Freeze-casting multicomponent aerogel membrane with controllable asymmetric multilayer configuration for high flux gravity-driven separation of oil-water emulsion

Freeze-casting has been widely used to mix one or several functional components to form aerogel where the resulting structure is uniform and has no distinctive asymmetrical morphology and characteristics. Hence, a multilayered, multicomponent aerogel with tunable physical and chemical properties is desirable as it can extend the multifunctionality and versatility of the aerogel by integrating multiple functional materials. Here, a facile stacked freeze-casting method is reported to fabricate multilayered aerogel membrane with asymmetric morphology and opposing surface wettability from polyvinyl alcohol(PVA)/leached carbon black waste (LCBW) solutions and carbon nanotube (CNT) dispersion for separation of water-in-oil emulsions. The results show that the aerogel membrane can easily demulsify the emulsion at a remarkably high permeate flux (up to 427 ± 40 × 103 Lm−2hr-1bar−1) with rejection higher than ∼96% at an ultralow driving pressure of ∼640 Pa.