Chromophoric Effects of the Undissolved Lignin with Na_2SO_3 Treatment
Li You-ming; Chen Zhong-hao(South China University of Technology, 510641)
Milled wood lignin(MWL) was treated with Na2SO3, the undissolved portion, known as the treatedundissolved lignin(TUL) is analogous to the lignin in chemi-mechanical pulp. The chromophores of the TUL and their chromophoric effect were then quantified. Na2SO3 treatment brought about increases in the contents of O-quinone, catechol and conjugated carbonyls in the lignin. This was the reason for the deep coloration of the TUL. The O-quinone structure was the primary source for the coloring. It made a color contribution trom 49% to 75% to the TUL. About 33% of the coloration of the TUL came from the catechol structure complexing with ferric ions, and less than 10% from the conjugated carbonyle. The TUL had more residual color contribution than the MWL, this was caused by unknown chromophoric structures in the TUL.
【CateGory Index】： TS74