FTIR analysis of lignin regenerated from Pinus radiata and Eucalyptus globulus woods dissolved in imidazolium-based ionic liquids

BACKGROUND: The dissolution of wood and the regeneration of compounds such as cellulose and lignin is one of the challenges currently facing biorefineries. Lignin can be processed and employed for value-added products; therefore, environmentally friendly methods for wood solubilization and lignin regeneration are required and ionic liquids (ILs) offer an attractive alternative approach. RESULTS: Dissolution of Pinus radiata and Eucalyptus globulus woods in imidazolium-based ILs ( 1-butyl-3-methylimidazolium acetate, 1-ethyl-3-methylimidazolium acetate and 1-ethyl-3-methylimidazolium chloride) was studied as well as the regeneration of lignin from wood liquors. The dissolution of wood in ILs was verified using an optical microscope to select the most appropriate ILs and the best experimental time and temperature conditions. Ligninwas regenerated fromwood dissolved in 1-ethyl-3-methylimidazolium chloride after 24 h at 150. C by precipitation with an antisolvent. The regenerated solid was analyzed by Fourier transform infrared spectroscopy and compared with Indulin AT ( reference). Furthermore, the influence of the wood dissolution time, the antisolvent employed and the antisolvent/ wood solution ratio in the lignin recovery was studied. CONCLUSIONS: The current study shows that 1-ethyl-3-methylimidazolium chloride can be employed effectively to dissolve wood at 150. C for 24 h and lignin can be regenerated using methanol or ethanol as antisolvents. (C) 2012 Society of Chemical Industry