聚合物对离子交换膜脱盐性能的影响及其污染特性

Influence of Polymer on Desalination Performance and Fouling Characteristics of Ion Exchange Membrane

通过自制的电渗析(ED)装置,从聚合物(部分水解型聚丙烯酰胺,HPAM)浓度、操作电压以及进水流速等方面研究了HPAM对离子交换膜脱盐性能的影响,并结合HPAM在膜上的吸附情况,分析了其污染特性。结果表明,聚合物对离子交换膜的脱盐性能有显著的影响,聚合物浓度的增加会加大HPAM的单位膜面积吸附量,加剧膜污染,降低膜脱盐效率;升高操作电压,同样会促进HPAM在膜上的吸附,但不及对溶液离子迁移的影响,脱盐效果虽得到提高,但能耗增加;提高进水流速,可以减少HPAM在膜上的吸附,减轻膜污染,同时提高离子扩散速率,增强脱盐效果,但增强幅度不如提高电压的明显,且在一定范围内对能耗的影响不显著。另外,SEM分析发现,阴膜污染相比阳膜更为严重,且FTIR分析验证了膜表面的污染物质为HPAM。

The influences of partially hydrolyzed polyacrylamide （HPAM） polymer on desalination performance of ion exchange membrane were investigated using a homemade electrodialysis （ED） device. HPAM concentration, operating voltage and influent flow rate were examined. The membrane fouling characteristics were analyzed from the adsorption of HPAM on the membrane. The results showed that the polymer had a significant impact on the desalination performance of ion exchange membrane. The in- crease of polymer concentration led to an increase of HPAM adsorption per unit membrane area, thus ex- acerbating membrane fouling and reducing the desalination efficiency. The increase of operating voltage could also promote the adsorption of HPAM on the membrane, but less than the impetus to ionic migra- tion. The result was improved desalination effect but increased energy consumption. Improving the influ- ent flow rate could reduce the adsorption of HPAM and thus reduced membrane fouling. Meanwhile, the ionic diffusion rate was improved. The desalination effect was enhanced to a lower extent than that from increasing the operating voltage, and within a certain range, there was no significant effect on energy con-sumption. In addition, SEM analysis found that the fouling of the anionic membrane was more serious than that of the cationic membrane, and the FTIR analysis proved that the foulant on the membrane sur- face was HPAM.