Unveiling Exceptional Membrane Distillation Performance via a Wettability Transition in Covalent Organic Frameworks

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Membrane distillation (MD) utilizes low-grade heat for water distillation from hypersaline wastewater, addressing water-energy nexus challenges.
• Traditional membranes face limitations in flux and antifouling performance, hindering efficient hypersaline wastewater treatment.

Purpose of the Study:

• To develop an advanced membrane with improved flux and antifouling capabilities for membrane distillation.
• To engineer a covalent organic framework (COF) film with tunable wettability for enhanced water recovery.

Main Methods:

• Fabrication of a highly aligned covalent organic framework (COF) film with in situ growth and reversible hydrolysis.
• Tuning pore wettability from hydrophilic to hydrophobic under alkaline conditions.
• Characterization of membrane performance in terms of flux, antifouling, and concentration polarization.

Main Results:

• The engineered COF film exhibited a tunable hydrophilic-to-hydrophobic wettability transition.
• Achieved an unprecedented flux of 185.86 L/(m²·h) for hypersaline wastewater treatment, 3.9 times higher than commercial membranes.
• Demonstrated enhanced antifouling properties against oil and surfactants, reducing concentration polarization.

Conclusions:

• The developed COF membrane offers superior permeability, antifouling resistance, and sustainability for membrane distillation.
• This advancement holds significant potential for efficient water recovery from hypersaline wastewater.
• The tunable wettability and surface charge engineering provide a new strategy for advanced membrane design.