Scalable and universal polyphenol-mediated prussian blue nanocomposite membranes: Underliquid dual superlyophobicity and catalytic self-cleaning

Self-adaptive biomimetic superwetting membranes with distinctive underliquid dual superlyophobic surfaces showcase attractive features for the on-demand separation of multifarious oil/water systems. It yet remains a great challenge for introducing the catalytic function into the design of underliquid dual superlyophobic membranes, to strengthen self-cleaning ability. Herein, a polyphenol-mediated interfacial assembly strategy was proposed to construct multi-functional membranes with underliquid dual superlyophobicity and catalytic self-cleaning, through self-assembly of metal-tannic acid (Fe-TA) networks and then in-situ coordination growth of Prussia blue (PB) nanocrystals at the interface at room temperature. We found that the PB/Fe-TA nanocomposite coating can make hydrophilic and hydrophobic porous membranes, as well as smooth surfaces being underwater superoleophobic and underoil superhydrophobic. The Fe-TA networks were favored for good growth of PB nanocrystals. Using quartz fiber (QF) membrane as the basement substrate, the PB/Fe-TA@QF nanocomposite membrane can separate light/heavy oil/water mixtures and oil-in-water/water-in-oil emulsions under gravity drive, with efficiencies above 99%. The PB/Fe-TA@QF nanocomposite membrane exhibits a superior degradation ability of carmine dye by peroxymonosulfate (PMS) activation, with the removal ratio as high as 99.8% within 30 min and meanwhile has an excellent antifouling and catalytic self-cleaning performance after cycling emulsion separation. Excellent acid, alkali and salt toleration, as well as good repeatability, provide the potential for application in wastewater treatment. This research puts forward a green, versatile and scalable pathway to fabricate multifunctional superwetting membranes for various applications in the fields including the environment, energy and beyond.