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Voiland College of Engineering and Architecture Innovation 2014

Super absorbent gel could help farmers save water

infographic of Jinwen Zhang and absorbent gel

A group of WSU researchers have developed a biodegradable gel that can absorb more than 250 times its weight in water and help farmers hold onto water in drought-stricken fields.

Professor Jinwen Zhang’s gel is similar to that used in diapers to absorb water. But instead of being a petroleum-based product, the hydrogel pellets are made from agricultural material and are biodegradable. Zhang has developed the product in his lab and applied for a patent. He has begun working with mOasis, Inc., a California-based company that already produces other agricultural hydrogels to begin testing the product in fields.

There is increased demand for such hydrogels, which are mostly petroleum-based, in a number of industries, such as hygienic products and soil treatment. In addition, there is a large amount of research being conducted for their application in the biomedical field.

In agriculture, companies have been studying the potential of hydrogels as a way of helping drought-affected farmers for several decades. Hydrogel pellets could be used as a soil conditioner, making the soil better able to retain moisture. The pellets could also be useful in applying liquid pesticides and herbicides in a controlled manner. However, because they are petroleum-based, current hydrogels could also create a contamination problem. “Farmers are very cautious,” says Zhang.

While a few biologically based gel materials are available, they are generally used in higher value food and biomedical applications. They are also more expensive and less durable than synthetic gels.

Zhang’s product, which is made mostly of soy protein, is a crosslinked polymer, or a polymer with a molecular chain loosely linked in three dimensions. The ions and other water-absorbing parts in the polymer attract water and grow in weight by up to 250 times. “It’s impressive,” he says. “That’s a lot.”

Because Zhang’s gel is bio-based, it has less environmental impact and would be more sustainable in the long-term, says Zhang. When it degrades, there would no residue in the soil. And, the soy protein could actually be a source of nitrogen that could help plants grow.

“Once it degrades, it would be beneficial,” he says.

A soy-based product would also lessen dependence on foreign oil imports. The U.S. produces about half of the world supply of soybeans, says Zhang.

The work was supported by the United Soybean Board, a USDA-affiliated program that conducts research and market development related to soybean farming.