Carvão ativado de resíduos de Tectona grandis

Abstract

The activated carbon is an adsorbent material used in various procedures such as treatment of liquid and gaseous effluents, purification, discoloration, etc; in pharmaceutical, food, paint, paper and cellulose, polymers, among other industries. These adsorbents may be made from different carboniferous material such as agricultural and forest residues. In this study, the activated carbon was produced from thin trunks, branches, and antlers of Tectona grandis (teak); and forest residues generated in large volume. Chemical activation was carried out using ZnCl2, NaCl and CuSO4, and physical activation was performed using CO2. Teak residues were characterized in relation to contents of lignin, holocellulose, ash and extractives; basic density, elemental analysis (CHNS-O), thermogravimetric analysis (TGA), and infrared spectroscopy (FTIR). The activated carbon was characterized by CHNS-O, TGA and FTIR, surface functional groups analysis, and surface area analysis. In addition, it was tested in relation to contaminants adsorption capacity in aqueous solution such as methylene blue, phenol, and Cr+6 ions. The elemental analysis resulted in the increase of carbon content, and in the reduction of content of oxygen and hydrogen, after pyrolysis and activation. The thermogravimetric analysis resulted in greater thermal stability of activated carbon than of forest residues. The IR spectroscopy confirmed the material carbonization. The chemical activation with ZnCl2 (CA_ZnCl2) showed predominantly microporous aspect and greater surface area, while the physical activation showed mesoporous aspect. Beyond this, the CA_ZnCl2 was more effective in the adsorption of methylene blue and phenol. The adsorption of Cr+6 was not effective for none of activated carbons. The carbon activated with CuSO4 showed functional groups very different from other reagents-based activation, however, was not successful for adsorption. Besides, the carbon activation with CO2 was the second best in relation to adsorption performance and gravimetric income, while the carbon activation with NaCl showed good phenol adsorption capacity.