TEXTILES.ORG
Cornell University researchers have developed a sustainable way to clean up waterways by reusing one waste product to remove another. Led by Larissa Shepherd, assistant professor in the Dept. of Human Centered Design, College of Human Ecology, the team has proposed using discarded silk yarn for the removal of dye and oil from water.
Studies on several different forms of silk—fabrics, yarns and fibers—revealed that yarn unraveled from silk fabric, soaked up methylene blue (MB), a common textile dye, from water at a substantially higher rate than other forms of silk they tested. What’s more, the silk yarn can be cleaned and reused. Shepherd’s group found that the textile can withstand at least 10 cycles, with minimal loss of functionality.
Shepherd is the corresponding author of “Waste Bombyx Mori Silk Textiles as Efficient and Reuseable Bio-Adsorbents for Methylene Blue Dye Removal and Oil-Water Separation,” published Nov. 14 in the journal Fibers. Co-authors are Hansadi Jayamaha, doctoral candidate in the field of fiber science, and Isabel Schorn ’26, a fiber science undergraduate.
Jayamaha had been studying properties of silk as part of her doctoral thesis work and developed hollow sphere silk particles in order to test their potential for adsorption—the adhesion of molecules from a gas or liquid to a surface. In doing so, they also tested other forms of silk, including unraveled silk yarn from a textile item.
“Structure is really important in my lab, so we start from the nano scale and work up to that finished textile,” Shepherd said. “We were looking for a structure that was optimum for this adsorption, and we initially thought that the silk fabrics coated with particles were going to work best, but we found that just disassembling the fabric itself to the yarn stage actually showed, for the same weight, even faster adsorption.”
Jayamaha found that 12 milligrams of silk filament yarn has 90 percent MB dye removal efficiency within 10 minutes of exposure, for concentrations up to 100 parts per million, substantially greater than the efficiency of other forms, even electrospun fiber mats or fabrics treated with the hollow silk microparticle spheres.
The group also tested silk textile adsorption capacity with oil, and found that Noil fabric (a textile that contains silk yarns composed of short fibers, rather than filament) displays oil adsorption capacities three times the initial weight of the fabric for corn oil, and close to twice the weight for gasoline. Tests on both materials showed that, following a diminishment of function after the first cleaning-reuse cycle, the material maintained its functionality for the subsequent nine cycles.
This intrinsic property of silk as a dye adsorbent, the group found, can be achieved without chemical or other alteration of the material – just deconstructing the textile product.
“When you regenerate silk, you have to use very harsh chemicals,” Shepherd said. “In our case, we’re just using the fabrics themselves. Yes, we may have to unravel them to get the benefit, but that’s much better than putting these harsh chemicals out into the environment.”