title: Using confocal Raman microscopy to real-time monitor poplar cell wall swelling and dissolution during ionic liquid pretreatment.
abstract: The ionic liquids (ILs) are recognized as the potential solvents for the pretreatment of lignocellulosic materials before biomass conversion. However, little knowledge of how the cell wall of biomass responds to the IL locally and dynamically during the pretreatment is available. In the current work, the process of IL pretreatment of poplar using 1-ethyl-3-methylimidazolium acetate ([C2 mim][OAc]) was real-time monitored on a cellular level by employing confocal Raman microscopy. The results showed that the biomass dissolution during the IL pretreatment can be clearly divided into two stages: (1) slow penetration of IL, and (2) rapid dissolution of lignin and carbohydrates. In this case, the onset of the dissolution of these compositions occurred only after the cell wall of biomass swelled to a certain extent. Because the first stage was a slow process which determined the process reaction rate, it can be deduced that enhancing the penetration capacity of IL was crucial for improving the pretreatment efficiency. Based on the obtained results, a model was proposed to better understand how the plant cell wall responds to the IL before, during, and after pretreatment.
authors.affiliation: Beijing Key Laboratory of Lignocellulosic Chemistry, Beijing Forestry University, Beijing, 100083, China.
authors.forename: Xun
authors.initials: X
authors.lastname: Zhang
authors.forename: Jing
authors.initials: J
authors.lastname: Ma
authors.forename: Zhe
authors.initials: Z
authors.lastname: Ji
authors.forename: Gui-Hua
authors.initials: GH
authors.lastname: Yang
authors.forename: Xia
authors.initials: X
authors.lastname: Zhou
authors.forename: Feng
authors.initials: F
authors.lastname: Xu
mesh_terms: D018533:Biomass; D002473:Cell Wall / Q000187:drug effects* / Q000648:ultrastructure; D007093:Imidazoles / Q000494:pharmacology*; D052578:Ionic Liquids / Q000494:pharmacology*; D008031:Lignin / Q000737:chemistry; D032107:Populus / Q000187:drug effects* / Q000648:ultrastructure; D012995:Solubility; D013059:Spectrum Analysis, Raman / Q000379:methods*; D013997:Time Factors
chemical_list: D007093:Imidazoles; D052578:Ionic Liquids; C036909:lignocellulose; D008031:Lignin; C518739:1-ethyl-3-methylimidazolium
keywords: confocal Raman microscopy; ionic liquid; plant cell wall; poplar; pretreatment