Correlação entre a adsorção de HPA e a concentração de grupos silanóis em adsorventes sintéticos e naturais

Abstract

Nanostructured materials have received attention in recent years regarding applications at the construction of technological devices as well as environmental applications. In this scenario, Ordered Mesoporous Silica (SMO) stands out. In this work, SMOs were synthesized using the sol-gel method and addition of structure-directing agents to an inorganic network architecture. Thus, two types of SMO were used: the SBA-15 (Santa Bárbara Amorphous number 15) and the MCM-41 (Mobil Composition of Matter number 41). In addition, the present work sought to analyze the characteristics of Diatomite, which has a microstructural architecture, being a material from the macroporous family, to compare with the results presented by SBA-15 and MCM-41. All materials were heat treated at different temperatures, which was also a benchmark. The materials were analyzed by infrared spectroscopy (FTIR) and by the HPA Benzo[a]pyrene adsorption efficiency in aqueous medium, to obtain such results the materials were submitted to quantification analysis (synchronized fluorescence spectroscopy). The results showed that there was a reduction in the amounts of silanol groups on the silica surfaces as a function of calcining temperatures. The adsorption tests in aqueous media indicated that there is an adsorption limit as a function of time according to the calcining temperatures, influencing the adsorption efficiencies. The results of SBA-15 and MCM-41 have shown an adsorption efficiency superior to the results presented by Diatomite, making clear the relationship between the adsorption of HPA and the presence of surface silanol groups in nanostructured materials. All analyzes showed the influence of temperature on the efficiency of materials, Diatomite showed little variation in its structure, so there is a need for further studies for such comparisons since the material has larger pores in relation to SBA-15 and MCM-41.