Abstract:
The selective separation of metal species from various sources is highly desirable in applications such as hydrometallurgy, water treatment, and energy production but also challenging. Monovalent cation exchange membranes (CEMs) show a great potential to selectively separate one metal ion over others of the same or different valences from various effluents in electrodialysis. Selectivity among metal cations is influenced by both the inherent properties of membranes and the design and operating conditions of the electrodialysis process. The research progress and recent advances in membrane development and the implication of the electrodialysis systems on counter-ion selectivity are extensively reviewed in this work, focusing on both structure-property relationships of CEM materials and influences of process conditions and mass transport characteristics of target ions. Key membrane properties, such as charge density, water uptake, and polymer morphology, and strategies for enhancing ion selectivity are discussed. The implications of the boundary layer at the membrane surface are elucidated, where differences in the mass transport of ions at interfaces can be exploited to manipulate the transport ratio of competing counter-ions. Based on the progress, possible future R&D directions are also proposed.
摘要:
从各种来源中选择性分离金属物种在湿法冶金等应用中是非常理想的。水处理,和能源生产,但也具有挑战性。单价阳离子交换膜(CEM)显示出很大的潜力,可以选择性地将一种金属离子从电渗析中的各种流出物中分离出相同或不同价态的其他金属离子。金属阳离子之间的选择性受膜的固有性质以及电渗析过程的设计和操作条件的影响。本文广泛综述了膜发展的研究进展和最新进展,以及电渗析系统对反离子选择性的影响。重点研究了CEM材料的结构-性质关系以及工艺条件和靶离子传质特性的影响。关键膜性能,如电荷密度,吸水,和聚合物形态,并讨论了增强离子选择性的策略。阐明了边界层在膜表面的含义,其中可以利用离子在界面处的质量传输差异来操纵竞争抗衡离子的传输比率。根据进展,还提出了未来可能的研发方向。