Improving the ion sieving performance of MOF polycrystalline membranes based on interface modification

Area of Science:

• Materials Science
• Chemical Engineering
• Nanotechnology

Background:

• Metal-Organic Framework (MOF) membranes offer precise molecular sieving due to tunable pores.
• Achieving high-performance MOF membranes is hindered by weak interfacial interactions between MOFs and substrates, causing defects.

Purpose of the Study:

• To develop an interface-coating method to improve MOF membrane performance.
• To enhance interfacial compatibility and facilitate dense MOF crystal growth on substrates.
• To create ZIF-8 membranes with improved ion selectivity.

Main Methods:

• Co-assembly of polydopamine (PDA) and β-cyclodextrin (β-CD) on polyvinylidene fluoride (PVDF) substrates.
• Modification of surface chemistry to enhance interfacial compatibility.
• Facilitation of dense ZIF-8 crystal growth on the modified substrate.

Main Results:

• The ZIF-8/PVDF membranes exhibited a K+ permeance of 0.33 mol m-2 h-1.
• Achieved a K+/Mg2+ selectivity of 30.16.
• Simulation revealed higher energy barriers for Mg2+ transport through ZIF-8 compared to K+.

Conclusions:

• The interface-coating method effectively promotes dense MOF nucleation and growth.
• Enhanced interfacial compatibility leads to defect-free MOF membranes.
• The developed ZIF-8 membranes show excellent performance for K+/Mg2+ separation.