Synthesis of Titania-Silica-Iron Oxide Nanocomposites and Investigation of their Bactericidal Activities

Abstract

The multipurpose nanocomposites that combine superparamagnetic character, high photocatalytic activity with ability to degrade dye (methylene blue) and kill bacteria were synthesized and investigated. The magnetic nanocomposites consist of magnetite (Fe₃O₄) as the inner core, silica (SiO₂) as a middle layer and titania (TiO₂) as the outer shell. In order to synthesize the Titania-Silica-Iron Oxide Nanocomposites, a co-precipitation method was required to be used for both synthesis of iron oxide and coating silica layer. Besides, synthesis of titania shell was conducted by both co-precipitation and reverse microemulsion method. X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to characterize the prepared materials. Moreover, the photocatalytic activity of the synthesized nanocomposites was analyzed by using UV-visible absorption spectroscopy. According to the experiment, the thickness of the silica layer had been varied by differing the amount of TEOS at the ratio of 37.5, 150, 300, 600 and 900 µL/ 0.1 g magnetite. The result demonstrates that the nanocomposites consisting of 600 µL TEOS exhibits the highest efficiency of degrading the methylene blue. However, the nanocomposites revealed the inefficiency for bactericidal properties under the irradiation of blue UV blacklight. The products from the synthesis by using co-precipitation method were collected in larger amounts when compared with previous work [1] and could lead to the large-scale production of materials for wastewater treatment applications.