Separation and recovery of cellulose and lignin using ionic liquids: a process for recovery from paper-based waste

摘要

BACKGROUND: The production of paper makes use of cellulose and lignin as a raw material, and almost all cellulose and ligninproduction comes from raw wood materials, contributing to deforestation and resulting in potential environmental harm. It istherefore beneficial to develop technologies for cellulose and lignin recovery for re-use and sustainability of resources. RESULTS: Three imidazolium based ionic liquids (ILs), 1-(2-cyanoethyl)-3-methylimidazolium bromide (cyanoMIMBr), 1-propy1-3-methylimidazolium bromide (propylMlMBr) and 1-butyl-3-methylimidazolium chloride (butylMIMCI), were synthesised bymicrowave technology and fully characterised by mass spectrometry, thermogravimetric differential scanning calorimetry, thinlayer chromatography, nuclear magnetic resonance and Fourier transform infrared spectroscopies. Cellulose and lignin weresoluble in all three ILs with solubility being greatest in cyanoMlMBr. Regeneration of cellulose and lignin was achieved fromsaturated solutions of cellulose in IL and lignin in IL for all three ILs. The ILs propylMlMBr and butylMIMBr have been used forthe first time in the separation and recovery of cellulose and lignin and regeneration of the IL from a mixture of cellulose andlignin in IL. FTIR analysis confirms successful recovery. CONCLUSIONS: This work demonstrates the ability of ILs to separate and recover cellulose and lignin from a mixed system.