Changes in chromophoric composition of high-yield mechanical pulps due to hydrogen peroxide bleaching under acidic and alkaline conditions

The effects of bleaching of high-yield mechanical pulps (TMP, CTMP) with hydrogen peroxide under acidic and alkaline conditions were studied using different spectroscopic analytical methods. Diffuse reflectance laser flash photolysis (DRLFP) showed the differences in photochemical behavior reflecting transformation of chromophores upon treatment with acidic hydrogen peroxide. FT IR spectroscopic studies allowed to differentiate between the effects of the alkaline peroxide treatment with various stabilizing agents. FT-Raman technique provided additional information on localization of chemical changes after treatment under acidic and alkaline conditions, especially concerning the removal of coniferaldehyde-type groups.