Mixed Matrix Membrane for Cr(VI) Adsorption and Reduction: Joining Click Chemistry and MOFs

In this work, a maleimide-bearing biobased polyurethane is made to react with a metal-organic framework (MOF) containing thiol pendant groups (Zr-MSA), to produce a functional mixed matrix membrane (MMM). The membrane is synthesized following an innovative method in which Zr-MSA acts as a cross-linker through UV-promoted thiol-Michael addition while providing the ability to trap Cr-(VI) and reduce it to Cr-(III). By means of a comprehensive study of the surface morphology and adsorption kinetics, the adsorption mechanism is elucidated. The homogeneous distribution of the MOF allows for a high cross-linking degree and adsorption ability, resulting in an MMM with good mechanical properties and filtering capacity. Using the thiol-maleimide click reaction, this new strategy permits easy incorporation of MOFs into a membrane without affecting their functionality, leveraging them as active cross-linkers.