Preparação e caracterização de híbridos de Pani(ADBS)/óxidos magnéticos/TIO2 e sua avaliação em fotodegradação

Abstract

Polyaniline (PAni) is a polymer which has a special characteristic of electrical conduction due to the ability of being doped by a protonic acid, such characteristic is the target of recent research in photocatalysis. The magnetic iron oxides (OM) are ceramic materials abundant in nature, and are currently widely used in various fields of science. The magnetite (Fe3O4) and maghemite (γ-Fe2O3) in addition to the magnetic properties are also semiconducting materials, and objects of recent research in the field of photocatalysis. Titanium dioxide (TiO2) is a semiconductor inorganic dye widely used in the food, cosmetics and pharmaceuticals industries, which also has already studied the photocatalytic properties longer. Hybrid materials are junctions of organic and inorganic compounds for the purpose of adding specific properties. In this work were made syntheses of PAni doped with dodecylbenzenesulfonic acid (DBSA), OM, OM/TiO2 mixtures and hybrids of PAni (DBSA) / OM, PAni (DBSA) / TiO2 and PAni (DBSA) / OM/TiO2 order to verify the ability of each of these compounds in the photodegradation of methylene blue dye. The materials were characterized by the techniques of x-ray diffraction, vibrational spectroscopy in the infrared region, Mӧssbauer spectroscopy, magnetization, electrical conductivity and transmission electron microscopy. The characterizations showed formation of the synthesized compounds. A test of photodegradation of methylene blue was conducted by irradiation by means of ultraviolet lamp, a stock solution of the dye in the presence of an aliquot of the compounds obtained by evaluating exposure time (24, 48, 72, 96 and 120h). After irradiated solutions were analyzed by spectrophotometry UV / Visible, graphs were obtained where the dye concentration in solution versus time of exposure. The hybrid PAni (DBSA) / OM/TiO2 presented satisfactory results in view of its starting compounds. The concentration of dye in solution, after 120h, was reduced to zero, it is considered that there is a synergy as between the compounds present in the hybrid, considerably increasing the photocatalytic ability, as a material very promising in this area.