Isolation and Characterization of Organosolv Lignins From Wheat Straw


  • Run-Cang Sun
  • J. Mark Lawther
  • W. B. Banks


Wheat straw, organosolv lignin, phenolic acids and aldehydes, alkaline nitrobenzene oxidation, molecular weight, polysaccharides, Fourier transform infrared spectra


Delignification of wheat straw with aqueous methanol, ethanol, l-propanol, n-butanol, dioxane, and acetone in the presence of acid catalyst (0.02 N H2SO4) at low temperature (75°C) for 2 h was studied. The effect of ethanol-water ratios on the yield of dissolved lignin is also reported here. There was no significant difference in the organosolv lignin yields among the various organic solvents used, which accounted for 24-28% of the total amount of acidic chlorite lignin present in wheat straw. Increase of ethanol-water volume ratio from 40/60 to 70/30 resulted in raising lignin yields from 25 to 31%, while the reverse yield from 31 to 24% appeared in the increase of volume ratio from 70/30 to 90/10. The isolated organosolv lignin fractions contained low amounts of polysaccharide sugars (4.5-5.3%) and had low average molecular weights (1190-1650 Da), which corresponded with the ball-milling lignin, enzyme lignin, and alkali lignin obtained from wheat straw. The predominant components of the alkali nitrobenzene oxidation products were found to be vanillin and syringaldehyde. The yield of vanillin was slightly higher than that of syringaldehyde in all the nitrobenzene oxidation products of the isolated organosolv lignin preparations.


Ahmad, M., and L. Khan. 1988. Spectroscopic studies of lignins from wheat straw and kai grass. J. Chem. Soc. Pak. 10:299-302.nButa, J. G., F. Zadrazil, and G. C. Galletti. 1989. FTIR determination of lignin degradation in wheat straw by white rot fungus Stropharia rugosoannulata with different oxygen concentrations. J. Agric. Food Chem. 37:1382-1384.nGoyal, G. C., J. H. Lora, and E. K. Pye. 1992. Auto-catalyzed organosolv pulping of hardwoods: Effect of pulping conditions on pulp properties and characteristics of soluble and residual lignin. Tappi 75:110-116.nLawther, J. M., R.-C. Sun, and W. B. Banks. 1995. Extraction, fractionation, and characterization of structural polysaccharides from wheat straw. J. Agric. Food Chem. 43(3):667-675.nLawther, J. M., R.-C. Sun, and W. B. Banks. 1996. Extraction and comparative characterization of ball-milled lignin LM, enzyme lignin LE, and alkali lignin LA from wheat straw. Cellulose Chem. Technol. 30:395-410.nLora, J. H., and S. Aziz. 1995. Organosolv pulping: A versatile approach to wood refining. Tappi 68:94-97.nMcdonough, T. J. 1993. The chemistry of organosolv delignification. Tappi 76:186-193.nOrth, G. O., Jr., and R. D. Orth. 1977. US. Patent 4, 017, 642 pp.nPaszner, L., and H. J. Cho. 1989. Organosolv pulping: Acidic catalysis options and their effect on fiber quality and delignification. Tappi 72:135-142.nSarkanen, K. V. 1980. Acid-catalyzed delignification of lignocellulosics in organic solvents. Prog. Biomass Conv. 2:127-145.nSarkanen, K. V., and L. H. Hoo. 1981. Kinetics of hydrolysis of erythro-guaiacylglycerol β-(2-methoxyphenyl) ether and its veratryl analogue using HC1 and aluminum chloride as catalysts. J. Wood Chem. Technol. 1:11-27.nScalbert, A., and B. Monties. 1986. Composition of wheat straw lignin preparations. Holzforschung 40:249-254.nScalbert, A., B. Monties, E. Guittet, and J. Y. Lallemand. 1986. Comparison of wheat straw lignin preparations I. Chemical and spectroscopic characterizations. Holzforschung 40:119-129.nSelvam, P. V. P., T. K. Ghose, and P. Ghosh. 1983. Catalytic solvent delignification of agricultural residues: Inorganic catalysts. Proc. Biochem. 13:13-15.nSun, R.-C., J. M. Lawther, and W. B. Banks. 1995. Influence of alkaline pre-treatments on the cell wall components of wheat straw. Indust. Crops Prod. 4:127-145.nSun, R.-C., J. M. Lawther, and W. B. Banks. 1996. Effects of pre-treatment time and different alkalis on the composition of alkali-soluble wheat straw lignin. J. Agric. Food Chem. 44:3965-3970.nTirtowidjojo, S., K. V. Sarkanen, F. Pla, and J. L. Mccarthy. 1988. Kinetics of organosolv delignification in batch- and flow-through reaction. Holzforschung 42:177-183.nVázquez-Torres, H., G., Canché-escamilla, and C. A. Cruz-Ramos. 1992. Coconut husk lignin. 1. Extraction and characterization. J. Appl. Polym. Sci. 45:633-644.n






Research Contributions