title: Structural variation of eucalyptus lignin in a combination of hydrothermal and alkali treatments.
abstract: In this work, the structural features of the lignin isolated with 2% NaOH at 90°C for 2.5h from the hydrothermally pretreated eucalyptus fibers at different temperatures (100-200°C) for different times (15-60min) were thoroughly investigated. Results showed that the hydrothermal pretreatment facilitated the separation of alkali lignin from the pretreated fibers. It was found that the linkages of β-O-4, β-β, and β-5 decreased gradually with the increase of hydrothermal severity. Furthermore, decreased molecular weights (1630-510g/mol), associated carbohydrates contents (1.99-0.05%) and aliphatic OH contents (3.37-0.65mmol/g), and increased phenolic OH contents (0.71-2.98mmol/g) and thermal stability of the alkali lignins were observed with the increase of the hydrothermal severity.
authors.affiliation: Beijing Key Laboratory of Lignocellulosic Chemistry, Beijing Forestry University, Beijing 100083, China.
authors.forename: Shao-Ni
authors.initials: SN
authors.lastname: Sun
authors.affiliation: Beijing Key Laboratory of Lignocellulosic Chemistry, Beijing Forestry University, Beijing 100083, China.
authors.forename: Han-Yin
authors.initials: HY
authors.lastname: Li
authors.affiliation: State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou 510640, China. Electronic address: yifanfeixiang@163.com.
authors.forename: Xue-Fei
authors.initials: XF
authors.lastname: Cao
authors.affiliation: Beijing Key Laboratory of Lignocellulosic Chemistry, Beijing Forestry University, Beijing 100083, China.
authors.forename: Feng
authors.initials: F
authors.lastname: Xu
authors.affiliation: Beijing Key Laboratory of Lignocellulosic Chemistry, Beijing Forestry University, Beijing 100083, China. Electronic address: rcsun3@bjfu.edu.cn.
authors.forename: Run-Cang
authors.initials: RC
authors.lastname: Sun
mesh_terms: D000468:Alkalies / Q000737:chemistry; D005591:Chemical Fractionation; D002850:Chromatography, Gel; D005052:Eucalyptus / Q000737:chemistry*; D008031:Lignin / Q000737:chemistry*; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature; D013818:Thermogravimetry
chemical_list: D000468:Alkalies; D008031:Lignin
keywords: Alkali treatment; Eucalyptus fibers; Hydrothermal pretreatment; Lignin; Structure