Molecular sponge absorbs toxins, produces biofuel

University of Saskatchewan | Cost effective way to produce biofuel using polysaccharides

Lee Wilson thinks he has found a cost effective way to help produce biofuel using wheat straw.

In a lab at the University of Saskatchewan, the chemist and his team of graduate students have developed various types of what Wilson terms “molecular sponges.”

Some sponges are designed to take specific impurities out of water, such as pesticides. Others can remove toxins from water used in the oilsands.

Still another sponge separates ethanol and water to make cellulosic ethanol.

“It’s a game changer for parts of the agro economy,” he said.

Wilson’s sponges comprise building blocks of components in plant materials that can be isolated and further modified to form different molecular sponge materials. In other words, they can be customized for the job.

“With our material, it’s a purely physical process,” he said.

“We’re not adding any chemicals in. The polysaccharides that we’ve engineered are not soluble in water. It’s like a powder you sprinkle in but it doesn’t dissolve. You can regenerate that back again just by filtering it off. It’s basically a green chemistry approach.”

Biomaterials like straw are known to have an affinity for chemical separations. Wilson described a “wow moment” three years ago when he recognized what the bioactive component was in wheat straw.

Having access to that component in its purified form helped him build a better sorbent material.

He said wheat straw has three or four to one separation ability.

“Our materials had a 60 to 1 separation. It jumped up to a factor of 15 and that was the first go around. We need to optimize this. We’re hoping that if we can boost this up to 100 to1 or more, (it) would be great, but even as it stands now is exciting,” he said.

“What it means is what was previously an energy intensive chemical separation using distillation, we can now do spontaneously at room temperature.”

Ron Kehrig of Enterprise Saskatchewan isn’t familiar with Wilson’s technology, but he said doing something else at the energy intensive part of the distillation stage would be good if it reduces energy consumption.

“Anything that can be done to reduce the energy consumption in the dehydration of ethanol would be something that the industry would obviously take a look at very seriously and would improve the energy balance of the entire ethanol plant,” he said.

Wilson said the process is done without chemicals because the sponges are not dissolving in water. They stay put as a solid device. Dirty sponges can be washed and reused.

Companies and government have become interested.

“It’s beyond theoretical because we have results that show,” he said.

“We’ve been able to pull pesticide residues out of water down to low enough levels that if you had a contaminated drinking water supply you could really use a system like this to wash out all the pesticides and have clean drinking water.”

Wilson said the technology is well suited for producing cellulosic ethanol, which has traditionally relied upon distillation.

While conventional techniques work, he questions whether they are economically feasible.

“The commercial value of ethanol production is not all that high because the energy inputs are quite high that go along with it.”

He said the advantage of molecular sponge material is that the process is done at room temperature without distillation.

“My personal feeling is that’s the way to go but it requires a retooling how the refining actually happens.The nature of the industrial process has to be completely redesigned.”

He said using the molecular sponge technology to make biofuel could result in a 50 to 90 percent saving in energy and perhaps more.

“It’s a huge processing saving,” he said.

More lab related research needs to be done, but Wilson and his team are working with engineers and companies to carry it along the chain of development.

“We need to develop the process so that it can be implemented into a flow system, so there’s engineering and there’s more optimization in terms of the material development,” he said.

“If we can capitalize on the success we’ve already achieved, I think you’ll probably hear some really big things in the next year or two.”

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