Photoactive anatase TiO 2 nanoparticles with a size less than 10 nm were coated on barium ferrite forming complete coverage by the controlled hydrolysis and condensation of titanium bis-ammonium lactato dihydroxide in the presence of polyethyleneimine at a relatively low temperature (95 °C). The as-prepared composite particles (hard magnetic barium ferrite (core)-anatase TiO 2 nanoparticles (shell)) can be utilized as a magnetic photocatalyst, which can be fluidized and recovered by an applied magnetic field enhancing both the separation and mixing efficiency for remediating fluids. The morphology of composite particles was characterized with scanning electron microscopy and transmission electron microscopy. The crystalline structure of TiO 2 was characterized by X-ray diffraction and electron diffraction. Energy-dispersive spectroscopy was utilized for the elemental analysis of the products. The as-prepared TiO 2 -barium ferrite composite has higher photocatalytic activities than the TiO 2 -barium ferrite composite heat-treated at 500 °C for 1 h. The higher photoactivities of the unheated composite are ascribed to higher specific surface area and preservation of the surface hydroxyl groups on TiO 2 .
A magnetically agitated photocatalytic reactor (MAPR) has been developed and assessed for oxidation of phenol. The MAPR uses a titanium dioxide composite photocatalyst with a ferromagnetic barium ferrite core. The catalyst motion was controlled with a dual-component magnetic field. First, a permanent magnet above the reactor provided a static magnetic field to counteract the force of gravity, hence increasing catalyst exposure to UV. Second, an alternating magnetic field generated by a solenoid was used to agitate the catalyst, thus increasing mass transfer between pollutants and byproducts to the catalyst. Optimal performance of the MAPR was achieved with the permanent magnet present and 1 A of alternating current to the solenoid between 20 and 80 Hz. Operating with a 60-Hz signal at 1 A with the permanent magnet present and 100 mg of catalyst, the system reduced an 11 mg/L phenol concentration by97% and decreased nonpurgeable dissolved organic carbon by 93% in 7 h using three 8-W 365-nm peak UV lamps.
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