亲水化改性PVDF超滤膜的抗污染特性研究

STUDY ON HYDROPHILIC MODIFICATION OF PVDF ULTRAFILTRATION MEMBRAN AND ITS ANTI-FOULING PROPERTY

以不同通量的自制亲水化纳米SiO2改性PVDF超滤膜(PS)和聚乙烯醇改性PVDF超滤膜(PA),对城市污水二级出水(EfOM)和牛血清蛋白(BSA)水溶液进行了过滤试验,通过对比未添加改性剂的PVDF超滤膜,考察通量衰减率、膜污染阻力构成、通量恢复率等指标,分析水质与膜材料间的相互关系对超滤膜抗污染能力的影响。结果表明,在BSA料液中,3种通量下,低通量的膜抗污染能力好于高通量膜。20 min内PA膜表现出最低的膜通量衰减,而P膜在过滤初期通量就急剧下降。在EfOM料液中,各通量下,P膜通量衰减严重且产生了不可逆的堵孔阻力,亲水化改性后膜通量衰减率降低,稳态通量高,膜污染阻力主要来自于浓差极化和滤饼层阻力,其中PS膜通量下降率最低,而PA膜清洗后通量易恢复。

Hydrophilic modification of PVDF-SiO2（PS）and PVDF-PVA（PA） ultrafiltration membrane with different flux were prepared,respectively.Secondary effluent of municipal sewage（EfOM） and bovine serum albumin（BSA） aqueous solution were tested by different hydrophilic membranes.Compared with the unmodified membrane,the pollution indicators of flux decline rate,membrane fouling resistance and flux recovery rate were investigated which in order to analyze the relationship between water quality and membrane materials on membrane anti-pollution ability.The results showed that in the filtration process to BSA,the membrane with low flux had better fouling-resistant capability than that with high flux.It indicated that flux descending ratio of the PA membrane is the lowest,however,P membrane had a sharp flux decline in the beginning.In the filtration process to EfOM,the serious flux decline of P membrane produced irreversible pore blocking resistance,but the flux decay rate of modified hydrophilic membrane decreased,the steady-state flux was improved,the main membrane resistances were caused by concentration polarization and cake layer resistance.Flux descending ratio of the PS membrane was the lowest,and the flux of PA membrane was easy to restore after backwashing.