孔径对PVDF中空纤维膜净化地表水性能的影响

Effects of pore size on surface water purification performance of PVDF hollow fiber membrane

将聚偏氟乙烯(PVDF)中空纤维膜应用于地表水处理,考察了4种孔径PVDF膜通量随过滤时间的变化趋势,分析了膜污染阻力分布及过滤前后膜孔径分布的变化情况。结果表明:随着孔径的增大,PVDF膜过滤微污染地表水的渗透通量减小,膜污染阻力增大;孔径为25 nm的PVDF超滤膜的渗透通量随时间衰减最慢,稳定通量为133.2 L/(m^(2)·h),浊度去除率最高,对地表水中有机物去除率为40%~50%;PVDF膜处理地表水的膜污染阻力主要是浓差极化阻力(R_(p))和滤饼阻力(R_(c));随着操作压力的增大,膜污染总阻力(R_(t))逐渐增大,堵孔阻力(R_(a))在0.1 MPa时达到最大并保持稳定,R_(c)和R_(p)阻力占比变化趋势相反。在地表水处理中试实验中,孔径为25 nm的PVDF膜性能优于进口膜产品的PVDF膜性能。

Four polyvinylidene fluoride(PVDF)hollow fiber membranes with different pore sizes were applied to treat surface water.The filtration performance and anti-fouling behavior of the membranes were characterized.The influence of pore size on membrane fouling was studied through the change of resistance distribution and pore size distribution.Results showed that with the increase of pore size,the permeation flux of PVDF membrane to filter micro-polluted surface water decreased,and the membrane pollution resistance increased.PVDF membrane with an average pore size of 25 nm obtained the slowest flux decline,the stable flux was 133.2 L/(m^(2)·h),the turbidity removal rate was the highest,and the removal rate of organic matter in surface water was 40%-50%.The membrane fouling was endowed mainly by cake layer stacking(R_(c))and concentration polarization(R_(p)).With the increase of operating pressure,the total membrane fouling resistance(R_(t))gradually increased and blocking resistance(R_(a))reached the maximum and maintained stable at 0.1 MPa.The resistance ratio of R_(c) and R_(p) changed in the opposite direction.In the pilot experiment of surface water treatment,the performance of PVDF membrane with an average pore size of 25 nm was better than that of the imported brands in the pilot scale surface water treatment.