溶液特性及共存物对纳滤膜去除水中全氟辛酸的影响

利用聚酰胺复合纳滤（NF）膜去除水中的持久性有机污染物－全氟辛酸（PFOA），分别研究了PFOA浓度、溶液离子强度、pH值、典型大分子有机物－牛血清蛋白（BSA）以及BSA与Na⁺共存对PFOA截留率的影响.结果表明，在0.8MPa下过滤24h，随着PFOA浓度增大，PFOA截留率提高；溶液离子强度、pH值越高，PFOA截留率越高；当PFOA原液中加入BSA时，BSA不但会堵塞一部分膜孔，同时会在膜面上形成有机污染层，增大膜面负电量，这样一方面增强NF膜的筛分作用，另一方面增强其静电排斥作用；当BSA与Na⁺共存时，NF膜的孔堵程度更加严重，且Na⁺使形成的有机污染层更加密实，NF膜的筛分能力进一步增强.

Effects of solution characteristics and coexisted substances on the removal of perfluorooctanoic acid from water by nanofiltration membrane

Polyamide composite nanofiltration (NF) membrane was used to remove persistent organic pollutant-perfluorooctanoate acid (PFOA) from water. This research investigated the influence of PFOA concentration, ionic strength, pH value, typical macromolecular organic matter-bovine serum albumin (BSA), and the coexistence of BSA and Na⁺ in feed solution on PFOA rejection, respectively. The filtration experiments were conducted at an operating pressure of 0.8MPa for 24h. Results showed that the retention of PFOA increased with increasing PFOA concentration. The higher the ionic strength or pH of the feed solution, the higher the rejection rate of PFOA was. When BSA presented in PFOA feed solution, BSA could not only block some membrane pores, but also form an organic fouling layer on the membrane surface which increased the negative charge of the membrane surface. Thus, both size exclusion and electrostatic repulsion abilities of the NF membrane were enhanced. When BSA coexisted with Na⁺ in the feed water, the pore blocking degree of the NF membrane was more serious. The presence of Na⁺ made the organic fouling layer much thicker. Therefore, the sieving capacity of the NF membrane was enhanced.