Posts Categorized: News 2022

Traffic-related pollution in Toronto: Prof. Jeff Brook featured in The Narwhal

Professor Jeff Brook has studied traffic-related air pollution for over 20 years and is now the principal investigator on a team developing interactive tools that allow users to combine air pollution modelled on a map with socioeconomic data from the census.

This story is part of Toronto’s Climate Right Now, a collaboration with The Local about vulnerability and adaptation in Canada’s largest city. Read the full news story.

Curbside dining: SOCAAR featured in The Toronto Star

With curbside patios out in full force along Toronto city streets, Professor Greg Evans says that the air quality pros outweigh the cons when it comes to outdoor dining. Read the full story by The Toronto Star
titled ‘How unhealthy is it to eat in a curbside patio next to traffic? Most CaféTO diners can breathe easy.’

Recovering nickel from mining waste

Leonardo Shen

Shen pictured conducting his research in the lab.

The mining industry in northern Ontario, particularly in Sudbury, has been the economic backbone of this region. As the mining operations generate profits, they also produce large amounts of waste in the form of pyrrhotite tailings, which has become an environmental burden. Under the supervision of Professor Vlad Papangelakis, Heping (Leonardo) Shen (ChemE PhD student) is finding ways to alleviate the economic burden of neutralizing pyrrhotites through a project entitled, nickel recovery from pyrrhotite tailings using a two-step microbially catalyzed process.

“According to 2010 estimates, the total dry weight of pyrrhotite tailings had reached between 50 – 100 million metric tonnes. They are now stored under water, which is more of a containment rather than a treatment. This is not sustainable, as dissolved oxygen in the water will slowly but surely oxidize the buried wastes causing what’s called the acid-mine drainage. During this process, massive acid production will occur, lowering the pH of the water body below 3, which is enough to eliminate almost all living organisms in surrounding ecosystem. An environmentally friendly and economically viable process needs to be developed to ensure the sustainability of the mining operations in this area,” details Shen.

Current treatment of pyrrhotite is associated with enormous costs in neutralization because of the acid production. However, Shen discovered a silver lining!

“A very small amount of nickel (up to 1 wt%) is entrapped in those wastes and recovering this valuable metal could potentially alleviate economic burden. Some acidophilic (acid-loving) microbes like Acidithiobacillus ferrooxidans and can help in the digestion of those solid wastes, liberating the nickel for recovery,” explains Shen.

This is a process called bioleaching, which has several advantages compared to conventional pyrometallurgical (i.e. burning solids) processes. Most notably, it produces no air pollution and requires significantly less energy input.

Leonardo Shen's research equipment

The bioreactor Shen used for his continuous ferrous bio-oxidation experiments.

“If we think the pyrrhotite tailings with nickel entrapped as the enemy to be broken apart, then ferric ions (Fe3+) are the soldiers we deploy. Once the enemy (pyrrhotite) is attacked (leaching), our soldiers are sadly spent … together with freshly released iron from the pyrrhotite they become ferrous ion (Fe2+),” analogizes Shen.

“Now is the time for our microbes to shine! Normally in acidic conditions the conversion of ferric ions (Fe3+) to ferrous ion (Fe2+) is extremely slow, but microbes like At. ferrooxidans can greatly accelerate this process, making sure there’s always enough soldiers to attack the enemy. The only problem is that those microbes will also convert released elemental sulfur to sulfuric acid when there’s oxygen, and we want to minimize that,” explains Shen.

Shen’s approach separates the ferric ion attack and the ferric ion regeneration into two steps, removing the released elemental sulfur in between via simple solid-liquid separation. By doing this, his method avoids the mass production of acid and benefits from the accelerated reaction speed from the microbes.

With the growing need for nickel in EV-battery manufacturing and the depletion of high-grade nickel ores on a global scale, the mining industry is turning its eyes to low-grade ores and wastes, like pyrrhotite tailings. The process Shen is developing and the mechanistic understanding he has learned from developing this process compliments this industrial-focus shift, as well as strengthens sustainability of mining operations in northern Ontario.

Shen’s research was conducted in collaboration with fellow ChemE researchers Dazhi Ren, Srinath Garg, and Christine Romano. Their work has been published in the COM2020 proceedings in 2020 and is set to be published at the IBS conference, which will take place at the end of this year. Their project is funded by the Ontario Ministry of Research and Innovation and Ministry of Northern Development and Mines, Genome British Columbia, and NSERC.

Grads to Watch 2022

With the University’s Convocation ceremony on June 16, 2022 U of T Engineering students mark the end of one journey and the beginning of another.

