Avaliação da inflência da temperatura e de ativadores químicos na produção de carvão ativado obtido a partir do bagaço de maçã gala

Abstract

Activated charcoal is a material that has wide applicability, given its high adsorptive capacity, resulting from its elevated surface area, composed of pores of different sizes. Within this context, this work aimed to prepare and characterize activated charcoal, from the pyrolysis of the Gala apple pomace. The material was, initially, pyrolyzed at 500 ºC and 700 ºC, to evaluate the influence of temperature on the process. As expected, high temperatures resulted in more developed biochars, but with a lower yield. Then, the samples were chemically activated with iron (II) chloride and zinc chloride, maintaining the same carbonization patterns of the biochars, at of 700 ºC. The materials obtained were characterized using different techniques, including Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and Brunauer–Emmett–Teller method (BET). The results showed that the activation is effective and favorable to the synthesis of activated charcoal, mainly with the use of zinc chloride as activator. This activated charcoal presented a large increase in the value of specific surface area, with the value enhancing from 2,3 m²/g to 1034,1 m²/g. Furthermore, the average pore diameter decreases considerably from 102,3 Å to 18,3 Å. There was also a significant loss of oxygen in the samples, which is characteristic of charcoal with high surface area. Activated charcoals with these characteristics have high selectivity and can be applied in adsorption of gases, for example. Finally, it was possible to conclude that the thermal conversion of the Gala apple pomace is a promising alternative for the reuse of this material and for increasing its added value. [resumo fornecido pelo autor]