Exploring the Potential of Defective UiO-66 as Reverse Osmosis Membranes for Desalination

Abstract

Defects in metal–organic frameworks (MOFs) can play an important role in the development of MOFs as promising reverse osmosis (RO) membranes for water desalination. By employing molecular dynamics techniques, we explore the effects of experimentally relevant defects in UiO-66 on their desalination performance. Different defect types with varying densities and chemical compensations are studied. Our results show that defective membranes can possess substantially improved water permeability and an enhanced water intrusion rate by orders of magnitude compared to the defect-free one while still maintaining an excellent ability to reject salts. Further, the relationship between adsorption energetics and transport kinetics of water is established to shed light on the permeation behaviors of MOF membranes at an atomic scale. The outcomes of this work suggest that controlling structural defects provides opportunities toward the optimization of MOFs as RO membranes for reduced energy and cost requirements in desalination.

Robust ultrathin nanoporous MOF membrane with intra-crystalline defects for fast water transport

“…The system temperature was modulated using the Nosé–Hoover thermostat with a damping factor of 100 time steps 58 . We note that, prior to the PV simulations, each framework structure was first saturated with water molecules via a reverse osmosis process at an applied pressure of ~300 Pa using a simulation set similar to a prior study 32 . It is also worth mentioning that, before sampling PV desalination performance, a sufficiently long simulation was first conducted to reach a steady-state flow.…”

“…However, the manipulation of defects to improve permeation performance is uncommon. Existing strategies of defect chemistry control in MOF crystals 32 – 34 provide us with some inspiration to rationally design MOF membranes with favorable intra-crystalline defects to enhance permeation performance, without compromising selectivity. Especially, modulation of intra-crystalline missing-linker defects is considered as a feasible method using carboxylic-acid as modulator since it can coordinate with metal clusters by competing with carboxylic-bearing linkers 35 , 36 .…”

Disclosing the Role of Defect‐Engineered Metal–Organic Frameworks in Mixed Matrix Membranes for Efficient CO2 Separation: A Joint Experimental‐Computational Exploration

“…Overall, the results on intrinsic permeability of defect-engineered UiO-66 imply that defect engineering of MOFs would also be possible for the design of high-performance pure MOF membranes. [68]…”

Experimental Demonstration of Dynamic Temperature-Dependent Behavior of UiO-66 Metal–Organic Framework: Compaction of Hydroxylated and Dehydroxylated Forms of UiO-66 for High-Pressure Hydrogen Storage

“…Metal-organic frameworks have shown great promise in applications such as gas storage, gas separation, water treatment, catalysis, and as support materials in batteries [1][2][3] . The system integration of MOFs in application-specific technologies is envisaged on shaped MOF materials compared to MOFs in their pristine powder form [4][5][6] .…”