Having enriched the U of T Engineering community as undergraduate and graduate students, they will join our vibrant, global network of Skule™ alumni, where they will continue to address pressing challenges around the world and inspire the next generation.

This year’s 14 “Grads to Watch” — selected by their home departments and institutes — embody the spirit of U of T Engineering. Their stories illustrate the creativity, innovation and global impact that define our community. Among the group are Brohath Amrithraj (ChemE 2T1 + 1) and John Anawati (ChemE PhD 2T2). Watch their next steps!

Teaching legacy of the two Bills

Bill Burgess and Bill Graydon

L-R: Bill Burgess and Bill Graydon, 1979

The very first issue of Interfaces* back in Spring 2003, ran a story about the “two Bills,” Bill Graydon (ChemE 4T2, MASc 4T5) and Bill Burgess (ChemE 3T9). The story highlighted their love for teaching. Snippets are presented here:

The two Bills first met in 1954 in the basement of Wallberg. They felt an instant affinity. Burgess still fondly recalls the dehydrated orange on Graydon’s desk, the subject of an experiment about water evaporation.

 When asked to describe a memorable day, each Bill recounted a similar incident. Graydon came to a lecture in which all the students sported white cotton batting on their chins in imitation of his beard. Burgess, who routinely wore a red cardigan and bow tie, walked into class and found all his students similarly attired. Both Bills were touched by what they regarded as an affectionate gesture.

Discussing his love of teaching, Prof. Burgess said: “There’s nothing so wonderful as when the light bulb goes on…. as I look out and see all the students, I see myself. The wonderful feeling when you finally understand something, and you want to share your insight with others to help them understand too.” Graydon, whose father was the manager of Shea’s Theatre on Bay Street where Red Skelton began his career, says that students remember him for his humour: “When they’re laughing, they trust you.” He summed up with the following remark: “I believe nobody teaches anybody anything. All you do is provoke people to learn, and humour is the best way.”

Professor Graydon retired in 1984 and fondly kept the dehydrated orange in his prize possession until his passing on February 28, 2011. Professor Burgess who retired in 1989 continues to hold his dear friend close to his heart. Their friendship and affection for teaching inspired thousands of students including ChemE Professors Grant Allen (ChemE 8T1, MASc 8T3), Levente Diosady (ChemE 6T6, MASc 6T8, PhD 7T2), Don Kirk,(ChemE 7T2, MASc 7T5, PhD 7T9), Mark Kortschot (ChemE 8T4, MASc 8T5), Joseph Paradi (ChemE 6T5, MASc 6T6, PhD 7T5), Michael Sefton (ChemE 7T1), and Christopher Yip (ChemE 8T8) just to name a few.

“I believe I can speak on behalf of all of their former students and colleagues, when I say that the two Bills lived to motivate and encourage everyone around them,” says Christopher Yip, Dean of the Faculty of Applied Science & Engineering. “They not only opened our minds to the positive impacts we could create, but also demonstrated the powerful and lasting impression that teachers have on students … An amazing teacher is hard to find, and even more impossible to forget.”

On November 24, 2021 the bench in front of the Wallberg Building was officially dedicated to the two Bills. Dozens of family, friends, former colleagues, and students gathered on June 11, 2022 by the bench to celebrate the remarkable influence that the two Bills have had on teaching within U of T Engineering.

Among those in attendance was Professor Emeritus Joseph Paradi. “I had both Bills as professors when I was an undergraduate student. They were such great friends and did so much for the department. One memory that sticks with me is when Professor Graydon paid for new windows out of his own pocket so we could have natural light in one of our main lecture rooms,” recalls Paradi. “It is because of the professors like the two Bills that ChemE continues to attract the best and brightest when it comes to faculty and students.”

If you were a former student or colleague and are on campus, we invite you to share a bench selfie. If you are on Facebook, Professor Burgess would love to hear from you.

*Interfaces was an alumni magazine for the Department of Chemical Engineering & Applied Chemistry, produced and distributed annually between 2003-2017.

Wood-derived prototype could lead to self-powered biosensors

Wood-derived materials can be used to harvest electrical energy from everyday movements such as walking, according to a new study from researchers at U of T Engineering and the University of Waterloo.

In a paper recently published in Nano Energy, the team demonstrated the use of lignocellulosic nanofibrils, derived from tree bark, in a prototype self-powered device capable of sending a wireless signal to a smartphone via Bluetooth.

