Facile Preparation of Ni Foam/Bacterial Nanocellulose Composite for Oil/Water Separation

Developing efficient and effective oil/water separation materials with both high treatment flux and rejection by a low cost and simple way have been the main goal pursued by researchers. In this paper, a porous metal foam (Ni foam plate and slice) with high strength is selected as the substrate and bacterial nanocellulose fiber (BNC) is used as hydrophilic fibers for modification. Driven by concentration difference, we constructed Ni foam/BNC composite, where the BNC fibers could insert into the foam body and regulate the pore size of foam by only changing the fiber content. This enables the intrinsic large pores of the pristine Ni foam to decrease quickly while maintaining high porosity. Compared to the thick Ni foam plate, the stacks composed of thin Ni foam slices with various pore sizes can effectively separate different oil/water mixtures (i.e. layered oil/water mixtures, oil/water emulsions with and without surfactant) solely by gravity with high treatment flux and satisfactory oil rejection. Furthermore, the modified Ni foams show good reusability only through ethanol washing. The modified Ni foams could be used in the situations with severe water impact and large pressure difference owing to their high compressive modulus. It is expected that this facile pore size adjustment technology can provide us an easy scaled up method to construct filtering materials with high strength and oil/water separation efficiency.