Tag Archives: Dennis O’Carroll

Canadian soil remediation expert in Australia

3 Replies

Back in my Nov. 4, 2011 posting where I reviewed the third episode in a limited series on nanotechnology, broadcast as a Nature of Things television science programme on  Canadian Broadcasting Corporation stations, I noted Dr. Dennis O’Carroll’s soil remediation work in southern Ontario.

There’s more news about professor O’Carroll, currently visiting Australia, in a June 4, 2012 news item on Nanowerk,

“Toxic contamination of soils is an historical problem,” says Dr Denis O’Carroll, a visiting academic at the University of New South Wales (UNSW) Water Research Lab. “Until the 1970s, people wrongly believed that if we put these toxins into the ground they would simply disappear – that the subsurface would act as a natural filtration unit.”

“The possibility of this waste polluting the environment, and potentially contaminating groundwater sources and remaining there for decades was ignored,” he says.

Far from magically disappearing, chemical contaminants from spilled gas and solvents, when not directly polluting surface waters, seep down into the earth, travelling through microscopic soil cracks, where they accumulate and can eventually reach the groundwater table.

Traditional clean-up methods have focussed on pumping out the contaminated water or flushing out toxins with a specially designed cleansing solution, but these are limited by difficulties in accurately pinpointing and accessing locations where contamination has occurred, says O’Carroll.

His approach is to tackle toxic contaminants with nanotechnology. O’Carroll, who is visiting UNSW from the University of Western Ontario in Canada, has been trialling an innovative new groundwater clean-up technology using metal nanoparticles 500 to 5,000 times narrower than a human hair.

There are more details about O’Carroll’s specific innovations in this field in the June 4, 2012 news item. As well, I published, in its entirety (and with permission), an excellent description of nanotechnology-enabled soil remediation by Joe Martin, a graduate student at the University of Michigan, in my March 30, 2012 posting. Here’s a tidbit from Joe’s article,

… The use of iron oxides to adsorb and immobilize metals and arsenic is not a new concept, but nano-particles offer new advantages. When I wrote “adsorb”, I was not making a spelling error; adsorption is a process by which particles adhere to the surface of another material, but do not penetrate into the interior. This makes surface area, not volume, the important characteristic. Nano-particles provide the maximum surface area-to-weight ratio, maximizing the adsorptive surfaces onto which these elements can attach. These adsorptive processes a very effective at binding and immobilizing metals and arsenic, but they do not allow for the removal of the toxic components. This may be less-than-ideal, but in places like Bangladesh, where arsenic contamination of groundwater poses major health risks, it may be just short of a miracle.

There’s an extensive list with links to further reading and videos on the topic of nanotechnology and site remediation at the end of the March 30, 2012 posting.

Nature of Things’ series: The Nano Revolution (Episode 3); Will Nano Save the Planet?

2 Replies

I’m never thrilled with titles of this ilk, Will Nano Save the Planet? Refreshingly, this episode featured some work being done by Canadian scientists (two of them) although the average Canadian could be forgiven for thinking that it’s the only nanotechnology research taking place in Canada.

It’s a little puzzling that they chose this final episode for a description of the term nanoscale. David Suzuki, the host, mentioned the ridges of skin on your fingers and noted that a nanoparticle is 80,000 times smaller than the distance between the ridges. (If you want a really good description of scale, I recommend listening to Professor Ravi Silva’s audio interview with Alok Jha on the (UK) Guardian’s Oct. 14, 2011 Science Weekly podcast.)

In general, I found the descriptions of the science in this episode were not of the same standard as the previous two, which were very good.

The vignettes, as always, were problematic largely since they were internal monologues of some character who’s grappling with ethical issues and other social impacts of these technologies. Interestingly, men starred in the vignettes where the ‘big’ issues are covered: ethics of health care; longer life; access to energy sources; pollution from nanotechnology-enabled products; etc. The woman who starred in the vignettes from episode one (as I noted in my review) was concerned with cleanliness, tidiness, shopping, and privacy. I guess things don’t change that much in our future, especially in 2050 where nanotechnology protestors are putting up banners, spraypainting, and leafletting (almost as if it were 1968) to express their opposition (in episode three).

There was some interesting work being covered. They profiled Professor Ted Sargent, based at the University of Toronto, who’s doing some exciting work with solar cells (he wants to make them flexible and, even, paintable). His latest breakthrough is mentioned in my Sept. 20, 2011 posting.

Professor Vicki Colvin, Rice University in Texas, is working to purify water. The project is in Mexico and highlights the difficulties when water supplies are contaminated, in this case, with arsenic. (Here in the Pacific Northwest we tend to forget that access to fresh clean water is not easy in many parts of the world.) Colvin and her colleagues are working on a simple solution that can be implemented with some sand, gravel, a tube, and active nanoparticles. (Her work with the Environmental Nanoscience Initiative; a UK/US collaboration was mentioned in my Jan. 28, 2011 posting.)

The third project was focussed on soil remediation and a team from the University of Western Ontario headed by Professor Dennis O’Carroll. I have not come across O’Carroll’s work previously so this was a find for me. As you may or may not know, there are many sites with contaminated soil throughout North America and elsewhere. If successful, O’Carroll’s technique promises to remediate (rehabiltate) the soil without having to move massive amounts of soil and use big  equipment.

This episode featured more discussion about the risks and uncertainties associated with nanotechnology and its use. Unfortunately, I did not recognize the names and (one of my major pet peeves with this series) they either didn’t write out the names on screen or they flashed them briefly which meant that unless I recognized the names it was difficult to find out more about the experts.

I did recognize the mesocosm project at Duke University, which was featured here in my August 15, 2011 posting. The researchers are trying to understand what impact silver nanoparticles have on life. They spray silver nanoparticles in various mesocosms (they look like raised plant beds) and then track what happens to the plant, the soil, and the water supply as the silver nanoparticles cycle through.

There’s work in the UK examining air and the nanoparticles released through the use of internal combustion engines (cars/trucks) as well as our newly engineered nanoparticles. I’m glad to see this material in the episode, perhaps it will finally motivate some public discussion in Canada.