Bridging Link Triggered-Assembled Graphene Oxide Membranes with High Dye–Salt Separation Performance

Abstract

The stability and efficiency of separation membranes for dye–salt solutions limit their broader application in environmental protection. Graphene oxide (GO) is promising due to its atomic-level thickness and nanochannel structure, but its narrow channels and solubility issues restrict permeability and stability. This work employed a 0D/2D double cross-linking strategy to modify GO membranes using tannic acid (TA) and Cu²⁺ with a stable ternary structure. The resulting Cu/GO-TA membrane with increased interlayer spacing (from 8.9 to 11.6 Å) displayed enhanced water flux that was three times greater than that of pristine GO while maintaining a high dye rejection rate (93.4% for methyl blue). The membrane effectively separated mixed dye–salt solutions, allowing the permeation of inorganic salts while rejecting dyes, and demonstrated consistent performance under different transmembrane pressures. The synergistic effects of TA and Cu²⁺ improved the mechanical strength and reduced the swelling of the GO membrane, optimizing selective dye–salt separation. This bridging link modification provides an efficient technological approach to enhance membrane performance and provides a feasible solution for more efficient and reliable treatment of dye wastewater.