Acid hydrolysis of olive-pruning debris for D-xylose production

Selective hydrolysis of the hemicellulose fraction of olive-pruning debris was attempted in order to achieve a maximum yield of fermentable D-xylose without degrading the cellulose fraction. To this end, hydrolysis with a dilute acid was conducted in a heterogeneous stirred tank reactor at mild temperature (70-90 degrees C) and sulfuric acid concentration (0.0-0.5 mol l(-1)) for 300 min. Temperature was the determining factor in sugar formation and fiber conversion. The highest hemicellulose and cellulose conversion at 90 degrees C were 92.9 and 16.0%, respectively. From 100 g of the raw material, 35.8 g of sugars were recovered. At this temperature, using 0.5 M H2SO4 for 4.5 h, D-glucose and D-xylose yields of 13.1 and 10.4%, respectively, were obtained.