Superwetting Oil/Water Separation Membrane Constructed from In Situ Assembled Metal–Phenolic Networks and Metal–Organic Frameworks

Superwetting membranes with opposite wettability to oil and water have drawn intense attention in recent years for oil/water separation. Superhydrophilic and underwater superoleophobic membranes have shown unique advantages in the efficient treatment of oily wastewater containing oil-in-water emulsions. Facile interfacial engineering and microstructural design of the hierarchical architectures and the hydrophilic chemistry is of significance but still challenging. In this study, a hydrophilic hierarchical hybrid layer derived from metal-phenolic network (MPN)/metal-organic framework (MOF) synergy is constructed on the membrane surface via a proposed coordination-directed alternating assembly strategy. The assembly of MPN multilayers provides a hydrophilic chemical basis, and the assembly of MOF nanocrystals provides a hierarchical structural basis. Notably, the coordination interfacial interaction enables the formation of well-defined hydrophilic hierarchical architectures. The obtained membrane is thus endowed with robust superhydrophilicity, underwater superoleophobicity, and anti-oil-adhesion capability, which make it capable of highly efficient oil-water separation with high water permeance (above 6300 L/m2 h), high oil rejection (above 99.4%), and recyclable antifouling property. The high performance of the developed superwetting membrane makes it a competitive candidate for oil/water separation. Additionally, the demonstrated MPN/MOF assembly strategy may offer new prospects for the facile and versatile design of other superwetting materials.