Hierarchical Fe3O4@titanate microspheres with superior removal capability for water treatment: in situ growth and structure tailoring via hydrothermal assisted etching

Abstract

Hierarchical flower-like Fe₃O₄@titanate microspheres with ultrathin nanosheets-assembled shell were fabricated via an effective step-by-step approach. Superparamagnetic Fe₃O₄ microspheres pre-formed were used as templates for perfect deposition of the following coatings. Silica middle layer was introduced by Stöber method in order to direct the formation of amorphous titania coverage via the hydrolysis of tetraisopropyl titanate. Under alkaline hydrothermal environment, titanate nanosheets crystallized and grew in situ attaching on the surface of Fe₃O₄ spheres, generating the flower-like microspheres which exhibit excellent adsorption properties. Meanwhile, the hierarchical structures can be tailored by varying the hydrothermal temperature and alkalinity, and the roles of sodium hydroxide and hydrogen peroxide were proposed.