A non-isothermal model incorporating temperature-dependent ion transport and interfacial selectivity for high-performance electrodialysis

Electrodialysis is a membrane-based separation process driven by an electric field, which shows considerable potential for desalination, wastewater treatment, and resource recovery. However, current electrodialysis models mainly focus on bulk solution properties and neglect the influence of temperature on membrane structure, limiting their application in non-isothermal scenario. In this work, a non-isothermal electrodialysis model is developed by accounting for the effects of temperature on membrane structural properties and ion diffusion. Employing temperature-dependent membrane water uptake and electrolyte volume fraction as inputs, the model predicts the ion diffusion coefficients within the membrane at different temperatures through the Mackie–Meares and Donnan–Manning corrections, providing a basis for evaluating electrodialysis performance.The results show that temperature gradients enhance transmembrane ion transport, while reduce the interfacial Donnan barrier and thus weaken the ion selectivity. Simultaneous heating at the inlet and outlet gives the best overall concentration and deep desalination performance. Under asymmetric heating modes, heating at the inlet performs better than heating at the outlet because it better preserves interfacial Donnan equilibrium and suppresses co-ion back-transport. Membrane fixed charge density determines the separation limit, whereas the thermal operating mode mainly controls interfacial stability and the distribution of transport resistance. The work provides a new model for non-isothermal electrodialysis and offers the guidance for the thermal enhancement of desalination.