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Investigation on the Lignin Removal From Tobacco Stem by a Solvothermal Method Using Ethylene Glycol as a Solvent

Summary High lignin content of tobacco stem has been addressed as a drawback for its utilization on manufacture of reconstituted tobacco sheet. Therefore, the solvothermal method using ethylene glycol was investigated for the removal of lignin from tobacco stem. It was found that the removal efficiency of ethylene glycol on tobacco stem is much lower than that achieved on wheat straw and corncob, i.e., 13.9% vs. 39.3% and 44.1%, respectively. This can be rationalized in terms of the presence of solanesol in tobacco stem, which retards the strong hydrogen bond interaction between ethylene glycol and the free hydroxyl groups present in lignin. When solanesol was eliminated by applying an n-hexane extraction procedure, 40.5% of lignin was successfully dissolved from tobacco stem. The successful removal of lignin was further confirmed by the characterizing results of SEM, FT-IR and N2-sorption. The developed method provides a promising way to attenuate the negative effects of lignin on utilization of the otherwise wasted tobacco stem for production of reconstituted tobacco sheet.