Discarded silk can clean up polluted waterways – researchers develop hollow spherical silk particles to test adsorption

Researchers at Cornell University have developed an elegant and sustainable way to clean waterways by reusing some waste and removing others.

The team, led by Larissa Shepherd, assistant professor in the Department of Human-Centered Design in the School of Human Ecology, proposed using discarded silk thread to remove dyes and oils from water. Studies on several different forms of silk, namely fabrics, yarns, and fibers, have shown that threads unravel from silk fabrics and absorb methylene blue (MB), a common textile dye, at a significantly higher rate than other forms of silk tested. It has been shown that it is absorbed from water.

Additionally, the silk thread can be washed and reused. Shepherd’s group found that the fiber could withstand at least 10 cycles with minimal loss of function.

Shepherd is the corresponding author of “Bombshell mori silk textile waste as an efficient and reusable biosorbent for methylene blue dye removal and oil-water separation,” published Nov. 14 in the journal Fibers. . Co-authors are Hansadi Jayamaha, a doctoral candidate in textile science, and Isabelle Schon, an undergraduate student in textile science.

Jayamaha has been studying the properties of silk as part of her doctoral thesis research, and developed hollow spherical silk particles to test the potential for adsorption, or attachment of molecules from gases or liquids to surfaces. In doing so, they also tested other forms of silk, including silk threads unraveled from textile products.

“In my lab, structure is very important, so we start at the nanoscale and work our way into the final textile,” Sheppard said.

“We were looking for the best structure for this adsorption, and initially thought a silk fabric coated with particles would be the most effective, but in reality we only need to break down the fabric itself down to the thread stage. We found that it has the same effect. It’s lighter in weight and absorbs even faster.”

Jayamaha shows that 12 milligrams of silk filament yarn has a 90% MB dye removal efficiency within 10 minutes of exposure at concentrations up to 100 ppm, which is higher than other formats (electrospun fiber mats and hollow fibers). found that the efficiency was significantly higher than that of even treated fabrics. Researchers said their discovery of silk microspheres was a surprise.

“By creating the spheres, we were creating a more hydrophilic surface compared to silk fabrics, which are more hydrophobic. However, by breaking the fabric down to the yarn stage, we were creating a higher surface area. , thereby increasing the durability of the surface,” Jayamaha said. adsorption. “

The group also tested the adsorption capacity of silk fabrics for oil and found that noil fabrics (woven fabrics containing silk threads made up of short fibers rather than filaments) had an oil adsorption capacity for corn oil that was three times the fabric’s initial weight. I discovered that it shows. It weighs twice as much as gasoline.

Testing of both materials showed that after a loss of functionality after the first wash and reuse cycle, the materials maintained their functionality over the subsequent nine cycles.

The research group found that this unique property of silk as a dye adsorbent can be achieved simply by dismantling the textile, without any chemical or other material modification.

“When you regenerate silk, you have to use very harsh chemicals,” Shepherd says. “In our case, we’re just using the fabric itself. Sure, you may have to loosen the fabric to get the benefit, but it’s better than releasing these powerful chemicals into the environment.” is also much better.”

Sheppard believes that the “pillows,” which contain unraveled silk from discarded textiles and offcuts from cutting and sewing operations in the textile industry, are part of runoff and waste containing MB dye, which is harmful to farmland and waterways. It is envisioned that it will be an effective means of purifying the environment. If accidentally released from a textile factory.

“We realized we could kill two birds with one stone. We could eliminate waste textiles, which is a huge problem in the textile industry in general,” Shepherd said. “And we found that because of its natural structural properties, it actually has very good adsorption power.”

This research utilized shared facilities at the Cornell Center for Materials Research and the Cornell Nanoscale Science and Technology Facility, a member of the National Nanotechnology Coordinating Infrastructure supported by the National Science Foundation.