Preparation of agglomerated particles of TiO2 and silica-coated magnetic particle

Agglomerated particles of TiO2 and silica-coated magnetic particles were prepared and utilized as a magnetically separated photocatalyst. The magnetic particle, gamma-Fe2O3, was prepared by a reduction-precipitation method. Silica was coated onto gamma-Fe2O3 by the hydrolysis of sodium silicate solution. Agglomerated particles of TiO2 and silica-coated magnetic particles were prepared by mixing TiO2 particles and silica-coated magnetic particles and followed by calcination at 500 degrees C for 30 min. The prepared sample responded to magnetic field. The coating of silica intermediate layer was found to improve acid resistance of the catalyst. Moreover, the coating suppressed the electron-hole recombination and the electron-hole transfer from the TiO2 particle to the gamma-Fe2O3 core. Photocatalytic activity of the catalysts either with or without the silica layer towards methylene blue decomposition was in the order of TiO2 > T-SdF > T-SF > SF > Blank congruent to > T-F > F catalysts. (C) 2007 Elsevier B.V. All rights reserved.