Insights into the facilitated transport mechanisms of Cr(VI) in ionic liquid-based polymer inclusion membrane – Electrodialysis (PIM-ED) process

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Vol. 397; p. 125324
• Main Authors: Li, Zhenyu, Liu, Yang, Wang, Baoying, Lang, Qiaolin, Tan, Ming, Lee, Manseung, Peng, Changsheng, Zhang, Yang
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.10.2020
• Subjects: Chromium; Electrodialysis; Mechanism; Polymer inclusion membrane; Threshold; Chromium; Polymer inclusion membrane; Mechanism; Electrodialysis; Threshold
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2020.125324

[Display omitted] •Low diffusion efficiency of PIMs was significantly improved by integrating ED.•Both thresholds of carrier content and current intensity were observed.•Fixed-site jumping mechanism in PIM is confirmed by the electro-transport.•High current intensity induced a continuous pathway transport of Cr(VI).•Multi-membrane stacks PIM-ED system is feasible for industrial application. To improve the relatively low transport efficiency of ionic liquid-based polymer inclusion membrane (PIM), an integration of electrodialysis (ED) with PIM is explored for the facilitated transport of Cr(VI). Several parameters such as current density, carrier concentration, initial composition and properties of feed and stripping solutions have been systematically studied. Current intensity was crucial to the facilitating transport of Cr(VI), while a threshold of current density was observed at around 7 mA cm−2, and the highest permeability coefficient was achieved at 10 mA cm−2. By using the integrated system at optimized condition, the permeability coefficient increased from 0.62 to 3.33 μm s−1 below threshold, while from 3.33 to 23.53 μm s−1 above threshold to 10 mA cm−2. Under optimum conditions, the initial flux of Cr(VI) in our experiment can reach 116 μmol m−2 s−1. Therefore, the facilitated transport was proposed to be achieved by promoting fixed-site jumping mechanism in electric field below the threshold value, while a continuous pathway manner was hypothesized above the threshold value. The PIM exhibited high stability in PIM-ED system in 9 repeated experiments with slightly decrease for Cr(VI) transport performance. The transport efficiency can be further improved by using multistage operation which is appropriate for scale-up applications.