Dissolution of dissolving pulp in alkaline solvents after steam explosion pretreatments

Kihlman, Martin; Wallberg, Ola; Stigsson, Lars; Germgård, Ulf

doi:10.1515/hf.2011.094

Cited by 16 publications

(15 citation statements)

References 32 publications

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“…The steam explosion (STEX) pretreatment procedure was performed as described elsewhere (Kihlman et al 2011 ). The STEX S pulp was treated with 0.2 % sulphuric acid (H 2 SO 4 ) at 226 ° C for 15 min, whereas the STEX D pulp was treated by the same procedure but without H 2 SO 4 .…”

Section: Methodsmentioning

confidence: 99%

Effect of various pulp properties on the solubility of cellulose in sodium hydroxide solutions

Kihlman

Aldaeus²,

Chedid³

et al. 2012

Holzforschung

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The dissolution of pulps with varying characteristic properties, for example cellulose chain length or content of hemicellulose, has been investigated in two alkaline solvent systems [sodium hydroxide (NaOH)/urea/thiourea (8:8:6.5 by wt.) and NaOH/zince oxide (ZnO) (9:0.5 by wt.)]. One standard paper pulp, two dissolving pulps and three pretreated pulps were selected for this study. The dissolution parameters in focus were the fi ber dimensions, average degree of poly merization (DP), polydispersity, water retention value and content of hemicelluloses. The solubility was not infl uenced by the fi ber dimensions. The only signifi cant properties, according to variable importance plot, were DP and composition of the hemicelluloses. It was also established that mass transfer effects during the dissolution stage plays an important role in the dissolution of cellulose derived from pulp fi bers.

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Section: Methodsmentioning

confidence: 99%

Effect of various pulp properties on the solubility of cellulose in sodium hydroxide solutions

Kihlman

Aldaeus²,

Chedid³

et al. 2012

Holzforschung

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“…New environmentally benign principles for production of dissolving pulps were proposed, for example by monoethanol pulping (Claus et al 2004), or by upgrading of paper-grade pulps to dissolving pulps by nitren extraction (Janzon et al 2006) or by enzymatic treatments (Ibarra et al 2009). Dissolution properties of dissolving pulps are essential for industrial application (Kihlman et al 2011) and after derivatization, a high regioselectivity (the even distribution of substituents) is a relevant parameter, which can be determined by enzymatic and chemical methods in combination with GPC (Saake et al 2004;Rußler et al 2006). Dissolution properties of dissolving pulps are essential for industrial application (Kihlman et al 2011) and after derivatization, a high regioselectivity (the even distribution of substituents) is a relevant parameter, which can be determined by enzymatic and chemical methods in combination with GPC (Saake et al 2004;Rußler et al 2006).…”

Section: Introductionmentioning

confidence: 99%

The influence of extended mercerization on some properties of carboxymethyl cellulose (CMC)

Almlöf¹,

Kreutz²,

Jardeby³

et al. 2012

Holzforschung

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Carboxymethyl cellulose (CMC) is produced commercially in a two stage process consisting of a mercerization stage in which the pulp is treated with alkali in a water alcohol solution and a second etherification stage whereby monochloroacetic acid is added to the pulp slurry. In this study, the influence of the conditions of an extended mercerization stage was evaluated on the etherification stage concerning the degree of substitution (DS) and the filterability of the resulting CMC. The parameters studied were: (1) the ratio of cellulose I and cellulose II in the original pulp, (2) the concentration of alkali, (3) the temperature and (4) the retention time in the mercerization stage. The DS results indicate that the NaOH concentration in the mercerization stage is the most important among the parameters studied. When the NaOH concentration in the mercerization stage was high (27.5%), cellulose II showed a lower reactivity than cellulose I with respect to the DS obtained in the resulting CMC. The results from the filtration ability of CMC water solutions are interpreted that the amount of cellulose II in the original pulp and the temperature has a negative influence, while the NaOH concentration in the mercerization stage has a positive influence on the filtration ability. Retention time between 1 h-48 h in the mercerization stage had no effect on the DS or the filtration value. The filtration ability was assumed to be highly influenced by the presence of poorly reacted cellulose segments. The CMC samples with the lowest filtration ability at a given DS can be assumed to have the highest degree of unevenly substituted segments.

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“…The probable reasons could be because the release of high pressure during the steam explosion increased the surface area of dissolving pulp and promoted fibre separation due to the fragmentation caused by the mechanical shearing force. The accessibility of cellulose to the solvents (NaOH/urea/thiourea) was thus increased ,. Similarly, mechanical refining increases the surface area of cellulose pulps through external fibrillation, internal delamination and fibre cutting, which create certain microfibrils on the surface of fibres, swell and loosen the internal structures of fibres ,.…”

Section: Resultsmentioning

confidence: 99%

“…Different treatments reportedly or potentially improved the cellulose reactivity of dissolving pulp. Previous work showed that steam explosion and mechanical refining resulted in an increase in dissolving pulp cellulose reactivity presumably via increased pore size, surface area, and swelling . Acid or enzymatic treatments have been used for increasing cellulose reactivity by decreasing the cellulose DP .…”

Section: Introductionmentioning

confidence: 99%

The Influence of Cold Caustic Extraction on the Purity, Accessibility and Reactivity of Dissolving‐Grade Pulp

Dou

Tang

2017

ChemistrySelect

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Prehydrolysis and cold caustic extraction (CCE) are two effective approaches to convert the traditional Kraft pulp to a dissolving‐grade pulp. Compared to prehydrolysis, CCE has several positive attributes but reduces final pulp reactivity. To gain insight into the factors that influence the reactivity of CCE treated cellulose, we compared the surface morphology, supramolecular properties and fibre properties of commercial dissolving pulp from prehydrolysis to dissolving grade cellulose upgraded using CCE. CCE treatment promoted the fibril aggregation and modified the initial cellulose I on Kraft pulps to cellulose II, thus decreasing final pulp reactivity. Various “post‐treatments” such as mechanical refining, steam explosion, induction of fibre kink and curl, sulfuric acid hydrolysis and endoglucanase hydrolysis effectively recover the reactivity lost during the production of dissolving pulp cellulose using a CCE step. Mechanical refining combined with endoglucanase treatment had the greatest effect increasing the reactivity from 32% to 75%.

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Dissolution of dissolving pulp in alkaline solvents after steam explosion pretreatments

Cited by 16 publications

References 32 publications

Effect of various pulp properties on the solubility of cellulose in sodium hydroxide solutions

Effect of various pulp properties on the solubility of cellulose in sodium hydroxide solutions

The influence of extended mercerization on some properties of carboxymethyl cellulose (CMC)

The Influence of Cold Caustic Extraction on the Purity, Accessibility and Reactivity of Dissolving‐Grade Pulp

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