Personal protective equipment materials that combine high efficiency filtration and bactericidal effects

Most of the air purification devices currently on the market rely on fibrous mesh filters having a certain density and thickness. These filters exhibit excellent PM capture efficiency, but cannot achieve the killing effect on harmful microorganisms. As bacteria, fungi, viruses, etc. continue to breed, the life of the filter will be greatly reduced. Therefore, the development of a PM filter out particles can not only sterilization green integrated air purification materials is particularly important.

Professor Wang Bo from the Beijing Institute of Technology, combined with previous research work, prepared a series of metal-organic frameworks (MOFs) with photocatalytic activity, and screened ZIF-8 with ultra-high photocatalytic activity to achieve Escherichia coli in water. Efficient killing. Then, a new type of high-efficiency integrated air filter (MOFilter) was designed and synthesized by hot pressing method. The PM particle capture efficiency can reach more than 98%, and it can also kill 99.99% of bacteria in the air.

Schematic diagram for integrated air purification and personal protection

The authors first compared a series of MOFs with photocatalytic activity. The experimental results showed that the killing efficiency of ZIF-8 against E. coli was more than 99.9999% after 2 h of simulated sunlight. It was verified by ICP-MS and photocatalytic bactericidal experiments that the excellent bactericidal properties of ZIF-8 mainly come from the reactive oxygen species generated by photocatalysis, rather than the bactericidal effect of released Zn2+. At the same time, compared with traditional photocatalytic sterilization semiconductors, ZIF-8 photocatalytic sterilization effect and rate are higher than ZnO and TiO2.

ZIF-8 photocatalytic bactericidal properties

In order to simulate the real use environment, the author synthesized a ZIF-8-based MOFilter for filtering PM particles and photocatalytic sterilization, and can achieve large-area preparation. The experimental results show that the MOFilter has a PM filtration rate of up to 98%. At the same time, after 30 minutes of simulated sunlight, the air sterilization rate of MOFilter is greater than 99.99%. The used MOFilter was randomly cut out into 5 pieces and cultured in a liquid medium for 20 h. No recovery of bacteria was observed, further indicating that MOFilter truly achieved photocatalytic sterilization. More importantly, under the condition of initial concentration of bacteria of 105 CFU·mL-1, the MOFilter can be used continuously for 5 times, and the sterilization rate can be maintained above 99%, which lays a foundation for the commercialization of the material.

Characterization of MOFilter and Comprehensive Purification Properties of Air

To achieve personal protection, the research team developed a MOFilter-based personal protective device (MOFilter mask ). The actual use scenario was simulated by spraying microbial aerosols, and then the bacterial survival rate on the MOFilter mask was detected, and no bacteria survived after 30 minutes of illumination. At the same time, compared with the commercial N95 mask, under the same conditions, a large number of live bacteria remained in the commercial mask. Based on the results of this experiment, the author also heat-pressed ZIF-8 on silk cloth for processing self-cleaning garments. This research has a very high application prospect in personal protection.

Personal protective properties of MOFilter masks

The related results were published in "Nature Communications" under the title "Metal-organic frameworks with photocatalytic bactericidal activity for integrated air cleaning".