Asymmetric Interfacial Stress-Driven Demulsification in Heterogeneous Wetting MOF Beds

Separating surfactant-stabilized dual-type oil/water emulsions remains challenging due to the intrinsic limitations of traditional single-wettability filters. Herein, a heterogeneous composite particle-based bed was constructed by blending pristine hydrophilic MOF UiO-66-NH2 with oleyl phosphate-modified hydrophobic MOF UiO-66-NH2–OP. The mixed bed combines droplet capture with interfacial destabilization: tortuous interparticle channels promote hydrodynamic deformation, while adjacent domains of contrasting wettability are proposed to induce asymmetric interfacial stresses and Marangoni-driven film disruption. Subsequent droplet coalescence and interception enable separation of both emulsion types. Filtration tests proved the composite bed outperformed single-wettability counterparts for dual-type emulsions, achieving over 90% rejection and a peak permeance of 5861.3 L·m–2·h–1·bar–1. This work establishes an emulsion separation strategy via MOF wettability modulation and particle-bed construction, shedding light on the design of high-performance, tunable separation materials.