Durable hydrophobic ceramics of Al2O3–ZrO2 modified by hydrophilic silane with high oil/water separation efficiency

Separating materials of oil/water are widely used to deal with oil leakage and industrial oily wastewater. Herein, hydrophobic–oleophilic porous ceramics of Al2O3–ZrO2 were prepared by combustion synthesis-molding method and modified with 3-amino-propyltriethoxysilane (APTES). The effects of Al2O3–ZrO2 mole ratio, starch content and sintering temperature on permeability of porous ceramics were investigated in detail. When the molar ratio of Al2O3–ZrO2 is 1:0.15 and the amount of starch is 35 wt%, the porous ceramics with average pore diameter of about 42 nm and porosity of about 46% can be obtained after sintering at 1450 °C for 2 h. APTES was adopted to modify the porous ceramic of Al2O3–ZrO2 to construct the hydrophobic surface. The optimum conditions of modification for the Al2O3–ZrO2 ceramic were that the time was 4 h, the temperature was 70 °C and the modifier concentration was 2%. Most notably, the as-prepared hydrophobic ceramic was a rare example that adopted hydrophilic molecule to build hydrophobic material. Due to the favorable permeability and hydrophobicity, the Al2O3–ZrO2 ceramic was designed into sand core to separate oil/water mixture. The ceramic displays high separation efficiency (93%), good reuse performance (10 cycles) and super abrasion resistance (10 times).