Journal of South China University of Technology(Natural Science Edition) ›› 2019, Vol. 47 ›› Issue (5): 18-24,31.doi: 10.12141/j.issn.1000-565X.180253

• Chemistry & Chemical Engineering • Previous Articles     Next Articles

Dissolution Mechanism of Wheat Straw Alkaline Lignin in Alkaline Ionic Liquid ［Bmim］［OH］

 HOU Yi ZHANG Xiao LIU Chao LI Youming   

  1.  State Key Laboratory of Pulp and Paper Engineering，South China University of Technology，Guangzhou 510640，Guangdong，China
  • Received:2018-05-31 Revised:2018-10-22 Online:2019-05-25 Published:2019-04-01
  • Contact: 李友明( 1957-) ，男，教授，博士生导师，主要从事制浆造纸清洁生产技术、造纸化学品等的研究 E-mail:ymli3@scut.edu.cn
  • About author:侯轶( 1973-) ，女，教授，博士生导师，主要从事工业废水处理、烟草薄片生产过程控制、生物质结构分析等的研 究．
  • Supported by:
     Supported by the National Key Scientific and Technological Project( 2017YFB0307901) ，the National Natural Science Foundation of China( 21476091) and the Science and Technology Planning Project of Guangdong Province( 2015A020215009)

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Abstract: This paper deals with the structure variation of wheat straw alkali lignin in alkaline ionic liquid ［Bmim］ ［OH］and the dissolution mechanism of alkali lignin． The dissolution was assisted by microwave heating with a microwave power of 500 W，a temperature of 90 ℃，a reaction period of 30 min and a solid-to-liquid ratio of 1∶10． By using ［Bmim］ ［OH］ionic liquid as a solvent，the lignin dissolution process was characterized and analyzed by means of FT-IR，GPC，elemental analysis，2D HSQC NMR and Py-GC-MS． The results indicate that，during the dissolution of alkali lignin in ionic liquid ［Bmim］［OH］，the aromatic rings remains stable and there mainly occurs the substitution of the side chain or the removal of oxygen-containing groups; and that，after the dissolution，the relative molecular mass of the regenerated lignin slightly decreases，the molecular mass distribution become more uniform and the degree of unsaturation increases due to the dehydration reaction during the dissolution processes． Moreover，2D HSQC NMR and Py-GC-MS results prove that there mainly happens the cleavage of β-O-4' aryl ether linkages during the dissolution of lignin in strongly basic ionic liquid system，followed by β-β and β-5 structures，and the S /G ratio remarkably decreases． This research provides basic data and an approach to the development of relevant theories and the application of high-value alkali lignin

Key words: dissolutionalkaline lignin, alkaline ionic liquid, dissolution mechanism

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