Sulfuric acid hydrolysis of various lignocellulosic materials and its mixture in ethanol production

Abstract

Lignocellulosic materials sustainability in ethanol production could be supported by the use of mixed raw materials. Therefore the effect of mixed raw materials to hydrolysis kinetics needs to be studied. For this purpose each raw material was hydrolyzed and the mixed raw materials were also hydrolyzed. As a result, a comparison of the kinetics models of dilute sulfuric acid hydrolysis between various lignocellulosic materials (leaf, twig, corn cob, sawdust) and its mixture was obtained. It was observed that a pseudo-homogeneous model can quantitatively describe individual materials as well as mixed materials with different levels of accuracy. Besides the kinetics model, the influence of various lignocellulosic materials on sugar yield was also investigated. The results showed that the lignin content of the raw material influenced the sugar yield of the hydrolysis. Moreover the mixed lignocellulosic materials did not proportionally provide a yield based on its composition. Some hydrolyzates were fermented to verify whether the sugars formed could be converted into ethanol using Saccharomyces cerevisiae. The fermentation results showed that high sugar concentrations of hydrolyzates did not produce high ethanol yields. The various sugar types and the chemical substance of the sugar degradation affected the ethanol yield from sugars.

Keywords:

• dilute acid hydrolysis
• ethanol
• homogeneous kinetics model
• mixtures of materials
• various materials

Acknowledgement

This work was supported by Competence Research Grant by DIKTI 288/UN37.3.1/LT/2014.

Disclosure statement

No potential conflict of interest was reported by the authors.