Ultra-high nitrate-selective metal-polymer membranes based on cardo polybenzimidazole for electrodialysis

• Published in: Journal of membrane science 2025-02, Vol.716, p.123518, Article 123518
• Main Authors: Lysova, A.A., Manin, A.D., Golubenko, D.V., Ponomarev, I.I., Altynov, V.A., Hilal, N., Yaroslavtsev, A.B.
• Format: Article
• Language: English
• Subjects: Anion exchange membranes; Desalination; Electrodialysis; Metal-polymer membranes; Nitrate selectivity; Water purification
• ISSN: 0376-7388
• DOI: 10.1016/j.memsci.2024.123518

Ion exchange membranes with high monovalent ion selectivity are essential for extracting valuable components from natural and waste waters. One of the approaches to their fabrication is the creation of nanostructured materials with ion-conducting channels. In this study, materials based on cardo polybenzimidazole (PBI–O-PhT) containing Zn2+, Cr3+ and Cu2+ ions were obtained and used for the first time for electrodialysis separation. The formation of crosslinked structure due to metal-benzimidazole coordination bonds was demonstrated. The obtained metal-polymer membranes have ionic conductivity comparable to commercial ones, reaching 0.32 mS cm−1, and high values of nitrate ion transport numbers (99.2 %). It is shown that the obtained membranes achieve incredibly high values of selectivity coefficients for anion separation. The highest and most stable values were obtained for the copper-containing membrane PBI/Cu-50, which are P(NO3/SO4) = 729, P(Cl/SO4) = 109 and P(NO3/Cl) = 6.66. [Display omitted] •PBI membranes with Zn2+, Cu2+, Cr3+ were synthesized for selective ion separation.•Membranes achieve up to 99.2 % nitrate ion transport, ideal for water desalination.•Copper-containing membranes achieve a nitrate/sulphate selectivity of 729.•Membranes exhibit conductivity of 0.32 mS cm⁻1, comparable to commercial standards.•PBI/Me membranes using in electrodialysis shows promise in wastewater treatment.