Abstract: The individual role of Ca2+ salts and amino acids on membrane fouling from a bipolar membrane electrodialysis (BMED) of simulated monosodium glutamate isoelectric supernatant was studied with a constant voltage batch operation mode. Experimental results showed that some amino acids including Glu, Ala, Gly, Thr and Lys were detected in a content order of Glu>Ala>Gly>Thr>Lys in the base cell, which was proportional to their respective content in salt solution. The calcium existing in feed liquor was responsible mainly for fouling of the cationic exchange membrane (CEM) in contact with base cell, which resulted in some solid deposits on the CEM surface. During a consecutive batch BMED of simulated feed liquor with different amino acid contents, the end electrical conductivity gradually rose up with the batch going on, which increased from 1.32 mS/cm of the first batch to 10.56 mS/cm of the fourth batch for the feed liquor with the highest amino acid content. As an estimate of membrane fouling, the initial current was also characterized. It dropped down with the batch run and higher amino acid content, which was reduced from 3.91 A of the first batch to 3.27 A of the fourth batch for the feed liquor with the highest amino acid content. These results indicated that the amino acid tended to deteriorate some performance parameters of BMED. It was observed with SEM that the CEM of base cell suffered from some pollution to different degrees (JCM C>JCM B>JCM A) after the BMED of simulated feed liquor with different amino acid contents. With the further elemental analysis of the pollutant, the calcium and oxygen on polluted CEM surface were found to increase significantly, indicating that the pollutant could be deposits of Ca(OH)2/CaCO3 and amino acidic organic matter.

Key words: calcium salt, amino acid, bipolar membrane electrodialysis, membrane fouling, performance parameter

摘要： 采用恒压分批操作方式考察了味精等电母液模拟料液中钙盐和氨基酸对双极膜电渗析过程膜污染的影响. 结果表明，在处理含氨基酸和Ca2+的盐溶液时，碱室溶液中检测到各氨基酸含量为Glu>Ala>Gly>Thr>Lys，它们与料液中NH4+同步迁移至碱室，迁移量与料液中氨基酸浓度成正比；料液中Ca2+是引起碱室侧阳膜面出现固形污染物的主要因素. 以3种不同氨基酸浓度模拟料液进行连续批次双极膜电渗析实验，氨基酸浓度最大的料液的终点电导率从第1批的1.32 mS/cm增至第4批的10.56 mS/cm；以每批初始电流判断膜污染，在最大氨基酸浓度时料液初始电流从第1批的3.91 A降至第4批的3.27 A，表明料液中氨基酸会导致电渗析性能恶化. 不同氨基酸浓度、钙含量相同的盐溶液经连续批次双极膜电渗析处理后，碱室侧阳膜面的污染量顺序为JCM C>JCM B>JCM A，即随料液中氨基酸浓度升高而增多；污染阳膜面元素分析表明Ca和O元素含量增加，最终推断污染物为Ca(OH)2/CaCO3沉淀及氨基酸有机物.

关键词: 钙盐, 氨基酸, 双极膜电渗析, 膜污染, 性能参数