Chemical pulping

Untreated and hot water-treated birch (Betula pendula) sawdust were cooked by the oxygen-alkali method under the same cooking conditions (temperature = 170°C, liquor-to-wood ratio = 5 L/kg, and 19% sodium hydroxide charge on the ovendry sawdust). The pretreatment of feedstock clearly facilitated delignification. After a cooking time of 90 min, the kappa numbers were 47.6 for the untreated birch and 10.3 for the hot water-treated birch. Additionally, the amounts of hydroxy acids in black liquors based on the pretreated sawdust were higher (19.5-22.5g/L) than those in the untreated sawdust black liquors (14.8-15.5 g/L). In contrast, in the former case, the amounts of acetic acid were lower in the pretreated sawdust (13.3-14.8 g/L vs. 16.9-19.1 g/L) because the partial hydrolysis of the acetyl groups in xylan already took place during the hot water extraction of feedstock. The sulfur-free fractions in the pretreatment hydrolysates (mainly carbohydrates and acetic acid) and in black liquors (mainly lignin and aliphatic carboxylic acids) were considered as attractive novel byproducts of chemical pulping.

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CHEMICAL PULPING. Oxidative degradation of AOX in softwood-based kraft mill effluents from E C F bleachin g

Nordic Pulp & Paper Research Journal ◽

10.3183/npprj-2012-27-04-p707-713 ◽

2012 ◽

Vol 27 (4) ◽

pp. 707-713 ◽

Cited By ~ 1

Author(s):

Jukka Pekka lsoaho ◽

Suvi Tarkkanen ◽

Raimo Alen ◽

Juha Fiskari

Keyword(s):

Reaction Time ◽

Oxidative Degradation ◽

Cost Effective ◽

Process Conditions ◽

Main Process ◽

Chemical Pulping ◽

Kraft Mill ◽

Organic Halogens ◽

Aox Removal ◽

Adsorbable Organic Halogens

Abstract Softwood-based kraft mill bleaching effluents from the initial bleaching stages D0 and E1 (the bleaching sequence being D0E 1D 1 E2D2) were treated by the oxidative Fenton method (H20rFeS04) to decompose organic pollutants contammg adsorbable organic halogens (AOX). Experiments designed using the Taguchi method were applied to predict the process conditions that would result in a cost-effective and adequate removal of AOX. In addition to the composition and concentration of the reagents (H202 and Fe2+), the main process parameters selected were temperature and reaction time, while pH was adj usted to an approximate value of 4 (the volumetric ratio of the mixed effluents D0:E 1 was 3 :2). The results indicated that an AOX removal of about 70% for this mixture ( corresponding to about 50% for the mill) was achieved when the eftluent samples were treated for 60 min at 70°C with H202 and Fe2+ at a concentration of 1 600 mg/1 and 28 mg/1, respectively.

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Effect of different locations on the morphological, chemical, pulping and papermaking properties of Trema orientalis (Nalita)

Bioresource Technology ◽

10.1016/j.biortech.2009.10.024 ◽

2010 ◽

Vol 101 (6) ◽

pp. 1892-1898 ◽

Cited By ~ 11

Author(s):

M. Sarwar Jahan ◽

Nasima Chowdhury ◽

Yonghao Ni

Keyword(s):

Trema Orientalis ◽

Chemical Pulping

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CHEMICAL PULPING: The dependency of energy consumption on cutting angles in the canter chipping process

Nordic Pulp & Paper Research Journal ◽

10.3183/npprj-2012-27-05-p886-889 ◽

2012 ◽

Vol 27 (5) ◽

pp. 886-889 ◽

Cited By ~ 1

Author(s):

Helen Lusth ◽

Per A. Gradin ◽

Lisbeth M. Hellström

Keyword(s):

Energy Consumption ◽

Chemical Pulping

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Chemical Pulping Processe: Sections 4.2.8–4.3.6.5

Handbook of Pulp ◽

10.1002/9783527619887.ch4c ◽

2008 ◽

pp. 366-509

Keyword(s):

Chemical Pulping

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Equilibrium moisture content in wet pressing of paper

TAPPI Journal ◽

10.32964/tj19.7.333 ◽

2020 ◽

Vol 19 (7) ◽

pp. 330-340

Author(s):

RICHARD KEREKES ◽

DAVID MCDONALD

Keyword(s):

Energy Expenditure ◽

Moisture Content ◽

Pore Size Distribution ◽

Pore Size ◽

Pore Volume ◽

Limiting Factor ◽

High Solids ◽

Solute Exclusion ◽

Chemical Pulping ◽

Pulp Strength

Equilibrium moisture is a limiting factor in achieving high solids in the later stages of pressing or pressing low basis weight grades. We have developed a model that relates equilibrium moisture directly to the pore size distribution of fibers as measured by the solute exclusion technique. The model shows that chemical pulping and refining increase equilibrium moisture by increasing pore volume at given pore sizes in fibers, which leads to lower pressed solids and greater energy expenditure in the dryer section. Means to increase equilibrium moisture without compromising pulp strength are briefly discussed.

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