Defect-Engineered Ultrathin Zeolitic Imidazolate Frameworks-8 Membranes: Unlocking Ultrafast Water Transport and...

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Sustainable saline wastewater treatment is crucial for global water security.
• Metal-organic frameworks (MOF) show promise for membrane applications but face challenges in performance.
• Achieving high permeability and selectivity simultaneously remains a key hurdle.

Purpose of the Study:

• To develop high-performance MOF membranes for efficient saline wastewater treatment.
• To engineer specific defects in ZIF-8 membranes to enhance water permeance and dye rejection.
• To overcome the permeability-selectivity trade-off in membrane-based separations.

Main Methods:

• Fabrication of ultrathin zeolitic imidazolate frameworks-8 (ZIF-8) membranes using a dual metal source strategy.
• Controlled introduction of missing-linker defects via ligand thermolysis.
• Characterization of membrane architecture, pore size, and surface properties.

Main Results:

• Achieved ultrahigh water permeance (122.5 L m⁻² h⁻¹ bar⁻¹) due to enhanced water affinity, larger pores, and reduced thickness.
• Demonstrated near-complete dye rejection (>99.8%) with minimal NaCl rejection (9.4%).
• Obtained a high salt/dye separation factor (303.2), outperforming existing nanofiltration membranes.

Conclusions:

• Controlled defect engineering is a viable strategy to enhance MOF membrane performance.
• The developed ZIF-8 membrane offers a promising solution for single-step purification of dye-contaminated saline streams.
• This approach provides a pathway for sustainable water treatment and resource recovery.