Condensed lignin structures and re-localization achieved at high severities in autohydrolysis ofEucalyptus globuluswood and their relationship with cellulose accessibility

The objective of this study was to investigate structural changes and lignin redistribution in Eucalyptus globulus pre-treated by steam explosion under different degrees of severity (S0), in order to evaluate their effect on cellulose accessibility by enzymatic hydrolysis. Approximately 87.7% to 98.5% of original glucans were retained in the pre-treated material. Glucose yields after the enzymatic hydrolysis of pre-treated material improved from 19.4% to 85.1% when S0 was increased from 8.53 to 10.42. One of the main reasons for the increase in glucose yield was the redistribution of lignin as micro-particles were deposited on the surface and interior of the fibre cell wall. This information was confirmed by laser scanning confocal fluorescence and FT-IR imaging; these microscopic techniques show changes in the physical and chemical characteristics of pre-treated fibres. In addition, the results allowed the construction of an explanatory model for microscale understanding of the enzymatic accessibility mechanism in the pre-treated lignocellulose.

Download Full-text

Conversion of Lignocellulosic Biomass to Nanocellulose: Structure and Chemical Process

The Scientific World JOURNAL ◽

10.1155/2014/631013 ◽

2014 ◽

Vol 2014 ◽

pp. 1-20 ◽

Cited By ~ 141

Author(s):

H. V. Lee ◽

S. B. A. Hamid ◽

S. K. Zain

Keyword(s):

Molecular Structure ◽

Mechanical Properties ◽

Lignocellulosic Biomass ◽

Chemical Process ◽

Catalyst Design ◽

Natural Resistance ◽

Cellulose Crystallinity ◽

Biomass Recalcitrance ◽

Cellulose Accessibility ◽

High Cellulose

Lignocellulosic biomass is a complex biopolymer that is primary composed of cellulose, hemicellulose, and lignin. The presence of cellulose in biomass is able to depolymerise into nanodimension biomaterial, with exceptional mechanical properties for biocomposites, pharmaceutical carriers, and electronic substrate’s application. However, the entangled biomass ultrastructure consists of inherent properties, such as strong lignin layers, low cellulose accessibility to chemicals, and high cellulose crystallinity, which inhibit the digestibility of the biomass for cellulose extraction. This situation offers both challenges and promises for the biomass biorefinery development to utilize the cellulose from lignocellulosic biomass. Thus, multistep biorefinery processes are necessary to ensure the deconstruction of noncellulosic content in lignocellulosic biomass, while maintaining cellulose product for further hydrolysis into nanocellulose material. In this review, we discuss the molecular structure basis for biomass recalcitrance, reengineering process of lignocellulosic biomass into nanocellulose via chemical, and novel catalytic approaches. Furthermore, review on catalyst design to overcome key barriers regarding the natural resistance of biomass will be presented herein.

Download Full-text