Gradient-Pore-Engineered Janus Membranes for Sequential Molecular Sieving in Membrane Desalination.

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Membrane distillation (MD) is promising for hypersaline wastewater desalination.
• Existing MD membranes struggle to reject both volatile and nonvolatile pollutants simultaneously.
• Treating complex industrial wastewater requires advanced membrane solutions.

Purpose of the Study:

• To develop an advanced membrane for efficient hypersaline wastewater desalination.
• To investigate the role of a novel interlayer in membrane performance.
• To address the limitations of current membrane technologies in pollutant rejection.

Main Methods:

• Fabrication of asymmetric Janus membranes with gradient pores using electrospun PVDF, graphene oxide (GO), and m-phenylenediamine (MPD).
• Sequential vacuum filtration and interfacial polymerization to form an ultrathin polyamide (PA) layer.
• Systematic investigation of the PA@MPD-GO configuration's structural properties and transport behavior.

Main Results:

• The MPD-GO interlayer reduced water mass transfer resistance and enabled the formation of a ~9 nm ultrathin PA layer.
• Achieved high water flux (63 L m⁻² h⁻¹) under a 40 °C temperature gradient.
• Demonstrated 97.55% rejection of volatile phenylamine with excellent antifouling, antiwetting, and antiscaling properties.

Conclusions:

• The developed gradient membrane design offers a promising approach for advanced thermal desalination.
• The thermo-osmosis-evaporation (TOE) system shows potential for treating hypersaline wastewater in complex scenarios.
• This technology advances membrane-based solutions for challenging water treatment applications.