| With the acceleration of industrialization in various countries,air pollution,especially solid particulate pollution,is becoming more and more obvious.Solid particulate matter in the air,such as PM1.0 and PM2.5,can carry a variety of viruses,organic pollutants and some harmful heavy metals and other harmful pollutants.Studies have found that PM2.5 causes various respiratory diseases due to its deposition in the respiratory tract of the human body.Therefore,the development of an air filtration membrane capable of efficiently filtering PM2.5 is essential to solving the air pollution problem.In the air filtration materials currently studied,electret melt-blown fibers can capture PM2.5 by electrostatic adsorption while maintaining a low-pressure drop,making them the first choice for industrial filtration materials.Then,its electrostatic effect will rapidly fail in high temperature and humid environments,so its filtration stability is poor,and it cannot adapt to the complex working environment.In view of this,this paper focuses on the modification of polypropylene（PP）fibers and their in-situ growth of metal-organic frameworks（MOFs）on the fiber surface to prepare composite fiber membranes with high efficiency and stable filtration performance.The main research contents are as follows:（1）Introducing active groups on the surface of the inert PP fiber by gammairradiation to lead the inert PP fiber to have a carboxyl group capable of providing sites for in-situ growth.Then PP@MOFs were prepared in three different synthesis environments to explore the effect of growth conditions on in-situ growth uniformity.It was found that the PP fiber was activated well under the irradiation dose of 30 k Gy,and the PP@ZIF-8 membrane prepared at normal temperature and pressure had the best uniformity.The PP@ZIF-8 membrane’s filtration efficiency and the quality factor of the PM1.0 are 64.8%and 0.0193 Pa-1,respectively,which are 39.06%and 38.69%higher than those of the PP membrane of 46.6%and 0.139 Pa-1,respectively.And the pressure drop of the PP@ZIF-8 membrane is 54 Pa.（2）Inert PP fibers are modified by adopting polyacrylamide to carry amide groupson the surfaces so that metal ions can be fixed and sites are provided for in-situ growth.And then,by adjusting the ratio of metal/organic ligands of the ZIF-8 and Cu-BTC MOFs materials,nano-sized MOFs are grown on the surface of the modified PP fiber in situ.The air filtration performance,filtration stability and the binding stability of MOFs nanoparticles and fibers were studied.For PM1.0 particles,which are more difficult to filter,the filtration efficiency and quality factor of PP@ZIF-8 membrane are66.4%and 0.0230 Pa-1,respectively,which are 19.42%and 18.77%higher than those of PP membrane of 55.6%and 0.0193 Pa-1,respectively.At the same time,the filtration efficiency and quality factor of PP@Cu-BTC membrane for PM1.0 are 83%and 0.0306Pa-1,respectively,which are 49.28%and 58.04%higher than those of PP membrane.After the membranes were maintained in an ultrasonic water bath of up to 600 W for30 minutes,87%of the MOFs particles were still supported on the fiber surface.The results showed that the PP fiber membrane prepared by this method had stable and efficient filtration performance,and the combination of MOFs particles and fibers was very stable. |
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