Scientists address corrosion issues

There is a long history of lead pipes being used for drinking water distribution, in Canada and around the world. Many homeowners – with the financial fortitude to do so – have replaced them with specialized plastic over the years but lead pipes still remain in many Canadian homes.

Lead pipes are susceptible to corrosion due to the ions present in water, which can cause the lead to leach out of the piping and into the water. To try to prevent this leaching, historically some of the lead pipes in Canada were exchanged with copper pipes. However, when the replacement was only partial, the new connection of copper to lead accelerated the problem through galvanic corrosion.

This is a serious issue as lead can be very toxic to the body, says Yolanda Hedberg, Western’s Canada Research Chair in in Corrosion Science.

Yolanda Hedberg

Yolanda Hedberg is a Canada Research Chair in corrosion science.

“Cancer is a very good example, as 75 per cent of it is caused by lifestyle factors or environmental factors that can be avoided. And metal exposure, due to corrosion, is one of these issues,” said Hedberg, noting ingestion of lead can also result in reproductive toxicity, anemia, and kidney and brain damage.

Hedberg accepted her new academic appointment and moved to London last year from KTH Royal Institute of Technology in Stockholm, Sweden, in part, because of Western’s bench strength in chemistry, surface science and healthcare at the Schulich School of Medicine & Dentistry.

While her research is based on predicting corrosion and surface reactions, her collaborations and focus are grounded in health, environmental, and societal safety.

“Our workplaces and home environments are causing a lot of cancer. And sadly, metal exposure is usually affecting people disproportionately in terms of socio-economic status,” said Hedberg. “For example, people who can’t afford to get the new materials to replace corroded pipes usually get a higher exposure. They also more commonly work in occupations where you have chemical exposures. Indigenous reserves also, historically, have very high contamination rates with different metals.”

As an example, it was reported in 2016 that more than 200 homes in London, Ont. (pop. 404,699) had lead pipes replaced but it was estimated that about 4,350 homes in the city were still fully serviced with lead pipes.

“If your home was built before 1953, you should check out the water service because there is a possibility it could still be lead,” said Hedberg, a chemistry professor.

Hedberg says homes aren’t the only place where corrosion is a problem. And perhaps the biggest is the long-term storage of Canada’s used nuclear fuel, a research area of her colleague, chemistry professor Jamie Noël.

About 15 percent of Canada’s electricity comes from nuclear power. Once the power is harnessed in the nuclear reactors, the produced used fuel bundles require storage until they are no longer radioactive. There are approximately 2.9 million used fuel bundles that require permanent storage. That’s enough to fill eight hockey rinks from the ice to the top of the boards. The used fuel bundles are stored first in pools, also known as wet storage, and then in dry storage. During this time, the radioactivity of the bundles significantly decreases. The radioactivity of these bundles will diminish to the level of the natural uranium ore after approximately 100,000 years.

Jamie Noel

Jamie Noël

“We need a long-term storage solution,” said Noël, noting the Nuclear Waste Management Organization in Canada suggests the commission of a deep geological repository, in which the used fuel will be placed in copper-coated and carbon steel reinforced canisters.

These copper-coated canisters would be placed in bentonite clay boxes and buried 500 meters below ground in Canada’s bedrock. Noël’s research group at Western is studying the corrosion of these canisters to ensure that Canada’s groundwaters do not reach the fuel bundles, which could lead to the possible contamination of the surrounding environment.

Another major corrosion issue is the effects of salt on steel-reinforced concrete in Canada’s roads and highways.

In the winter, road salt is used to lower the melting point of ice. Applying it helps increase the safety of Canada’s roads by keeping them free of ice but there are drawbacks, one of which is the corrosion of metal parts of vehicles, according to Western postdoctoral associate Arthur Situm.

He explains, as the ice melts, the salty water from the road seeps into the steel-reinforced concrete of bridges, accelerating the corrosion of the steel rebar within the bridge and eventually causing the surrounding concrete to break off in a process known as spalling. This damage is costly, as it typically requires the replacement of the concrete structures, and, if left unchecked, can lead to safety concerns.

The Gardiner Expressway in Toronto is a notable example, says Situm. In 2012, after multiple instances where sections of concrete fell onto the road (and in one case a car was even struck), it was estimated by the city that a backlog of more than $500 million worth of repairs were needed.

Arthur Situm

Arthur Situm at the Canadian Light Source synchrotron. Photo: Dave Stobbe (StobbePhoto.ca)

To bring attention to the staggering US $2.5 trillion annual costs of corrosion worldwide, the World Corrosion Organization acknowledges April 24, 2021 as Corrosion Awareness Day. As part of the campaign, Hedberg, Noël, Situm, and Western students Lila Laundry-Mottiar, Claire Tully and Saman Nikpour produced a video outlining some of the major issues of corrosion:

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