Magnetic porous ferrospinel NiFe2O4: A novel ozonation catalyst with strong catalytic property for degradation of di-n-butyl phthalate and convenient separation from water

Magnetic porous ferrospinel NiFe2O4 prepared by a sol-gel method is introduced as a novel catalyst in the ozonation of refractory di-n-butyl phthalate (DBP), which is scarcely adsorbed on the catalyst surface under the investigated conditions in water. Such ferrospinel showed remarkable and stable catalytic ozonation acceleration on the degradation of DBP compared with the case of ozonation alone at pH 7.7. The catalytic ozonation process was pH dependent, and an uncharged surface was more active than a charged surface. The results revealed that NiFe2O4 catalytic ozonation followed a radical-type mechanism. The experiment related to the influence of phosphate and FTIR results showed that the surface hydroxyl groups acted as the main active sites in promoting hydroxyl radical (OH) generation. Concerning these finds and XPS results, we proposed that Ni2+ transferred electron from the surface to induce ozone decomposition in the catalytic process, the oxidation of lattice oxygen played an essential role in enhancing the reversion of Ni3+ to Ni2+, and the promotion of OH reaction was a combined balance action of Ni2+/Ni3+ and O2-/O-2. (C) 2012 Elsevier Inc. All rights reserved.