Sunday, September 24, 2023

Study finds low-grade cotton may have use as valuable gel

Noureddine Abidi
Texas Tech University Professor Noureddine Abidi led a team that developed a process for converting low-grade cotton into a valuable cellulosic gel — photo courtesy Texas Tech University

A big 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 can influence cotton crops negatively as well. When that happens, farmers may 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, under the Texas Tech University College of Agricultural Sciences & Natural Resources, 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. That can then be converted into a gel 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% 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.”

His goal is to be able to take the gel 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 water-contamination 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.”

A simple process

Dissolving cotton into a gel is actually a simple process. After cleaning the cotton, the fibers are placed into a solution that begins to break them down into a single cellulosic chain. Over about a 24-hour period, the fibers 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 a desired shape.

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 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 degrees centigrade (932 degrees Fahrenheit), then, of course, I’m not going to use it. But for anything below 200 degrees centigrade (392 degrees Fahrenheit), it’s perfect.”

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.

However, 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.

More to the story

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 petroleum-based 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.

Texas Tech University contributed this article.

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