Produção e caracterização de carvão ativado obtido a partir da casca de eucalipto (Eucalyptus globulus Labill)

Abstract

Eucalyptus (Eucalyptus globulus Labill) is a variety of tree plant, widely cultivated in Brazilian territory, this species is responsible for generating a considerable amount of waste after the harvesting process, which manifests itself in the form of bark, leaves and branches. Such waste demonstrates the ability to serve as input in the production of activated carbon, used in the effluent treatment procedure. Given the above, the present work presented as its central purpose the production of activated carbon, obtained from eucalyptus bark (Eucalyptus globulus Labill), which was used in the adsorption of methylene blue dye and the drugs ibuprofen and diclofenac sodium. The eucalyptus bark received chemical treatment through impregnation with phosphoric acid (H3PO4) and the charcoal was produced through pyrolysis of the impregnated bark under an inert nitrogen atmosphere at a temperature of 500°C. The shell and adsorbent were characterized in relation to their physical and physicochemical properties. Furthermore, in order to evaluate the carbon removal efficiency for the dye and drugs, adsorption kinetics experiments were carried out. Results consistent with the literature were observed for the characterization of eucalyptus bark. After charcoal production, an adsorbent was obtained that met the criteria for activated carbons with dp of 0.0403 mm. TGA and XRD analyzes indicated degradation of hemicellulose and cellulose after acid treatment. The adsorption processes for the studied compounds showed distinct characteristics. Removal efficiencies of 95.98%, 72.50% and 88.31% were estimated for Methylene Blue, Ibuprofen and Diclofenac Sodium, respectively. In the case of the dye, the time required to reach equilibrium was approximately 120 min, revealing a process that involves both convection and diffusion mass transfer. Regarding ibuprofen, it took about 300 min to reach adsorption equilibrium, indicating a process governed mainly by diffusion. As for diclofenac sodium, adsorption equilibrium was reached in just 50 min, characterizing a mostly convective process. Based on the studies carried out, it can be stated that eucalyptus residue presented satisfactory results regarding its use for the production of activated carbon.