Chem. J. Chinese Universities ›› 2013, Vol. 34 ›› Issue (1): 218.doi: 10.7503/cjcu20120354

• Polymer Chemistry • Previous Articles     Next Articles

Structure and Adsorption Characterization of Sodium Lignosulfonate by Laccase Modification

ZHOU Hai-Feng, YANG Dong-Jie, WU Xiao-Lei, QIU Xue-Qing   

  1. State Key Lab of Pulp and Paper Engineering, School of Chemistry and Chemical Engineering, South China University of Technology, Guangdong 510640, China
  • Received:2012-04-13 Published:2012-12-31

Abstract:

Sodium lignosulfonate(SL) was modified by commercial laccase and the structural characterization of SL by laccase modification was determined by the gel permeation chromatography(GPC), potentiometric titration, infrared spectroscopy(IR) and nuclear magnetic resonance(NMR). It suggests that the modification does not affect the content of sulfonic group and the surface charge. Laccase is able to promote both polymerization and depolymerization. In the beginning, some linkages broken and demethylation by laccase oxidation decrease the molecular weight(Mw) of SL, accompanied by the increase of the content of phenolic group. With the increase of the incubation time, the content of the phenolic group decreases and the Mw of SL increases, which indicates that the polymerization is predominant. The adsorption of SL by laccase modification was studied by electrostatic self-assembly technology. The results of UV-Vis spectra and atomic force microscopy(AFM) indicate that with laccase incubated for 2 h, the SL macromolecule is an ellipsoidal microgel form, which is helpful to adsorption process, so the adsorbed amount and root-mean-square(RMS) are largest. However, with laccase incubated for 36 h, the SL macromolecule shifts to a more spherical form, the stronger steric hindrance between SL macromolecule makes weaker adsorption.

Key words: Laccase, Sodium lignosulfonate, Molecular weight distribution, Structural characterization, Adsorption

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