Abstract:

This work reports on the optimization of hydrolysis conditions of corn bran hemicellulose by a supported solid
acid catalyst, SO₄^2－/Fe₂O₃/γ-Al₂O₃. First of all, the one factor-at-a-time method was used to examine the effects of catalyst
dosage, hydrolysis temperature, time and material-to-solvent ratio on total sugar content and pentose yield. Subsequently,
optimization of the four reaction conditions was performed using response surface methodology based on Box-Behnken
experimental design. Results indicated that the optimal conditions for hydrolysis of corn bran hemicellulose were determined
as follows: catalyst amount, 12 mL/10 g corn bran; hydrolysis temperature, 120 ℃; hydrolysis time, 4 h; and solid-toliquid
ratio, 1:10. The maximum pentose yield of 22.45%, which was close to the predicted value, was obtained under these
conditions. Monosaccharide composition and contents of the hydrolysate, as analyzed by HPLC, showed that the relative
contents of three main monosaccharides were glucose 4.99%, xylose 34.78%, and arabinose 55.90%, respectively. Infrared
(IR) spectra of corn bran and its hydrolysis residues showed that the structure of xylose and arabinose changed, indicating
that hemicellulose is degraded.

Key words: corn bran, hemicellulose, hydrolysis, solid acid catalyst, response surface methodology