THE EFFECT OF MAGNESIUM-BASE SULPHITE-LIQUOR COMPOSITION ON THE RATE OF DELIGNIFICATION OF SPRUCE WOOD AND YIELD OF PULP

1938 ◽  
Vol 16b (7) ◽  
pp. 242-252
Author(s):  
J. M. Calhoun ◽  
J. J. R. Cannon ◽  
F. H. Yorston ◽  
O. Maass
Keyword(s):  
Sulphur Dioxide ◽  
Lignin Content ◽  
Simple Equation ◽  
Type Formula ◽  
Wood Meal ◽  
Spruce Wood ◽  
Rate Of Reaction ◽  
Mole Percentage ◽  
Free Sulphur

The rate of delignification of resin extracted spruce wood-meal in magnesium base sulphite liquor has been determined at 130 °C. over the concentration range 0.5 to 4% combined, and 2 to 10% free, sulphur dioxide. The rate of reaction is roughly proportional to the concentration of free sulphur dioxide when the combined is constant, but decreases with increase in the concentration of combined when the free is constant. The relation of the rate of delignification to the liquor composition cannot be expressed by any simple equation of the type:[Formula: see text]where K and n are constants. The rate of cooking is somewhat greater in magnesium base sulphite liquor than in calcium base liquor of the same mole percentage composition.The yield of pulp at any given lignin content is independent of the free sulphur dioxide over the whole concentration range, but increases with increase in the concentration of the combined to a maximum at about 3%, and decreases at slightly higher concentrations. When the concentration of combined sulphur dioxide is greater than 1% the yield of pulp obtained from magnesium base cooks is slightly higher than that from corresponding calcium base cooks.

THE EFFECT OF SULPHITE LIQUOR COMPOSITION ON THE RATE OF DELIGNIFICATION OF SPRUCE WOOD AND YIELD OF PULP

1937 ◽  
Vol 15b (11) ◽  
pp. 457-474 ◽  
Author(s):  
J. M. Calhoun ◽  
F. H. Yorston ◽  
O. Maass
Keyword(s):  
Sulphur Dioxide ◽  
Lignin Content ◽  
Order Relation ◽  
Ion Concentration ◽  
Quantitative Relation ◽  
Systematic Deviation ◽  
Hydrogen Ion Concentration ◽  
First Order ◽  
Spruce Wood ◽  
Free Sulphur

A technique has been devised for studying the delignification of wood in sulphite liquor under accurately controlled conditions. The rate of delignification of resin extracted spruce wood-meal has been determined at 130 °C. over the concentration range 0.2 to 1.4% combined, and 2 to 14% total, sulphur dioxide. The reaction shows a systematic deviation from the first order relation that is the same for any composition of liquor. A quantitative relation between the rate of delignification and the concentration of free sulphur dioxide, or better, the partial pressure of sulphur dioxide gas, has been established. The nature and significance of this relation is discussed in connection with the mechanism of the delignification process. It has been shown that the hydrogen ion concentration alone does not determine the rate of cooking, but evidence is presented that indicates that the product of the concentrations of the hydrogen and bisulphite ions is the controlling factor.The yield of pulp for any given lignin content is independent of the free sulphur dioxide over the whole concentration range, but increases in a marked manner with the concentration of the combined. An explanation is offered, and the practical aspects are pointed out.

INVESTIGATION OF VARIOUS PHYSICO-CHEMICAL FACTORS WHICH INFLUENCE SULPHITE COOKING

1934 ◽  
Vol 10 (1) ◽  
pp. 24-35 ◽  
Author(s):  
H. H. Saunderson ◽  
O. Maass
Keyword(s):  
Low Temperature ◽  
Sulphur Dioxide ◽  
Spruce Wood ◽  
Physico Chemical ◽  
Free Sulphur ◽  
Chemical Factors

The penetration of aqueous sulphite solutions into differently shaped blocks of spruce wood has been investigated, the effect of the shape and type of wood, and of the presence of imprisoned air being determined. Measurements of the rates of diffusion of the constituents of calcium bisulphite solutions into pre-soaked blocks of wood showed that "free" sulphur dioxide diffused more readily than calcium bisulphite. Adsorption of sulphur dioxide and calcium bisulphite solutions by spruce wood was measured at 30° and 50 °C., and the influence of this factor on penetration was determined. The effect of penetration on delignification indicated the necessity of a satisfactory distribution of the lime salt at a low temperature to avoid localization of the lime during the pulping process.

PENETRATION DURING SULPHITE COOKING

1933 ◽  
Vol 8 (5) ◽  
pp. 415-428 ◽  
Author(s):  
H. Saunderson ◽  
H. W. Johnston ◽  
O. Maass
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Experimental Technique ◽  
Sulphur Dioxide ◽  
Surface Effect ◽  
Rate Of Penetration ◽  
Spruce Wood ◽  
Cooking Process ◽  
Free Sulphur ◽  
Opening Up

This paper deals with some of the factors which influence the penetration of sulphite liquor into wood during the cooking process. The experimental technique for this purpose is described. The particular factors investigated in this paper are the influence of the calcium sulphite precipitate and the composition of the liquor on penetration.Certain conclusions may be drawn from the experimental results presented. These are summarized as follows:(1) The rate of penetration of sulphite liquor through a block of spruce wood is constant for a fixed low temperature. At a constant high temperature the rate of penetration increases continuously during the duration of a run, due to the opening up of the wood. This "cooking" action becomes evident at about 90 °C. for heartwood, and below 70 °C. for sapwood.(2) The rate of penetration of sulphite liquor is greater for a higher concentration of free sulphur dioxide. This increase in rate with sulphur dioxide concentration becomes more noticeable at higher temperatures, indicating that at least a part of the effect is due to cooking action.(3) The formation of a precipitate of calcium sulphite on the wood at high temperatures decreases the rate of forced penetration. This effect is more noticeable with porous wood, where the pressure differential is small. The plugging action is largely a surface effect, due to the formation of a layer of precipitate over the ends of the tracheids of the wood.

