Physical–chemical characterization and thermal behavior of cassava harvest waste for application in thermochemical processes

Bioenergy generation from agroindustrial wastes has been investigated worldwide because of rising fossil fuel prices and the requirements of environmental legislation to reduce greenhouse gas emissions. In this research, the thermal behavior of cassava harvest wastes (husks, stalks, leaves) was investigated under two atmospheres: combustion (oxidizing) and pyrolysis (inert) by thermal analysis (TG/DTG curves). Other analytical techniques, such as X-ray diffraction, proximate and ultimate analyses, calorimetric analysis (HHV/LHV), scanning electron microscopy (SEM), Fourier transform infrared (FTIR), energy-dispersive spectroscopy (EDS), and inductively coupled plasma optical emission spectrometry (ICP-OES), were also applied to characterize them. The TG/DTG curves identified the main thermal degradation stages of the lignocellulosic materials, which correspond to average contents of hemicellulose (49.1%), cellulose (31.7%), lignin (16.2%), moisture (10.0%), ash (6.3%), volatile materials (68.0%), and fixed carbon (16.0%). X-rays showed a crystallinity index for the biomasses between 53.0 and 60.0%, confirming crystalline and amorphous regions. Metal composition determination by ICP-OES identified the main metallic and inorganic materials (K, Ca, Al, and Fe) present in the samples. SEM images revealed some morphological and structural differences, for example pores, roughness, fibers, and lamellae. FTIR was used mainly to evaluate the presence of energy bands or oxygen, carbon, and hydrogen bonds, confirming the data obtained by the ultimate analysis. EDS identified the behavior of the main organic and inorganic elements. All the results presented demonstrate the importance of this research and its application to science.