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Herein, the effect of electrolyte composition (single vs salt mixture) on the performance of reverse electrodialysis (RED) has been investigated using lab-made sulfonated poly(ether ether ketone) (sPEEK) cation exchange membrane (CE) membrane and Neosepta, a commercially available anion exchange (AE) membrane. The efficiency of the RED cell was monitored by measuring open-circuit voltage (OCV), power density (PD), and gross power density (PD gross ). The effect of feed solution flow and concentration was analyzed by using several electrolytes (LiCl, NaCl, KCl, and NH 4 Cl) and mixed composition (NaKCl and NaNH 4 Cl). NaCl solution among single electrolytes exhibited the highest performance with a PD of 1.77 Wm −2 , which was improved further by intermixing with KCl and NH 4 Cl. For the case of binary mixtures, NaNH 4 Cl showed a PD of 2.51 Wm −2 , which is 42% higher compared to that of NaCl possibly due to the inferior stack resistance. A molecular dynamics (MD) simulation was performed to further investigate the adsorption-diffusion properties of CEM and AEM at the molecular scale. A positive correlation was observed between MD simulation and experimental measurements regarding the competitive adsorption of cations into the sPEEK membrane with the following trend NH 4 + > K + > Na + > Li + , which is associated with the ionic radius and hydration energies of respective cations.

The SEArcularMINE project aims to recover critical raw materials (CRMs) from brines from saltworks, thus facing a CRM shortage within Europe. To promote a fully circular scheme, the project valorises concentrated brines using electrodialysis with bipolar membranes (EDBM) to generate the required amounts of reactants (i.e., acids and bases). Regarding the performances of new non-woven cloth ion-exchange membranes (Suez): (i) an ultra-thin non-woven polyester cloth and (ii) a thin polypropylene cloth acting as the support structures were assessed. Additionally, the anion layer includes a catalyst to promote the water dissociation reaction. The effect of current density (100, 200, and 300 A m−2) on the performance of two combinations of membranes in an inter-laboratory exercise using 2 M NaCl was evaluated. According to statistical analysis ANOVA, there was an agreement on the results obtained in both laboratories. NaOH/HCl solutions up to 0.8 M were generated working at 300 A m−2 using both combinations of membranes. Regarding the performance parameters, stack set-ups incorporating thin polypropylene membranes showed lower specific energy consumption (SEC) and higher specific productivity (SP) than ultra-thin polypropylene ones. Hence, for ultra-thin polypropylene membranes, SEC was reported to be between 2.18 and 1.69 kWh kg−1NaOH and SP between 974 and 314 kg m−2 y−1.