An isoreticular series of Zr-tricarboxylate based metal-organic nanosheets for water purification applications.

Metal-organic nanosheets (MONs) are porous two-dimensional materials with enormous potential for creating membranes for a wide range of separation applications. Here, we investigate an isoreticular series of Zr-tricarboxylate based MONs bearing different organic ligands for dye separation. A modulated synthesis approach produced monolayer nanosheets with high aspect ratios for all three systems. Composite membranes were formed by spin-coating ethanol suspensions of the nanosheets onto porous polyethersulfone (PES) supports. All three nanosheet systems exhibited consistent performance, with high rejections (72.7-83%) and permeabilities (up to 119.6 L m-2 h-1 bar-1) observed for larger anionic dyes. The observed insensitivity to ligand functionalization, combined with the high permeation of dyes smaller than the pore aperture, indicates that size exclusion is the dominant separation mechanism. This study demonstrates the potential of Zr-tricarboxylate based MONs as a robust and structurally tunable platform for creating high-performance membranes for the effective removal of organic dyes from aqueous environments.