Fabrication of hierarchically porous superhydrophobic polystyrene foam for self-cleaning, oil absorbent, highly efficient oil–water separation

Here, P(St-EGD-DTDx) foams were prepared by a dual-emulsion template method using styrene (St) and divinyltetramethyldisiloxane (DVTMDSO) based on a high internal phase emulsion technology, which provided an attractive method for the preparation of ultralight polystyrene foam. The material exhibited superhydrophobicity and superoleophilicity, with WCA of 153° and an OCA of 0°. The low density and high porosity allowed P(St-EGD-DTD20) foam to adsorb from 49.6 to 112.8 g/g of representative oil pollutants. After adsorption saturation, regeneration of the foam by simple squeeze resulted in over 80 % oil removal and retained 90 % of the initial adsorption capacity after 10 adsorption-compression cycles. Importantly, the foam enabled separation of emulsions stabilized by Span80 with separation efficiencies in excess of 96 %. In addition, the foam displayed excellent self-cleaning properties and exhibited great mechanical durability and chemical stability in strongly acidic, alkaline, high-salt and other harsh environments. Finally, this foam could continuously separate oil–water mixtures with separation efficiencies of 99.63 % and 99.32 % for toluene and dichloromethane, respectively. For these prominent features, the present study provided a promising avenue for the separation of large-scale industrial oily wastewater.