Assessing the Lignin Fraction Extracted from Brazilian Energy Crops

This study quantifies the extraction performance and some properties of the lignin obtained from six crops with potential for generating thermal energy in Brazil. A full factorial design (22) with four replicates including two extraction methods and two particles size distributions was adopted for assessing the fraction of lignin, as well as its Higher Heating Value (HHV) and composition given by the proximate and ultimate analysis. It was verified that in all cases the HHV of the lignin is greater than that obtained for the respective raw material, suggesting that these lignins could be also used as fuel in thermochemical processes. The ANOVA analysis showed that at 95% of confidence level the lignin yield is influenced by the extraction methods, which employ different pH values during the hydrolysis treatment. In addition, it was found that, in most cases, a smaller biomass particle size contributed to more effective lignin extraction. Response surfaces were also included in order to show tendencies of the lignin yield obtained for each raw material in function of the pH value used by the extraction method and the biomass particle size range.