Development of Nanofibrous Membrane with Continuous Electret Treatment for Air Filtration
In this study,poly(vinylidene chloride)(PVDF)was selected as the raw material,N,N-dimethyl-formamide(DMF)as the solvent,and the mixture of titanium dioxide(TiO2)and silicon nitride(Si3N4)as the electret material.The nanofibrous membrane was prepared by electrospinning technology,and the electrostatic electret was carried out on it to further improve the filtration efficiency.By studying the structure,surface morphology and filtration performance of the prepared nanofibrous membrane,it was found that the filtration performance of the PVDF@TiO2/Si3N4 nanofibrous membrane doped with nanoparticles was better than that of the undoped PVDF nanofibrous membrane,and the nanofibrous membrane prepared with the concentration of doped nanoparticles reaching 5％had the best performance.In the electret process of PVDF@5％TiO2/Si3N4 nanofiber membrane with a concentration of 5％doped nanoparticles,it found that when PVDF@5％TiO2/Si3N4 nanofibrous membrane is electret,the diameter and pore size of the fiber will decrease,and the filtration efficiency will further increase to 99.93％.Performance improvement of 7.40％is achieved,compared to that before electret.This paper also tested the performance of the nanofibrous membrane after the electret was placed.After the placement,the electrical performance of the nanofibrous membrane would decay to different degrees,but it would still maintain a stable electric potential.In order to improve the electrical properties and filtration performance of the nanofibrous membrane,a secondary electret experiment on the nanofibrous membrane after placement was conducted.According to the experimental data,the longer the nanofibrous membrane is placed,the longer it takes to recover to the optimal potential.However,its filtration efficiency can still reach more than 99％,and the required time is all within 7 min.The purpose of long working time can be achieved by charging 7 min.
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