Superhydrophobic/Superoleophilic and Reinforced Ethyl Cellulose Sponges for Oil/Water Separation: Synergistic Strategies of Cross-linking, Carbon Nanotube Composite, and Nanosilica Modification

Superhydrophobic/superoleophilic and reinforced ethyl cellulose (SEC) sponges were prepared by cross-linking EC with epichlorohydrin (ECH) and complexing with silanized carbon nanotubes (Si-CNTs) followed by coating nanosilica on the surface of porous sponges and subsequent modification with hexadecyltrimethoxysilane (HDTMS). These synergistic strategies endowed the SEC sponges with the superhydrophobic/superoleophilic properties (theta(water) = 158.2 degrees, theta(oil) = 0 degrees, sliding angle = 3 degrees) and outstanding mechanical properties (could bear the pressure of 28.6 kPa without damage). The unique micronanostructures and properties of the porous sponges were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and water contact angle measurements. The as prepared SEC sponges with high mechanical strength were able to collect a wide range of oils and organic solvents with absorption capacity up to 64 times, of their own weight. Furthermore, the absorption capacity of the sponges decreased slightly to 86.4% of its initial value after 50 separation cycles, suggesting their excellent recyclable performance. The high efficiency and endurability of the sponges during oil/water separation made them ideal absorbent in oil spillage cleanup.