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We all want the things that we use every day to be greener.
Unfortunately, even if something feels really green in the hands of us consumers,
the path it took to get to us… might not be.
It might require hazardous chemicals to make, or generate a lot of waste.
Or be harmful to people actually making it as well as to the environment.
But it’s not like chemists don’t care. They want a greener world too.
And they’re in a position to do something about it.
That’s the idea behind green chemistry,
an approach chemists have been working on since the 1990s
to make chemistry safer at every step of the way — not just for consumers.
Green chemistry is about creating new technologies and processes
that will keep chemicals financially viable and effective,
but will also make sure they’re not harmful to the environment
or to the people who make them and use them.
And based on its guiding principle of “benign by design,”
green chemistry has already done a lot of good for the world.
So let’s take a look at five everyday things
that green chemistry has made safer and, well, greener.
It turns out that like money, decaf coffee doesn’t grow on trees.
You start with regular coffee, and take the caffeine out.
Technically, all you need to decaffeinate coffee is water.
Water is cycled through vats of green, unroasted beans,
picking up some of the caffeine on the way.
Then, the caffeine-infused water goes through a charcoal filter that removes some of
the caffeine, allowing the water to dissolve more, and the cycle repeats.
You might say that this process already sounds pretty green,
since it’s mostly based on good ol’ H2O.
That’s true, but the problem is that along with the caffeine,
it also can also remove a lot of the compounds responsible for flavor,
resulting in decaf that’s a little... bleh.
See, water is a very good solvent… too good.
So a lot of substances, like coffee flavor compounds,
can easily dissolve in it and hitch a ride out of the coffee bean.
So to improve on the process, decaf makers turned to less versatile solvents,
usually methylene chloride or ethyl acetate.
These certainly help preserve the coffee’s flavor, but concerns have been raised
about their safety — especially in the case of methylene chloride.
These solvents are common ingredients in things like degreasers or
nail polish removers, and can be toxic when not handled right.
For example, methylene chloride can cause respiratory damage
if you inhale too much.
But green chemistry aims to improve chemical safety for people
as well as reducing environmental impact.
And it has a solution that’s safer for coffee makers and drinkers alike.
It’s supercritical CO2.
The “supercritical” part doesn’t mean that it’s a chemical that’s really hard to please.
The name refers to the critical point, where a substance is
between two states: neither liquid, nor gas.
When carbon dioxide becomes supercritical, it turns into an amazing solvent.
Like a gas, it can easily penetrate all the nooks and crannies
of something like a caffeine-packed green coffee bean.
And like a liquid, it can easily pick up the caffeine and spirit it away.
It’s also much better at that than the solvents that came before.
It can extract more of the caffeine, around 98%.
And it’s much more of a selective caffeine sniper,
so it takes it away without destroying that rich coffee flavor.
It’s also not toxic, but you may be wondering how using carbon dioxide
could really be all that green.
After all, CO2 in the atmosphere is what’s responsible for climate change.
But in a decaffeination plant, the CO2 can be reused multiple times.
And since it’s extracted from the air in the first place,
it’s not going to increase the net amount of carbon dioxide in the atmosphere,
even if some of it accidentally gets released.
So thanks to green chemistry, you can sip your decaf
without worrying about harming the environment.
As long as you remember to recycle the cup.
Catalysts are substances that increase the rate of chemical reactions.
And they can increase it by a lot.
Something that takes a fraction of a second to make with a catalyst
could take years to produce without it.
The pharmaceutical industry is in the business of
using chemical reactions to produce complex molecules,
so they really could not exist without catalysts.
Those catalysts are often made from heavy metals,
or other substances with significant environmental impacts.
Thankfully, nature has provided us with a ready-made solution.
Once we’ve made appropriate tweaks, of course.
See, living cells happen to be experts at making catalysts.
They’re called enzymes, and they facilitate the many chemical reactions
that keep us alive.
Enzymes are made of protein, encoded by DNA.
Which means they’re biodegradable, and light on heavy metals.
And the pharmaceutical industry is starting to adopt them as greener catalysts.
Sitagliptin is one of the most commonly used type 2 diabetes medications.
Traditionally, the process of producing the drug required energy-heavy,
high-pressure equipment, as well as rhodium catalysts,
which are highly toxic and can cause cancer.
In 2009, two companies figured that all of that could be helped
by the use of transaminases.
Transaminases are enzymes that, among other things,
help our cells build the proteins that we’re made of.
In the drug, they instead make a chemical change
to help build the final desired molecule.
Naturally occurring transaminases weren’t efficient enough
to replace the rhodium catalysts.
But scientists used genetic engineering to create a beefed-up transaminase
that was 25,000 times more efficient than the transaminases found in our body.
That allowed the makers of sitagliptin to replace the energy-guzzling
high-pressure equipment and toxic catalysts with a simplified, greener process.
Another example is the widely used cholesterol-buster simvastatin.
This medication is derived from a fungus, but the process necessary to do that
involved the use of large amounts of hazardous chemicals.
