Abstract
Electric field-accelerated ion-permselective membrane (EISM) separation has attracted significant attention in recent years. Thus, herein, to further investigate the ion transport mechanism and optimize the separation efficiency, five types of ion-permselective membrane modules (IPMM I–V) based on the electrochemically switched ion exchange (ESIX) scheme were designed. Compared with the traditional ion separation systems, the in situ membrane-based ion separation system was set up with an extra pulse potential applied to the PPy/PSS/SSWM (polypyrrole/polystyrenesulfonate/stainless steel wire mesh) membrane. The continuous permselective separation of K+ as target ions was performed from dilute aqueous solution through the IPMM system. The pulse potential combined with the regulated cell voltage was functionalized synergistically to create an “ion-sieving effect” and effectively guide the target cations from the source cell to the receiving cell. Moreover, the formation of an equal potential volume in IPMM-V suppressed the reverse migration of the target ions and the detected ion flux across the membrane was 100 times that of the IPMM-I system. The ion transport mechanism was also analyzed in detail based on the equivalent circuit of the system, and the optimized operation parameters were obtained for the high-efficient ion separation system. These results can provide some beneficial information for the design and practical operation of novel EISM systems.
Highlights
Selective ion separation is an important process in the human body, which occurs during the removal of toxic ions that interfere physiological functions
The current efficiency of the in situ electric eld-accelerated ion transport system was determined based on a K+ transport experiment, where the pulse potential applied to the membrane was À1 V to 1 V, the pulse width was 60 s, and cell voltage for 5 h. 200 mL of 1 mM K+ solution was pumped into the source chamber and 200 mL of deionized water was pumped into the receiving chamber
A novel and effective electric eld-accelerated ion sieve system was designed for ion separation
Summary
Selective ion separation is an important process in the human body, which occurs during the removal of toxic ions that interfere physiological functions. System.[20,21] Later, Kaya et al employed a constant DC electric current to replace the electric voltage in the system, which resulted in signi cant improvements in the stability and efficiency.[22] Considering that the abovementioned processes are batch operations and difficult to apply in industry, Weidlich et al designed a semicontinuous operation cell, where two identical cation exchanger electrodes were divided by an anion exchange membrane and successfully removed Ca2+ and Mg2+ for water so ening.[23] it still has some defects, which require the electrodes to be reversed and the uids in the compartments be exchanged periodically To solve this problem, subsequently, Wallace et al developed a series of continuous cell systems with an ion-permselective membrane, which has been widely used in ion separation research to date.[24,25,26,27]. The mechanism and the effects of the operation parameters including the cell voltage and the pulse potential on the membrane were intensively analyzed
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