Introduction to Green Chemistry

Do you recycle? Compost? Turn off the lights when you leave a room? If so, you’re practicing environmental sustainability. You recognize that our planet has limited resources. And you support its long-term health.

Chemists design all kinds of products. These include plastics, pesticides and pharmaceuticals. In the past, they focused on these products’ usefulness. They didn’t necessarily think about sustainability. But many products turned out to be harmful for the environment. So did the processes used to make them. Chemists who focus on the environmental impacts of products work in a growing field called Green Chemistry.

In green chemistry, scientists think about a chemical’s impact from the laboratory, to the disposal site, to the environment. One way they can evaluate this impact is with the 12 Principles of Green Chemistry.

Let’s look at four of these principles in detail.

Principle #1 : The Prevention of Waste

This principle applies to many aspects of life, inside and outside the laboratory. You might try to produce less garbage at home. Chemists try to produce less chemical waste.

You might not think of a car as something that produces waste, but it does. Inside a car’s engine, fuel and oxygen from the air undergo a chemical reaction called combustion. This produces the energy needed to move the car. But it also produces harmful byproducts. These include carbon dioxide (CO₂) and nitrogen oxides (NOx). Both are greenhouse gases that trap heat in our atmosphere. They are causing our Earth to warm and our climate to change.

Luckily, cars have something that helps reduce the harmful chemicals they produce. It’s called a catalytic converter. This works while the car is running. It changes pollutants into less harmful molecules before they exit the car’s tailpipe. The molecules emitted include oxygen (O₂), nitrogen (N₂), and water (H₂O).

Image - Text Version

Shown is a colour illustration of a catalytic converter, cut to reveal the materials inside. The converter is a silver metal, almond-shaped object with open pipes at each end. On either side of the pipe openings are empty bolt holes. Layers are cut away from the nearest side. The outer layer of metal is cut away to reveal a layer of darker metal. Most of the cavity inside is filled with two oval shaped blocks. These are coated in a rough, speckled, pale grey material. Inside, the block is made of a pale orange honeycomb, or fine gridded material.

Did you know?

In 2021, transportation was the second largest source of greenhouse gas emissions in Canada. This sector accounted for 22% of total national emissions.

Principle #2 : Atom Economy

Imagine you’re making cookies. You measure out two cups of flour. But you only end up needing one. If you threw out the other cup, that would be very wasteful!

Sadly, chemists can also cause waste when making products with chemical reactions. Green chemists try to reduce this by looking at atom economy. Atom economy includes questions like, “What percent of atoms from the reactants are incorporated into the product? What percent of atoms are wasted?”

For example, photosynthesis is a reaction that occurs in plants. This leads to two products: glucose (C₆H₁₂O₆) and oxygen gas (O₂). If glucose was the desired product, then oxygen gas would be a waste product.

Students from the University of Toronto explain green chemistry principle #2, atom economy (3:57 min.).

In green chemistry, products should have a high atom economy. Most of the ingredients added during the process should be used to make the final product.

You might have an example of green chemistry in your medicine cabinet: ibuprofen. This is the active ingredient in Advil and Motrin. The old method of making ibuprofen was wasteful and inefficient. Of the atoms used, only 40% made it into the final product. In the 1990s, the manufacturer developed a new method, using principles of green chemistry. Since the change, 77% of the atoms from the reactants are now in the final product! This innovation earned the manufacturer a Green Chemistry Challenge Award in 1997.

Principle #9 : Catalytic Ingredients

A catalyst is a substance that helps a chemical reaction happen, or makes it go faster. Catalysts can lead to reactions that produce less waste or have a greater atom economy.

Remember the catalytic converter? As its name suggests, the converter contains a catalyst. This catalyst helps convert some toxic gases into less harmful ones.

As a bonus, the catalysts in the catalytic converter aren’t used up in each reaction! That means they can be used over and over again.

Did you know?

Vehicles with Diesel engines use different catalytic converters than vehicles with gasoline engines.

Principle #11 : Real-Time Pollution Prevention 

Imagine you have a leaky faucet. It's better to fix it right away, rather than waiting for the kitchen to flood, right? That's what real-time pollution prevention is all about. Chemists aim to fix problems before they can cause damage to the Earth.

One strategy is called carbon capture. The goal of carbon capture is to remove excess carbon dioxide from the air before it becomes a problem. Carbon capture technology works by:

• Collecting carbon dioxide before it can escape into the atmosphere
• Storing it safely
• Reusing or neutralising it to make it into useful materials

Did you know?

Two scientists at the University of Ottawa won Royal Society of Canada Medals for their work on carbon capture technology. Read about them here.

Careers in Green Chemistry 

Green chemistry principles are important. They help chemists make some products less harmful to the environment. They mean more efficient processes with less waste material, less energy used, and less hazardous waste to clean up!

If you're passionate about protecting the environment and you want to be part of the solution, a career in green chemistry might be perfect for you. Here are some exciting careers options:

Environmental Chemist: Finds solutions to environmental problems like pollution and climate change.

Chemical Engineer: Designs processes to create products in an environmentally friendly way.

Sustainability Consultant: Helps organisations become more environmentally responsible by advising them on green chemistry practices.

Research Scientist: Explores new ways to make chemicals and processes more sustainable.

Interested in learning more? Check out the profiles of some cool people who work with green chemistry!

Magali Houde (she/her)

Research Scientist

See Magali Houde (she/her)'s profile

Karissa Palinka (she/her)

Technical Engineer

See Karissa Palinka (she/her)'s profile

Rachel Chow

Wastewater Process Engineer

See Rachel Chow's profile

Somto Ibe

Engineer, Renewable Energy

See Somto Ibe's profile

Graham Ballachey

Vice President, Engineering

See Graham Ballachey's profile

Fairy Sahay

Civil Engineer (Green Economy Project)

See Fairy Sahay's profile

Even if you do not pursue a career in green chemistry, you can still apply green chemistry practices! For example: 

• Reduce the waste you produce by recycling or composting when possible
• Try to choose products made using green chemistry practices
• Be mindful of how you use transportation in your community
• Dispose of harmful waste carefully. For example, recycle batteries and electronics at designated locations. Or return unused medicine to your pharmacy instead of pouring it down the drain.