Science and Technology Daily News (Jinfeng Correspondent Zhang Jinfeng) as a key material in the filtering process of masks, a melt-blown cloth with a fiber diameter of only one-thirtieth of the hair, is the "heart" of medical surgical masks and KN95 masks. Recently, Nanjing University of Technology revealed that the Institute of Membrane Science and Technology of the School of Chemical Engineering (hereinafter referred to as the Institute of Membrane Science and Technology of South University of Technology) has developed a new type of filter material-nano-cobweb biomimetic membrane. Up to 99%, at the same time, it can also be washed with water and disinfected with alcohol, and has a long service life. At present, the membrane has been applied to the production of high-performance membrane masks. The research team also donated some masks to the Italian National Research Institute and the American Filtration and Separation Association.
The air contains a large amount of fine-particle pollutants with positive and negative charges. Traditional melt-blown materials have a large pore size and need to be treated by electrets. After being charged with static electricity, they can improve the filtration efficiency. When the charged particles in the air pass near the electret, they will be strongly adsorbed on the electret fiber. At the same time, the uncharged particles will be polarized by induction in the electric field formed by the electret and will also be adsorbed on the fiber. on. However, static electricity is affected by the temperature and humidity in the environment, which is difficult to maintain for a long time, and the filtration efficiency will rapidly decrease. Therefore, the medical masks produced by traditional melt-blown cloth can only be used once.
Professor Zhong Zhaoxiang from the Institute of Membrane Science of the South China University of Technology introduced that the diameter of the nano-web spider biomimetic membrane they developed is in the range of 100-200 nanometers, and the fibers are interlaced to form a three-dimensional cobweb-like structure. Small pore size, high filtration accuracy, no need to add static electricity, intercept pollutants through screening, can effectively filter more than 99% of non-oily particles, effectively intercept various solid aerosols, droplets and viruses, without worrying about the reduction of liquid filtration efficiency At the same time, it has good breathability and does not cause breathing discomfort.
At present, most medical surgical masks are disposable, and the general use time is four hours. Although the KN95 mask is used for a longer time, it cannot be used repeatedly for a long time. This is because the melt-blown material that adsorbs pollutants through the charging action is prone to electrostatic neutralization when it encounters water, which will reduce the filtering efficiency of the mask. Therefore, the masks produced with the melt-blown cloth cannot be reused after ordinary cleaning.
“The nano-spider-web bionic membrane material has a small pore size and mainly traps pollutants through physical action, without worrying about the problem of reduced efficiency in case of liquid.” Wu Junwei of Professor Zhong Zhaoxiang ’s team said that the team ’s researchers put the membrane material in water and 75% alcohol After immersion for many times, the filtration efficiency is not affected, and all of them are kept above 99%, indicating that the membrane material mask can be washed with water or disinfected with alcohol and reused, which greatly increases the utilization rate of the mask.
According to reports, the nano-cobweb bionic membrane material developed by the Membrane Department of NTU can be used not only for making masks, but also for medical protective clothing, air purifiers and other fields.
Zhong Zhaoxiang said that the protective clothing made based on the nano spider web bionic membrane material has good antibacterial and water-repellent properties, and is the highest-grade medical protective clothing in medical protection. It is characterized by the sweat of the human body can be radiated outward, while the outside The water, bacteria and viruses cannot enter.
In the industrial field, the air purification membrane modified by double thinning can be used for ultra-low emission control of smoke and dust. Hundreds of sets of engineering equipment have been promoted and applied, generating economic benefits of more than 2 billion yuan, and successively won the China Petroleum and Chemical Industry Federation. The first prize of technological invention, the first prize of science and technology of China Film Industry Association, the Hou Debang Chemical Science and Technology Youth Award and other awards.
During the epidemic situation, the membrane laboratory of the South China University of Technology has donated high-performance membrane masks to domestic and foreign institutions such as the Nanjing Pukou District Charity Federation, the Italian National Research Institute, and the American Filtering and Separation Association. In addition, with the help of the Nanjing Municipal Bureau of Industry and Information Technology and the Science and Technology Bureau, the air purification membrane technology has also received mask production from many companies.