Eucalyptus Bark Biochar: Production and Characterization

In recent years, biochar has garnered increasing attention due to its potential applications in soil amendment, adsorption, and carbon sequestration, which has driven a growing research interest in these areas. Moreover, lignocellulosic biomass is the primary feedstock for biochar production, typically obtained through pyrolysis under limited O2 conditions. Within this framework, the present study proposes a sustainable approach that valorizes an environmental byproduct from the forestry sector─Eucalyptus bark─for biochar production, aiming to improve soil properties through carbon and mineral supply and pH regulation. The raw material was characterized by determining its proximate composition, as well as its structural and chemical features (XRD and FTIR) and thermal behavior (TGA/DTG). After this initial characterization and the definition of suitable pyrolysis conditions, four treatments were carried out at 300 °C, 350 °C, 400 °C, and 450 °C with a fixed residence time of 2 h. Proximate analysis and yield measurements revealed an inverse relationship between fixed carbon content and gravimetric yield. Furthermore, XRD, FTIR, and TGA analyses confirmed chemical and structural transformations occurring during the thermochemical conversion process. Dynamic and isothermal thermogravimetric tests under an inert atmosphere were conducted to simulate the parameters used in a muffle furnace for larger-scale production. The maximum degradation rate temperature (T_max) of Eucalyptus bark was identified as 380 °C, determined from the DTG curve and corroborated by the TG curve. Overall, the biochar produced at 450 °C stood out for its high fixed carbon content, elevated pH, lower volatile matter, and greater thermal stability, which are associated with its amorphous and aromatized structure.