EDI过程中离子交换膜的性能变化及其影响

Ion exchange membrane properties variation and its effect in electrodeionization process

采用衰减全反射红外(ATR-IR)法测定离子交换膜内交换基团的变化,利用扫描电镜(SEM)观察离子交换膜的表面形貌;采用交流阻抗(AC)法测量膜的电阻,并通过在线测定的方式分析离子交换膜性能变化对EDI过程的影响.结果表明:离子交换膜在EDI过程中存在结垢和部分季铵基降解为叔胺基的行为;浓缩室阴膜表面发生结垢后旧膜的面电阻较新膜要高45%以上;通过更换膜堆内阴离子交换膜,发现在相同电流情况下,新的EDI膜堆拥有较高的产水电阻率值和较低的电压值.

Using the attenuated total reflection （ATR-IR） infrared method to determine the change of exchange groups;by scanning electron microscopy （SEM） technique to observe the surface morphology change of ion exchange membrane;By using alternating current impedance method （AC） to measure the resistance of membranes, the effect of ion exchange membrane on EDI progress is analyzed through the online measurement. The results show that the ion exchange membrane exist scaling and partial degradation from quarternary ammonium to tertiary amine type behavior in EDI process;anion membrane surface fouling occurs in concentrate compartment, surface resistance of the used membrane larger 45%than the new membrane. Further, by changing the anion exchange membrane, it is found that the EDI stack equipped with new ion exchange membranes have a higher product water resistivity and lower voltage in same current comparing to the EDI stack equipped with the ion exchange membranes used for a long time.