The petroleum industry produces a large amount of crude oil-contaminated water during the production process. Removing oil and grease components from crude oil/water mixtures is an urgent problem and a...
To alleviate the economic and environmental damage caused
by industrial
discharges of oily wastewater, materials applied for efficient oil/water
separation are receiving significant attention from researchers and
engineers. Among others, switchable wettable materials for bidirectional
oil/water separation show great potential for practical applications.
Inspired by mussels, we utilized a simple immersion method to construct
a polydopamine (PDA) coating on a peony-like copper phosphate surface.
Then, TiO2 was deposited on the PDA coating surface to
build a micro–nano hierarchical structure, which was modified
with octadecanethiol (ODT) to obtain a switchable wettable peony-like
superhydrophobic surface. The water contact angle of the obtained
superhydrophobic surface reached 153.5°, and the separation efficiency
was as high as 99.84% with a flux greater than 15,100 L/(m2·h) after 10 separation cycles for a variety of heavy oil/water
mixtures. Notably, the modified membranes have a unique photoresponsiveness,
transforming to superhydrophilic upon ultraviolet irradiation, achieving
separation efficiencies of up to 99.83% and separation fluxes greater
than 32,200 L/(m2·h) after 10 separation cycles for
a variety of light oil/water mixtures. More importantly, this switch
behavior is reversible, and the high hydrophobicity can be restored
after heating to achieve efficient separation of heavy oil/water mixtures.
In addition, the prepared membranes can maintain high hydrophobicity
under acid–base conditions and after 30 sandpaper abrasion
cycles, and damaged membranes can be restored to superhydrophobicity
after a brief modification in the ODT solution. This simple-to-prepare,
easy-to-repair, robust membrane with switchable wettability shows
great potential in the field of oil/water separation.
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