Synthesis and properties of a magnetic core-shell composite nano-adsorbent for fluoride removal from drinking water

An adsorbent for fluoride removal from drinking water was prepared by coating Fe-Ti bimetallic oxide on magnetic Fe3O4 particles by co-precipitation. The adsorbent was a nanosized composite with a core-shell structure comprising a magnetic Fe3O4 core of 10-20 nm in diameter and an amorphous adsorbent shell of several nanometer thickness. The synthesis parameters were optimized to give high adsorption capacity and high magnetization. The optimized mass ratio of the Fe-Ti bimetallic oxide shell to Fe3O4 core was 2.72. The adsorption isotherm was well fitted with the Langmuir isotherm and the saturation adsorption capacity 57.22 mg/g adsorbent. Adsorption was fast and reached equilibrium within 2 min. The nanoadsorbent was superparamagnetic with a saturation magnetization of 18.4 emu/g, which allowed rapid separation of the adsorbent from the water solution by an external magnet. (C) 2014 Elsevier B.V. All rights reserved.