天然有机物和离子对纳滤膜过滤性能的影响研究

Effects of NOM and ions on the filtration capacity of nanofiltration membrane

采用纳滤膜Desal 5 DK对天然有机物（NOM）和离子进行死端过滤实验,以考察进水组分对膜过滤性能的影响。结果表明,Desal 5 DK对NOM的截留率为60%~80%,由NOM引起的不可逆水通量降低占总水通量降低的70%。Desal 5 DK对水中Ca2＋的截留率〉90%,而对Na＋的截留率保持在20%~38%,离子与荷电纳滤膜之间的道南效应以及水合离子大小和扩散系数的不同引起二者截留率的差异,并导致了水通量衰减。

Nanofiltration membrane,Desal 5 DK,has been used for carrying through the dead-end filtration for NOM or ions,so as to investigate the effect of influent water components on the membrane filtration capacity.The results show that the rejection rate of NOM by Desal 5 DK is 60%-80% which causes 70% of the irreversible water flux decline of the total flux decline.The rejection rate of Ca2＋ in water is higher（90%）,but that of Na＋ remains on 20%-38%.The difference of the two rejection rates are caused by Donnon effect between ions and charged nanofil-tration membranes and the difference between the sizes of the hydrated ions and the diffusion coefficients.They also result in the decline of water flux.