Prediction of alkaline pulping yield: equation derivation and validation

Abstract

A method is described which allows prediction of alkaline pulp yield. It is based on an equation which relates the pulp yield to the cellulose content and cellulose degree of polymerization of the alkaline pulp. From the slope and intercept of this linear equation, the lignin-free pulp yield, Y 0 T , of a pulp sample can be calculated when the lignin-free cellulose content (G 0 ) and the cellulose degree of polymerization (DP) of the pulp fiber are determined by sugar analysis and viscosimetry, respectively. In this paper the yield prediction equation is derived and validated using model celluloses and hemicelluloses. As part of the yield prediction method, a new equation was developed which corrects the cellulose degree of polymerisation obtained from the pulp intrinsic viscosity for the hemicellulose content of the pulp. The approach was successfully validated by cooking of cotton at different temperatures (160-180°C), alkalinities (1.30-2.60 mol/L, the equivalent to an effective alkali (as Na 2 O) charge of 12-24 % at a L/W ratio of 4.0 L/kg), sulfidities (15 and 30 %) and anthraquinone charges (0, 0.05 and 0.1 %). The cellulose protecting effect of AQ was confirmed by the lower number of glucose units removed by alkaline peeling compared to that removed during conventional alkaline or kraft cooking. Keywords Cellulose degree of polymerization Á Cotton Á Alkaline pulping Á Pulp yield Á Theoretical derivation Abbreviations AQ Anthraquinone CED Cupriethylenediamine DMAC-Li Dimethylacetamide/lithium chloride HPAEC-PAD High performance anion exchange chromatography equipped with pulsed amperometric detector MCC Microcrystalline cellulose MHS Mark-Houwink-Sakurada equation MSA Metasaccharinic acid THF Tetrahydrofuran TOC Total organic carbon List of symbols DP Average cellulose degree of polymerization in pulp DP 0Average degree of polymerisation in wood G 0Lignin-free cellulose content of pulps TAPPI g Pulp viscosity measured according to TAPPI T 230 om-08 standard method

Study on Conditioning of SO2–Ethanol–Water Spent Liquor from Spruce Chips/Softwood Biomass for ABE Fermentation

“…). The intrinsic viscosity of spruce chips and softwood biomass pulps is 573 and 629 mL g –1 , respectively, which corresponds to viscosity-average degree of polymerization (DP) values of 2100 and 3260 . The low intrinsic viscosity and DP values suggest extensive cellulose hydrolysis at conditions of 12% SO 2 , L:W = 3:1, 150 °C, and 30 min (DP w of native cellulose in wood is about 10 000).…”

Evaluating the Potential to Modify Pulp and Paper Properties through Oxygen Delignification

“…The hemicellulose fraction of the pulp was calculated by the sum of the glucomannan and xylan fractions, and the viscosity of hemicellulose was defined as η hemicellulose = 70 mL/g. 16 The xylan, glucomannan, and cellulose contents were calculated from the monosaccharides according to Janson, 17 using a glucose/mannose ratio of 4.17. The carbohydrate composition was determined according to SCAN-CM 71:09 after the samples were subjected to acetone extraction according to SCAN-CM 49:03 and a subsequent grinding with a 40-mesh grid.…”

“… where x is the mass fraction of the pulp of cellulose ( x cellulose ) and hemicellulose ( x hemi ). The hemicellulose fraction of the pulp was calculated by the sum of the glucomannan and xylan fractions, and the viscosity of hemicellulose was defined as η hemicellulose = 70 mL/g . The xylan, glucomannan, and cellulose contents were calculated from the monosaccharides according to Janson, using a glucose/mannose ratio of 4.17.…”

Isolation and Characterization of Organosolv and Alkaline Lignins from Hardwood and Softwood Biomass

“…Furthermore, the hemicellulosic fraction is extensively degraded to saccharinic acids. Alternatively, methods used both for wood pulping and as pretreatment steps in a biorefinery context, such as alkaline , and organosolv, , are promising candidates to supply higher value lignin streams.…”