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Pretreatment is the main step that must be performed in order to isolate the cellulose, hemicellulose, and lignin contained in the lignocellulosic biomass. The objective of this study was to recover cellulose from pearl millet biomass through chemical (alkali and acid), physical (vapor explosion and size reduction) and combined treatments. The cellulosic fraction was characterized by Fourier transform spectroscopy (FTIR-ATR), X-ray diffraction (XRD), and Raman spectroscopy. The cellulose-rich fraction presented 100% and 99.86% of lignin and hemicellulose removal, respectively, and a high crystallinity index of 82.43% after two 4-hour alkaline extractions with 4% NaOH followed by 2 hours extraction with C2H2O4 5% in autoclave at a temperature of 125.6°C and 1.4 bar. Based on the analysis of FTIR-ATR, XRD, and Raman spectroscopy, it was possible to confirm the removal of hemicellulose and lignin from pearl millet biomass, highlighting the efficiency of the treatments evaluated in the process of solubilization of these compounds. The results presented in this study should contribute to improve the efficiency of the fractionation processes of lignocellulosic biomasses. |
