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Catalytic Degradation of Alkali Lignin by Laccase Mediator System and Its Structural Evolution Studies
Received:January 12, 2024  Revised:February 05, 2024
DOI:10.11981/j.issn.1000-6842.2024.02.44
Key Words:alkali lignin;laccase;mediator;degradation
Fund Project:广东省基础与应用基础研究基金(2022A1515012584,2022A1515110640);广东省科学院专项资金(2022GDASZH-2022010105)。
Author NameAffiliationPostcode
CUI Dingkai College of Light and Chemical Engineering, Guangdong University of Technology, Guangzhou, Guangdong Province, 510006 510006
YI Guobin College of Light and Chemical Engineering, Guangdong University of Technology, Guangzhou, Guangdong Province, 510006 510006
YE Dawei Institute of Chemical Engineering, Guangdong Academy of Sciences, Guangzhou, Guangdong Province, 510665 510665
ZHU Guozhi Institute of Chemical Engineering, Guangdong Academy of Sciences, Guangzhou, Guangdong Province, 510665 510665
XIAO Ying* Institute of Chemical Engineering, Guangdong Academy of Sciences, Guangzhou, Guangdong Province, 510665 510665
CHEN Jiazhi* Institute of Chemical Engineering, Guangdong Academy of Sciences, Guangzhou, Guangdong Province, 510665 510665
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Abstract:
      Laccase-mediator system (LMS), which uses the mediator as an electron shuttle, has been widely used in the degradation of environmental pollutants because of its higher catalytic efficiency for substrates. This study systematically investigated the degradation effects of laccase and laccase/H2O2, laccase/HBT (1-hydroxybenzotriazole) and laccase/ABTS (2,2’-bisazobis (3-ethylbenzothiazolin-6-sulfonic acid) diammonium salt) on alkali lignin, and explored the influencing factors of laccase/ABTS mediator system on degradation of alkali lignin. The structural characterization of alkali lignin before and after the reaction with laccase and the three LMS was also analyzed. The results showed that the highest degradation rate of alkali lignin was achieved by the laccase/ABTS mediator system, which could reach 39% under the reaction conditions at 32 ℃ for 24 h with pH valve of 5, and ABTS concentration of 2 mmol/L. The types of functional groups of alkali lignin obtained from the laccase treatment remained unchanged, but the polydispersity coefficient was decreased and the molecular mass was increased; and the polydispersity coefficient and the molecular mass of alkali lignin obtained from the LMS treatment were further decreased, especially the polydispersity coefficient and the molecular mass of alkali lignin obtained from the LMS treatment. In particular, the number average molecular weight of alkali lignin was reduced by 50.5% after laccase/ABTS treatment; the chemical bonds of alkali lignin were broken to different degrees after LMS treatment, which induced changes such as C—O and β-O-4 linkage breaking, demethylation reaction, and benzene ring-opening.
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