Fabrication of Thin Film Nanocomposite Membrane Incorporated with Metal-Organic Frameworks UiO-66-NH2 for Desalination

Membrane separation technique for water desalination is considered to be one of the most important solutions to the current worldwide water shortage [1]. In this report, a thin film nanocomposite (TFN) membrane was prepared by incorporating hydrophilic porous metal-organic framework (MOF)-UiO-66-NH2 into polyamide (PA) layer over the surface of the polyphenylsulfone (PPSU) support layer, through interfacial polymerization method. The physicochemical properties of the membranes were examined by attenuated total reflection Fourier transform infrared (ATR-FTIR), field emission scanning electron microscopy (FESEM), and contact angle measurement. The incorporation of UiO-66-NH2 nanoparticles notably changes the membrane morphology and chemistry, leading to an improvement of separation performance because of the porous structure and hydrophilic nature of UiO-66- NH2. The surface hydrophilicity of the TFN membranes was increased 38% due to the hydrophilic and porous UiO-66-NH2 nanoparticles loading, which is beneficial to improving the water flux. A cross-flow experimental setup was employed to evaluate the separation performance of the prepared TFN membranes at 25 ˚C and 8 bar. The best performing membrane incorporated with 0.05 wt.% UiO-66-NH2 exhibited an increased pure water flux from 44.7 L.m-2.h-1 to 54.4 L.m-2 .h-1 compared to the unmodified membrane, with no significant change in MgSO4 rejection. This increase of flux is probably due to change of structure in the PA layer (e.g. hydrophilicity), and also the porous structure of UiO-66-NH2. However, with further increase in the content of UiO-66-NH2 up to 0.05 wt. % a drop in the flux and also rejection happened. this behavior can be mainly caused by the filler aggregation and lower cross-linking extent of PA layer for percentages higher than 0.05 wt.% [2, 3]. The resultant membrane exhibited excellent operation stability for a long-time test. Moreover, the ICP-OES analysis showed that no leaching out of UiO-66-NH2 nanoparticles from the membrane occurred during the batch experiment. The high separation performance combined with its outstanding water stability suggests the developed PA-UiO-66-NH2/PPSU membrane as a promising candidate for water desalination.

Keywords:

Thin Film Nanocomposite (TFN) membrane , Polyamide (PA) , UiO-66-NH2 nanoparticles , Desalination