Like n-butyllithium, which...sort of turns the air
into an explosive when handled improperly.
It also generated a lot of harmful waste.
But just like with sitagliptin, researchers tried to find
naturally occurring enzymes that could make things better.
And what they ended up going with was a kind of acyltransferase, an enzyme which,
among other things, helps our cells process chemical signals.
The researchers bioengineered the enzyme
to jack up its efficiency as a catalyst by about 1,000 times.
That allowed them to greatly reduce waste and cut out
multiple dangerous chemicals, making the whole process much greener.
Your laundry can also be greener!
And not only when your whites get a new springtime sheen
thanks to that stray Incredible Hulk sock.
We’re talking about cold water detergents –
which get your laundry clean at lower temperatures than traditional ones.
Which means you’re doing the environment a favor
by using less electricity for the wash cycle.
But thanks to green chemistry, cold water detergents are also more
environmentally friendly even before you feed them into your washing machine.
Most laundry detergents are derived from petroleum –
you know, that stuff that’s also a fossil fuel.
But things changed with the discovery of metathesis, a new approach to
chemical synthesis that got its creators the 2005 Nobel Prize in chemistry.
To develop greener detergents,
a company called Elevance used metathesis to break apart plant-derived oils,
then assembled the resulting building blocks into novel chemicals.
That process cuts energy use and greenhouse gas emissions by half
when compared with detergents made from petroleum.
And reduces demand for petroleum itself.
So cold water detergents are a double whammy.
They’re helping you save energy and cut your carbon footprint.
And by cutting out petroleum and reducing energy usage,
chemical manufacturers are making them greener before they ever get to you.
In the late 1960s, firefighters started adding foaming agents to water
in order to make it better at fighting fires.
These are basically chemicals that turn water into foam.
Foamy water is better at absorbing heat, and it doesn’t evaporate as quickly,
which means it will easily seep into hot spots that could restart the fire.
And because it stays around for a while,
it forms a sort of blanket that cuts off the oxygen needed to keep a fire going.
Initially, firefighting foams used fluorinated surfactants,
which are also found in things like heat-resistant packaging.
These were useful for any kind of big fire — like building fires or forest fires.
But it turned out that these fluorine-based foaming agents
easily penetrated into groundwater and would stay there for decades.
They would also build up in the bodies of aquatic animals, not to mention us humans,
causing thyroid problems and several types of cancer.
So many governments have worked to phase out fluorine —
but it’s been hard to find a substitute that’s anywhere near as effective.
However, one major producer of firefighting chemicals
has come up with a greener alternative that still works to fight fires.
This new firefighting foam doesn’t contain any fluoride.
Instead, it uses polysaccharides, which are basically chains of sugar molecules.
This greener formula is better at quashing fires than traditional firefighting foams,
and it completely breaks down within 42 days,
instead of sticking around to cause problems.
There’s a lot we can learn from a DNA sample. But small amounts of DNA are often
not enough for our technology to read out and interpret.
So for everything from forensic analyses to testing for viral infections,
we usually start by turning a little DNA into a lot — using a technology called PCR.
PCR, or polymerase chain reaction,
is a way to chemically multiply the DNA in a sample that we want to test.
In theory, it produces billions of copies from just a single molecule.
And allows our devices to easily analyze it and do a lot of cool stuff with it,
like genome mapping or paternity testing.
But it’s not just for shocking reveals on talk shows.
Many of us, or those we know, have taken a PCR test —
because it’s one of the technologies that makes it possible
to diagnose someone with an active COVID-19 infection.
So this technology is a workhorse of both molecular biology and public health.
Which makes it unfortunate that it comes with a particular environmental drawback.
PCR needs deoxynucleotide triphosphates, or dNTPs, in the mix.
dNTPs are simply the building blocks
that those billions of copies of our DNA fragment will be assembled from.
But making these dNTPs requires the use of multiple hazardous chemicals,
like the highly corrosive zinc chloride — or methylene chloride,
the bane of caffeine extraction.
However, the biotech companies that supply the ingredients
for PCR are working to change that.
One company uses a new green synthesis process
that cuts down on those nasty solvents by 95%,
and it also creates ten times less chemical waste as a byproduct of making dNTPs.
We’re definitely not going to stop doing PCR — but this way, every year,
the environment gets hit with around 700,000 kilograms less of toxic waste
from just a single production plant.
There’s still a lot of progress to be made in ensuring
the chemical industry is as safe and as green as it can be.
Technically, chemical manufacturers aren’t yet required to prove
that the space-age plastic in your new smartphone
is not going to make you grow a new nose,
or make all the birds in your yard drop dead,
until you complain that it did.
Basically, green chemistry is something we rarely hear about:
activism within the scientific community to make their own field safer,
because the stuff they produce affects everyone, from firefighters to decaf makers.
And green chemistry principles are now being adopted by
key players in the chemical industry all over the world.
Which is going to make things in our everyday lives just a little bit safer —
for us and the planet.
Thanks for watching this episode of SciShow,
and thanks as always to our patrons for helping to make it happen.
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