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A few days ago, the team of Professor Wang Bo and Assistant Professor Ma Xiaojie of Beijing Institute of Technology has made new research progress in comprehensive air cleaning.
The relevant results were published in the top comprehensive international journal under the title "Metal-organic frameworks with photocatalytic bactericidal activity for integrated air cleaning".
"Nature Communications" on.
Air purifiers are the most commonly used air fresheners for haze weather.
At present, most air purification devices on the market rely on fibrous mesh filter elements with a certain density and thickness.
These filters exhibit excellent PM capture efficiency, but cannot achieve the killing effect of harmful microorganisms.
As bacteria, fungi, viruses, etc.
continue to multiply and breed on the filter membrane, the service life of the filter will be greatly reduced, and it will inevitably bring secondary pollution to the indoor air.
Traditional air disinfection technologies, including chemical disinfectants and ultraviolet radiation sterilization, have disadvantages such as high energy consumption, bacterial resistance to drug resistance, or ozone pollution.
Heterogeneous photocatalysis has become an emerging green and environmentally friendly sterilization method because it can produce reactive oxygen species (ROS) to inhibit the growth of harmful microorganisms.
However, in the case of high air velocity, PM and VOC and other pollutants coexist, its sterilization efficiency is also very limited.
Therefore, it is particularly important to develop a green and environmentally friendly comprehensive air purification material that can filter out PM particles and sterilize.
The research team combined the previous research work to prepare a series of MOFs with photocatalytic activity, and screened ZIF-8 with ultra-high photocatalytic bactericidal activity, which can effectively kill E.
coli in water bodies with a bactericidal rate of greater than 99.
9999%.
Then, a new type of high-efficiency integrated air filter (MOFilter) was designed and synthesized by the hot pressing method.
The PM particle capture efficiency can reach more than 98%, and it can also kill 99.
99% of the bacteria in the air.
Mechanism studies have found that ZIF-8 generates photo-generated electrons from LMCT under the action of solar photocatalysis, and can effectively activate O2 to form O2– and H2O2, which can oxidize pathogenic bacteria in the air to death.Figure 1 Schematic diagram for comprehensive air purification and personal protection.
The author first compared a series of MOFs with photocatalytic activity.
The experimental results show that ZIF-8 has a greater killing efficiency on E.
coli after 2 hours of simulated sunlight exposure.
99.
9999%.
It is verified by ICP-MS and photocatalytic sterilization experiments that the excellent sterilization performance of ZIF-8 mainly comes from the active oxygen free radicals generated by photocatalysis, rather than the sterilization effect of Zn2+ released.
At the same time, compared with the traditional photocatalytic sterilization semiconductor, the photocatalytic sterilization effect and rate of ZIF-8 are higher than that of ZnO and TiO2.Figure 2 The photocatalytic sterilization properties of ZIF-8.
In terms of the photocatalytic sterilization mechanism, the energy band structure of the material was determined by UV-vis, MS and VB-XPS, and theoretically predicted that it could produce O2– but not •OH.
.
In the course of the experiment, we also used some conventional characterization methods, such as EPR, ultraviolet absorption, fluorescence spectroscopy and other methods to detect the free radicals generated by the material under light conditions.
The results are consistent with theoretical predictions.
Free radical capture experiments proved that O2– and H2O2 produced in the photocatalysis process played a major role in bactericidal action.
The solid EPR of the test material under different atmosphere conditions at 77k proves that the photogenerated electrons are transferred from the ligand to the metal (LMCT), and then the oxygen in the air is activated to generate O2– and related H2O2. Figure 3 The energy band structure and photocatalytic sterilization mechanism of ZIF-8 In order to simulate the real use environment, the author synthesized a MOFilter based on ZIF-8 (single load is about 0.
15 mg cm-2), and can realize large-area preparation.
And used to filter out PM particles and photocatalytic sterilization.
Experimental results show that the filtration rate of PM by MOFilter is as high as 98%.
At the same time, after 30 min of simulated sunlight, the air sterilization rate of MOFilter is greater than 99.
99%.
Cut out 5 pieces of the used MOFilter randomly and culture them in liquid medium for 20 hours.
No recovery of bacteria was observed, which further shows that MOFilter truly achieves photocatalytic sterilization.
More importantly, under the condition that the initial bacterial concentration is 105 CFU mL-1, the MOFilter can be used continuously for 5 times, and its sterilization rate can be maintained above 99%, which also laid the foundation for the commercialization of the material. Figure 4 Characterization of MOFilter and comprehensive air purification properties In order to achieve personal protection, the author has developed a personal protective equipment (MOFilter mask) based on MOFilter.
By spraying microbial aerosols to simulate the real use scene, and then respectively detect the bacterial survival rate of the three layers of the MOFilter mask.
After 30 minutes of light, no bacteria survived on the three layers of the MOFilter mask.
At the same time, it was compared with the commercial N95 mask.
Under the same conditions, the commercial mask had a large amount of living bacteria.
On the basis of the experimental results, the author also hot-pressed ZIF-8 on silk cloth for processing and preparing self-cleaning clothes.
This research result has extremely high application prospects in personal protection.
Figure 5 The personal protective properties of MOFilter masks.
