Obtenção de peças de Nb2O5 com biomassa inativa para aplicação em processos de adsorção

Abstract

The main objective of this work was to obtain Nb2O5 pellets with inactive biomass (here called sludge) and to evaluate its adsorption capacity for manganese ions dispersed in an aqueous medium. First, the sludge was characterized by thermal analysis (TG/DTG), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Then, pellets were obtained in a mass ratio of 95% Nb2O5: 5% sludge, by uniaxial pressing and subjected to heat treatment at temperatures of 300, 400, 500, 600 and 900ºC. The pellets were characterized by apparent porosity, apparent density, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). When analyzing the results, it was observed that in the heat treatment at temperatures from 300°C to 600°C there were no significant variations in the characteristics of the parts, except for the apparent porosity, which gradually increased with the increase in the heat treatment temperature, ranging from 35% for the sample obtained at 300°C to 45% for the sample obtained at 900°C. On the other hand, the 900°C sample without sludge showed higher density and lower porosity, a fact also evidenced by SEM. In the adsorption studies for Mn2+ ions, there was no significant variation in the percentage of adsorption by the pellets obtained at different heat treatment temperatures. Analyzing the extreme temperatures, an adsorption of 65% was obtained in the pellet treated at 300ºC and 67% of adsorption in the samples treated at 900ºC. The samples obtained at 300°C with and without sludge were selected for the study of adsorption kinetics, adsorption isotherm and reuse. The adsorption kinetics followed the pseudo second order model both for samples with and without sludge. The isotherm model that best fitted was the Freundlich model for the sample without sludge and the Langmuir model for the samples with sludge. Finally, the material presented potential application for reuse. Used in five cycles of adsorption, the percentage of Mn2+ averaged 67% without the occurrence of desorption. Thus, the pellet presents stability in the retention of Mn2+ ions, and potential for the application and development of adsorbents for the removal of metallic ions.