MIT and Tufts University researchers found silk is good for more than clothes, cool furniture, or bulletproof vests. They found a way to extract tiny silk building blocks, called nanofibrils, that vastly improve filtration techniques. Others attempted to extract these nanofibers in the past, but largely failed, and the researchers detailed their process to success in a paper published recently in the journal Nano Letters.
These nanofibrils can be made into “advanced filtration membranes,” according to the researchers. In their paper, the scientists explained their four-step process, which involved exfoliating the silk, extracting nanofibrils via ultrasonic waves, and vacuum filtration. They utilized silk fibers made by domesticated silkworms.
The new membranes are not only more effective for filtration, they’re more environmentally friendly. Used filters biodegrade, resulting in “no lasting impact,” according to MIT. The nanofibrils membranes are less expensive too: one piece costs between five and 51 cents, while a comparable piece of commercial membrane costs $1.20.
The new membranes are very flexible and don’t dissolve in water, crucial for effective water filtration. The nanofibrils are also “negatively charged at neutral pH” which means they can snare positively charged molecules.
MIT postdoc student Shengjie Ling said, “There has been a renewed focus recently on developing these types of ultrathin filtration membranes…The challenge has always been to create these new ultrathin and low-cost devices while retaining mechanical strength and good separation performance. Cast silk fibroin membranes aren’t an option, because they do not have porous structure and dissolve in water if not pretreated. We knew there had to be a better way.”
The new membranes were designed in a collaboration between several different departments; material scientists and civil, computational, and biomedical engineers all worked together on the research. The new membranes could be used in research, food manufacturing, and to filter water.
Via MIT News