Highly Efficient Separation for Aqueous Viscous Oils Enabled by a Wood-Based Cellulose Aerogel with a Superhydrophilic Protonated Coating

Superhydrophilic materials, renowned for their capacity to establish a hydration layer that effectively mitigates oil pollution, have garnered considerable attention for oil–water separation. However, these materials have difficulties in separating water from high-viscosity oils, which can easily adhere to the surfaces of the materials, resulting in reduced separation efficiencies. In this work, a superhydrophilic wood-based cellulose aerogel coated with a protonated nanocomposite chitosan coating (PPNC-CS) was proposed to enhance water affinity and prevent viscous oil adhesion. The separation efficiency of the prepared cellulose aerogel@PPNC-CS reached an impressive 99.90% for high-viscosity crude oil and water. Notably, it exhibited an underwater–oil contact angle exceeding 160°, oil contamination prevention, and self-cleaning performances. These properties can be attributed to the presence of micronanoscale coating particles on the lamellar architecture of the cellulose aerogel@PPNC-CS, coupled with the formation of a robust hydration layer through electrostatic interaction and hydrogen bonding. Moreover, it exhibited enduring chemical stability, resistance to acid and alkali corrosion, and a notable capacity for high-concentration salt tolerance. This research introduces a promising material for the sustainable purification of aqueous viscous oils, offering low cost and environmental friendliness.