Chemically irreversible fouling (CIF) and erosion caused by chemical cleaning would result in the changes of desalination performance and membrane properties of the ion-exchange membranes (IEMs), which were defined as membrane ageing. Roles of CIF and chemical erosion in the ageing process and the interaction mechanisms have been systematically investigated during the electrodialysis treatment of flue gas desulfurization wastewater. The main foulants contributed to CIF were anionic polyacrylamide (APAM) and CaSO4 for anion-exchange membranes (AEMs) and CaSO4 for cation-exchange membranes. The variation in the ageing behaviors has undergone three main stages. The general tendency of desalination rates was initially decreased, subsequently increased, and gradually declined at last. Membrane morphology and chemical structure of the aged IEMs transformed as a result of the CIF as well as the alternant NaOH and HCl cleaning. Chemical erosion caused the degradation of functional groups and polymer matrix, which was demonstrated by the changes in ion exchange capacity, contact angle, thermal stability and mechanical strength. Cleaning efficiency was limited by CIF, while chemical erosion would in turn affect membrane fouling behaviors. The extended Derjaguin-Landau-Verwey-Overbeek analysis verified that the antifouling ability of aged AEMs enhanced with a decrease of the total interaction energy of APAM-AEM.

中文翻译：

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烟气脱硫废水电渗析处理过程中结垢与化学清洗对离子交换膜老化行为的相互作用机制


化学清洗引起的化学不可逆污垢 （CIF） 和侵蚀会导致离子交换膜 （IEM） 的海水淡化性能和膜特性发生变化，这些变化被定义为膜老化。在烟气脱硫废水的电渗析处理过程中，系统研究了 CIF 和化学侵蚀在老化过程中的作用以及相互作用机制。导致 CIF 的主要污染物是阴离子聚丙烯酰胺 （APAM） 和用于阴离子交换膜 （AEM） 的 CaSO4 和用于阳离子交换膜的 CaSO4。衰老行为的变化经历了三个主要阶段。海水淡化率的一般趋势最初是降低，随后增加，最后逐渐下降。由于 CIF 以及交替的 NaOH 和 HCl 清洁而改变的老化 IEM 的膜形态和化学结构。化学侵蚀导致官能团和聚合物基体降解，离子交换容量、接触角、热稳定性和机械强度的变化证明了这一点。清洁效率受 CIF 的限制，而化学腐蚀反过来会影响膜的污染行为。扩展的 Derjaguin-Landau-Verwey-Overbeek 分析证实，随着 APAM-AEM 总相互作用能的降低，老化的 AEM 的防污能力增强。