3D inner-outer asymmetric sponge for enormous-volume emulsion wastewater treatment based on a new 'demulsification-transport' mechanism

Although oily wastewater treatment realized by superwetting materials has attracted heightened attention in recent years, how to treat enormous-volume emulsion wastewater is still a tough problem, which is ascribed to the emulsion accumulation. Herein, to address this problem, a material is presented by subtly integrating chemical demulsification and 3D inner-outer asymmetric wettability to a sponge substrate, and thus wettability gradient-driven oil directional transport for achieving unprecedented enormous-volume emulsion wastewater treatment is realized based on a “demulsification-transport” mechanism. The maximum treatment volume realized by the sponge is as large as 3 L (2.08 × 104 L per cubic meter of the sponge) in one cycle, which is about 100 times of the reported materials. Besides, owing to the large pore size of the sponge, 9000 L m2 h−1 (LMH) separation flux and 99.5% separation efficiency are realized simultaneously, which overcomes the trade-off dilemma. Such a 3D inner-outer asymmetric sponge displaying unprecedented advantage in the treatment volume can promote the development of the oily wastewater treatment field, as well as expand the application prospects of superwetting materials, especially in continuous water treatment.