Title
Investigating the lignocellulosic composition during delignification using Confocal Raman spectroscopy Cross- Polarization Magic Angle Spinning Carbon 13 - Nuclear Magnetic Resonance (CP/MAS 13C-NMR) spectroscopy and atomic force microscopy
Authors
V. CHUNILALL T. BUSH and R. M. ERASMUS

Received November 21, 2011
Published Volume 46, Issue 3-4 March-April
Keywords atomic force microscopy, cellulose ‘aggregate’ area, cellulose crystallinity, confocal Raman spectroscopy,

Abstract
Changes in the lignocellulosic composition of four hardwoods, i.e. Eucalyptus grandis camaldulensis (E. gc), E. grandis urophylla (E. gu), E. dunnii and E. nitens, were investigated during different delignification processes using confocal Raman spectroscopy, Cross-Polarization Magic Angle Spinning Carbon 13 - Nuclear Magnetic Resonance (CP/MAS 13C-NMR) spectroscopy and Atomic Force Microscopy (AFM) in conjunction with image analysis. The confocal Raman results evidenced differences in the distribution of lignin between the middle lamella and the secondary cell wall layer for all clones and species investigated. The E. gc clone showed high levels of lignin in the secondary cell wall layer, compared to the E. gu clone, E. dunnii and E. nitens species. CP/MAS 13C-NMR spectroscopic results revealed an increase in cellulose crystallinity during chlorite delignification, acid bisulphite pulping and subsequent oxygen delignification, accompanied by an increase in the cellulose ‘aggregate’ area with a corresponding decrease in the ‘matrix’ area for each clone and species.