Dual-functional TFNC polyester membranes utilizing maltitol for dye/salt separation and desalination

To achieve a promising application prospect in nanofiltration (NF) membrane separation, a strategic design tailored to particular functions is crucial. Here, tailor-made thin film nanofibrous composite (TFNC) NF membranes for specific applications were fabricated via interfacial polymerization (IP) between maltitol and trimesoyl chloride (TMC) on PAN nanofibrous substrates. Owing to the moderate reactivity of maltitol, a range of sugar alcohol based polyester membranes with different morphologies and cross-linking degrees were obtained by varying the monomer concentration as well as the reaction time. In this case, the finely tuned loose Mal1TMC0.2-2 membrane exhibited a prominent permeability (110.34 L m - 2 h -1 bar -1 ) and an extraordinary selectivity for dye/salt mixed solution, with the rejection of Congo Red up to 99.11 % and NaCl retention of only 7.41 %, indicating its suitability for textile wastewater treatment. Further, the dense Mal2-TMC0.4-10 membrane showed an excellent Na 2 SO 4 rejection of 97.40 % with a good permeability of 18.65 L m - 2 h -1 bar - 1 , making it a candidate for seawater and brackish water desalination. In addition, both membranes demonstrated reliable chlorine and pressure resistance along with long-term stability. This study provided new insights and inspiration to the design and preparation of NF membranes for specialized applications.