Totally chlorine-free bleaching of prehydrolysis soda pulp from plantation hardwoods consisting of various lignin structures

Abstract

The process of prehydrolysis followed by soda-anthraquinone (AQ) cooking and totally chlorine-free (TCF) bleaching with peroxymonosulfuric acid (P sa ) was investigated to develop a biorefinery process. Eucalyptus globulus, showing a high syringaldehyde (S a ) to vanillin (V a ) molar ratio after nitrobenzene oxidation, was utilized. Xylooligosaccharide yield in the prehydrolysate (PHL) obtained at 150 °C for 2.5 h reached 7.2% of wood weight, indicating 47% extraction of xylan. Furfural yields increased with acid catalytic dehydration of the PHL to 1.0-1.8% of wood weight; adding an earlier acid post-hydrolysis of the PHL to generate monomeric xylose enhanced furfural production to 4.0%. Soda-AQ cooking, a non-sulfur process affording simpler alkali lignin isolation than kraft cooking, was utilized. Active alkali dosage increment decreased both S a to V a molar ratio (S/V ratio) and S a and V a yields of dissolved lignin. Gel permeation chromatography indicated decreased or increased purified lignin weight-average molecular weight (M w ) upon increased active alkali dosage or prehydrolysis temperature, respectively (e.g., 150 to 170 °C at 18% alkali increased M w 1653 to 2050). Chlorine dioxide (0.083% and 0.042% as active chlorine) inclusion during the 1st and 2nd P sa stages with P sa (0.2% and 0.1% as H 2 SO 5 weight, respectively) improved final bleached pulp viscosity from 6.0 to 7.2 mPa s.

Effects of Soluble Anthraquinone Application on Prehydrolysis Soda Cooking of Acacia crassicarpa Wood

“…It was unexpected that the characteristics of A. crassicarpa wood are advantageous over those of E. globulus for producing unbleached pulp. In a previous study 4) ,…”

“…3 ECF bleaching with P sa Each treatment of bleaching except oxygen bleaching was conducted by mixing the pulp with chemicals in a plastic bag and heating in a hot water bath, followed by press dewatering and washing. The conditions for each stage of the bleaching sequence (O-D 0 /P sa -E p -D 1 ) were as follows, according to a previous study 19 non-wood fibers have been used and investigated as dissolving pulp materials such as acacia, birch, eucalyptus, and bamboo [4][5][6] . Acacia species such as Acacia crassicarpa is grown in plantation areas in Southeast Asia including Indonesia and used for the pulp production of papermaking 7) .…”

“…Dionex ICS 3000 Ion Chromatograph was used to analyze monosaccharide in hydrolysates of wood meals (40-60 mesh) prepared from chips and pulp. These hydrolysates were obtained after 72％ sulfuric acid hydrolysis followed by 4％ sulfuric acid hydrolysis for 1 h at 121℃ 4) . Extractive content of the wood was determined using wood meals by acetone extraction for 8 h.…”

Mutagenicity of Tectona grandis Wood Extracts and Their Ability to Improve Carbohydrate Yield for Kraft Cooking Eucalyptus Wood

“…Chemical characterizations of E. globulus wood meal, such as acid-insoluble lignin (Klason lignin), ash content, and extractives were analyzed based on TAPPI test methods (T222 om-11, T211 om-93, and T204 om-88, respectively). For monosaccharide (i.e., glucose and xylose) analysis, wood meal was hydrolyzed with 72% sulfuric acid followed by 4% sulfuric acid for 1 h at 121 °C [ 22 ]; then, the resulting filtrate was analyzed using an ICS 3000 ion chromatograph (Dionex GmbH, Lohmar, Germany). The acid-soluble lignin content in the filtrate was determined according to TAPPI test method T222 om-88 using UV–Vis spectrophotometry at 205 nm.…”

“…The acid-soluble lignin content in the filtrate was determined according to TAPPI test method T222 om-88 using UV–Vis spectrophotometry at 205 nm. Yields of syringyl aldehyde (S) and vanillin (V) and the S/V molar ratio were determined in wood meal oxidized using nitrobenzene as described [ 22 ].…”