Nanoestrutura magnética TiO2: CoFe2O4 aplicada como fotocatalisador na degradação do diuron padrão por fotocatálise.

Abstract

A method considered efficient for the recalcitrant organic molecules degradation, such as diuron agrochemical, is the heterogeneous photocatalysis (FH) process using TiO2. The TiO2 in photocatalytic process is generally used in powder form consisting of nanometric particles, which makes difficult its recovery and reuse. An alternative that allows recovering the nanocatalyst from the reaction medium by magnetic separation is the synthesis of the same compound associated to a good magnetic property phase (CoFe2O4). Thus the present work had as objective to synthesize magnetic nanostructures, xTiO2:yCoFe2O4 in the mass proportions of x:y 90:10; 70:30 and 50:50 to be used as catalysts in the degradation and mineralization process of the standard diuron in aqueous solution by heterogeneous photocatalysis. In order to accomplish it, CoFe2O4 samples were synthesized by the combustion method and TiO2 and xTiO2: yCoFe2O4 were synthesized by the Pechini method, which were subjected to X-ray diffraction characterization with Rietvield refinement, chemical composition by X-ray fluorescence and textural analysis. The photocatalytic nanomaterials activity was evaluated in the photodegradation and mineralization of the standard diuron by quantifying the final diuron concentration and total organic carbon (TOC). The pH effects and the catalyst concentration were estimated through a factorial design. The magnetic nanostructures allowed the reaction medium separation by a magnetic field. All synthesized nanomaterials promoted 100% diuron degradation. The highest TOC removals for the magnetic catalysts were obtained with pH 3 and 0.5 mg/mL of catalyst and for TiO2 it was with pH 5 and 0.3 mg/mL of catalyst.