Pretreatment of Lignocellulosic Materials

Bioprvcessing cf Renewable Resources to Commodity Bioproducts, First Edition. Edited by Virendia S. Bisaria and Aldhiko Kondo. 

Lignocellulosic materials are composed of a variety of macromolecules, including cellulose, hemicelluloses, lignin, pectin, and minor amounts of inorganics. These materials represent a major fraction of agricultural residues, wood residues, and several waste streams from municipalities and companies (Taherzadeh and Karimi, 

Due to the complex structure of lignocelluloses, the release of fermentable sugars is a hurdle for the industrialization of this renewable resource (Zhao et al., 2012a). The complex structure of plants functions as protection against microbial and enzymatic attacks and is called biomass recalcitrance (Himmel and Picataggio, 

Understanding the chemistry and the morphological construction of biomass has a huge impact on the current pretreatment processes. Developing a deeper knowledge and more efficient technologies may be of great importance for future use. This 

TABLE 3.1 Average Composition of Different Lignocellulosic Materials 

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Several definitive reviews on pretreatment of lignocellulosic materials for improving cellulose hydrolysis (1,2,3) appeared a few years ago. More recently, two pretreatment methods (the Purdue process and the Iotech process) have been announced that claim superior perform-... 

The purposes of pretreatment of lignocellulosic materials are the removal of lignin and hemicellulose, reduction of cellulose crystallinity, and increase in the porosity of the materials. Among the physical methods, mechanical treatments, such as chipping, grinding and milling are used to reduce cellulose crystallinity. The... 

Acid hydrolysis has been successfully employed for pretreatment of lignocellulosic materials. Dilute sulfuric acid, used at either low or high temperature, achieves high xylan to xylose conversion. This is favorable to the overall economics, as xylan accounts for a large part of the total carbohydrates in the lignocellulosic materials. 

Galbe M, Zacchi G. (2007). Pretreatment of lignocellulosic materials for efficient bioethanol production. Biofuels, 108, 41-65. 

Brownell HH, Saddler JN. (1987). Steam pretreatment of lignocellulosic material for enhanced enzymatic hydrolysis. Biotechnol Bioeng, 29(2), 228-235. 

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