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A closer look at sustainability

Cutting Edge presents research on iron nanoparticles

On the evening of Thursday September 11 members of the public quietly packed into the quaint Redpath Museum auditorium, where just hours ago hundreds of students were in attendance for Soup and Science. It was now their turn to keep up to date with the latest scientific research and to mingle with leading scientists as part of Cutting Edge lectures.

Cutting Edge is a science lecture series, where every month a professor is invited to give a talk on their research, why it’s important, and why we, as a society, should be interested in it. The lectures are tailored to the public but are also useful for scientists from other disciplines.

The series remains one of the only forums in place to counter the barriers that exist between scientists and the public. Barriers such as scientific literature laden with heavy jargon are both inaccessible due to the presentation of the concepts and the financial cost of subscriptions needed to access them in the first place as an individual.

The need for Cutting Edge came from scientists who wanted to have a stronger basis of understanding between disciplines. As one organizer explained, “These lectures were conceived back in 2003 because a number of people here at McGill got […] fed up trying to understand what our colleagues in other departments were saying, and finding [their presentations] incomprehensible.” This frustration resulted in the creation of Cutting Edge.

The topic of this month’s lecture was green chemistry, featuring Audrey Moores, an associate professor from the chemistry department, as the main speaker. Green chemistry aims to minimize the hazardous effects that chemical products and processes have on human health and the environment. Moores believes sustainable chemistry can aid in the global project of sustainability.

Moores began her talk with an open question to the audience: “What do you know about sustainability?” Answers came in from confident and eager audience members and the question evolved to “What do you find unsustainable?” One audience member shouted “mobile phones,” another person “fisheries,” and someone else added “CO2 emissions.” Moores acknowledged that these answers all fall into the common perceptions of sustainability: biodiversity and the carbon cycle. She added “the problem of sustainability goes far beyond just carbon.”

Unbeknown to most, many electronics contain precious elements such as gold, silver, and platinum.The iPhone contains eight rare earth metals alone. Although mobile phones may use minute quantities of elements and rare earth metals, they are sold in extremely large quantities; Apple has sold more than 500 million iPhones since 2007. The high demand for electronics has resulted in a scarcity for certain elements and an excess in electronic waste, which is often mixed and thus very difficult to recycle – creating an unsustainable cycle. This has resulted in experts predicting metal and element shortages in the near future.

Phosphorus is an element that suffers from unsustainable usage. “We are talking about a resource that is essential for agriculture to allows us to grow food.” said Moores. Phosphorus can only be mined, and most of the world’s supply comes from four countries: China, Morocco, South Africa and the U.S.. Its high demand has caused global concern, with China stopping the exporting of its supply. While there is a scarcity in terms of obtaining phosphorus for agriculture, there is also an excess in terms of phosphorus leaching into lakes and rivers causing eutrophication, a type of water pollution that can disrupt an entire ecosystem by overloading it with nutrients. Recently, in August, a toxic algae bloom in Lake Erie caused hundreds of thousands of people in Ohio to switch to bottled water – the cause was linked to run-off phosphorus from fertilizers that leached into the lake. The overload of phosphorus, a nutrient, fed the algae and caused the bloom. Another example of scarcity and excess resulting in unsustainability.

A parallel can be drawn with the mining industry where the extraction of the minerals cause scarcity on one end, and the mixing and dilution of minerals result in excess on the other as the product becomes near- impossible to recyclable.

Tackling sustainability in chemistry, Moores’ research group focuses on specializing in the use of Fe0 (or iron zero) nanoparticles in traditional reactions such as hydrogenation. Fe0 nanoparticles are non-toxic and cheap due to the relative abundance of copper, and can be produced by grinding old iron scraps.

Hydrogenation, the addition of a hydrogen atom to a molecule, is used in a variety of fields from petrochemistry to pharmaceutics when producing ibuprofen. The problem with hydrogenation is its reliance on heavy metal catalysts such as palladium, platinum, and rhodium, which are all toxic and very expensive. In theory, heterogenous catalysts can be infinitely reused, but in reality they become deactivated over time and, like a printer cartridge, need to be replaced. In pharmaceutics, the heavy metal catalysts need to go through scavenger columns, which are costly machines with complicated polymers to filter out the metals that leached into the ibuprofen, to meet regulatory requirements on heavy metal concentration in the final product.

Using naked Fe0 nanoparticles is not a new phenomenon; however, they are impractical due to the extreme reaction with oxygen and water, creating a rust coating larger than the nanoparticle, and making it unreactive. Moores and her group are using Fe0 nanoparticles coated with a iron oxide, rust, shell that protects the Fe0 from oxidation with water allowing, it to maintain its reactivity. Moores pointed out another method for making Fe0 water-resistant including using a polymer block coating, making the use of Fe0 particles feasible in industry.

In the case of pharmaceutical hydrogenation, using the Fe0 nanoparticle coated with a iron oxide shell as an alternative catalyst to heavy metals provides a more economical and sustainable solution as the nanoparticles can be recovered due to their magnetic properties, and have a lower toxicity than the heavy metals. Moores mentioned several further applications of the nanoparticles she designed with her team, such as in biology, where it can be used to simplify the tracking of testosterone for researchers studying breast cancer development. The nanoparticles could also be used to purify contaminated ground water where the shelled Fe0 nanoparticles can transfer their electrons to destroy contaminants or sequester metals.

Moores’ research shows us there are ways to move away from precious metals in chemistry and replace them with abundant and environmentally friendlier metals such as iron, rust, and copper. The potential benefits of using iron oxide shell-protected Fe0 nanoparticles include reducing element scarcity by using more abundantly available elements, reducing pollution by using fewer elements and reusing chemicals, and improving food and drug safety by using non-toxic reagents. However, the human health and safety implications of nanoparticles remain vastly unexplored. Moores agrees more research is required to get a better perspective on the impact nanoparticles could have on humans in the long term.