This research work provides a reference for the development of porous photocatalytic antibacterial materials, and also opens the door to the application of these materials in comprehensive air purification.
The relevant results were published in the top comprehensive international journal under the title "Metal-organic frameworks with photocatalytic bactericidal activity for integrated air cleaning".
"Nature Communications" on.
Air purifiers are the most commonly used air fresheners for haze weather.
At present, most air purification devices on the market rely on fibrous mesh filter elements with a certain density and thickness.
These filters exhibit excellent PM capture efficiency, but cannot achieve the killing effect of harmful microorganisms.
As bacteria, fungi, viruses, etc.
continue to multiply and breed on the filter membrane, the service life of the filter will be greatly reduced, and it will inevitably bring secondary pollution to the indoor air.
Traditional air disinfection technologies, including chemical disinfectants and ultraviolet radiation sterilization, have disadvantages such as high energy consumption, bacterial resistance to drug resistance, or ozone pollution.
Heterogeneous photocatalysis has become an emerging green and environmentally friendly sterilization method because it can produce reactive oxygen species (ROS) to inhibit the growth of harmful microorganisms.
However, in the case of high air velocity, PM and VOC and other pollutants coexist, its sterilization efficiency is also very limited.
Therefore, it is particularly important to develop a green and environmentally friendly comprehensive air purification material that can filter out PM particles and sterilize.
The research team combined the previous research work to prepare a series of MOFs with photocatalytic activity, and screened ZIF-8 with ultra-high photocatalytic bactericidal activity, which can effectively kill E.
coli in water bodies with a bactericidal rate of greater than 99.
9999%.
Then, a new type of high-efficiency integrated air filter (MOFilter) was designed and synthesized by the hot pressing method.
The PM particle capture efficiency can reach more than 98%, and it can also kill 99.
99% of the bacteria in the air.
Mechanism studies have found that ZIF-8 generates photo-generated electrons from LMCT under the action of solar photocatalysis, and can effectively activate O2 to form O2– and H2O2, which can oxidize pathogenic bacteria in the air to death.Figure 1 Schematic diagram for comprehensive air purification and personal protection.
The author first compared a series of MOFs with photocatalytic activity.
The experimental results show that ZIF-8 has a greater killing efficiency on E.
coli after 2 hours of simulated sunlight exposure.
99.
9999%.
It is verified by ICP-MS and photocatalytic sterilization experiments that the excellent sterilization performance of ZIF-8 mainly comes from the active oxygen free radicals generated by photocatalysis, rather than the sterilization effect of Zn2+ released.
At the same time, compared with the traditional photocatalytic sterilization semiconductor, the photocatalytic sterilization effect and rate of ZIF-8 are higher than that of ZnO and TiO2.Figure 2 The photocatalytic sterilization properties of ZIF-8.
In terms of the photocatalytic sterilization mechanism, the energy band structure of the material was determined by UV-vis, MS and VB-XPS, and theoretically predicted that it could produce O2– but not •OH.
.
In the course of the experiment, we also used some conventional characterization methods, such as EPR, ultraviolet absorption, fluorescence spectroscopy and other methods to detect the free radicals generated by the material under light conditions.
The results are consistent with theoretical predictions.
Free radical capture experiments proved that O2– and H2O2 produced in the photocatalysis process played a major role in bactericidal action.
The solid EPR of the test material under different atmosphere conditions at 77k proves that the photogenerated electrons are transferred from the ligand to the metal (LMCT), and then the oxygen in the air is activated to generate O2– and related H2O2. Figure 3 The energy band structure and photocatalytic sterilization mechanism of ZIF-8 In order to simulate the real use environment, the author synthesized a MOFilter based on ZIF-8 (single load is about 0.
15 mg cm-2), and can realize large-area preparation.
And used to filter out PM particles and photocatalytic sterilization.
Experimental results show that the filtration rate of PM by MOFilter is as high as 98%.
At the same time, after 30 min of simulated sunlight, the air sterilization rate of MOFilter is greater than 99.
99%.
Cut out 5 pieces of the used MOFilter randomly and culture them in liquid medium for 20 hours.
No recovery of bacteria was observed, which further shows that MOFilter truly achieves photocatalytic sterilization.
More importantly, under the condition that the initial bacterial concentration is 105 CFU mL-1, the MOFilter can be used continuously for 5 times, and its sterilization rate can be maintained above 99%, which also laid the foundation for the commercialization of the material. Figure 4 Characterization of MOFilter and comprehensive air purification properties In order to achieve personal protection, the author has developed a personal protective equipment (MOFilter mask) based on MOFilter.
By spraying microbial aerosols to simulate the real use scene, and then respectively detect the bacterial survival rate of the three layers of the MOFilter mask.
After 30 minutes of light, no bacteria survived on the three layers of the MOFilter mask.
At the same time, it was compared with the commercial N95 mask.
Under the same conditions, the commercial mask had a large amount of living bacteria.
On the basis of the experimental results, the author also hot-pressed ZIF-8 on silk cloth for processing and preparing self-cleaning clothes.
This research result has extremely high application prospects in personal protection.
Figure 5 The personal protective properties of MOFilter masks.
This research work provides a reference for the development of porous photocatalytic antibacterial materials, and also opens the door to the application of these materials in comprehensive air purification.
