3D superhydrophobic/superoleophilic sponge with hierarchical porous structure and robust stability for high-efficiency and continuous separation of oily wastewater

Abstract

Three-dimensional (3D) superhydrophobic/superoleophilic polymeric materials, with highly efficient and continuous separation ability of immiscible oil/water mixtures and water-in-oil emulsions, combined with robust physical/chemical stability, are highly desirable for remediating complex oily wastewaters, but still remain a challenge to be realized. Herein, polystyrene-divinylbenzene-polydimethylsiloxane based superhydrophobic/superoleophilic foam with hierarchical porous structure was designed and prepared by high internal phase emulsion polymerization to overcome the aforementioned challenge. With hierarchical porous structure and superhydrophobic/superoleophilic properties (water/oil contact angles were 152° and 0°, respectively), the as-prepared foam could continuously separate different immiscible oil/water mixtures and water-in-oil emulsions with high separation efficiencies (>99.57 % and 99.1 %, respectively). Interestingly, our foam also displayed other properties such as stability, strong wear-resistance (the surface wettability was intact even after 100 abrasion cycles), robust anti-corrosive performance (the surface wettability and structure did not change after immersing the foam in acidic/basic/saline solutions or strongly polar organic solvents (DMF, DMSO) for a week), and broad range of temperature tolerance from −18 ℃ to 150 ℃. Due to these outstanding functions, our foam has great potential for remediation of complex oily wastewaters.