Chemical aspects of kraft pulping

Gierer, Josef

doi:10.1007/bf00383453

Cited by 384 publications

(296 citation statements)

References 32 publications

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“…This implies that temperature was the key parameter in the pulping process, at least within the interval in which this experiment took place. This finding is not surprising, given that during the bulk phase the rate of delignification is chemically controlled, as opposed to the initial phase, which is mostly diffusion-controlled (Gierer 1980). The effects of temperature in batch kraft cooking were studied by Jain and Mortha (2008), who reported increases in the delignification rate by two to three-fold per 10 ºC increase in reaction temperature.…”

Section: Experimental Design Analysis and Model Fittingmentioning

confidence: 96%

Modeling and Optimization of Eucalyptus globulus Bark and Wood Delignification using Response Surface Methodology

Neiva¹,

Gominho²,

Pereira³

2014

BioResources

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Statistical models and optimization of Eucalyptus globulus Labill. wood and bark delignification were achieved using response surface methodology (RSM). A central composite design was outlined to model the simultaneous influence of active alkali (AA), reaction temperature (T), and reaction time (t) on pulp yield (η) and kappa number (k) during the kraft pulping of wood and bark. Experimental results were fitted to a second-order polynomial with linear interaction of factors. The statistical models showed high coefficients of determination for both wood (R . Using these models, the optimum conditions to attain a pulp with the highest yield at an acceptable kappa number (below 17) were determined. For wood, the pulp yield was 51.6% (51.5% predicted) and the kappa number was 16.1 (16.9 predicted) under optimized conditions (AA = 21%, T = 151 ºC, and t = 118 min). For bark, the pulp yield was 51.3% (51.0% predicted) and the kappa number was 19.4 (16.9 predicted) under optimized conditions (AA = 15%, T = 166 ºC, and t = 114 min). The degree of polymerization (DP) of the carbohydrates for the optimized pulps, 1430 and 1151 for wood and bark, respectively, suggests low levels of polysaccharide degradation. The bark delignification showed similar behavior to wood.

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Section: Experimental Design Analysis and Model Fittingmentioning

confidence: 96%

Modeling and Optimization of Eucalyptus globulus Bark and Wood Delignification using Response Surface Methodology

Neiva¹,

Gominho²,

Pereira³

2014

BioResources

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“…It is well documented that kraft pulping occurs in three distinct kinetic phases: the initial phase, bulk phase, and residual phase. During the bulk reaction phase, 60% to 68% of the total delignification of the wood occurs (Gierer 1980;Chiang et al 1987). The use of sodium hydroxide and sodium sulfide offers a number of advantages when compared to other processes, especially in terms of fiber strength.…”

Section: H-lignin S-liginin G-ligninmentioning

confidence: 99%

Wood Based Lignin Reactions Important to the Biorefinery and Pulp and Paper Industries

Santos¹,

Hart²,

Jameel³

et al. 2013

BioResources

131

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“…vs. pyrolysis," BioResources 8(2), 2967-2980. 2973 During kraft pulping, the wood lignin is degraded by alkaline attack in the sidechain, a partial loss of Cγ atoms, and cleavage of β-O-4 and α-O-4 bonds (Gierer 1980), inducing lignin solubilisation, thereby decreasing lignin content in the pulps, and allowing fiber separation. The decrease of lignin during pulping was confirmed by 13 C-NMR and Py-GC/MS (del Rio et al 2001) for E. globulus, and our results also showed this variation, as can be seen in Table 1.…”

Section: Lignin Determination By Py-gc/fidmentioning

confidence: 99%

Comparison of Py-GC/FID and Wet Chemistry Analysis for Lignin Determination in Wood and Pulps from Eucalyptus globulus

Lourenço¹,

Gominho²,

Marques³

et al. 2013

BioResources

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The kraft pulps produced from heartwood and sapwood of Eucalyptus globulus at 130 ºC, 150 ºC, and 170 ºC were characterized by wet chemistry (total lignin as sum of Klason and soluble lignin fractions) and pyrolysis (total lignin denoted as py-lignin). The total lignin content obtained with both methods was similar. In the course of delignification, the py-lignin values were higher (by 2 to 5%) compared to Klason values, which is in line with the importance of soluble lignin for total lignin determination. Pyrolysis analysis presents advantages over wet chemical procedures, and it can be applied to wood and pulps to determine lignin contents at different stages of the delignification process. The py-lignin values were used for kinetic modelling of delignification, with very high predictive value and results similar to those of modelling using wet chemical determinations.

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Chemical aspects of kraft pulping

Cited by 384 publications

References 32 publications

Modeling and Optimization of Eucalyptus globulus Bark and Wood Delignification using Response Surface Methodology

Modeling and Optimization of Eucalyptus globulus Bark and Wood Delignification using Response Surface Methodology

Wood Based Lignin Reactions Important to the Biorefinery and Pulp and Paper Industries

Comparison of Py-GC/FID and Wet Chemistry Analysis for Lignin Determination in Wood and Pulps from Eucalyptus globulus

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