Such devices can be used to track biometric data such as heart rate, oxygen levels or skin conductivity. The innovation could improve the performance of these devices while lowering their environmental impact.

“Biosensors are common in wearable electronics, but today they are powered by batteries,” says Professor Ning Yan (ChemE), final author on the new paper.

“This makes them bulky, inconvenient and costly. Sensors without batteries could be thinner, smaller and cheaper. You would never again have to worry about forgetting to charge the battery. You could just stick it on your skin, and it would be powered by your natural movements.”

The principle behind the innovation is the trioboelectric effect, a form of static electricity. Because some materials attract electrons more than others, repeatedly bringing two different materials in contact and then separating them can cause an electrical charge to build up between them.

Read the full U of T Engineering News story.

Water capture and recycling using Forward Osmosis and Freeze Crystallization

Runlin Yuan and Noel Devaere in their lab

Runlin Yuan and Noel Devaere in their lab

Water scarcity has been a growing issue, including in developed countries. The lack of treatment methods for concentrated effluent in the mining and metals manufacturing industry is one of the contributors to the problem. Under the supervision of Professor Vlad Papangelakis, ChemE PhD students Noel Devaere and Runlin Yuan are focusing on water separation and recycling with Forward Osmosis (FO) and Freeze Crystallization (FC) to reduce the industrial reliance on freshwater in a low-energy cost-effective manner.

“Forward Osmosis and Freeze Crystallization are known technologies, but they have not been widely adopted because of certain disadvantages when operating as standalone treatment methods,” explains Devaere.

To mitigate these disadvantages, Devaere and Yuan have found that an FO-FC hybrid process works best, as it overcomes the stand-alone disadvantages and also reduces the overall energy requirements compared to traditional thermal recovery methods such as evaporation.

This hybrid process operates even better as a climate-driven process because of additional reductions in energy consumption under cold weather conditions, such as Canadian winters, particularly in the north where several mining operations exist.

Devaere and Yuan believe their project will provide an alternative solution for industrial wastewater recovery. They are also seeking to reduce the environmental impact of mine and metal refining operations to put Canadian primary metal production at the forefront of sustainability.

“In reducing the industrial wastewater discharge and reliance on freshwater, we are helping to preserve the aquatic environment and making the increasingly precious freshwater resource more accessible to the people in need,” says Yuan.

Titled, Hybrid forward osmosis – freeze concentration: A promising future in the desalination of effluents in cold regions, Devaere and Yuan’s research has been published in the Journal of Water Process Engineering. Their research was funded by NSERC, Agnico Eagle Mines Ltd, Vale, and Neo Performance Material Inc.

Alumna creating new & innovative 3D prints using glass flakes

Umema Khan

Umema Khan

Umema Khan (ChemE MASc 2021), a Materials Print Engineer at Markforged, applies the knowledge she’s gained during her grad studies to continue to create new and innovative 3D printing material formulations with additional kinds of 3D printing technologies.

Under the supervision of Dr. Mark Kortschot, Khan investigated new and innovative 3D printing materials. In her research titled, High stiffness glass flake reinforced composites produced using inverted stereolithography, Khan used a method of 3D printing called inverted stereolithography (iSLA). This method typically has fewer applications reliant on mechanical properties since the resins used do not have the properties to withstand the weight of such applications.

One of the major benefits of iSLA over other forms of 3D printing is its dimensional accuracy. “Within research, there was a major gap in combining customization of 3D printing combined with the precision of iSLA and the capability to withstand loadbearing applications,” Khan says. “I was able to bridge this gap by incorporating glass flakes into these resins and create a material that had a modulus of over 10GPa with the ability to increase this further. This is something that was beyond what was previously thought to have been achievable with this technology.”

Khan says what makes this research innovative is that using glass flakes circumvents the flow issues created by more traditional methods of reinforcing polymers, such as glass fibers and spherical particles, which affect the flow of the 3D printing process. “By incorporating glass flakes, I was able to achieve strong final mechanical properties and was simultaneously able to achieve successful prints.”

3D printed bird on a pumpkin

A sample of a fun metal print Umema made during her time at ChemE

Although her work is not yet published, Khan is hopeful that her research will soon open up doors for applications that will require precision, advanced 3D printing, and load-bearing capabilities.

Through the knowledge and experience that she gained during her graduate work, Khan now works on independently formulating and optimizing new materials based on their ability to print alongside their final material properties. In her role as a Materials Print Engineer at Markforged, she works with a different type of 3D printing technology called Fused Filament Fabrication (FFF), but also works to develop new materials that the company will ultimately sell to customers.

