Water recycling gets better with nanotechnology

 

- Edmonton, Alberta

Water, water everywhere. Did you know that the water spraying your vehicle in a car wash is recycled? That the golf course you're playing is irrigated with reused water?

New nanotechnology developed by the National Research Council of Canada (NRC), in partnership with IBM Almaden Research Center, the IBM Alberta Centre for Advanced Studies (IBM Alberta CAS), and the University of Alberta (UofA), could reduce the use of fresh water and decrease emissions in Alberta's oil sands.

The IBM-patented membrane technology has the potential to improve water re-use in everything from vehicle car washes to golf course irrigation to toilets.

"While our technology has been developed to support the backbone of Alberta's economy, it has far-reaching effects for Canada and the world," said Andrew Myles, R&D Director of the NRC's Nanotechnology Research Centre. "Our advanced nanotechnology offers a promising solution to those issues by more efficiently removing pollutants from oil-produced water."

Thanks to membranes that, like giant sieves, strain impurities out of water or separate good liquid from bad, the life of the world's water supply can be extended. But current technology is not enough to dampen the wide-ranging effects of global warming, extensive pollution and diminishing freshwater resources.

In many cases, freshwater usage is essential to industries that support local economies. Canada's Alberta oil sands, for example, requires water to soften and extract bitumen (thick, tar-like oil used in asphalt) from the sand so it can be sent through a pipeline to an oil refinery. While some of that water is being recycled, the limitations of existing technology restrict the quantities that can be processed.

At 165 billion barrels, the Alberta oil sands contains the world's third-largest oil reserves.

"We need large-scale water purification techniques that are less expensive, more robust and scalable," adds Myles.

A rising tide of membrane technology

The main obstacle preventing membranes from working effectively is organic, inorganic and biological substances that clog—or foul—their surfaces and pores. This not only reduces membrane performance, but also increases operating costs. An innovative and cost-effective solution is a newly developed membrane technology: star block copolymers (also known as polymeric nanoparticles), which improve membrane antifouling properties.

In 2016, under the leadership of IBM Alberta CAS, along with researchers from the NRC, IBM Research, and the UofA, a formal alliance was formed in Edmonton to develop an effective antifouling solution for water-purification membranes.

"IBM's vast portfolio of advanced materials, the NRC's exceptional infrastructure and expertise in nanoscale materials and characterization, and the UofA's in-depth knowledge of water purification techniques were the platform on which we built this productive project," said Mohtada Sadrzadeh, Director of the Advanced Water Research Lab at the UofA.

Researchers at IBM Research-Almaden invented the unique design of star block copolymer self-assembled monolayer coatings. Dr. Young-Hye Na leads the membrane materials project and energy storage program at IBM Almaden Research Center in San Jose, California. She is also an adjunct professor at the UofA.

Dr. Na took on the enormous challenge of improving the design of anti-fouling coatings technology for membranes, which is particularly difficult given the conflicting requirements of anti-fouling while not degrading membrane throughput. She also helped pioneer the use of self-assembling star polymers for antifouling membranes at IBM.

"The Canadian researchers (NRC and UofA) have outstanding characterization and membrane fabrication and testing capabilities, so the molecules-to-materials-to-technology spectrum was covered by this fantastic collaboration," said Na.

NRC nanotechnology researcher Jae-Young Cho agrees that IBM's patented membrane coatings using polymeric nanoparticles had exciting antifouling possibilities. While the product was a good candidate for holding stable coatings that repel oil and gas, it had to be examined and tested for a number of factors, including the ability to withstand high temperatures and rough processing.

A specialist in microscopy analysis, Cho used the NRC's electron and atomic force microscopes to bring the nanoparticles into sharp focus, pinpoint their characteristics, and conduct a number of tests. These included analyzing the effects of scraping and heating, assessing the membrane's thermal and mechanical stability, and detecting the tolerance of the surface for water (hydrophilicity and hydrophobicity).

"This is a difficult task that is absolutely critical to characterizing the membrane," Sadrzadeh says. "The images that Cho produced are the best I have ever seen and provided us with a new path to our research."

At the end of that path was an innovative solution for bringing hydrophilicity to the membrane: coating it with a unique polymeric nanoparticle that clings strongly to the surface and blocks fouling substances. 

Membranes: a mainstay of water purification

This collaborative research could have a significant impact on water management in the Alberta oil sands and beyond. In the oil sands, Sadrzadeh estimates the antifouling membranes could reduce freshwater usage by up to 15% and greenhouse gas emissions by another 15%. With proper maintenance, they can last for 5 to 7 years, significantly reducing industrial contamination and energy consumption.

Membranes can also be adapted for various processes in residential and municipal water treatment. There is no limit to the types of nanoparticles that can be used to coat the membranes—whatever their size—to filter out a range of contaminants including salt, impurities and viruses.

Myles points out that this project is a good illustration of how the NRC, by bringing together government, academia and industry, provides leadership in solving Canada's toughest problems.

"Our success is truly collaborative and is due to the commitment of all parties. The momentum we have gained will lead to continuing innovation and nanotechnology advancements," Myles says.