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Effect of Divalent Cations on RED Performance and Cation Exchange Membrane Selection to Enhance Power Densities
journal contribution
posted on 2017-09-26, 00:00 authored by Timon Rijnaarts, Elisa Huerta, Willem van Baak, Kitty NijmeijerReverse electrodialysis (RED) is
a membrane-based renewable energy
technology that can harvest energy from salinity gradients. The anticipated
feed streams are natural river and seawater, both of which contain
not only monovalent ions but also divalent ions. However, RED using
feed streams containing divalent ions experiences lower power densities
because of both uphill transport and increased membrane resistance.
In this study, we investigate the effects of divalent cations (Mg2+ and Ca2+) on RED and demonstrate the mitigation
of those effects using both novel and existing commercial cation exchange
membranes (CEMs). Monovalent-selective Neosepta CMS is known to block
divalent cations transport and can therefore mitigate reductions in
stack voltage. The new multivalent-permeable Fuji T1 is able to transport
divalent cations without a major increase in resistance. Both strategies
significantly improve power densities compared to standard-grade CEMs
when performing RED using streams containing divalent cations.