Efficient and reusable materials with pyrochlore structure for removing red dye from aqueous media

Mixed oxides of pyrochlore structure of the type La₂Zr₂O₇ and La₂M_0.3Zr_1.7O₇ (M = Fe or Ni) were synthesized through the modified proteic method and calcined at 900 °C for 2 h, this is a synthesis route not yet explored for materials with this structure and were characterized by X-ray diffraction, scanning electron microscopy images, point of zero charge (PZC) and specific surface area. Its abilities to remove pollutants from aqueous media by adsorption process were investigated using a model compound. Data analysis revealed that the synthesized materials correspond to the pyrochlore phase (La₂Zr₂O₇). They present particulate morphology with grains of different sizes and pores in their structure. The results of the adsorption studies show that the materials are efficient adsorbents for the removal of model compound in aqueous media, with efficiency above 90%. The adsorption kinetics of the compound in the adsorbents was studied. The materials were applied in reuse studies five times and maintained high efficiencies, highlighting the better performance presented by the material without doping. The obtained adsorbents were also submitted to removal of contaminants of industrial effluent tests and compared with the silica gel and activated carbon materials and also proved to be promising materials. (author)