Freeze-Casting Multicomponent Aerogel with Controllable Asymmetric Multilayer Configuration for High Flux Gravity-Driven Separation of Oil-Water Emulsions

Abstract

Freeze-casting has been widely used to mix one or several functional components to form aerogel where the resulting structure has no distinctive asymmetrical morphology and characteristics. Hence, a multilayered aerogel constituted by multicomponents with tunable structural configurations is desirable as it extends the multifunctionality of the aerogel by multiplying the number of functional materials to be possibly integrated and allowing varying morphologies within an aerog el. Here, a facile stacked freeze-casting method to fabricate multilayered aerogels with asymmetric configuration derived from solutions and dispersion is reported to fabricate an aerogel membrane with asymmetric wettability and morphology 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 x 10 3 Lm -2 hr -1 bar -1 ) with rejection higher than ~96% at an ultralow driving pressure of ~640 Pa.

Keywords: Freeze-casting, aerogel, oil/water emulsion, carbon, multilayer.