Nanofiltration Performance of a Functionalized UiO-66 Membrane

This research investigates the design principle for metal organic frameworks (MOF) deposited composite membranes for  nanofiltration using functionalized/modified UiO-66 (UiO stands for University of Oslo) nanoparticles for the purpose of  exploring the importance of functional groups around the nanopores. The nanoparticles were synthesized using water as  modulator and characterized by XRD, FTIR, TEM, BET and TGA. The XRD major (sharp) peaks indicated the crystallin ity of the nanoparticles whilst the minor peaks at 2θ = 6° originated from reo-nanoregions. The intensity of the reo peak  was correlated with the concentration of missing clusters/linkers, cluster defects in the samples and become prominent as  small amount of modulator was added. The particle sizes were found to be in the range of 150‐60 nm, 160-60 nm for UiO 66-NH2, UiO-66-CH3 frameworks respectively. The dependence of the particle size on the amount of water demonstrated  its role to accelerate the formation of crystal nuclei. The BET surface area and pore volume were found to be in the range  of 800-1000 m2/g and 0.37-0.44 m3/g without clear tendency on the framework type. The pore size distribution was sharp ly concentrated in the range of 0.7-0.8 nm whilst the weight loss due to ligand decomposition was found to have changed  by the water addition irrespective of the ligand functionalization. The functionalized UiO-66 formed polycrystalline, de fective nanoparticles and gave high flux compared to non-functionalized type and was found to be superior for leakage  tolerance irrespective of the frameworks. However, the tendency to leakage was found to be greater for smaller particle  size. Its polycrystalline nature played an important role whilst the modification affects the chemoselectivity and permea tion. The pore engineering geared towards changing the chemical environment played significant effects and unlock infor mation for proper understanding of the role of chemical environment in UiO-66-CH3 and UiO-66-NH2 nanocomposite  membranes.