Effect of the metal type in perovskites prepared by modified proteic method in dye adsorption from aqueous medium

The effect of the cation type (nickel or manganese) present in lanthanum perovskites on dye adsorption from aqueous medium was studied. These perovskites were synthesized by the modified proteic method using soy protein as the complexing agent. The materials were characterized by thermogravimetric analysis, Fourier Transform Infrared (FTIR) absorption spectroscopy, UV vis spectrophotometry, X-ray diffraction (XRD) and N-2 adsorption at 196 degrees C. A single phase was observed only for Mn2+ containing samples, this indicates that interactions of the soy protein with Mn2+ cations are favored over those with Ni2+. The application of the perovskites in removal of the congo red by adsorption from liquid phase showed that the samples containing Mn2+ exhibited higher adsorption efficiency than Ni2+ ones. Kinetic studies showed that the pseudo-second order model exhibited the best fit with the experimental data with R-2 values closer to the unit. The possibility of adsorbent regeneration has been examined with promising results.