In order to break down the dyed materials, the researchers had to increase the amount of time and enzymes used. For fabrics treated with durable press chemicals, they had to use a chemical pre-treatment before adding the enzymes.
“The dye that you choose has a big impact on the potential degradation of the fabric,” said the study’s lead author Jeannie Egan, a graduate student at NC State. “Also, we found the biggest obstacle so far is the wrinkle-resistant finish. The chemistry behind that creates a significant block for the enzyme to access the cellulose. Without pre-treating it, we achieved less than 10% degradation, but after, with two enzyme doses, we were able to fully degrade it, which was a really exciting result.”
Researchers said the polyester could be recycled, while the slurry of cotton fragments could be valuable as an additive for paper or useful addition to composite materials. They’re also investigating whether the glucose could be used to make biofuels.
“The slurry is made of residual cotton fragments that resist a very powerful enzymatic degradation,” Salmon said. “It has potential value as a strengthening agent. For the glucose syrup, we’re collaborating on a project to see if we can feed it into an anaerobic digester to make biofuel. We’d be taking waste and turning it into bioenergy, which would be much better than throwing it into a landfill.”
The study, “Enzymatic textile fiber separation for sustainable waste processing,” was published in Resources, Environment, and Sustainability. Co-authors included Siyan Wang, Jialong Shen, Oliver Baars, and Geoffrey Moxley. Funding was provided by the Environmental Research and Education Foundation, Kaneka Corporation, and the Department of Textile Engineering, Chemistry, and Science at NC State.