Acid hydrolysis of wheat straw: A kinetic study

Biotechnological xylitol production can be enhanced if the needed xylose solutions can be obtained from hydrolysis of low-cost lignocellulosic wastes. The hydrolysis of wheat straw to obtain xylose solutions has a double consequence, the elimination of a waste and the generation of a value-added product. The objective of this work was to study the xylose production from wheat straw by sulphuric acid hydrolysis at 130 °C. Several mass fraction of acid (1, 2, 3, 4 or 5%) were evaluated. Kinetic models were developed to explain the variation with time of xylose, glucose, arabinose, furfural, 5-(hydroxymethyl)-2-furaldehyde and acetic acid in the hydrolysates. Optimal conditions found were a H2SO4 mass fraction of 2% at 130 °C for 29 min, which yielded a solution with xylose, 18.9 kg m−3; glucose, 3.5 kg m−3; arabinose, 3.1 kg m−3; furfural, 0.6 kg m−3; 5-(hydroxymethyl)-2-furaldehyde, 0.3 kg m−3 and acetic acid, 2.3 kg m−3. In these conditions, 99% of the hemicelluloses and 11% of the glucan were hydrolysed.