Converting low-grade cotton into gel with variable use qualities

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By George Watson

Abig part of what makes West Texas one of the leading cotton-producing regions in the world is the hot, dry weather that defines the area and is ideal for encouraging cotton growth.

But that weather also can be unpredictable and, therefore, can influence cotton crops negatively as well. Given the impact the cotton industry has on both local and world economies, all steps are taken to ensure as promising a cotton crop as possible each year.

When that doesn’t happen, though, it’s vital for farmers to be able to salvage as much of their crop as possible, even if it is not of the highest-quality cotton. Thanks to research being conducted at the Fiber and Biopolymer Research Institute (FBRI), under the College of Agricultural Sciences & Natural Resources at Texas Tech University, low-grade cotton could end up being just as valuable as the high-grade yields.

Noureddine Abidi, the Leidigh Professor in the Department of Plant and Soil Science and managing director of the FBRI, has been awarded a patent for a process he developed that can break down low-grade cotton into pure cellulose, which then can be converted into a gel that can be used in 3D printing, for example, or other processes to create usable, biodegradable products.

“The idea is to find a new use for low-grade cotton or any recyclable that is 100 percent cotton, and trying to replace, to some extent, petroleum-based products,” Abidi said. “It is still a valuable product that we need to transform into something else.”

Abidi’s goal with the research is to be able to take the gel from low-grade cotton and use it to replace as many nonbiodegradable products, like plastic trash bags, as possible. Abidi and fellow researchers already have shown in the FBRI laboratory that the process will work, using it to convert low-grade cotton into products such as protective film and dye-absorbent material that, in theory, could be used to help with watercontamination cleanup.

“This process, I think, can open new applications for cotton as long as the application can tolerate it, like with high temperatures,” Abidi said. “That is the variable. But as long as you have the gel, you can think of unlimited uses.”

Dissolving cotton

Dissolving cotton into a gel is actually a pretty simple process.

After cleaning the cotton, the fibres are placed into a solution that begins to break them down into a single cellulosic chain. Over about a 24-hour period, the fibres transform into their pure cellulose state, then the water and solvent are drained from the solution, leaving the pliable gel that can be formed into any desired shape.

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For purposes of their research, Abidi and his colleagues inserted the gel into a 3D printer jet to produce scaffolds, or the skeleton of other products, or placed it in a mold to give it a certain shape.

About the only limit to the process is whether there is a need for a product that can withstand high heat.

“If you want to make something like reusable Starbucks cups or the Keurig cups, it’s not really limited by the application,” Abidi said. “If I want something that can resist high temperatures, like 500°C, then, of course, I’m not going to use it. But for anything below 200°C, it’s perfect.”

The gel created from dissolved cotton can be used in a number of ways, including replacing some petroleum-based products.

With the introduction between the layers of cellulose of a conductive polymer, cotton could then be converted into something feasible for use with microelectronics.

There is one other small limitation, but Abidi’s process has already found a way around that.

Cotton, and cellulose itself, is not a conductive material, meaning that it is not a good material for electronics. But with this patented process, Abidi can take layers of the gel and, in between the layers of cellulose, introduce a polymer that has the best conductive properties. This would make the product feasible for use with microelectronics and the like.

Taking it further

Developing the dissolution process and being able to add properties to the gel to make it an electrically conductive product would have been impressive enough. But it might not have made it economically viable.

Therefore, in cooperation with the Department of Chemistry & Biochemistry, Abidi and other researchers applied for an international patent for another product. They developed a solvent and process that can reduce the dissolution time dramatically, from 24 hours to less than 15 minutes.

“If you use the first approach, then it may not be economical to compete with petroleumbased products,” Abidi said. “But with the new process we have right now, you can speed up the process and save time and energy to convert the cotton into cellulose solution or gel.”

The process is proven. Now comes the hard part, Abidi said, in finding either a company to pick up the research and make it into a viable product, or secure additional funding to continue the research even further.

“We are really limited by what we can do in terms of funding,” Abidi said. “We’re not to that point quite yet.”

Abidi said the process is not just limited to cotton. Cellulose can be extracted from any biomass, such as trees, which means this process can be applied globally. Also, because cellulose is biodegradable, it has no known environmental or health-related issues.

But at least to this point, it has been proven that there is no such thing as wasted cotton, regardless of how good or poor the yield is. Eventually, this could open up many more markets for farmers in West Texas who rely on one of the most exported products in the US.

“If they produce a good premium cotton, then anybody can buy it,” Abidi said. “But we don’t always know if that will happen. So it is better to have a new use for the cotton that is being discounted. If we can develop products from this, then there will be a company that takes the remaining cotton, which is beneficial for all farmers.”