by applying pure mechanical energy rather than adding any kind of chemical helper. And this 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 science’s great unsolved questions. Now, by understanding how fluids flow in our fluidized vortex device, simply by applying mechanical energy, we are taking a huge step forward. The application possibilities are huge.
We recently published a paper on Chemical Science which shows how immiscible liquids behave in very small dimensions. Immiscible liquids are ones you wouldn’t normally think of mixing – like oil and water. But we have shown how the VFD can mix immiscible liquids at nanometer dimensions. It took over 100,000 experiments to figure this out, but the implications are huge. We make emulsions with implications for everything from drug delivery to salad dressings.
Understanding how fluids flow has been one of science’s great unsolved questions.
We recently published on Nature: Food Science. We put fish oil nanoparticles in apple juice. If you use a homogenizer, then everyone can taste and smell the fish oil. But if you do it on a nanometer scale in the VFD, kids can’t tell the difference between drinking apple juice and apple juice with all the good omega 3s in it.
So what is a VFD? It’s basically a rotating test tube with a little lip on top and you tilt it off-axis to 45 degrees. You have fluid in there, and then you introduce rotational mechanical energy into that fluid. Now you have maximum cross gravity pushing down and you have centrifugal force holding the fluid in the tube.
The device is only 20 mm in diameter and about 20 cm long, but you can build larger units for high volume processing. That’s all. You can have jet feeds that deliver reagent liquids into the tube. And as they swirl and come out of the tube, they undergo all these changes. This is your streaming process.
With this device, you get the formation of Faraday waves in the liquid and get Coriolis forces from the base of the tube. And all this mechanical energy is transmitted in less than one micron in dimensional regimes. Knowing this is the key to all these other great apps.
With VFD we can partially wash an egg, which we do by folding proteins.
With VFD we can partially wash an egg, which we do by folding proteins. The protein patent is a huge deal for the pharmaceutical industry. We were also able to speed up a variety of enzymatic reactions, which is another big deal.
A paper has just come out showing how we can make graphene oxide. There are many applications of graphene oxide, but the way it is traditionally made 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 trademark.
We have also published work on the use of VFD to extract DNA from formalin-preserved extinct species. Some of these items are over 150 years old.
A test that took four hours is reduced to four minutes on the VFD.
We use VFD to enhance biomarker detection. Initially, it focused on COVID-19 – a test that took four hours is reduced to four minutes at VFD. In the future, there are some good applications of VFD in wine processing because you are not adding chemicals. At certain processing parameters, we can cut carbon nanotubes into specific lengths for device applications. It’s too big.
Because we now understand the fluid flow in the device, it accelerates more and more applications. Although we have published more than 100 papers on VFD applications, we have not yet reached the end of the beginning.
My interest in chemistry “exploded” in year 12 at John Curtin High School in Perth in 1967. My chemistry teacher blew my mind. He was very young, Mr. Stockdale. He taught in the country but came to Curtin – and had it all together.
If you fully understand your chemistry, you understand your environment.
Our school overlooked Fremantle Harbour, and at the time they were blasting for a deep water channel. We would look out the classroom window and periodically see these huge clouds of water rise up after these explosions. And he was like, “Oh, I can do better than that.”
He had then created experiments that were very exciting. But then we would sit down and do all the chemistry to explain it. Then I realized that if you fully understand your chemistry, you also understand your environment. I haven’t looked back.
As he told Graem Sims for Cosmos Weekly.
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