双极膜电渗析处理精制浓海水制备酸碱

Preparation of Acid and Base by Refined Content Contentrated Seawater with Bipolar Membrane Electrodialysis Process

采用自行研制的三隔室型双极膜电渗析(BMED)膜堆,以模拟精制浓海水为原料制备酸碱,考察了操作条件对膜堆性能的影响和运行过程中酸碱室的盐组分泄漏问题。结果表明,在电流密度为30 m A/cm^2,精制浓海水盐的质量浓度为147 g/L,碱(酸)与盐初始溶液体积比为1:1的条件下,实验范围内产品碱的收率可达56.4%;膜堆产率和碱收率随电流密度的提高而提高,但电流效率随之下降;较大的碱(酸)与盐初始溶液体积比有利于盐离子的迁移,电流效率相应上升,过程能耗减小;膜堆电阻随浓海水盐含量的升高而减小,过程能耗降低,但产品碱的收率有所下降。实验过程在酸室中检测到有Na^+、K^+,而碱室中检测到Cl^-,表明所用双极膜和阴阳离子交换膜存在一定程度的离子泄漏,且随过程运行逐步加剧。

Using self-designed t hree-compartment bipolar membrane ele ctrodialysis（BMED） stack, acid and base is prepared by refined content contentrated seawater. The effect of operation conditions on performance of membrane module and the salt leakage between acid-base compartment was studied. The results show that： when the current density is 30 m A/cm2, the mass content contentration of salt is 147 g/L and the initial volume ratio of base（acid） and salt is 1：1,the base recovery can reach 56.4%; when current density increases, the yields and recovery of base will be increased,but the current efficiency will decrease; the larger volume ratio, which is in favor of the ions migration, will be accompanied by a corresponding increase in current efficiency, and t he energy consumption will reduce; the higher content of salt which leads to a smaller stack res istance can reduce energy consumption, but the base recovery declines. During the experiment, Na＋ and K＋ were detected in the acid compartment, and Cl- was detected in the base compartment, which verified the non-ideal permselectivity of bipolar membrane and ion exchange membrane. And this salt leakage gradually increased over time.