Ceramic membranes with mussel-inspired and nanostructured coatings for water-in-oil emulsions separation

The effective removing water from water-in-oil emulsions is of great importance in fuel oil production and waste oil recovery. Ceramic membranes with excellent mechanical, and chemical stability have been increasingly used in the treatment of water-in-oil emulsions. However, membrane fouling is still a challenge needed to be solved due to the intrinsic hydrophilic property of these ceramic membranes. Herein, mussel-inspired and nanostructured coatings have been fabricated to modify the ceramic membrane with superhydrophobic/oleophilic surfaces. First, polydopamine (PDA) is deposited on the ceramic membrane surface using CuSO4/H2O2 as a trigger. Then, the formed PDA coating acts as a platform to induce the metallization of Ag ions into Ag nanoparticles. Subsequently hexadecanethiol (HDT) is grafted on the obtained membranes. The membrane morphologies, chemistry and wettability after each step of surface modification are characterized. CuSO4/H2O2 accelerates the deposition process of PDA on ceramic membrane surface with much more uniformity. Hierarchical nanostructure by silver nanoparticles is formed on PDA coated membranes. And the synergistic effect of surface hierarchical structure and HDT modification leads to the membrane surfaces superhydrophobicity in air and a non-adhesive behavior to the water droplet under oil. The final modified membranes also show good stability in a series of solvents, and show excellent antifouling property in the filtration of water-in-oil emulsions. This modification method provides a facile and efficient strategy for preparing durable antifouling ceramic membranes for the treatment of organic solvents.