Effect of synthesis method of LaNiO3 type materials with perovskite structure on their features and in the methylene blue dye removal from aqueous media

Abstract

Oxides with perovskite structure are the target of important studies, as they are versatile materials that have shown magnetic, electrical, optical, catalytic, adsorptive applications, among others, and are also easily synthesized. These applications are potentially influenced by the synthesis method, and in this sense, several methods have been used to prepare these materials, in order to optimize their characteristics and properties. The methods: modified protein using gelatin as a complexing agent, mechanosynthesis and combustion method in the heating plate and microwave were used to prepare LaNiO₃ type materials with perovskite structure used in the present work. The materials obtained were characterized by physical-chemical techniques (X-ray diffraction, nitrogen adsorption at 77 K and determination of the point of zero charge) and evaluated as an adsorbent for the removal of methylene blue dye in aqueous medium. All materials showed potential for removing the dye from the medium, with emphasis on the material obtained by mechanosynthesis, which presented higher methylene blue dye discoloration efficiency, due its smaller crystallite size and larger surface area. After the dye removal tests, the perovskite structure was preserved and the adsorbent was reused after being subjected to calcination at 900 °C for 2 hours when simultaneous degradation of the previously adsorbed dye occurred. The reused materials still had a high potential for dye removal.