- •Pulp Purification Herbert Sixta
- •9.2.2.1 Introduction
- •Introduction
- •10.4 Emissions to the Aquatic Environment
- •Is converted into carbon dioxide, while the other half is converted into biomass
- •Into alcohols and aldehydes; (c) conversion of these intermediates into acetic acid and
- •10 Environmental Aspects of Pulp Production
- •In North America, effluent color is a parameter which must be monitored.
- •It is not contaminated with other trace elements such as mercury, lead, or cadmium.
- •10.6 Outlook
- •Increase pollution by causing a higher demand for a chemical to achieve identical
- •In addition negatively affect fiber strength, which in turn triggers a higher
- •Introduction
- •2002, Paper-grade pulp accounts for almost 98% of the total wood pulp production
- •Important pulping method until the 1930s) continuously loses ground and finds
- •Importance in newsprint has been declining in recent years with the increasing
- •Isbn: 3-527-30999-3
- •Virtually all paper and paperboard grades in order to improve strength properties.
- •In fact, the word kraft is the Swedish and German word for strength. Unbleached
- •Importance is in the printing and writing grades. In these grades, softwood
- •In this chapter, the main emphasis is placed on a comprehensive discussion of
- •1010 11 Pulp Properties and Applications
- •Is particularly sensitive to alkaline cleavage. The decrease in uronic acid content
- •Xylan in the surface layers of kraft pulps as compared to sulfite pulps has been
- •80% Cellulose content the fiber strength greatly diminishes [14]. This may be due
- •Viscoelastic and capable of absorbing more energy under mechanical stress. The
- •11.2 Paper-Grade Pulp 1011
- •Various pulping treatments using black spruce with low fibril
- •In the viscoelastic regions. Fibers of high modulus and elasticity tend to peel their
- •1012 11 Pulp Properties and Applications
- •11.2 Paper-Grade Pulp
- •Viscosity mL g–1 793 635 833 802 1020 868 1123
- •Xylose % od pulp 7.3 6.9 18.4 25.5 4.1 2.7 12.2
- •11 Pulp Properties and Applications
- •Inorganic Compounds
- •11.2 Paper-Grade Pulp
- •Insight into many aspects of pulp origin and properties, including the type of
- •Indicate oxidative damage of carbohydrates).
- •In general, the r-values of paper pulps are typically at higher levels as predicted
- •Is true for sulfite pulps. Even though the r-values of sulfite pulps are generally
- •Is rather unstable in acid sulfite pulping, and this results in a low (hemicellulose)
- •11 Pulp Properties and Applications
- •Ing process, for example the kraft process, the cellulose:hemicellulose ratio is
- •Increases by up to 100%. In contrast to fiber strength, the sheet strength is highly
- •Identified as the major influencing parameter of sheet strength properties. It has
- •In contrast to dissolving pulp specification, the standard characterization of
- •Is observed for beech kraft pulp, which seems to correlate with the enhanced
- •11.2 Paper-Grade Pulp
- •11 Pulp Properties and Applications
- •Is significantly higher for the sulfite as compared to the kraft pulps, and indicates
- •11.2 Paper-Grade Pulp
- •Xylan [24].
- •11 Pulp Properties and Applications
- •11.2 Paper-Grade Pulp
- •11 Pulp Properties and Applications
- •Introduction
- •Various cellulose-derived products such as regenerated fibers or films (e.G.,
- •Viscose, Lyocell), cellulose esters (acetates, propionates, butyrates, nitrates) and
- •In pulping and bleaching operations are required in order to obtain a highquality
- •Important pioneer of cellulose chemistry and technology, by the statement that
- •11.3 Dissolving Grade Pulp
- •Involves the extensive characterization of the cellulose structure at three different
- •Is an important characteristic of dissolving pulps. Finally, the qualitative and
- •Inorganic compounds
- •11 Pulp Properties and Applications
- •11.3.2.1 Pulp Origin, Pulp Consumers
- •Include the recently evaluated Formacell procedure [7], as well as the prehydrolysis-
- •11.3 Dissolving Grade Pulp
- •Viscose
- •11 Pulp Properties and Applications
- •11.3.2.2 Chemical Properties
- •11.3.2.2.1 Chemical Composition
- •In the polymer. The available purification processes – particularly the hot and cold
- •11.3 Dissolving Grade Pulp
- •In the steeping lye inhibits cellulose degradation during ageing due to the
- •Is governed by a low content of noncellulosic impurities, particularly pentosans,
