Preparation and characterization of a novel fluorine-free and pH-sensitive hydrophobic porous diatomite ceramic as highly efficient sorbent for oil-water separation

The development of sorbents with hydrophobicity or hydrophilicity is key in tackling increasingly serious oil spill/leakage problems. In this work, fluorine-free and pH-sensitive hydrophobic porous diatomite ceramics modified by isobutylene-maleic anhydride copolymer were successfully synthesized for the first time, via a simple but novel impregnation and heat-treatment method. Upon the removal of hydroxyl groups via 1 h heating at 573 K in a 5% H-2/Ar atmosphere, the amide groups in the original isobutylene-maleic anhydride copolymer were transformed to imide groups, conferring excellent hydrophobicity and oil/water separation capacity on the final porous ceramics. As-prepared hydrophobic porous diatomite ceramics were pH-sensitive and exhibited hydrophobic behavior in strong acid (pH = 1) whereas hydrophilic behavior in strong alkali (pH = 13). Their adsorption capacity for oil/water separation was 1.7-60 times as high as that of their conventional inorganic sorbent counterparts.