Layer-by-layer construction of CS-CNCs multilayer modified mesh with robust anti-crude-oil-fouling performance for efficient oil/water separation

Filtration membranes, with excellent anti-fouling capability, are ideal for actual oily sewage treatment, but the absence of a pre-hydration procedure is still a challenge. In this study, we demonstrated an environmentally friendly, and economical route to solve this problem by depositing chitosan (CS)-cellulose nanocrystals (CNCs) multilayer on stainless steel mesh (SSM) via simple layer-by-layer (LBL) self-assembly method. Due to the chemical structure , the CNCs have a large number of hydrophilic groups that are tightly bound to the surface, so the CS-CNCs multilayer modified mesh can maintain their strong surface hydration ability in air or oil, and will not be contaminated by crude oil even in a dry state. Besides, the CS-CNCs multilayer modified mesh exhibits superamphiphilic, underwater superoleophobic, and under-oil superhydrophilic functions. Moreover, the modified mesh also shows high rejection rate for crude oil/water mixture (99.92%) and diverse oil-in-water emulsions (>99.58%). What's more, the mesh has excellent reusability and chemical stability. The outstanding advantages in low-cost, environmental protection, biodegradability, anti-crude-oil-fouling performance, and efficient oil/water separation, endow our CS-CNCs multilayer modified mesh with great potential in complicated oily sewage purification.