A study of the formation and elimination of chromophores in wood under mechanical pulping conditions using spectroscopy

作者：Logenius Louise^*; Agnemo Roland; Hoglund Hans

来源：Paperi Ja Puu-Paper and Timber, 2010, 92(5): 35-39.

• Light scattering coefficient
• Light absorption coefficient
• Brightness
• Wood shaving
• Chromophore

Thin sections of wood, i.e., shavings, were used in spectroscopic measurements studying the formation and elimination of chromophores under mechanical pulping conditions. Light absorption coefficients, light scattering coefficients, and brightness were monitored.
The method was applied to study how temperature in the absence of mechanical energy affects wood brightness. An increase in absorption coefficient at 420 nm indicates formation of ortho-quinone structures. By applying mechanical pulp processing conditions, the light absorption coefficient increased in the 400-500-nm wavelength region, probably due to the formation of chromophores in the lignin. Comparison of heat treated wood shavings with mechanical pulps indicated that additional chromophores were created during the mechanical pulping processes.
The method was also used in studying how high-temperature hydrogen peroxide bleaching of the wood shavings affects the light absorption coefficients. The light absorption spectra reveal information about chromophore elimination in wood chemical components during hydrogen peroxide bleaching at slightly pressurized conditions. This is relevant to processes, such as the alkaline peroxide mechanical pulp process, in which the wood chips are impregnated with bleaching chemicals before refining. The easy penetration of chemicals into the wood shavings ensures rapid and even distribution of the treatment chemicals. A change in light absorption coefficient at shorter wavelengths (400-500 nm) was observed.

• 出版日期2010