Facile preparation of UiO-66-NH2-coated mesh membrane with underwater superoleophobicity for high efficiency oil-water separation

The metal organic framework (MOF) polycrystalline membranes on stainless steel mesh (SSM) are urgently required for effective oil-water separation, but the affordable preparation still remains a challenge. Herein, we report a series of UiO-66-NH2/SSM films, which are developed by a rational 'seeding-assisted secondary growth' method. Results depict that the proposed method greatly shortens the synthesis time, and helps to achieve a continuous and uniform modification of UiO-66-NH2 on SSM, and hence contributes to a superior hydrophilicity and superoleophobicity for UiO-66-NH2/SSM with minimum water contact angle of 32° and maximum underwater oil contact angle of 150°, respectively. Specifically, the UiO-66-NH2/SSM-600-2 has total permeation fluxes and separation efficiencies of ca. 8.4×104 L·m-2·h-1 and 100% for the n-hexane-, petroleum ether- and chloroform-water emulsions (1% volume ratio), which exceed numerous polycrystalline membranes reported so far. It also exhibits a great durability with only 0.1% loss of separation efficiency after 8 cycles. Furthermore, outstanding acid-resistivity and salt-tolerance are also presented. Our work supplies a new strategy to construct UiO-66-NH2/SSM, and the decent properties confirm a huge potential for practical use in oil-water separation.