Collaborative research will improve outcomes for retinal-detachment surgeries

Retinal detachment (RD) is a serious medical condition in which vision in an eye is partially or fully lost because of the separation of the retina from the retinal pigment epithelium (RPE). ChemE Professor Arun Ramchandran and Dr. Rajeev Muni, Vice Chair in the Department of Ophthalmology & Vision Sciences at U of T and an eye surgeon at St. Michael’s Hospital and Kensington Eye Institute, are collaborating to improve outcomes following surgeries that repair RDs.

Two of the common procedures used to treat RD include pars plana vitrectomy (PPV) and pneumatic retinopexy (PnR). Although most patients have a reattachment of the retina after one of these procedures, patients can suffer from a post-surgical visual disturbances or distortion. One potential adverse outcome after RD repair includes retinal displacement. This occurs when the retina is significantly displaced from its original position relative to the RPE.

“Retinal displacement can lead to the patient seeing objects as smaller or distorted in the operated eye and this can compromise the patient’s functional vision,” explains Muni. One study performed by the group revealed that 44% of PPV surgeries result in displacement, as compared to only 14% in PnR surgeries. The groups of Ramchandran and Muni are working together to understand how the type of ocular tamponade that is used during the procedure can impact the risk of retinal displacement. They have also expanded their work to explain the physiology of how corrugations in the retina can occur with RD and the potential implications of this.

“Lubrication stresses, fluid relocation in the sub-retinal region, and hydration induced swelling and corrugation of the retina are three mechanisms that have been explored in our work to explain the differences in the risk of displacement with PPV vs PnR,” say Ramchandran. “We have also been able to characterize abnormalities that occur in the retina at the time of RD (outer retinal corrugations); and based on mathematical models, have been able to shed light on their pathophysiology. This is critical as it has given us great insights on how the retina should be best reattached,” elaborates Muni.

Ramchandran and Muni have already published three papers regarding the mechanistic details of displacement with different types and sizes of tamponade, and they are anticipating one on corrugations and its implications for management. Additionally, the pair along with Muni’s colleague Dr. Hillier, have been invited to prepare a review paper for the highest impact journal in the field of Ophthalmology. Their research contributions will pave the path for significantly improving therapeutic strategies for RD. Specifically, creating new RD-repair techniques that reattach the retina as close as possible to its original status.

Research on liquid film stability reveals mechanism behind destabilization on solid surfaces

Suraj Borkar

Suraj Borkar (ChemE PhD student)

For his research project titled “A New Perspective on the Stability of Liquid Films on Solid Surfaces”, Suraj Borkar (ChemE PhD student), under the guidance of Professor Arun Ramchandran, set out to better understand the cause of destabilization of films of hydrophobic liquids (for example oil) sandwiched between a liquid medium (like water) and a solid surface. Thin films of oil tend to break up into droplets under such conditions.

“For decades, researchers have accepted that for this thin film of oil to remain stable (i.e. it does not break up into droplets), the film thickness must be large, typically greater than 100 nm,” Borkar explains. “When films are thin (less than 100 nm), intermolecular forces can cause the oil film to become wavy, eventually causing the film to break up into oil droplets.”

While the mechanism behind the destabilization of thin layers was well understood, thicker layers were also observed to destabilize and this process was more mysterious. Classical theories explain that the destabilization occurs as a result of the presence of tiny and unavoidable dirt particles in the oil film. “However, even when researchers took extreme effort to avoid dirt particles, thick films still destabilized. Hence, the origin of instability for thick films has been a mystery until now” says Borkar.

The culmination of his research led to the discovery that the insolubility of the two liquids is not absolutely zero, and that this trace solubility was the cause of the destabilization, causing droplets to eventually form on the solid surface over time.

“We stumbled upon this observation back in 2015 and it took us seven years to thoroughly understand the mechanistic details” says Borkar. “I think the novelty of this research is that dissolved material spontaneously condenses on the solid surface in the form of droplets, without changing any thermodynamic property, such as temperature or pressure, that can lead to oversaturation conditions.”

Borkar says the utility of this discovery has applications in both industrial and commercial settings, for example the extraction of crude oil or the recycling of plastics. “A more niche area of research involves DNA transcription where transcription factors (typically water-soluble proteins) condense on a DNA molecule and commences the process of copying the genetic material in the DNA into a messenger RNA.”

Borkar’s research was published in the September 2021 issue of Nature Communications, a peer-reviewed, open access, scientific journal.

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