One kilogram of moist sugarcane bagasse, with additional layers of chitin and silver nanoparticles, can be used to produce 5 three-layer facemasks, to filter out dust and block UV light.
When Phan Van Thinh, a DTU fourth-year student, saw used sugarcane bagasse accumulating at nearby drinks stalls, until it was removed in a garbage cart, he started searching for a way to recycle it. Van Thinh studies Economics but does not know much about Biochemistry, so he asked friends from the Faculty of Nursing about his idea. The bagasse degrades in a month or two because of its cellulose content and the group decided to use it to make masks that would degrade quicker than traditional ones, in order to reduce environmental pollution.
In early March 2020, Van Thinh and his team collected some source materials. At first they were embarrassed, because nobody believed facemasks could be made from bagasse. He said, “At the time we didn’t know whether we’d succeed
in making our product, but we tried to do our best.”
From crystallized sugarcane bagasse, the group draws out a synthetic solution, which is then woven into thin fibers Photo: NVCC
Each of the subsequent processing and preparation stages were carried out in the university laboratories, which the team had access to after class hours. They submerged the bagasse in water, then boiled it in caustic soda to break it into small fibers and obtain a clear solution. They then filtered it to obtain crystallized bagasse, which was then rolled thin and dried. “After sterilization, the product is a thin, yellow, odorless material,” said Van Thinh.
However, due to its cellulose content, the material easily absorbed water and tore. The team needed an extra month and the advice of their lecturers to create a thin water-resistant and antibacterial chitin layer from shrimp shells. The chitin is smeared on the outer layer of the facemask.
After experimentation, the chitin layer still did not stick to the material, causing more problems. The main function of the facemask is to keep water out and Van Thinh said, “Searching for a solution, we discovered that the shrimp shells should first be ground even finer in order to increase the stickiness of the chitin layer on the facemask material.”
A second layer was then mixed with activated carbon and silver nanoparticles to make the mask tighter and keep bacteria and dust out. The tightly woven cellulose fiber in the two protective layers could then block ultra-small droplets measuring 3 to 5 micrometers. The inner layer, which is in direct contact with the skin, was also pressed to make the fabric softer and more porous, without irritation.
After seven months of work, the group tested their first facemasks on their lecturers and friends at the university. Feedback confirmed that users could breathe freely, without itching. Van Thinh added that they also sent samples to several hospitals and healthcare centers for safety testing and evaluation to improve their product based on expert opinions.
“If we can market them, one facemask would cost about four thousand dong,” said Van Thinh. “We are now in contact with several companies who want to develop it with us.”
(Media Center)