Kn95 masks that can be washed, sterilized with alcohol and used many times are here! A new type of filter material, nano arachnoid biomimetic membrane, has been developed by the membrane science and Technology Research Institute of Nanjing University of technology, and has been applied to the production of high performance mask. Because of its high porosity, small pore size, low filtration resistance and high filtration accuracy, this kind of nano arachnoid bionic membrane material can be reused without adding static electricity. It can effectively intercept all kinds of solid aerosols, droplets and viruses through screening, without worrying about the problem of low filtration efficiency of liquid.
Since novel coronavirus pneumonia outbreak grow with each passing day, the demand for mask has been increasing day by day, and more than 3000 enterprises in the country have added masks. As the key material of mask filtration, the melt blown cloth with fiber diameter only one thirtieth of hair can be regarded as the "heart" of medical surgical mask and kn95 mask. The supply is very tight, and the market price has increased by more than ten times. In order to alleviate the shortage of melt blown cloth in the current market, many research institutions at home and abroad, through the development of various "black technology" masks, contribute to the anti epidemic.
According to the introduction, the traditional melt blown material itself has a large aperture, so it needs to add static electricity to improve the filtering efficiency. However, the static electricity is affected by the temperature and humidity in the environment, and it will fail in a short time, so the filtering efficiency is rapidly reduced, so the medical mask produced by the traditional melt blown cloth can only be used once in the market.
Based on the existing scientific and technological achievements, Professor Zhong Zhaoxiang's team of membrane science and Technology Research Institute of Nanjing University of technology has developed high-performance air purification membrane materials. The material has a three-dimensional spider like web structure composed of nanofibers, the micro pore size can be controlled in the range of 0.1 to 0.5 μ m, which can effectively filter more than 99% of non oil particles, effectively intercept various solid aerosols, droplets and viruses, and has good air permeability without respiratory discomfort.
Magic nano arachnoid biomimetic membrane material
The diameter of the nanocobweb biomimetic membrane fiber is in the range of 100-200nm, and the fibers interlace with each other to form a three-dimensional cobweb structure. The size of the micropores can be controlled in the range of 0.1 to 0.5 μ m. "Compared with the melt blown materials with disordered fiber stacking and a diameter of more than 1000 nm, the nano arachnoid biomimetic membrane has the advantages of high porosity, small pore diameter, low filtration resistance and high filtration accuracy." Introduction of Professor Zhong Zhaoxiang, Department of membrane science, School of chemical engineering, Nanjing University of technology.
Generally, there are a large number of fine particles with positive and negative charges in the air. When these charged particles in the air pass through the vicinity of the electret, they will be strongly adsorbed on the electret fiber. Meanwhile, the uncharged particles will be polarized by induction in the electric field formed by the electret, and will also be adsorbed on the fiber. The traditional melt blown material has a large aperture, so it needs to add static electricity to improve the filtration efficiency. However, the static electricity is affected by the temperature and humidity in the environment, and it will fail in a short time, so the filtration efficiency is rapidly reduced, so the medical mask produced by the traditional melt blown cloth can only be used once in the market.
Professor Zhong Zhaoxiang said that the nano arachnoid bionic membrane material, due to its characteristics of high porosity, small pore size, low filtration resistance and high filtration accuracy, does not need to add static electricity. Through screening, it can effectively filter more than 99% of non oil particles, effectively intercept various solid aerosols, droplets and viruses, and does not need to worry about the problem of low filtration efficiency in case of liquid. At the same time, it has the advantages of Good air permeability, no discomfort of breathing.
Overcome the obstacles of water washing and alcohol disinfection
At present, most of the medical surgical masks on the market are disposable, with a maximum use time of 4 hours. Although kn95 masks have a longer use time, they cannot be used repeatedly for a long time. This is because once the melt blown material adsorbs pollutants by charging, it is easy to have static neutralization phenomenon when encountering water, which will reduce the filtering efficiency of the mask, so the mask produced by melt blown cloth cannot be reused after ordinary cleaning.
"Nano arachnoid biomimetic membrane materials have small pore size, which mainly intercept pollutants through physical action, so there is no need to worry about the reduction of liquid efficiency." Wu Junwei, a doctoral student of Professor Zhong Zhaoxiang's team, said, "after our team researchers soaked the membrane materials in water and 75% alcohol for many times, the filtration efficiency was not affected, and they all kept above 99%. This shows that the membrane materials mask can be washed with water or reused after alcohol disinfection, which greatly increases the utilization rate of the mask."
"Our multiple comparative experiments on service life, reusability and air permeability show that as a new type of filter material, nano arachnoid biomimetic membrane material has more excellent retention and air permeability than traditional melt blown materials, so it can be reused and has a longer service life," Wu said
It can also be used for medical "protective clothing", etc
According to reports, the nano arachnoid biomimetic membrane material developed by the membrane Department of Nanjing University of technology can be used not only for making masks, but also for medical protective clothing, air purifier and other fields.
Zhong Zhaoxiang said that the protective clothing made of nano arachnoid biomimetic membrane material has good antibacterial and water repellent performance, and is the highest level of medical protective clothing, which is characterized by the fact that the sweat gas of the human body can be emitted outwards, while the outside water, bacteria and viruses cannot enter. "The nano arachnoid biomimetic membrane material has about 1 billion holes per square centimeter, with porosity of more than 90%. The pore diameter is about 0.2 μ m, which is one thousandth of the diameter of the water drop, but it is about 700 times larger than the size of the water vapor molecule. The liquid water can not enter, and the sweat gas can penetrate, so it can achieve excellent waterproof and moisture permeability."
In the industrial field, through the application of double sparse modified air purification membrane for ultra-low emission control of smoke and dust, hundreds of sets of engineering equipment have been promoted and applied, with economic benefits of more than 2 billion yuan. It has successively won the first prize of technology invention of China Petroleum and Chemical Industry Federation, the first prize of science and technology of China Film Industry Association, the youth prize of chemical science and technology of Hou Debang, etc.
At present, air purification membrane materials and membrane masks have been used in hundreds of units, providing a strong guarantee for the staff who adhere to the front line of epidemic prevention. Recently, the Institute of membrane science and technology of Nanjing University of technology has also received letters of thanks from the Charity Federation of Pukou District, Nanjing City, Italy national research institute, American filtration and separation Association and other institutions at home and abroad, thanking the Institute of membrane science and technology for donating materials of membrane technology anti epidemic mask. At the theme meeting of epidemic prevention materials held by Nanjing municipal government, the air purification membrane technology was highly valued by Nanjing industry and Information Bureau, science and Technology Bureau and other departments, helping to contact and implement many enterprises to carry out the production docking of air purification membrane masks, and making contributions to the victory of the epidemic.
Source: China Science News, Xinhua News