Spray-deposited thin-film composite MOFs membranes for dyes removal

Fabrication of thin-film composite metal-organic frameworks (MOFs) membranes (TFCMMs) has great potential to broaden the application scale due to excellent properties of MOFs, such as adjustable pore structure, high surface area, and uniform pore size. However, there are still some limitations on the TFCMMs such as low MOFs mass ratio and poor compatibility. Here, a simplistic "spray deposition cum post-stabilization (SDS)" technique is proposed to precisely fabricate compact thin-films of different MOFs including ZIF-L, UiO-66-NH2, and MIL-101NH2 on porous substrates. The SDS strategy can fix various MOFs via crosslinking reaction between the aryl chloride groups of trimesoyl chloride and the amino groups of polyethyleneimine or MOFs in the functional layer, leading to durable TFCMMs with good compatibility and high MOFs mass ratio. The resulting membranes also show high water permeance and excellent dye rejection (99.2% for methyl blue and 97.5% for metanil yellow) as compared to the traditional polyamide membrane.