Preparation of Highly Hydrophobic Sand Core and Its Oil–Water Separation Performance

Abstract Through a chemical grafting method, long chains of dodecyltrimethoxysilane (SCA‐K12M) were successfully grafted onto a micro‐rough surface sand core substrate to prepare hydrophobic‐oleophilic functionalized sand core material. Scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) morphological analysis, Fourier transform infrared spectroscopy (FTIR) functional group detection, and X‐ray photoelectron spectroscopy (XPS) elemental characterization confirmed the effective grafting of SCA‐K12M on the sand core surface. The modified sand core exhibited water repellency and oil affinity with a water contact angle of 142.3°. Specifically, its adhesion capacity increased by 62.5%, 47.5%, and 60% for liquid paraffin, diesel, and rapeseed oil, respectively, while showing threefold, sevenfold, and eightfold enhancements for n‐hexane, methanol, and acetone. The separation efficiency exceeded 95% under varying oil‐to‐water ratios, demonstrating excellent recyclability. The modified sand core (G3‐type) achieved an oil‐phase flux of 12.45 L/(m 2 ·min) under a pressure differential of 0.03 MPa. Additionally, it exhibited strong resistance to mechanical abrasion and acid corrosion. Therefore, the facile preparation process, low cost, and superior oil separation/absorption would endow the hydrophobic oleophilic sand cores with high potential when dealing with oily wastewater.