PVDF膜在碱液下的性能衰减

为了研究聚偏氟乙烯(PVDF)膜在碱液下的性能变化,采用单侧浸润方法对PVDF膜的接触角、临界水入口压力、气体渗透通量、孔径和孔隙率进行了分析.结果表明,当在浓度为1.5 mol/L的碱液中浸润300 h后,PVDF膜表面疏水性下降,膜孔被润湿,传质阻力增大.PVDF膜的疏水性随着碱液浓度的增加而降低.当PVDF膜的浸润时间为150~250 h时,PVDF膜的气体渗透通量和孔径的变化幅度最大.浸润300 h后,PVDF膜的孔隙率增加,传质系数降低,传质阻力增加.随着碱液浓度的增加,PVDF膜的结构性能变化得更为明显.

Performance degradation of PVDF membrane in alkali solution

In order to research the performance change of polyvinylidene fluoride(PVDF)membrane in alkali solution, the contact angle, critical water inlet pressure for the membrane, gas permeation flux, pore size, and porosity of PVDF membrane were analyzed with the unilateral immersion method. The results show that after immersing in the alkali solution with the concentration of 1.5 mol/L for 300 h, the surface hydrophobic performance of PVDF membrane declines, the membrane pores are wetted, and the mass transfer resistance increases. In addition, the hydrophobic performance of PVDF membrane decreases with increasing the concentration of alkali solution. When the immersion time of PVDF membrane is between 150 h and 250 h, the gas permeation flux and pore size exhibit the maximum variation amplitude. After immersing for 300 h, the porosity of PVDF membrane increases, the mass transfer coefficient decreases, and the mass transfer resistance increases. With increasing the concentration of alkali solution, the change in the structure and performance of PVDF membrane is more obvious.