Contributed by David Constable, Contributed by David Constable, Director, ACS Green Chemistry Institute®
Last week I attended and spoke at a Materials Research Society meeting. It was very interesting despite having only a short time to spend there, but I was reminded once again of how many ways in which the lines between chemistry, chemical engineering, physics, biology and other sciences are blurred in certain areas of scientific pursuit. I have often said that for me, the really interesting science occurs at the interfaces of many different scientific and engineering disciplines, and that is especially true in sustainable and green chemistry and engineering. There are a great many areas where a better understanding and use of new materials in alternative energy, transportation, carbon capture, etc. will significantly impact efforts to make society more sustainable.
It’s the end of the year and one of the things I’m often asked about is to opine on what I think is important in green chemistry and engineering. So, I’d like to take just a few moments and lay that out at a very high level. I generally chop things up into four areas: Chemicals, chemistries, design and processes.
When it comes to chemicals, I think chemists need to think more about where things come from, and they need to start making different choices about the chemicals they use. This falls into two general categories, but in both cases, the emphasis needs to be on sustainably sourcing chemicals. The two areas are inorganics and organics. From an inorganic perspective, it’s mainly about metals and key elements like platinum group metals (elements that are crucial to electronics as we currently manufacture them), rare earths, and basically anything that isn’t earth abundant. For organics, it’s mainly about getting chemicals from something other than petroleum or other fossil sources of carbon (natural gas, coal/syngas, etc.). There is too much to write in a short post, but I think we need to move from fossil-based feedstocks and non-renewable elements to renewable feedstocks and closed-loop systems, with a lot more attention paid to what is known as waste valorization or getting chemicals from what we now think of as waste.
In order for us to transition to sustainable and green chemicals, we will need to think about different ways in which we do chemistry. What I have in mind here for organic chemistry is different reaction chemistries, separation processes, and chemical manufacturing processes optimized for non-fossil based sources, greater reliance on synthetic biology and/or other bio-based production platforms to perform industrial-scale synthesis.Think about it for a moment. All of the organic chemistry we are taught is predominantly about using something we get from petroleum and activating a limited number of framework molecules, or functionalizing them, or otherwise changing the oxidation states of the carbon atoms. By comparison, framework molecules from biological sources are generally highly functionalized and in different oxidation states, so we need to think about how we change the functionality and build new molecules in a way that doesn’t require a lot of mass and energy. If we think about inorganics, we typically use heat and pressure to make what we want, and that translates into some very high energy processes. In addition, a lot of materials we use now and which are the darlings of the automotive industry, electronics, or the alternative energy industry are just not terribly abundant.
Which brings me to thinking about chemical and product design and how that needs to change. Here, it’s my opinion that we need to think more about function-based chemical/product design approaches; e.g., rather than designing a chemical that kills a bacteria, we design a surface that doesn’t allow microbial adhesion so it does not have a place to grow, or we don’t allow bacteria to create a film that promotes their collective growth and survival. Or, we think about adhesion in some applications like we see with a gecko; i.e., use Van der Waals forces to hold things together vs. forming a chemical bond. There are a variety of examples like this, so I won’t belabor the point. If you think about what it is that you want in terms of the specific outcome and work back from that, it can change the way in which you approach the problem or the solution we deliver.
Finally, we need to think about changing the way we make things. From manufacturing processes to things we do as we pass through our days need to use less mass and energy; i.e., we need to do more with less, with less waste and with less toxic chemicals. The idea that society will always be able to obtain what it needs to support an ever-increasing population with new and interesting products and basic needs like adequate food, water and shelter without any problems is just not sustainable.
This is a whirlwind summary that begs for additional clarification and hopefully I can speak a bit more about these things in the next year. It’s hard to believe that another year has drawn to a close, but there is no lack of challenges and those challenges are creating an abundance of opportunities. I look forward to next year and continuing to move green chemistry and engineering forward with you. Thanks for all you’ve done this year to make the world a better place.
As always, let me know what you think.
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