Induction-heated membrane distillation using Fe3O4-PANI-FAS-coated omniphobic membranes: antiwetting, antifouling, and mechanistic insights

Membrane distillation (MD) offers a promising route for treating high-salinity and complex wastewater streams; however, its practical implementation is often hindered by membrane wetting, inorganic scaling, and organic fouling. Here, we report an induction-heating membrane distillation (IH-MD) platform enabled by an omniphobic Fe₃O₄/PANI/FAS membrane that integrates localized thermal management with advanced surface design. The hierarchical structure, combining reentrant surface geometry and low surface energy, effectively suppresses liquid intrusion and reduces foulant adhesion, while preserving rapid interfacial heating (~2.0 °C·s⁻¹). COMSOL simulations further revealed that vaporization-induced latent heat consumption substantially influences interfacial temperature and vapor flux predictions, highlighting the importance of realistic heat-transfer accounting in induction-heated membrane distillation. Compared with Fe₃O₄/PANI membrane, the omniphobic Fe₃O₄/PANI/FAS membrane demonstrates enhanced operational stability across a range of challenging conditions, including surfactant-induced wetting, calcium-based scaling, organic fouling, and complex reverse osmosis (RO) retentate feeds. In surfactant-containing systems, stable flux and low permeate conductivity (~3 µS·cm⁻¹) were maintained, whereas severe wetting was observed for non-modified membranes (~12,000 µS·cm⁻¹). Under inorganic scaling conditions, reduced deposition of Ca- and S-containing species indicates suppressed crystal nucleation and adhesion. Long-term operation (5 h) under organic fouling further confirms improved flux stability. In complex RO retentate, the omniphobic membrane exhibits markedly reduced accumulation of multivalent ions (e.g., Ca and S) compared to non-modified membranes, indicating improved resistance to inorganic deposition under multi-component conditions. These findings demonstrate that coupling omniphobic surface engineering with localized induction heating provides a synergistic strategy to suppress wetting, scaling, and fouling, offering a pathway toward robust and energy-efficient MD operation in complex water treatment applications.