Abstract

PINEROS-CASTRO, Yineth et al. Production of fermentables sugars by enzymatic hydrolysis of steam-exploded rice husks. Rev. ion [online]. 2011, vol.24, n.2, pp.23-28. ISSN 0120-100X.

One of the alternatives proposed as sustainable option for exploiting lignocellulosic materials is their conversion to fermentable sugars to produce feedstock for ethanol. Rice Industry in Colombia generates 400000 tons per year of rice husks, a high availability and low cost material which basic is composed by lignin, cellulose and hemicellulose; resulting in an adequate substrate for sugar conversion. However, this feedstock must be pretreated in order to improve the sugar fermentation process by modifying its complex structure. One effective method is the steaming explosion, which is carried out through exposing the lignocellulosic material to steam at fixed temperature between 190-230°C. After a specific steaming time the substrate undergoes sudden decompression forcing the disintegration and partial destruction of the lignin-carbohydrate bonds; resulting in a new material where the exposure of cellulose to enzymatic hydrolysis is higher. The same treatment has been applied using acid catalysts (sulfuric acid) resulting in higher yields during the enzymatic hydrolysis. The last technology has not been evaluated on rice husk; this work steaming explosion process applied at 190°C (10 y 25 min) to rice husks impregnated with both water and 0.5% v sulfuric acid. The results show partial solubilization of hemicellulose and clear degradation of the material structure, reflected in an increased sugars production by the enzymatic hydrolysis. A maximum glucose yield for pretreatment and enzymatic hydrolysis of 14,98% w was achieved (0.5% v H₂SO₄, 25 minutos, 190°C), a considerable superior value than 0.7% w obtained for the untreated material.

Keywords : fermentable sugars; lignocellulosic materials; biomass exploitation; rice.

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