All cellulose-based superwetting aerogel/wood composite with disordered/ordered pores structure for rapid emulsion separation

Abstract

Rapid and efficient separation of oil from emulsions is critically required prior to addressing the global challenge of oily sewage, but most separation membranes encounter intractable challenges in terms of the trade-off effect between separation efficiency and flux, as well as the use of petrochemical feedstocks. Herein, an all-biomass wood/aerogel composite with a disordered/ordered structure was constructed by filling cellulose nanofibers aerogel into the intertubular cavities of delignified wood using cotton and wood as building blocks through a series of processes, including casting, regeneration, and freeze-drying. The parallel channels of wood and the porous structure of aerogel constitute the special disordered/ordered pores structure, which accelerates vertically oriented permeation and enhances emulsified droplets coalescence for demulsification. In addition, the aerogel/wood composite retains the inherent hydrophilicity of cellulose and exhibites excellent underwater superoleophobicity with an underwater oil contact angle of 159.6°, which is chemically stable and salt resistant. The unique disordered/ordered structure and superwettability of the aerogel/wood composite contribute to its exceptional separation efficiency (99.25 %) and high flux (2580 L·m−2·h−1) for the separation of oil-in-water emulsions when driven only by gravity. Additionally, the composite shows good utility and ease of cycling. These outstanding properties highlight its promising practical application in the oil-related industry.