Structure, morphology and adsorption properties of titania shell immobilized onto cobalt ferrite nanoparticle core

A magnetic core-shell adsorbent was synthesized by immobilization of titanium dioxide nanodusters on the cobalt ferrite nanoparticles. The synthesis was carried out using a modified Pechini sol-gel method with citric acid and ethylene glycol as chelating agents. The structure and morphology of reference TiO2, pristine CoFe2O4 and resulting nanocomposite CoFe2O4@TiO2 were thoroughly characterized using XRD, XRF, BET, SEM, IR spectroscopy and Mossbauer spectroscopy. The obtained spectral data indicate that a shift of electron density from titanium to oxygen atoms takes place. Antistructure modeling suggests that some titanium atoms are entered into the CoFe2O4 spinel structure resulting in defects of crystalline structure. In this way additional adsorption centers arise. The adsorption efficiency of the CoFe2O4@TiO2 nanocomposite was found to be more than twice as high as compared to TiO2 and CoFe2O4 alone. The observed synergistic effect is associated just with the formation of distorted titania nanocrystals. The obtained magnetic nanoadsorbent proved to be efficient in water purification from dichromate anions (83% removal) and Congo Red dye (61% removal). (C) 2019 Elsevier B.V. All rights reserved.