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Dissolution of Pinus radiata and Eucalyptus globulus woods in ionic liquids under microwave radiation: Lignin regeneration and characterization

2012; Elsevier BV; Volume: 97; Linguagem: Inglês

10.1016/j.seppur.2011.12.032

1873-3794

Ana Casas, Mercedes Oliet, M. Virginia Alonso, Francisco Rodrı́guez,

Enzyme-mediated dye degradation

Lignin is a renewable bioresource with a variety of applications. The development of green processes for wood dissolution and lignin regeneration would be really useful in the context of biorefinery and biomass efficient employment. Ionic liquids offer an interesting alternative in this regard. In this paper, regeneration of lignin from Pinus radiata and Eucalyptus globulus woods dissolved in imidazolium-based ionic liquids was studied. Microwave radiation was employed as thermal source in order to decrease the wood dissolution time. Several ionic liquids were used for wood dissolution: 1-butyl-3-methylimidazolium acetate (BmimAc), 1-ethyl-3-methylimidazolium acetate (EmimAc), 1-ethyl-3-methylimidazolium chloride (EmimCl), 1-butyl-3-methylimidazolium chloride (BmimCl) and 1-allyl-3-methylimidazolium chloride (AmimCl). All the ionic liquids were able to dissolve wood. Furthermore, lignin was successfully regenerated by precipitation with an antisolvent from solutions of wood in AmimCl, BmimCl or EmimCl. Regenerated lignin, characterized by Fourier transform infrared spectroscopy, 13C nuclear magnetic resonance, elemental analysis, thermogravimetric analysis, and differential scanning calorimetry, was compared to Indulin AT lignin, and showed different properties depending on the ionic liquid employed and the wood species.