Highly Water-Stable Zirconium Metal–Organic Framework UiO-66 Membranes Supported on Alumina Hollow Fibers for Desalination

Abstract

In this study, continuous zirconium(IV)-based metal-organic framework (Zr-MOF) membranes were prepared. The pure-phase Zr-MOF (i.e., UiO-66) polycrystalline membranes were fabricated on alumina hollow fibers using an in situ solvothermal synthesis method. Single-gas permeation and ion rejection tests were carried out to confirm membrane integrity and functionality. The membrane exhibited excellent multivalent ion rejection (e.g., 86.3% for Ca(2+), 98.0% for Mg(2+), and 99.3% for Al(3+)) on the basis of size exclusion with moderate permeance (0.14 L m(-2) h(-1) bar(-1)) and good permeability (0.28 L m(-2) h(-1) bar(-1) μm). Benefiting from the exceptional chemical stability of the UiO-66 material, no degradation of membrane performance was observed for various tests up to 170 h toward a wide range of saline solutions. The high separation performance combined with its outstanding water stability suggests the developed UiO-66 membrane as a promising candidate for water desalination.

Controlling the size and shape of Mg-MOF-74 crystals to optimise film synthesis on alumina substrates

“…The choice of tubular supports allows for the high surface area to volume ratios required for industrial separations. The growth of MOFs on modular supports such as tubular supports 34 and hollow fibres [35][36][37] has previously been demonstrated for ZIF-8 and UiO-66 but not for any of the M-MOF-74 series. We controlled the size of Mg-MOF-74 crystals via the addition of ethanol and water to synthesis solutions.…”

Mass transport through metal organic framework membranes

“…Similarly, the continuous ultra-stable UiO-66 membrane with entrance size of 6 Å achieved improved water flux as well as the excellent rejection due to the size sieve effect (Fig. 14b) [147].…”

“…In the recent years, there is a blooming development of MOF membranes for mass separation [85,88,117,156]. The mass, including molecules and ions, transports through the channels of MOF membranes has been great attractive [68,91,147]. While, more difficulties lie in the fabrication of MOF membranes than powders, and they still need to be synthesized on the porous substrates.…”

All-gas-phase synthesis of UiO-66 through modulated atomic layer deposition

“…Due to their very high porosity, MOFs are promising for a number of applications such as gas storage2, catalysis3, drug delivery4, handling and destruction of toxins567, and as membranes for desalination8. Practical routes for deposition of thin and conformal films of porous materials will lead to many new applications, particularly within membrane development or within microelectronics for use as active material in highly sensitive gas sensors based on cantilevers or as low- κ dielectrics, as envisioned by Allendorf et al 9…”