Enhancing Permeability of Thin Film Nanocomposite Membranes via Covalent Linking of Polyamide with the Incorporated Metal-Organic Frameworks

Thin film nanocomposite (TFN) membranes were invented in 2007 to enhance the permeability of thin film composite (TFC) membranes. Surface modification of nanofillers was a common method to improve the interaction and compatibility at polymer/nanofiller interfaces. Accordingly, as an amino-functionalized zirconium-based metal-organic framework (MOF), UiO-66-NH2 was synthesized and introduced into the preparation of TFN membranes via interfacial polymerization in this study. The superhydrophilic characteristic of UiO-66-NH2 made it possible to be well dispersed in aqueous solution and the amino groups on particle surfaces could react with 1,3,5-benzenetricarboxylic acid chloride (TMC) to form covalent interaction with polymer thus inhibiting the formation of nonselective defects at PA/nanofiller interfaces. The morphology images and FT-IR spectra revealed the PA selective layer successfully formed on the top of hydrolyzed polyacrylonitrile (HPAN) supports. The EDX characterization demonstrated UiO-66-NH2 nanoparticles were successfully introduced into the TFN membranes. The UiO-66-NH2 nanoparticles increased the surface hydrophilicity and roughness of the membranes, and provided additional passageways for mass transfer. Pure water permeability increased from 6.89 LMH/bar for TFC membrane to 14.55 LMH/bar for TFN-0.10 membrane indicating the distinct permeability elevation after the incorporation of UiO-66-NH2 nanoparticles. And the Na2SO4 rejection of TFN-0.10 membrane was up to about 99.0% and NaCl rejection was 38.1% at 4 bar, which was higher than that of TFN membrane incorporated with pristine UiO-66.