Thin film nanocomposite (TFN) membranes filled with a novel metal organic framework for reverse osmosis applications

This paper reports the synthesis and use of a novel metal-organic framework (MOF), named Zr-BADS, within the thin-film nanocomposite (TFN) membranes for reverse osmosis (RO) applications. Two types of zirconium-based MOFs, Zr-BADS-1 and Zr-BADS-2, were synthesized via a solvothermal method using bicinchoninic acid disodium salt as a linker and either dimethylformamide or ethanol as solvent, respectively. TFN membranes were prepared by embedding these MOFs within the polyamide thin film supported by a polysulfone support sheet. The specific surface area of Zr-BADS-1 and Zr-BADS-2 was determined to be 396.1 and 278.6 m2/g, respectively, indicating significant surface area conducive to water permeation. Scanning electron microscopic analysis revealed a uniform distribution of Zr-BADS nanoparticles (NPs) with particle sizes < 100 nm within the TFN membranes. TEM images confirmed the dense packing of NPs within the membranes, influencing their texture and enhancing performance. FTIR spectroscopy demonstrated the presence of characteristic peaks corresponding to MOFs within the TFN membranes, with changes observed at higher loading ratios. The observed contact angle decreased with increasing MOF loadings, indicating an enhancement in the hydrophilicity. Zr-BADS-1 NPs increased water flux at its optimal loading of 0.3%, and the flux raised to 5.4 L/m2 h bar. Salt rejection slightly decreased at low concentrations but improved at higher loading ratios, indicating the interplay between porosity and charge effects. Zr-BADS-1 outperformed other MOFs in salt rejection and water flux, suggesting it is a remarkable RO membrane filler. This study demonstrates the potential of Zr-BADS MOFs for future membrane applications in the environment.