## 4 Conclusions  
The study of fabricated PES and sPES IEMs and their characterization analysis results are summarized below. Based on electrodialysis testing with PES membranes with different solvent evaporation times, the solvent evaporation time of 3 h was determined to be optimal based on several figures of merit (e.g., current density, current efficiency, salinity reduction, and normalized specific energy consumption), while the sPES membranes evaporated within 1 h show the best performance based on the same figures of merit. With electrodialysis test conditions of 3 cm/s flow velocity, 0.8 V/cell-pair, and 3 g/L NaCl feed water, for PES membranes, the average current density was 97 A/m\({}^{2}\), the current efficiency was 50%, the salinity reduction after 60 min of running was 24%, and the normalized specific energy consumption was approximately 0.045 kWh/m\({}^{3}\)/(meq/L). Under the same running conditions, for sPES membranes, the average current density was 130 A/m\({}^{2}\), the current efficiency was 48%, the salinity reduction after 60 min of running was 33%, and the normalized specific energy consumption was approximately 0.045 kWh/m\({}^{3}\)/(meq/L). In addition, the IEC of the sPES membrane is particularly notable at 2.67 meq/g, indicating superior ion exchange capacity. Generally, ED performance shows that the process of sulfonation increases the performance of salinity reduction from PES membranes to sPES membranes.  
The increase in surface roughness from 0.996 nm for the PES membrane to 3.149 nm for the sPES membrane, as observed in AFM images, indicates the impact of the sulfonation process. This process increases the degree of sulfonation, which is further evidenced by the strengthened peaks in the FTIR-ATR and XPS spectra for the sPES membrane.  
The developed PES and sPES membranes are highly effective for electrodialysis, especially in desalination and water purification. Their high IEC and competitive performance metrics make them suitable for large-scale industrial applications. New ion exchange membranes can significantly enhance the applicability, efficacy, and efficiency of ion removal processes in water treatment and resource recovery, especially with electrically driven separation processes, providing cost-effective and scalable solutions for improving water quality in various settings [45].  
Conceptualization, L.C., E.M.D. and W.S.W.; Methodology, L.C., E.M.D. and W.S.W.; Software, L.C.; Validation, L.C., E.M.D. and X.L.; Formal analysis, L.C.; Investigation, L.C.; Resources, E.M.D., X.L. and W.S.W.; Data curation, L.C.; Writing--original draft preparation, L.C.; Writing--review and editing, X.L. and W.S.W.; Visualization, L.C.; Supervision, X.L. and W.S.W.; Project administration, W.S.W.; Funding acquisition, X.L. and W.S.W. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the National Science Foundation through the Nanosystems Engineering Research Center (ERC) for Nanotechnology-Enabled Water Treatment (NEWT), grant number EEC-1449500. We would also like to acknowledge financial support from the U.S. NSF (IIP2122712 and CHE2216473), CPRIT(RP210165), NIH/NIAID (R41 AI162477), and AAFS Lucas grants.  
Not applicable.  
The original contributions presented in this study are included in the article. Further inquiries can be directed to the corresponding author.  
The authors declare no conflicts of interest.