Smart Sand by Surface Engineering: Toward Controllable\nOil/Water Separation

Abstract

Sand, an abundant resource from the\nnature, is a promising candidate\nfor oil/water separation. Herein, raw sand was designed with switchable\nsurface wettability to enable recyclability and versatility in practical\noil/water separation. The “smart” sand was fabricated\nby grafting pH-responsive poly­(4-vinylpyridine) (P4VP) and oleophilic/hydrophobic\noctadecyltrimethoxysilane (OTS) onto its surface. The decorated sand\ncan be used as the oil sorbent for controllable oil sorption and desorption\nin response to different pHs, as well as a filter to selectively separate\neither oil or water on demand. This novel design offers an intelligent,\nlow-cost, large-scale, and highly efficient route to potentially settle\nthe issues of industrial oily wastewater and oil spill.