Researchers at Trent University, Canada, have developed a novel method to accelerate the production of magnesite at room temperature in an attempt to fight climate change.
Magnesite (MgCO3), a naturally-forming mineral found in playa, or dry lake, environments, can capture and store carbon dioxide — the notorious greenhouse gas — from the environment.
Scientists have been researching ways to harness this capability to use in the fight against climate change, but up until now the carbon sequestration process was far too slow.
When magnesite crystals form, they absorb surrounding carbon dioxide in a process called mineral carbonation. Researchers around the world have been investigating this process as a potential method of removing greenhouse gasses from the atmosphere.
In nature, a metric ton of magnesite is capable of extracting half a metric ton of carbon dioxide from the atmosphere. It also provides a stable way of storing carbon dioxide in the long term.
But it grows at an incredibly slow rate. As a result, the idea of using it to sequester carbon on a large scale has been completely unfeasible, up until now.
For the first time, researchers have explained how magnesite forms at low temperatures and devised an effective way to accelerate the speed of its formation.
“The rate is very slow and it can take hundreds to thousands of years for magnesite crystals to form,” said lead researcher Ian Power, an environmental geochemist at Trent University and founder of PowerGeoLab, an environmental geochemistry lab based in the School of the Environment.
“The reason for these sluggish rates is that magnesium ions in solution are tightly surrounded by six molecules, which makes it difficult to form an anhydrous mineral like magnesite.”
The researchers used polystyrene microspheres to catalyze the process, dramatically speeding up the crystallization rate.
Previous research by co-author Paul Kenward, a postdoctoral fellow in the Department of Earth, Ocean and Atmospheric Sciences at the University of British Columbia, suggested that the use of these microspheres could facilitate mineral formation.
“In experiments, we used carboxylated reactive surfaces that are able to pull away some of those water molecules, thus targeting the rate limitation and facilitating magnesite formation on the scale of tens of days at room temperature,” said Power.
With the microspheres as a catalyst, magnesite crystals would form within 72 days. The process occurs at room temperature, so it is energy-efficient. The polystyrene microspheres are also unchanged in the process, so they can be reused.
These characteristics suggest that the process — if scaled up significantly — could be used as an effective tool to remove carbon dioxide from the atmosphere.
“The big advantages of storing carbon dioxide in carbonate minerals is that they are stable for long periods of time and environmentally safe,” Power said.
“There are many researchers studying various ways to sequester carbon dioxide, including technologies that form carbonate minerals. Our research has shown a novel pathway for magnesite formation, but it’s certainly not the only option available for capturing and storing carbon dioxide in minerals.”
The field of carbon capture and storage (CCS) has been on the rise in recent years, as researchers around the world have led efforts to find methods of sequestering inert carbon dioxide.
Scientists have explored using everything from water ferns to laser pulses to pull in the greenhouse gas. A number of these experiments have been promising, but are difficult to replicate on a large scale.
“The challenge with all carbon sequestration technologies is developing ones that not only work (many have been shown to work), but are cost-effective,” said Power.
“I’m a strong believer that we need a multitude of solutions to reduce greenhouse gas emissions, and I’d be very pleased if our research can be one of a large number (thousands) of solutions.”
