Post by Andrei Tchentchik on May 1, 2020 11:34:30 GMT 2
(.#A.092).- A solution to the problem of micro-plastics in the sea.
Blue planet, green ideas: polymers of the sea.
PHOTO DAVID BOILY, THE PRESS
Dried shrimp shells used by chemists to extract the chitin.
A solution to the problem of microplastics pollution in the sea may already be found ... in the ocean. A team from McGill University is working to create a biodegradable plastic from shrimp, crab and lobster shells.
Posted on April 6, 2020 at 8:00 a.m.
JUDITH LACHAPELLE
LA PRESSE
For now, these are just small white or green plastic pellets that can only be found in the basement of the chemistry pavilion at McGill University. But tomorrow, this bioplastic may be found in the form of coffee sticks, bottles of juice, utensils, in short, everyday objects which, if they are thrown into the sea, will slowly disappear , without even leaving microtraces.
A solution to the problem of persistent microplastics in the oceans? The team of chemistry professor Audrey Moores is working hard to develop one. And the main ingredient in eco-friendly plastic that chemists are developing comes from marine waste: the shell of crustaceans.
PHOTO DAVID BOILY, THE PRESS
Audrey Moores, Associate Professor in Chemistry, in her laboratory at McGill University
It basically contains three things: protein, calcium, and most importantly, chitin. "Chitin is a cellulose-like polymer - the one found in plants," says Professor Moores, showing flakes of dried shrimp shells. "It is a polymer which has very interesting mechanical properties, it is resistant and flexible at the same time. "
To use the properties of chitin, it must first be transformed into chitosan. But the classic transformation process, developed several years ago, requires a large amount of toxic and corrosive solvents, in addition to using a lot, a lot of water. Even though it has huge stocks of crustacean waste, Canada does not produce chitosan and imports the material (used in particular in pharmaceuticals) from China.
"So we wondered if we could change the transformation process," says Audrey Moores. Instead of using solvents to separate the shell components, his team turned to mechanical chemistry.
The virtues of brewing
In a small container, chemists mix crushed shell powder with sodium hydroxide powder (soda). The container is placed in an agitator which will vigorously stir the mixture - at the rate of 30 movements per second - for five minutes, to initiate the chemical transformation.
Then, the mixture is left to stand in an oven at low temperature (50 degrees) with a controlled humidity level. Three days later, the chemical transformation is complete, and all you have to do is rinse the chitosan with a little water to be able to use it.
"This mechanochemistry technique is starting to become very popular," says Moores.
'' We realize that we can do things that normally require large amounts of solvents. It doesn't work for everything, but there are chemical reactions for which it works really well, and for which the environmental footprint is reduced.
- Audrey Moores, professor of chemistry
At the end of the operation, the new process to transform chitin into chitosan will have required much less chemicals, water and energy than the usual process.
And above all, discovered the chemists of McGill, their chitosan is not soluble in water, contrary to the usual chitosan which one uses in particular in pharmaceutical or food (do not panic for the allergic ones: the allergenic protein of the crustacean is destroyed during the process). "We discovered that our chitosan had all the properties of the one produced with the usual processes, but that in addition, the fiber was much less damaged by the process. "
PHOTO DAVID BOILY, THE PRESS
In beige and green, the polymer pellets made from chitosan extracted from the shell of crustaceans, which we see in the center of the image. The shell powder is mixed with sodium hydroxide powder (and beads to better stir the mixture) to create the chitosan.
This opens the door to its use in a panoply of solid objects that will not fear the presence of water. “Chitosan is a very interesting product. It is antibacterial, and has the property of capturing metals in water. It is also biodegradable. "If it were to end up in nature, we know that this material will eventually decompose. We don't know yet how long it will take, but we do know that there are all the microbes, all the enzymes in the sea to be able to break them down. "
Recovering waste from the sea
So far, Audrey Moores has perfected the process by producing a few grams of chitosan at a time. But soon, the experiment will go into high gear thanks to the arrival of several kilos of crustaceans from Nova Scotia in the Montreal lab.
No, chemists will not stuff themselves with Maritime lobster just for the sake of science… They will rather use the shell of the green crab, an invasive species that has destroyed ecosystems in Kejimkujik National Park, in southern New Scotland, and which biologists are happy to get rid of for a good cause.
CANADIAN PRESS ARCHIVE PHOTO
A green crab, photographed in the waters of Kejimkujik National Park in Nova Scotia. This invasive species destroys eelgrass aquatic plants in particular, where migratory birds nest.
One thing is certain, there is no shortage of crustaceans in the country to feed the researchers' shredders. "The companies that process shellfish in the Maritimes and Quebec are facing a waste problem," says Moores. "There is a big demand from people in the industry to promote this product. "
According to studies, almost 9 million tonnes of plastic waste end up in the oceans each year. The amount of crustacean waste, on the other hand, amounts to around 8 million tonnes per year. "We're not going to replace all the plastics in the world with this bioplastic," says Audrey Moores. "But if we replace single-use plastics, already, we will tackle part of the problem. That’s the goal. "
F I N .
