2026/07/20 by Zelalem B. Deress, Simon B.B. Solberg, Simon Birger Byremo Solberg +2
Engineering · Chemical Engineering · #Membrane-based Ion Separation Techniques #Extraction and Separation Processes #Chemical and Physical Properties in Aqueous Solutions
paper · doi:10.1016/j.desal.2026.120535
Understanding the transport phenomena in ion-exchange membranes (IEMs) in contact with Lithium-Nickel-Manganese-Cobalt (LNMC) sulfates is of utmost importance for establishing membrane-based processes in the recycling of lithium-ion batteries (LIBs). In this work, we analyzed new measurements of electric potentials across commercial Selemion IEMs in contact with aqueous single-salt solutions of LNMC sulfates using the framework of non-equilibrium thermodynamics. Ionic transport numbers and water transference coefficients are extracted using the permselectivity analysis method. The transport numbers obtained for membrane unit cells with LNMC sulfates were , 1.003 ± 0.008 , 0.90 ± 0.02 for NiSO 4 , CoSO 4 , and MnSO 4 , respectively, and a salt transport number of t Li 2 SO 4 = 0.450 ± 0.016 for Li 2 SO 4 . The water transference coefficients were determined to be t w = 16 ± 2 , 15 ± 3 , 25 ± 7 , and 7 ± 4 for NiSO 4 , CoSO 4 , MnSO 4 , and Li 2 SO 4 , respectively.These results suggest that the membranes were found to be selective toward and ions in NiSO 4 and CoSO 4 electrolytes, respectively, exhibiting near-ideal migration behavior for these divalent sulfate systems. The co-transport of water significantly contributes to deviations from ideal transport behavior. The membranes in solutions of MnSO 4 deviate from ideality, which could be due to oxidation of or concentration-dependent water transference. Systems of Li 2 SO 4 suggest that ion pairing occurs, and analysis of the measured transport numbers using the proposed model indicates that may contribute up to 5 % of the electric current transport through the anion-exchange membrane. The findings provide new insights into interactions between ionic species and water transport in IEMs, highlighting the importance of accounting for water transport in the design of electrodialysis processes in LIB recycling. Moreover, this work can support the development of more efficient membranes tailored for specific applications.