Precisely regulated in-plane pore sizes of Co-MOF nanosheet membranes for efficient dye recovery

Abstract

<p>Nanofiltration (NF) is widely used to treat highly saline textile waters, but its efficiency in dye recovery is limited by low permeance. This study presents a novel class of Co-based metal-organic framework (Co-MOF) nanosheet membranes for efficient and selective dye recovery. The Co-MOF membranes have precisely regulated in-plane pore sizes and exhibit superior permeance and selectivity compared to non-porous nanosheet membranes. By adjusting the length of the ligand, the in-plane pore size was precisely tuned from 1.01 × 0.63 to 1.43 × 0.64 nm2. The Co-MOF membranes exhibited high selectivity for salts over dye in both diffusion and pressure-driven filtration modes, along with excellent and tunable pure water permeance and high rejection of the dye OII. The remarkable permeability and selectivity of the Co-MOF membranes were attributed to the in-plane pores on the nanosheets, which serve as extra fast “lifts” for water and salts while exhibiting high rejection to the dye molecules. Long-term filtration performance and Co leaching tests demonstrated the stability of the Co-MOF membranes, making them promising candidates for practical dye recovery applications. Overall, this work provides a new approach for the development of high-performance membranes for textile wastewater treatment.</p>