Blue planet, green ideas: polymers of the sea.
PHOTO DAVID BOILY, THE PRESS
Dried shrimp shells used by chemists to extract the chitin.
A solution to the problem of microplastics pollution in the sea may already be found ... in the ocean. A team from McGill University is working to create a biodegradable plastic from shrimp, crab and lobster shells.
Posted on April 6, 2020 at 8:00 a.m.
JUDITH LACHAPELLE
LA PRESSE
For now, these are just small white or green plastic pellets that can only be found in the basement of the chemistry pavilion at McGill University. But tomorrow, this bioplastic may be found in the form of coffee sticks, bottles of juice, utensils, in short, everyday objects which, if they are thrown into the sea, will slowly disappear , without even leaving microtraces.
A solution to the problem of persistent microplastics in the oceans? The team of chemistry professor Audrey Moores is working hard to develop one. And the main ingredient in eco-friendly plastic that chemists are developing comes from marine waste: the shell of crustaceans.
PHOTO DAVID BOILY, THE PRESS
Audrey Moores, Associate Professor in Chemistry, in her laboratory at McGill University
It basically contains three things: protein, calcium, and most importantly, chitin. "Chitin is a cellulose-like polymer - the one found in plants," says Professor Moores, showing flakes of dried shrimp shells. "It is a polymer which has very interesting mechanical properties, it is resistant and flexible at the same time. "
To use the properties of chitin, it must first be transformed into chitosan. But the classic transformation process, developed several years ago, requires a large amount of toxic and corrosive solvents, in addition to using a lot, a lot of water. Even though it has huge stocks of crustacean waste, Canada does not produce chitosan and imports the material (used in particular in pharmaceuticals) from China.
"So we wondered if we could change the transformation process," says Audrey Moores. Instead of using solvents to separate the shell components, his team turned to mechanical chemistry.
The virtues of brewing
In a small container, chemists mix crushed shell powder with sodium hydroxide powder (soda). The container is placed in an agitator which will vigorously stir the mixture - at the rate of 30 movements per second - for five minutes, to initiate the chemical transformation.
Then, the mixture is left to stand in an oven at low temperature (50 degrees) with a controlled humidity level. Three days later, the chemical transformation is complete, and all you have to do is rinse the chitosan with a little water to be able to use it.
"This mechanochemistry technique is starting to become very popular," says Moores.
'' We realize that we can do things that normally require large amounts of solvents. It doesn't work for everything, but there are chemical reactions for which it works really well, and for which the environmental footprint is reduced.
- Audrey Moores, professor of chemistry
At the end of the operation, the new process to transform chitin into chitosan will have required much less chemicals, water and energy than the usual process.
And above all, discovered the chemists of McGill, their chitosan is not soluble in water, contrary to the usual chitosan which one uses in particular in pharmaceutical or food (do not panic for the allergic ones: the allergenic protein of the crustacean is destroyed during the process). "We discovered that our chitosan had all the properties of the one produced with the usual processes, but that in addition, the fiber was much less damaged by the process. "
PHOTO DAVID BOILY, THE PRESS
In beige and green, the polymer pellets made from chitosan extracted from the shell of crustaceans, which we see in the center of the image. The shell powder is mixed with sodium hydroxide powder (and beads to better stir the mixture) to create the chitosan.
This opens the door to its use in a panoply of solid objects that will not fear the presence of water. “Chitosan is a very interesting product. It is antibacterial, and has the property of capturing metals in water. It is also biodegradable. "If it were to end up in nature, we know that this material will eventually decompose. We don't know yet how long it will take, but we do know that there are all the microbes, all the enzymes in the sea to be able to break them down. "
Recovering waste from the sea
So far, Audrey Moores has perfected the process by producing a few grams of chitosan at a time. But soon, the experiment will go into high gear thanks to the arrival of several kilos of crustaceans from Nova Scotia in the Montreal lab.
No, chemists will not stuff themselves with Maritime lobster just for the sake of science… They will rather use the shell of the green crab, an invasive species that has destroyed ecosystems in Kejimkujik National Park, in southern New Scotland, and which biologists are happy to get rid of for a good cause.
CANADIAN PRESS ARCHIVE PHOTO
A green crab, photographed in the waters of Kejimkujik National Park in Nova Scotia. This invasive species destroys eelgrass aquatic plants in particular, where migratory birds nest.
One thing is certain, there is no shortage of crustaceans in the country to feed the researchers' shredders. "The companies that process shellfish in the Maritimes and Quebec are facing a waste problem," says Moores. "There is a big demand from people in the industry to promote this product. "
According to studies, almost 9 million tonnes of plastic waste end up in the oceans each year. The amount of crustacean waste, on the other hand, amounts to around 8 million tonnes per year. "We're not going to replace all the plastics in the world with this bioplastic," says Audrey Moores. "But if we replace single-use plastics, already, we will tackle part of the problem. That’s the goal. "
F I N .
