Fabrication of superhydrophilic and underwater superoleophobic membranes for fast and effective oil/water separation with excellent durability

Abstract

Oily wastewater has caused serve environmental pollution in nowadays, and it is highly urgent to develop an effective method for disposing of it. The development superhydrophilic and underwater superoleophobic (SUS) membranes bring hope of solving this global challenge. Previously, deformable hydrogels/hydrophilic polymers, brittle and chemically weak inorganic/metal oxides have been widely employed for fabricating SUS membranes, while most of these materials are likely to be corroded under practical severe conditions. In this work, we report a novel SUS membrane with excellent durability as achieved by introducing polyhedral oligomeric silsesquioxane (POSS) nanoparticles on cotton fabric (CF) followed by thiol-ene functionalization to graft hydrophilic carboxyl group. It is found that the prepared SUS membrane can withstand long-term mechanical abrasion, ultrasonic washing, UV light irradiation and corrosive aqueous solutions without reducing the underwater superoleophobicity. This SUS membrane is also able to separate various oil/water and oil/corrosive aqueous solution mixtures, and only water phase is allowed to permeate through it. The measured water fluxes are very high (up to 88,214 L m−2 h−1), the initial separation efficiencies of this membrane for various oil/water mixtures are over 99% and those values are still maintained at high level (around 98%) after 50 separation cycles even in severe conditions. We believe that this work would be helpful for fabrication of advanced SUS membranes with excellent durability.