Bio-inspired surface engineered multilayer Janus membrane for efficient desalination of highly saline water in membrane distillation

Membrane distillation (MD) faces critical challenges at the industrial scale, including poor permeate flux and membrane fouling. To address these issues and efficiently treat highly saline water, this study presents a nature-inspired approach to fabricating a robust multilayer Janus membrane using a gecko-inspired adhesion mechanism. The proposed membrane was fabricated using a layer-by-layer co-deposition method, combining a surface-roughened PVDF flat-sheet membrane prepared via phase inversion with an electrosprayed hydrophobic PVDF-HFP interfacial layer modified with CuO nanoparticles and an electrospun hydrophilic PEI fiber bottom layer. The hydrophobic top layer exhibited a water contact angle of 131.5°, followed by a superhydrophobic interfacial layer and the bottom/support layer with a contact angle of 41.4°, enabling superior directional wettability. The Janus membrane achieved an impressive water gap membrane distillation (WGMD) flux of 37.16 kg m⁻² h⁻¹ with a high salt rejection rate of 99.99% over 24 h. Furthermore, the membrane demonstrated long-term stability and excellent resistance to fouling and delamination in harsh saline environments, maintaining performance over 60 h of continuous MD operation. This work highlights the potential of bio-inspired engineering in developing efficient and durable membranes, offering a promising pathway for advancing MD technology for industrial-scale desalination.