Deep insights into the atmospheric Sodium hydroxide-hydrogen peroxide
extraction process of hemicellulose in bagasse
Abstract
The alkali dissolution characteristics and mechanism of hemicellulose in
bagasse pith have been deeply analyzed. Firstly, the technical
uncertainty of alkali-extraction and ethanol-separation process has been
evaluated. The results showed that the effects of extraction process
by-products (i.e., lignin and ash, etc) could be neglected and directly
use ethanol precipitation without pre-neutralization for separation of
hemicellulose in lye is reasonable. The kinetic behavior test showed
that there exists an optimal alkali concentration
(~100g/L) to maximize the extraction yield of
hemicellulose, attributing to the ratio of 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.