Field of research gains credence in face of growing environmental concerns

If you've ever stripped paint with solvent, you know it's a nasty job. Not only does it hurt if you get paint stripper on your skin, but you end up with a gooey mess of solvent and dissolved paint that should be disposed of as hazardous waste.
Stripping paint with solvent can be a mucky job but advances in green chemistry may improve the process. ((iStock))
If you've ever stripped paint with solvent, you know it's a nasty job. Not only does it hurt if you get paint stripper on your skin, but you end up with a gooey mess of solvent and dissolved paint that should be disposed of as hazardous waste.

What if you had a solvent that would remove the paint from your old furniture and then change its properties so the paint would separate from the solvent again? You'd be left with a small quantity of old paint, and clean solvent that could be reused.

It may sound like a dream induced by breathing paint-stripper fumes, but Philip Jessop, Canada research chair in green chemistry at Queen's University in Kingston, Ont., has developed a switchable solvent that will strip paint after being exposed to carbon dioxide, then separate from the paint when exposed to air.

Making the solvent reusable means less hazardous waste. And it's no coincidence Jessop's discovery uses carbon dioxide and air — both plentiful and harmless — to switch the solvent. Green chemistry is about chemists looking for more environmentally friendly ways to do their work.

Jessop has been doing green chemistry since the early 1990s, which puts him among the pioneers in this field of research. He is now technical director of GreenCentre Canada, a green chemistry centre headquartered at Queen's and supported by federal, provincial and industry funding. 

GreenCentre's creation earlier this year is a sign green chemistry is going mainstream.

In a 1998 book called Green Chemistry: Theory and Practice, Paul Anastas and John Warner laid out 12 principles of green chemistry. It takes a chemist to understand all the details, but the gist of them is as follows:

  • It is better to prevent waste than to clean it up.
  • It's better to produce non-toxic substances than toxic ones.
  • It's better to produce no byproducts, or at least safe ones.
  • It's better to use as little energy as possible.
  • It's better to use renewable materials.

While only a handful of Canadian researchers call themselves green chemists, the principles of green chemistry affect many chemists' work today.

"Green chemistry as a field is mostly a new way of thinking," says Chao-Jan Li, Canada research chair in green chemistry at McGill University in Montreal.

Often, though not always, those goals lead green chemists away from using petroleum products — the most common raw materials for chemical processes in the past — to using plant materials like cellulose and common substances such as air, water and carbon dioxide.

Li says almost any chemical can be made from renewables — the challenge is finding economical and efficient processes for doing so.

Tak-Hang Chan, a McGill University professor and founding co-ordinator of the Canadian Green Chemistry Network, has focused much of his work on finding ways to replace hydrocarbon-based solvents with water in chemical processes. This idea has gained acceptance, he says, but isn't yet widely used in industry.

Green chemistry is starting to get industry's attention for several reasons, most involving cost. As laws increasingly require polluters to pay for cleaning up after themselves, the economic arguments for finding cleaner processes get stronger. And, Jessop notes, eliminating waste is not just an environmental issue.

"Those atoms of pollutant are atoms that the company paid for," he says, adding that a less wasteful process is generally more economical.

Laboratory-factory disconnect

Despite the interest, there has been a gap between laboratories and manufacturers. When a multinational company hears of something interesting, Jessop says, it may contact the researcher and ask for a few kilograms of a chemical to do some tests. But the researcher usually has the facilities to produce grams, not kilograms.

"We were trying to get industry engaged by providing them with a milligram of material in the bottom of a vial," says Rui Resendes, executive director of GreenCentre Canada.

So GreenCentre Canada is not only bringing representatives of industry and academia together to improve communication, but providing support services to help get green chemistry ideas from the lab to the factory.

Moving green chemistry from lab to factory "really comes down to ensuring our survival," Resendes argues. But how much can it help?

Asked if greening chemical processes is just stalling in the face of a real need to reduce humanity's consumption, Resendes says no. The 150-year-old chemical industry is only in its infancy, he says, and there is room for huge improvements.

"I think it'll make a big difference on several levels," says Andy King, national health, safety and environmental co-ordinator for the United Steelworkers in Toronto. The union is part of Take Charge on Toxics, a coalition of health, environment and labour organizations that endorsed new Ontario regulations issued last spring to reduce toxic substances.

Besides environmental benefits, King says, green chemistry should increase worker safety.

Still, green chemistry is just one step toward solving environmental problems.

Chemical manufacturing is largely based on hydrocarbons, but still only accounts for 5 to 10 per cent of the petroleum we use, Chan says. Transportation eats up most of the rest, so to achieve serious reductions in carbon emissions, "we have to tackle the problem of using carbon for energy."

Green chemistry might help by finding better ways to produce ethanol, perhaps from cellulose, Chan says. He considers this one important challenge facing green chemistry.

Jessop says another is water purification. "If we could have an easy and inexpensive and environmentally friendly way of purifying water," he says, "that would solve so many problems."