Abstract
The development of the most effective, suitable and economic ion-exchange membranes is crucial for reverse electrodialysis (RED)—the most widely studied process to harvest salinity gradient energy from mixing seawater and river water. RED utilizes two types of membranes as core elements, namely cation exchange membranes (CEM) and anion exchange membranes (AEM). Since the preparation of AEMs is more complex compared to CEMs, the design and development of anion exchange membranes have been the focus in this study. Homogeneous AEMs based on two types of polyepichlorohydrin (PECH) with different chlorine amounts (PECH-H, 37 wt% and PECH-C, 25 wt%) were synthesized, and first-time benchmarking of the membrane properties was conducted. In addition to physicochemical membrane properties, some instrumental analyses such as SEM, FTIR and DSC were investigated to characterize these anion-exchange membranes. Based on the results, although the PECH-H-type membrane had enhanced ion-exchange properties, PECH-C-based anion-exchange membranes exhibited a higher power density of 0.316 W/m2 in a lab-scale RED system. Evidently, there is room for the development of new types of PECH-C-based AEMs with great potential for energy generation in the RED process.
Highlights
Energy, water and food have represented three global issues faced by humankind for a long time
In order to attain sufficient film-forming properties and to make benchmarking with commercial anion exchange membranes (AEM), PECH-based membranes with about 150 μm were fabricated in this work
Many commercial ion-exchange membranes for reverse electrodialysis (RED), ED, EDI, or other electromembrane processes have about a 100–150 μm film thickness (e.g., Neosepta, Selemion), al
Summary
Water and food have represented three global issues faced by humankind for a long time. Other SGE technologies exist, such as microbial RED, accumulator mediated mixing, hydrocratic generator, reverse vapor compression, and some other adsorption/desorption processes [9] Among all those techniques, RED and CAPMIX utilize ion-exchange materials, and ion transport happens in an electrochemical manner. RED is the most widely studied technique and has experienced sharp growth in recent years because of its unique advantages [2,7,10,11] It is, for instance, the most efficient process when sea water and river water are considered as the feed, there are applications wherein very-high-salinity solutions can be used [12,13,14]. Reyes-Aguilera et al used the electrospinning technique to prepare PECH membranes where the membrane morphology was varied with different electrospinning parameters [34] These studies already presented some promising AEMs for RED applications; there is always room for development. First-time benchmarking of these properties with the commercially available membrane has been performed using the lab-scale RED system
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