Functional UiO-66 Series Membranes with High Perm Selectivity of Monovalent and Bivalent Anions for Electrodialysis Applications

Abstract

Metal−organic frameworks (MOFs) have a good separation potential due to their uniform pore size, easy functionalization, and adjustable structure. Therefore, we make use of this feature of MOFs for the separation of Cl − /SO 4 2− systems with different charges and sizes. In this work, two kinds of UiO-66 membranes with different functional groups were synthesized and applied to the monovalent perm-selective separation of the Cl − /SO 4 2− system in electrodialysis (ED). UiO-66-NH 2 membranes were used to investigate the influence of current density and initial solution concentration on perm selectivity. A layer of UiO-66-NH 2 was first grown on the anodic alumina oxide (AAO) disks. After that, short chains containing sulfonic acid groups were grafted onto the amino groups by the ring-opening reaction of 1,3propanesulfonate. The structural stability of the MOF layer was confirmed by XRD analysis of the membrane surface after the ED test. Ion exchange capacity (IEC) and elemental mapping were used to confirm the comparison changes in the degree of sulfonation. It was found that UiO-66-NH 2 membranes exhibited a higher monovalent anion perm selectivity with a peak value of 36.23 (initial mixture solution of 0.05 M NaCl and 0.05 M Na 2 SO 4 ) at lower current density (2.5 mA•cm −2 ). The perm selectivity of UiO-66-SO 3 H membranes increased with running time under 24 h of sulfonation time. In particular, with low IEC value of 0.10−0.16, it still showed a good performance on perm selectivity. Compared with published polymer ion exchange membranes (perm selectivity < 5) for ED, it has higher perm selectivity, more convenient functionalization, and resistance to organic solvents.

Bio-Inspired Salinity-Gradient Power Generation With UiO-66-NH2 Metal-Organic Framework Based Composite Membrane

“…This property offers new opportunities for manufacturing high-performance salinity-gradient osmotic energy generation ( Lu et al, 2021 ), however, has not been systematically investigated till now. Particularly, UiO-66-based MOFs with tailorable surface chemistry have recently been used for ion transport ( Wan et al, 2017 ; Li et al, 2019 ; Ruan et al, 2021 ). The channels of UiO-66-based MOFs comprise angstrom-sized windows and nm-sized cavities that comparable to most hydrated ions in water, showing great potential for highly efficient harvesting of osmotic energy.…”

Metal–organic frameworks on versatile substrates

“…Porous alumina hollow bers are selected as substrates to fabricate MOFs with their costefficiency, heat resistance, non-toxicity, and good chemical stability. [230][231][232][233][234][235][236][237][238][239][240][241][242][243][244][245][246] ZrCl 4 and H 2 BDC were rst dissolved in deionized water and DMF at a molar ratio of metal salt/ligand/H 2 O/ DMF of 1 : 1 : 1 : 500 and kept at 120 °C for three days. Aer that, a UiO-66 lm was obtained on substrate Al 2 O 3 as depicted in Fig.…”

Fabrication of a Cation-Exchange Membrane via the Blending of SPES/N-Phthaloyl Chitosan/MIL-101(Fe) Using Response Surface Methodology for Desalination

“…Based on the abovementioned characteristics, the MOF-based mixed matrix ion exchange membranes have attracted much more attention because of their improvement of IEC, ionic conductivity and interfacial compatibility [6,18,26,27]. The current state of knowledge reveals that the combination of MIL-101(Fe) composite nanoparticles and an acidic functionalized polymer matrix can utilize each of their strengths to improve the performance abilities [28][29][30]. For constructing a MIL-101(Fe)-based composite membrane with flexible and mechanical ability, classic and easy-to-operate methods were adopted to ensure the dispersion of MIL-101(Fe) nanoparticles within the whole of the acidic functionalized polymer matrix.…”