Influence of Sequential Acid-alkali Treatment on Palm Biomass Waste Properties

Palm biomass (Archontophoenix alexandrae) is a natural crop of the food industry, even with a high potential to produce sustainable and innovative products. Thus, the purpose of this work was to evaluate the effect of sequential acid-alkali treatment followed by precipitation with concentrated H2SO4 on fiber's microstructure, chemical, and physical properties. So, the raw fiber, the pre-treated fiber, and the precipitated lignin were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, and thermogravimetric analysis (TGA). Results indicated changes in lignocellulosic structure by SEM analysis, which confirms the defibrillation due to the reduction of the average diameter and lengths of treated fiber compared to raw fiber (similar to 50%). FTIR and XRD also proved the partial removal of amorphous structures such as hemicellulose and lignin components, with changes in the intensity of absorption bands and the increase in the crystalline index after the sequential treatment (similar to 58%). TGA and DTG analysis provided evidence of an enhancement in treated fiber and lignin's thermal stability compared to raw fiber, confirming the adopted methodology's efficiency to isolate the main lignocellulosic structures and disrupting the biomass recalcitrance.