- •Increase in the xylan content in the respective viscose fibers clearly support the
- •11.3 Dissolving Grade Pulp
- •Instability. Diacetate color is measured by determining the yellowness coefficient
- •Xylan content [%]
- •11 Pulp Properties and Applications
- •Xylan content [%]
- •11.3 Dissolving Grade Pulp
- •11.3 Dissolving Grade Pulp
- •Is, however, not the only factor determining the optical properties of cellulosic
- •In the case of alkaline derivatization procedures (e.G., viscose, ethers). In industrial
- •11.3 Dissolving Grade Pulp
- •Viscose
- •Viscose
- •In order to bring out the effect of mwd on the strength properties of viscose
- •Imitating the regular production of rayon fibers. To obtain a representative view
- •11 Pulp Properties and Applications
- •Viscose Ether (hv) Viscose Acetate Acetate
- •Xylan % 3.6 3.1 1.5 0.9 0.2
- •1.3 Dtex regular viscose fibers in the conditioned
- •11.3 Dissolving Grade Pulp
- •Is more pronounced for sulfite than for phk pulps. Surprisingly, a clear correlation
- •Viscose fibers in the conditioned state related to the carbonyl
- •1038 11 Pulp Properties and Applications
- •In a comprehensive study, the effect of placing ozonation before (z-p) and after
- •Increased from 22.9 to 38.4 lmol g–1 in the case of a pz-sequence, whereas
- •22.3 To 24.2 lmol g–1. The courses of viscosity and carboxyl group contents were
- •Viscosity measurement additionally induces depolymerization due to strong
- •11 Pulp Properties and Applications
- •Increasing ozone charges. For more detailed
- •11.3 Dissolving Grade Pulp
- •Is more selective when ozonation represents the final stage according to an
- •11.3.2.3 Supramolecular Structure
- •1042 11 Pulp Properties and Applications
- •Is further altered by subsequent bleaching and purification processes. This
- •Involved in intra- and intermolecular hydrogen bonds. The softened state favors
- •11.3 Dissolving Grade Pulp
- •Interestingly, the resistance to mercerization, which refers to the concentration of
- •11 Pulp Properties and Applications
- •Illustrate that the difference in lye concentration between the two types of dissolving
- •Intensity (see Fig. 11.18: hw-phk high p-factor) clearly changes the supramolecular
- •11.3 Dissolving Grade Pulp
- •Viscose filterability, thus indicating an improved reactivity.
- •11 Pulp Properties and Applications
- •Impairs the accessibility of the acetylation agent. When subjecting a low-grade dissolving
- •Identification of the cell wall layers is possible by the preferred orientation of
- •Viscose pulp (low p-factor) (Fig. 11.21b, top). Apparently, the type of pulp – as well
- •11 Pulp Properties and Applications
- •150 °C for 2 h, more than 70% of a xylan, which was added to the cooking liquor
- •20% In the case of alkali concentrations up to 50 g l–1 [67]. Xylan redeposition has
- •11.3 Dissolving Grade Pulp
- •Xylan added linters cooked without xylan linters cooked with xylan
- •Viscosity
- •In the surface layer than in the inner fiber wall. This is in agreement with
- •11 Pulp Properties and Applications
- •Xylan content in peelings [wt%]
- •Xylan content located in the outermost layers of the beech phk fibers suggests
- •11.3.2.5 Fiber Morphology
- •11 Pulp Properties and Applications
- •50 And 90%. Moreover, bleachability of the screened pulps from which the wood
- •11.3.2.6 Pore Structure, Accessibility
- •11.3 Dissolving Grade Pulp
- •Volume (Vp), wrv and specific pore surface (Op) were seen between acid sulfite
- •11 Pulp Properties and Applications
- •Irreversible loss of fiber swelling occurs; indeed, Maloney and Paulapuro reported
- •In microcrystalline areas as the main reason for hornification [85]. The effect of
- •105 °C, thermal degradation proceeds in parallel with hornification, as shown in
- •Increased, particularly at temperatures above 105 °c. The increase in carbonyl
- •In pore volume is clearly illustrated in Fig. 11.28.
- •11.3 Dissolving Grade Pulp
- •Viscosity
- •11 Pulp Properties and Applications
- •Increase in the yellowness coefficient, haze, and the amount of undissolved particles.
- •11.3.2.7 Degradation of Dissolving Pulps
- •In mwd. A comprehensive description of all relevant cellulose degradation processes
- •Is reviewed in Ref. [4]. The different modes of cellulose degradation comprise
- •11.3 Dissolving Grade Pulp
- •50 °C, is illustrated graphically in Fig. 11.29.
- •11 Pulp Properties and Applications
- •In the crystalline regions.
