Facial fabrication of superhydrophobic ZIF-7 coatings with fast self-healing ability for ultra-efficient emulsion separation

Abstract

Superhydrophobic materials for efficient separation of stabilized oil/water emulsions are in an urgent need to deal with an enormous amount of oily wastewater worldwide. The stainless steel mesh supported zeolitic imidazolate framework-7 (ZIF-7-coated SSM) was fabricated by way of secondary hydrothermal growth, it was further modified by using coordinated polysiloxane elastomer (CPE). Based on characterization by using SEM, XRD, FT-IR and contact angle measurements, the as-synthesized CPE-ZIF-7-coated SSM possessed a rough surface structure of microscale ravines with both superhydrophobicity and superoleophilicity. The stabilities of CPE-ZIF-7-coated SSM were investigated with respect to various treatments including high temperature, corrosion and ultrasonication. The self-healing ability and working mechanism of CPE-ZIF-7-coated SSM were explored by responding to continuous abrasion and O2 plasma etching. The CPE-ZIF-7-coated SSM exhibited high water-in-oil emulsion separation efficiencies of over 99.9% with a remarkably fast self-healing ability upon damage in less than 10 min without any externally imposed input of matter/energy. The superhydrophobic CPE-ZIF-7-coated SSM with fast self-healing ability would be a promising alternative material for practical applications in separation of emulsive oil/water mixtures.