氯化锂共混改性对PVDF超滤膜耐氯性的影响

EFFECT OF LITHIUM CHLORIDE BLENDING ON CHLORINE RESISTANCE OF PVDF ULTRAFILTRATION MEMBRANE

为考察氯化锂(LiCl)共混改性对聚偏氟乙烯(PVDF)超滤膜耐氯性的影响,采用聚乙烯吡咯烷酮(PVP)作为致孔剂和亲水改性剂,通过非溶剂致相分离法制备了PVDF和PVDF/LiCl膜,考察了次氯酸钠(NaClO)静态加速老化前后2种膜性质和性能的变化。结果表明:添加LiCl使得相转化成膜过程中更多的PVP保留在膜上,且增加了PVDF的极性β相比例,使PVDF/LiCl膜的亲水性增强,孔隙率增加;NaClO老化造成PVP氧化流失和膜亲水性降低,采用牛血清蛋白作为模型有机物的过滤实验表明,NaClO老化使PVDF和PVDF/LiCl膜的污染阻力分别增加88%和49%,PVDF/LiCl膜抗污染性能下降幅度明显小于PVDF膜。总体而言,LiCl共混改性减缓了NaClO造成的PVDF膜性质的变化,提升了PVDF膜的耐氯性。

To investigate the effect of lithium chloride(LiCl)blending on chlorine resistance of polyvinylidene fluoride(PVDF)ultrafiltration membrane,PVDF and PVDF/LiCl membranes were prepared by non-solvent induced phase separation method using polyvinylpyrrolidone(PVP)as the pore-forming agent and hydrophilic additive.The changes in membrane properties and performance due to static accelerated sodium hypochlorite(NaClO)aging were investigated.The results showed that the addition of LiCl enabled more PVP to remain on the membrane during the phase conversion process,and increased the proportion of polarβPVDF.Therefore,the hydrophilicity and porosity of the PVDF/LiCl membrane were higher than those of the PVDF membrane.NaClO aging resulted in oxidation and dislodgement of PVP and a decrease in membrane hydrophilicity.Filtration experiments using bovine serum protein as a model organic foulant showed that NaClO aging increased the fouling resistance of PVDF and PVDF/LiCl membranes by 88%and 49%,respectively.The deterioration of fouling resistance of PVDF/LiCl membrane,due to NaClO aging,was significantly lower than that of PVDF membrane.In general,LiCl blending can improve the chlorine resistance of PVDF membranes by alleviating the change of membrane properties,due to NaClO aging.