- •11.3 Dissolving Grade Pulp
- •Important dissolving pulps, derived from hardwood, softwood and cotton linters
- •11.3 Dissolving Grade Pulp 1061
- •Xylan rel% ax/ec-pad 2.5 3.5 1.3 1.0 3.2 0.4
- •Viscosity mL g–1 scan-cm 15:99 500 450 820 730 1500 2000
- •1062 11 Pulp Properties and Applications
Increase pollution by causing a higher demand for a chemical to achieve identical
results. Pulping to very low kappa number for less bleaching chemical demand
and effluent load might result in a lower yield, and so require more wood. It can
In addition negatively affect fiber strength, which in turn triggers a higher
demand for strong reinforcement fiber. Taken together, all of these “pros” and
“cons” can result in a negative ecobalance for the positive intention.
Slogans such as effluent-free, chlorine-free or closed loop must be placed into
perspective and analyzed very carefully for their total impact. Unfortunately, the
tendency to simplify a complicated matter, and the desire to impress with achievements,
have caused misleading impressions about the feasibility and impact of
loop closure. On occasion, frequent loop opening is described as the use of kidneys,
and the yield on wood as a parameter to be neglected. One study which aims
to bring together all parameters into a realistic perspective is the Ecocyclic pulp
mill project [15]. It demonstrates the potential for improvements and aims to set
priorities. An increasing knowledge of the processes will doubtless generate the
potential to balance the different interests of the conservation and the intelligent
use of resources, with a minimum impact on the environment at best fiber quality,
to name only three parameters.
1007
1008 10 Environmental Aspects of Pulp Production
References
1 D. Fengel, G. Wegener, Wood: Chemistry,
ultrastructure, reactions. De Gruyter, New
York, 1983.
2 Integrated pollution prevention and
control, Reference document on best
available techniques in the pulp and
paper industry, European Commission,
Sevilla, Spain, December, 2001.
3 Draft main report: Development of new
environmental emission guide lines for
any new bleached eucalyptus kraft pulp
mill in Tasmania, Vols. 1–3. Resource
Planning and Development Commission,
Hobart, Tasmania, 2004
http//www.rpdc.tas.gov.au.
4 W. Sandermann, Die Kulturgeschichte des
Papiers. Springer-Verlag, 1988.
5 P. Perolle, H.H. Myburgh, A. Roberts,
Pulp Pap. 1969; 43(10): 148–150;
G. Rowlandson, Continuous oxygen
bleaching in commercial production.
Tappi J., 1971; 54(6): 962–967.
6 H. Klein, J.P. Franzreb, Delignifizierende
Bleiche von Sulfitzellstoffen mit Wasserstoffperoxid.
Eucepa Tagung, Helsinki,
1980: 9:1–9:25.
7 H. Solbach, Erfahrungen mit der Abwaserbehandlung
in einer integrierten
Zellstoff- und Papierfabrik. Papier, 1977;
31(10A): V87–V91.
8 D.W. Reeve, G. Rowlandson,
W.H. Rapson, The effluent-free
bleached kraft pulp mill. Pulp Paper
Canada, 1977; 78(3): T50–T56;
D.W. Reeve, The effluent-free bleached
kraft pulp mill – Part XIII: The second
fifteen years of development. Pulp Paper
Canada, 1984; 85(2): T24–T27.
9 K. Kringstad, K. Lindstrom, Spent
liquors from pulp bleaching. Environ.
Sci. Technol., 1984; 18(8): 236–238.
10 H.U. Suss, Die peroxidgestutzte Sauerstoffdelignifizierung
von Sulfitzellstoff
– ein Schritt zur Verringerung der AOXBelastung.
Papier, 1986; 40(4): 150–153;
H.U. Suss, N. Nimmerfroh, W. Eul,
J. Meier, Approaches to minimize the
formation of AOX in Kraft pulp bleaching.
Papier, 1990; 44(7): 339–348.
11 C.H. Mobius, Abwasser der Papier- und
Zellstoffindustrie, 3. Auflage, 2002,
revised December, 2004. Available as
pdf file at: www.cm-consult.de.
12 F. de Souza, M.-C Kolar, K.P. Kringstad,
S.E. Swanson, C. Rappe, B. Glas, Influence
of chlorine ratio and oxygen
bleaching on the formation of PCDFs
and PCDDs in pulp bleaching. Tappi J.,
1989; 72(4): 147–153.
13 N. Nimmerfroh, H.U. Suess,
H.P. Boettcher, W. Luettgen,
A. Geisenheiner, The German approach
to the closed-cycle sulfite mill – development
and implementation. Pulp Paper
Canada, 1995; 96(12): T414–T420.
14 www.aet.org/reports/markets/trends90–
01.
15 Kretsloppsanpassad massafabrik,
Ecocyclic pulp mill, Final report KAM 1,
1996–1999. English version.
1009
11
Pulp Properties and Applications
Herbert Sixta
11.1