“双极膜-电去离子”耦合过程处理含镍离子溶液

Nickel ions-containing solution treatment by 'BPM-EDI' coupled process

电去离子是一种以离子交换膜与树脂表面的水解离产物对树脂动态"电再生"为特点,实现连续去离子的优势脱盐技术。为避免电去离子处理含有重金属离子的溶液时,膜堆内部可能出现的金属氢氧化物结垢问题,将双极膜引入常规电去离子装置,构建了一种"双极膜-电去离子"耦合(BMEDI)过程,并以含Ni2+离子溶液为对象探索了这一新型EDI技术用于重金属废水处理的可行性。结果表明,电流密度升至13.0mA.cm-2时,CM表面未出现水解离效应,升至15.0mA.cm-2时,AM表面也未出现水解离效应,膜堆内部无金属氢氧化物结垢。电流密度为15.0mA.cm-2时,未从淡水出水中检出Ni2+离子,7h后淡水出水电导率稳定在3.9μs.cm-1,出水水质较好。

Electrodeionization is an advanced technology in the field of desalination ,with the characteristics that resins can be regenerated continuously by H^＋ and OH^-ions as result of water dissociation on the ion-exchange membranes and resins. However,the characteristics may lead to precipitation of metal-hydroxides when the feed solution contains metal ions. In order to avoid the unfavorable phenomenon,a coupled electrodeionization process with the bipolar membrane （BMEDI） was introduced,and its effect on nickel removal was tested. Results indicated that when the current density rose to 13.0 mA·cm^-2,no water dissociation was found on the surface of the cation-exchange membrane. When the current density rose to 15.0 mA·cm^-2,water dissociation on the surface of the anion exchange membrane was also prevented,and the conductivity of diluted stream was stabilized at about 3.9 μs·cm^-1 after seven hours,with no Ni^2＋ ions detected.