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 (θ_water = 158.2°, θ_oil = 0°, sliding angle = 3°) 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

Influence of content of microcapsules on flexural strength restoration of cement paste: (a) standard curing (b) water curing.

<p>Influence of content of microcapsules on flexural strength restoration of cement paste: (a) standard curing (b) water curing.</p

SEM-EDS micrographs of damaging specimens at different stages: (a) 30%<i>f</i> (b) 60%<i>f</i> (c) capsules layout at 100%<i>f</i> (d) healing cracks at 100%<i>f</i>.

<p>SEM-EDS micrographs of damaging specimens at different stages: (a) 30%<i>f</i> (b) 60%<i>f</i> (c) capsules layout at 100%<i>f</i> (d) healing cracks at 100%<i>f</i>.</p

Reloading-displacement curves for blank cement paste after healing.

<p>Reloading-displacement curves for blank cement paste after healing.</p

Load-displacement curves for blank cement paste during pre-damage: (a) standard curing (b) water curing.

<p>Load-displacement curves for blank cement paste during pre-damage: (a) standard curing (b) water curing.</p

Water sorption of cement paste during healing: (a) reference (b) 1% of microcapsules (c) 2% of microcapsules.

<p>Water sorption of cement paste during healing: (a) reference (b) 1% of microcapsules (c) 2% of microcapsules.</p

OM micrographs of microcapsules prepared: (a) ×4 (b) ×10.

<p>OM micrographs of microcapsules prepared: (a) ×4 (b) ×10.</p

Reloading-displacement curves for cement paste with 1% of microcapsules after healing.

<p>Reloading-displacement curves for cement paste with 1% of microcapsules after healing.</p

Crack penetration of specimens before failure: (a) reference (b) 1% of microcapsules (c) 2% of microcapsules.

<p>Crack penetration of specimens before failure: (a) reference (b) 1% of microcapsules (c) 2% of microcapsules.</p

Influence of content of microcapsules on compressive strength restoration of cement paste: (a) standard curing (b) water curing.

<p>Influence of content of microcapsules on compressive strength restoration of cement paste: (a) standard curing (b) water curing.</p