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

Thermal degradation of açaí seeds and potential application in thermochemical processes

“…On the other hand, higher levels of oxygen (O) present in the samples reduce the HHV of a biofuel, mainly due to the enthalpy values of the bonds, since a high energy is necessary to occur break in the bonds formed by oxygen atoms (Braz, 2014). Despite the high oxygen content (47.42%), the açaí seeds presented a high HHV value, slightly higher than that found by Cruz et al (2021) and Cruz et al (2018) for the cassava leaves (18.86 MJ kg -1 ) and sugarcane bagasse (17.47 MJ kg -1 ), respectively. It is worth mentioning that this latter biomass is widely used for the electric energy generation in biorefineries, a factor that corroborates with the use of açaí seeds can be applied in thermochemical conversion processes for the of clean energy generation.…”

“…The crystallinity index (CI) for açaí seeds was calculated by Equation 2, which presented a value of 23%, and is slightly lower than that found by Rambo, Schmidt and Ferreira (2015) for the açaí seeds (30%), indicating that the açaí seeds studied presented around 77% of amorphous regions in their structural composition. It is a biomass with low crystallinity when compared with other biomasses studied by other authors, for instance, tucumã seed (CI = 57.4%), sugarcane bagasse (CI = 64.8%) (Cruz et al, 2018) and the cassava stem (CI = 60.2%) (Cruz et al, 2021). Biomasses with characteristics amorphous are more reactive when compared to crystalline ones, since the absence of crystalline agglomerates makes these lignocellulosic materials more susceptible to complex reactions of thermal degradation (Silva et al, 2019), or are easier to be accessed by chemical treatments or biological factors (Cruz et al, 2018).…”

“…By means of the ultimate analysis (Table 1), and based on the levels of carbon, hydrogen, oxygen, nitrogen and sulfur were obtained, the chemical formula for the açaí seeds was constructed, i.e., dividing the quantified percentage of each element (C, H, O, N, S) by the respective atomic weights (Cruz et al, 2021). From the chemical formula (C3.89H5.18N0.05O2.96) obtained for this lignocellulosic compound, it is possible to predict the yield of the complex chemical reactions during thermal decomposition and also estimate the gaseous emissions of these materials when subjected to thermochemical processes (Braz, 2014).…”

“…The residues of the açaí fruits presented nitrogen as a minor component, i.e., 0.68%. Lower values of this element are suitable for the combustion process, since nitrogen in high quantities can react with oxygen in the atmospheric air, forming NOx (90% NO, 10% NO2 and N2O in minority), gases responsible for the occurrence of acid rain and problems of corrosion in industrial equipments (Cruz et al, 2021).…”

“…The volatile materials content for a determined biomass depend on its nature and are in the range from 75 to 90% (Cruz et al, 2021). The volatile material content is used to determine the ignition easily and burning of solid fuels.…”