GO-PEAA framework enabled lamellar nanocomposite membranes for enhanced organic solvent nanofiltration

Graphene oxide (GO) membranes hold great promise for organic solvent recovery. However, their performance is often limited owing to its high swelling effect, narrow interlayer spacing, and long diffusion pathways. To address these issue, in this work, we first synthesized a micellar supramolecule, (poly (ethylene adenine carboxylic acid))/(PEAA), and subsequently fabricated nanocomposite membranes by integrating GO with PEAA via pressure-driven filtration method. The incorporation of the PEAA resulted not only an increase in the interlayer distance between the GO nanolayers but also crosslinked on the surface of GO nanosheets. This expansion was facilitated by the formation of covalent bonds between the hydroxyl and epoxide functional groups of GO with the carboxylic acid groups of the PEAA. The resultant GO-PEAA nanocomposite membranes exhibited enhanced solvent flux (73.29 and 57.12 L/m²h in acetone and methanol, respectively) under an operating pressure of 1 bar, along with superior rejection capabilities, and excellent durability in harsh solvents. Particularly, the optimized GS13 membrane exhibited a consistent rejection rate above 95 % for CR and MB dyes across all organic solvents, while maintaining stable flux in ethanol and a constant CR rejection rate in long-term stability test. This demonstrates a favorable flux-rejection balance, overcoming the trade-off in conventional GO membranes. Overall, the integration of PEAA into GO membranes significantly amplifies solvent flux as well as dye rejection, and maintains the robustness of GO-based nanocomposite membranes when subjected to various organic solvents. These findings signify the potential of GO-PEAA nanocomposite membranes for practical applications in the area of OSN.