Superhydrophobic sand grains structured with aligned Cu(OH)2 nano-needles for efficient oily water treatment

Publication date: 5 December 2017
Source:Materials & Design, Volume 135
Author(s): Liwei Chen, Yang Wu, Zhiguang Guo
Desert sand as an abundant natural resource rarely has been reconsidered and reutilized due to its superhydrophilicity. Aiming at the combination of super-wettability with sand resource, we successfully design the aligned Cu(OH)2 nano-needles on the sand grain surfaces through a skillful strategy and conferred superhydrophobic properties on them in this study. The water contact angle and rolling angle are shown to be ~158° and ~6°, which break our traditional understanding towards desert sand, i.e., superhydrophilicity. More importantly, the selective superhydrophobic-superoleophilic wettability and the cavities between nano-needles and sand grains allow the sand to be a good candidate for efficient oily water treatment. The as-prepared superhydrophibic sand can not only absorb light oils from water surface, but separate heavy oils from oil/water mixtures. The speed of oil/water separation is up to 16,985Lm⁻²h⁻¹ when a 0.35cm thickness of superhydrophobic sand layer is used. Significantly, it exhibits both high separation rate and high separation efficiency (>99.5%). The as-prepared superhydrophobic sands are expected to become a new candidate of highly efficient oil/water separation material and to realize the reutilization of desert sand resource.

Graphical abstract

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