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

FT-Raman, FT-infrared and NIR spectroscopic characterization of oxygen-delignified kraft pulp treated with hydrogen peroxide under acidic and alkaline conditions

“…Water desorption was carried out at room temperature for two weeks. Next, normal pressure in the desiccator was restored, by introducing dry air from the washer filled with D 2 O [11]. After two days, the pulp samples were placed into another desiccator for two weeks, above D 2 O at room temperature (100% RH).…”

“…4) [37]. Consequently, the studied pulp samples, having no more than 2.2% of lignin-originating structures, could not be analyzed with the same efficiency as the lignin-rich mechanical pulps [10,11]. As shown in Fig.…”

“…The enhancement of peroxide delignifying efficiency may be attained by the use of an acidic medium at the preliminary bleaching stage [5]. The two-stage hydrogen peroxide treatment under acidic and then alkaline conditions may be beneficial both as regards the peroxide consumption and the final pulp brightness [6][7][8][9][10][11]. Hydrogen peroxide is relatively stable under acidic conditions; therefore, transition metal catalysts are used for its activation [12].…”

“…While much has been done to elucidate the chemistry and technological effects of the two-stage hydrogen peroxide bleaching of mechanical pulps [6,7,[9][10][11][12], little attention has been given to chemical pulps [5]. There is a lack of information concerning the influence of acidic and alkaline conditions of the peroxide bleaching on the chemical pulp components, especially on lignin and its chromophores.…”

Process intensification effect of ball milling on the hydrothermal pretreatment for corn straw enzymolysis

“…Dilute acid pretreatment method is an efficient chemical method for cellulosic biomass [13], but, its major disadvantage is the concomitants of sugar degradation products like hydroxymethyl furfural (HMF) and furfural (FF), which are toxic for enzymolysis process [14]. Hydrogen peroxide has been reported to be efficient reagent for the removing or degrading lignin and hemicellulose [15], because of its effect with the hydrogen bond and relatively stability in acidic medium [16]. It contributes to destroy the crystal structure of cellulose and disrupt the force among three components.…”