Preparation of alkylated hollow polyaniline and its application in oil/water separation

Owing to its good environmental stability and facile modification, polyaniline (PANI) is regarded as a promising candidate as a corrosion inhibitor and hydrophobic modifier. For the purpose of extending the application of PANI in the oil removal field, a hollow-structured shell was designed to achieve greater space to accommodate oil, and the shell surfaces were hydrophobically modified in order to attain hydrophobic affinity toward organics and thus improve their oil separation efficiency. Three types of hollow polyaniline shells were obtained by eliminating the SiO₂ core from precursor composites prepared via the in situ polymerization of aniline monomers on a silica microsphere template. To enhance their hydrophobicity, these PANI shells were alkylated by reacting them with 1-bromododecane. The alkylated PANI shells were then used to adsorb simulant oils from an aqueous mixture, as well as to modify a polyurethane sponge to filter oil from water. Consequently, 91.3% of benzene was removed from a dilute solution, and 87.0% of dispersed hexane was separated from an emulsion. The sponge coated with alkylated PANI shells efficiently filtered the bulk of organics from water, with recovery as high as 99.1%. Those impressive results provide evidence of the significance of the hollow structure and hydrophobic modification, which endow the PANI materials with high application potential in oil/water separation.