Deep Insights into the Atmospheric Sodium Hydroxide–Hydrogen Peroxide Extraction Process of Hemicellulose in Bagasse Pith: Technical Uncertainty, Dissolution Kinetics Behavior, and Mechanism

The alkali dissolution characteristics and mechanism of hemicellulose in bagasse pith have been deeply analyzed. First, the technical uncertainty of alkali-extraction and ethanol-separation process has been evaluated. The results showed that the effect of extraction process byproducts (i.e., lignin, ash, etc.) could be neglected and directly using an ethanol precipitation technique without preneutralization for separation of hemicellulose in lye is reasonable. The kinetic behavior test showed that there exists an optimal alkali concentration (∼100 g/L) to maximize the extraction yield of hemicellulose, attributing to the ratio of the hydrodynamic diameter of hydrates and the intersheet distance of cellulosic microfibers. The activation energy of 22.19 kJ/mol indicated that the time-dependent dissolution process of hemicellulose could be mainly attributed to a diffusion-controlled process. The developed model has been proved to be effective for prediction of hemicellulose concentration in the process-lye of atmospheric NaOH–H2O2 extraction of a bagasse pith under the experimental conditions studied.