THE INFLUENCE OF PENETRATION IN THE ALKALINE DELIGNIFICATION OF WOOD

1937 ◽  
Vol 15b (3) ◽  
pp. 89-97 ◽  
Author(s):  
Gerard L. Larocque ◽  
O. Maass
Keyword(s):  
Particle Size ◽  
Penetration Rate ◽  
Lignin Content ◽  
Chip Thickness ◽  
Wood Meal ◽  
Dense Wood ◽  
Spruce Wood ◽  
Wetting Agents ◽  
Alkaline Delignification

The effect of various factors that might possibly influence the penetration of soda liquor into spruce wood has been examined. It was found that the rate of delignification was the same irrespective of the size of the sample, from a wood-meal of 0.005 mm. particle size up to a limiting chip thickness of about 10 mm. The density of the wood had no influence on the delignification other than that which would be expected from the higher original lignin content of the more dense wood. The presence of moisture in the chips was without result other than that of diluting the liquor, and the addition of wetting agents for facilitating the penetration rate was without significant effect.

A STUDY OF THE MECHANISM AND KINETICS OF THE SULPHITE PROCESS

1939 ◽  
Vol 17b (4) ◽  
pp. 121-132 ◽  
Author(s):  
J. M. Calhoun ◽  
F. H. Yorston ◽  
O. Maass
Keyword(s):  
Temperature Coefficient ◽  
Arrhenius Equation ◽  
Practical Interest ◽  
Effect Of Temperature ◽  
Wood Meal ◽  
Spruce Wood ◽  
Mechanism And Kinetics ◽  
Kinetics Of

The rate of delignification of resin extracted spruce wood-meal has been determined in calcium-base sulphite liquor at temperatures from 130 °C. down to 50 °C. No break was found in the temperature coefficient curve at the lower temperatures, the reaction following the Arrhenius equation closely. Possible mechanisms of the reaction are discussed in the light of existing theories, and the effect of temperature on the yield of pulp is pointed out for its practical interest.

scholarly journals Kinetics of thiamin cleavage by sulphite

1969 ◽  
Vol 113 (4) ◽  
pp. 611-615 ◽  
Author(s):  
J. Leichter ◽  
M. A. Joslyn
Keyword(s):  
Aqueous Solutions ◽  
Rate Constant ◽  
Sulphur Dioxide ◽  
First Order ◽  
Ph Values ◽  
Rate Of Reaction ◽  
Kinetics Of

Results are presented on the rate of thiamin cleavage by sulphite in aqueous solutions as affected by temperature (20–70°), pH(2·5–7·0), and variation of the concentration of either thiamin (1–20μm) or sulphite (10–5000μm as sulphur dioxide). Plots of the logarithm of percentage of residual thiamin against time were found to be linear and cleavage thus was first-order with respect to thiamin. At pH5 the rate was also found to be proportional to the sulphite concentration. In the pH region 2·5–7·0 at 25° the rate constant was 50m−1hr.−1 at pH5·5–6·0, and decreased at higher or lower pH values. The rate of reaction increased between 20° and 70°, indicating a heat of activation of 13·6kcal./mole.

scholarly journals Progress in understanding the use of diffusive gradients in thin films (DGT) – back to basics

2012 ◽  
Vol 9 (1) ◽  
pp. 1 ◽  
Author(s):  
William Davison ◽  
Hao Zhang
Keyword(s):  
Thin Films ◽  
Natural Waters ◽  
Kinetic Studies ◽  
Simple Equation ◽  
Charge Effects ◽  
The Past ◽  
Soils And Sediments ◽  
Rate Of Reaction ◽  
Simple Equations ◽  
Diffusive Gradients

Environmental contextIt is now nearly 20 years since the introduction of the technique of diffusive gradients in thin films, which can provide information on solute concentrations and dynamics in sediments, soils and water. The interpretation of these measurements in terms of concentrations relies on simple equations and associated assumptions. This review examines how well they have stood the test of time. AbstractDiffusive gradients in thin films (DGT) is now widely used to measure a range of determinands in waters, soils and sediments. In most cases the mass accumulated is interpreted in terms of a labile form of the component being measured using a simple equation that applies to steady-state conditions. During the past decade several publications have revealed phenomena that question some of the assumptions necessary for use of the simple equation. This review systematically examines the available evidence relating to appropriate geometry, possible charge effects, binding of solutes and ligands to the diffusive gel and filter, the rate of reaction with the binding layer, the effects of solution complexation and kinetic limitation, necessary time for deployment and the measurement of nanoparticles. DGT emerges as a robust monitoring tool for labile components in solution. Although there is evidence, for some conditions, of binding of metals and, more moderately, humic substances to the diffusive gel and filter membrane, this is unlikely to affect DGT measurement in natural waters for deployment times exceeding a few days. Detailed speciation and kinetic studies require a more thorough interpretation of the mass accumulated by DGT. A coherent theory has emerged for relatively simple solutions, but systems with complex heterogeneous ligands, as is the case for natural waters, are challenging. The size discrimination of DGT is still poorly known. Systematic measurements with well characterised nanoparticles are required to define the distribution of pore sizes in the gels and to establish the contribution of natural colloids to the DGT measurement.

Sign in / Sign up

Export Citation Format

Share Document