Effect of Co-Existing Ions on Salinity Gradient Power Generation by Reverse Electrodialysis Using Different Ion Exchange Membrane Pairs

Abstract

This study investigates the influence of co-existing ions on the salinity gradient power generation performance of the reverse electrodialysis (RED) using three different commercial ion exchange membrane pairs. The feed solutions, including the mixture of two different salts, were prepared with 90 wt.% of NaCl and 10 wt.% of LiCl, KCl, CaCl2, MgCl2 or Na2SO4 by keeping the salt ratio between high concentrate solution and low concentrate solution constant as 1:30 (g/g) at various flow velocities (50, 125 and 200 mL/min). It was observed that the divalent ions exhibited a negative impact on the performance of the RED system due to their high valence and low ionic mobility depending on their high hydrated radius and low diffusion coefficients compared to those of the monovalent ions. On the other hand, the effect of the monovalent ions differed according to the properties of ion exchange membranes used in the RED stack. When the power generation performances of ion exchange membrane pairs employed in the RED stack were compared, it was considered that Neosepta AMX and CMX membranes provided the highest power density due to their low membrane thicknesses, low electrical resistances, and relatively high ion exchange capacities compared to other two commercial ion exchange membrane pairs.

Advances in Two-Dimensional Ion-Selective Membranes: Bridging Nanoscale Insights to Industrial-Scale Salinity Gradient Energy Harvesting

“…Multivalent ions had a greater negative impact on open circuit voltage because of their higher charge and weaker permselectivity. The internal resistance of solutions containing divalent ions was higher than that of artificial NaCl solution, owing to their lower diffusion coefficients and larger hydrated radius …”

“…The internal resistance of solutions containing divalent ions was higher than that of artificial NaCl solution, owing to their lower diffusion coefficients and larger hydrated radius. 179 Compared with the commercial IEMs, 2D ion-selective membranes offer significant advantages in terms of high ion selectivity and power density, which are desirable candidates to achieve high output power at large-scale areas. First, 2D ionselective membranes have intrinsic nanopores and nanochannels, which are similar in size to the EDL, leading to improved ion selectivity.…”

Nanocomposite use in MFCs: a state of the art review

“…However, due to high capital and operating costs as well as poor conversion efficiencies, it is still challenging to render renewable energyproducing equipment commercially viable. [1][2][3][4][5] Considering the above, there is a substantial demand for environmentally friendly alternatives as sources of energy or fuel. These sources must meet specic sustainability requirements such as minimal carbon footprint, 6 affordability, 7 safety, 8 and the possibility of being employed in off-grid areas, particularly in developing countries, where access to electricity is crucial for social development and well-being.…”