Smart Sand by Surface Engineering: Toward Controllable Oil/Water Separation

Sand, an abundant resource from the
nature, is a promising candidate
for oil/water separation. Herein, raw sand was designed with switchable
surface wettability to enable recyclability and versatility in practical
oil/water separation. The “smart” sand was fabricated
by grafting pH-responsive poly­(4-vinylpyridine) (P4VP) and oleophilic/hydrophobic
octadecyltrimethoxysilane (OTS) onto its surface. The decorated sand
can be used as the oil sorbent for controllable oil sorption and desorption
in response to different pHs, as well as a filter to selectively separate
either oil or water on demand. This novel design offers an intelligent,
low-cost, large-scale, and highly efficient route to potentially settle
the issues of industrial oily wastewater and oil spill.