Carboxymethylcellulose (CMC)/glutaraldehyde (GA)-modified Ti3C2Tx membrane and its efficient ion sieving performance

2D nanosheet membranes show promise for ion sieving. However, nanosheet swelling still adversely affects the ion sieving performance. In this study, Ti3C2Tx was mixed with carboxymethylcellulose sodium (CMC) and stirred in an ice bath; then, glutaraldehyde (GA) was added to cross-link the CMC distributed between Ti3C2Tx interlayers to obtain a CMC/GA-modified Ti3C2Tx membrane ([email protected]). The strong chemical bonding between the Ti3C2Tx andd CMC prevented swelling of the Ti3C2Tx nanosheets in aqueous solutions. A stable effective interlayer spacing (4.8±0.1 Å) was obtained, and the mechanical strength of the membrane was improved. Due to size sieving and image force repulsions, [email protected] exhibited efficient divalent ion retention performance. The [email protected] selectivity for monovalent/divalent ions was approximately 30; this value was 14 times higher than that of the original Ti3C2Tx membrane (OTM). In addition, based on aldol condensation reaction, GA blocked the exposed oxygen-containing groups in the CMC to form a water-insoluble macromolecular network, which improved the water stability of the membrane. [email protected] exhibited excellent membrane performance during long-term (72 h) operation. The effects of applied voltages on the separation performance were tested. The results showed that Mg2+ transport was significantly inhibited at -0.6 V, and the Li+/Mg2+ selectivity was increased.