Influence of variables in the hydrothermal treatment of rice straw on the composition of the resulting fractions.

The influence of the hydrothermal treatment conditions of rice straw (temperature--150-190 degrees C , time--0-20 min after reaching the operation temperature, and liquid/solid ratio--6-8), on the composition of liquid and solid fractions was studied. Polynomial models were found for to reproduce the experimental results with errors less than 6%. Operating to 190 degrees C, 15 min and 9 liquid/solid ratio was obtained high values of glucose (1.92 g/L), xylose (3.97 g/L), arabinose (0.99 g/L) and acetic acid (1.96 g/L), what allows to save capital when not operating with the maximum time and/or liquid/solid ratio; yield in the solid fraction is 88.1% and lignin content 24.43%. If what it is required to obtain good values of yield (96.46%) and lignin content, is necessary to operate to 150 degrees C, obtaining lower concentrations glucose (1.11%), xylose (2.78%), arabinose (0.56%) and acetic acid (0.39%). Ethanolamine pulping of solid fraction of hydrothermal treatment provides pulp with higher or similar properties to those obtained of pulping rice straw with ethanolamine or soda.