Introduction

Sixta, Herbert

doi:10.1002/9783527619887.ch1

Cited by 38 publications

(41 citation statements)

References 11 publications

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“…[37] Scheme 1outlines these two reactions in typicalsul-fite pulping processes under acidic conditions. [37][38][39][40][41][42][43][44][45] Alternatively, ac ondensation reaction may occur between the benzylic carbon of one molecule and the meta-carbon (6th) position of the aromatic ring of another molecule, due to the presence of the benzylic cation;t his mayp revent the sulfonation reaction because it occurs at the a position. [39] Next, sulfite ions presenti ns olution add to this intermediate structure at the a position to form benzyl sulfonica cid units (sulfonation), which contributes to increasing the solubility of the lignosulfonates.…”

Section: Lignosulfonates From Sulfite Spent Liquormentioning

confidence: 99%

“…[39] Next, sulfite ions presenti ns olution add to this intermediate structure at the a position to form benzyl sulfonica cid units (sulfonation), which contributes to increasing the solubility of the lignosulfonates. [37][38][39][40][41][42][43][44][45] Alternatively, ac ondensation reaction may occur between the benzylic carbon of one molecule and the meta-carbon (6th) position of the aromatic ring of another molecule, due to the presence of the benzylic cation;t his mayp revent the sulfonation reaction because it occurs at the a position. [39] Scheme 2o utlines the sulfonation reaction occurring during neutral sulfite pulpingt op roduce lignosulfonates.…”

Section: Lignosulfonates From Sulfite Spent Liquormentioning

confidence: 99%

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Production and Application of Lignosulfonates and Sulfonated Lignin

2017

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Lignin is the largest reservoir of aromatic compounds on earth and has great potential to be used in many industrial applications. Alternative methods to produce lignosulfonates from spent sulfite pulping liquors and kraft lignin from black liquor of kraft pulping process are critically reviewed herein. Furthermore, options to increase the sulfonate contents of lignin-based products are outlined and the industrial attractiveness of them is evaluated. This evaluation includes sulfonation and sulfomethylation of lignin. To increase the sulfomethylation efficiency of lignin, various scenarios, including hydrolysis, oxidation, and hydroxymethylation, were compared. The application of sulfonated lignin-based products is assessed and the impact of the properties of these products on the characteristics of their end-use application is critically evaluated. Sulfonated lignin-based products have been used as dispersants in cement admixtures and dye solutions more than other applications, and their molecular weight and degree of sulfonation were crucial in determining their efficiency. The use of lignin-based sulfonated products in composites may result in an increase in the hydrophilicity of some composites, but the sulfonated products may need to be desulfonated with an alkali and/or oxygen prior to their use in composites. To be used as a flocculant, sulfonated lignin-based products may need to be cross-linked to increase their molecular weight. The challenges associated with the use of lignin-based products in these applications are comprehensively discussed herein.

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Section: Lignosulfonates From Sulfite Spent Liquormentioning

confidence: 99%

Section: Lignosulfonates From Sulfite Spent Liquormentioning

confidence: 99%

Production and Application of Lignosulfonates and Sulfonated Lignin

2017

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“…The accumulation of non-process elements (NPE) -Fe, Cu, Cl, K, Si, Al, Mg, Ca and Mn -throughout the watercircuit closure was simulated from input variables inserted into the Aspen-Plus® software (Table 3). The components ClO 2 , steam and metals content, which are part of the process, were inputted from the Aspen-Plus® database, and the more complex components, such as residual lignin, were inserted into the modeling according to Sixta (2006).…”

Section: Computational Modelingmentioning

confidence: 99%

Partial circuit closure of filtrate in an ECF bleaching plant

Batista

Silva

Santos

et al. 2020

Nordic Pulp &Amp; Paper Research Journal

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The bleaching sector of the wood pulp industry is its largest effluent generator. The aim of this study was to reuse the bleaching filtrate in order to reduce water consumption. The experiment was conducted by simulating the D0(EP)D1 bleaching sequence and recirculating different amounts of filtrate from the oxidation stage to control the pulp consistency of the delignification stage (pre-O). Physical, mechanical, chemical and optical properties of the pulp were studied. The accumulation of the non-process elements (NPE) and their effects were evaluated with the Aspen-Plus® computer simulator. The results of the computational modeling were satisfactory. The recirculation of filtrates increased the saturation index of the system by 19 %, but remained at sub-saturation levels. The pulp viscosity and elongation remained statistically stable. Recirculation of up to 50 % of the filtrate did not produce differences in pulp brightness; however, there were slight losses in the pulp resistances. In order to maintain 84 % ISO brightness, there was a higher consumption of the bleaching reagents. Up to 50 % of recirculation of the filtrates was accomplished without jeopardizing the system and the pulp quality and resulted in a savings of 55 m3 h−1 of water – 7 % of the consumption of the entire mill.

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“…This is an exothermal reaction and generates approx. 65 kJ/mol (Sixta, 2006). The slaked lime reacts with the carbonate ions according to Eq 2.…”

Section: Cao H O → Ca Ohmentioning

confidence: 99%

Characterization of a dusting lime kiln – A mill study

Dernegård

Brelid

Theliander

2017

Nordic Pulp &Amp; Paper Research Journal

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The white liquor preparation is one of the main purposes of the recovery cycle in a kraft pulp mill and the lime kiln, being the single unit operation handling bulk solid materials, poses particular challenges in the recovery cycle. In this study, the influence of a dusting lime kiln on the preparation of white liquor was studied. The investigation showed that the dusting lime kiln produced a burned lime with a substantial fraction of fines at the expense of the fraction of granules, whereas a clear lime kiln had virtually no fines and more granules instead. Burned lime from both dusting and clear periods were collected and separated into fines and granules. The different fractions were slaked and causticized in a synthetic green liquor. The study found that the fines always delivered a lower effective alkali in the resulting white liquor, and that the particle sizes of the lime mud were always larger than those originating from the granules, implying that the fines were sintered harder. The industrial consequence is that a dusting lime kiln increases the load on the kiln because the yield of effective alkali is lower; it also introduces a greater dead load into the liquor cycle.

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Introduction

Cited by 38 publications

References 11 publications

Production and Application of Lignosulfonates and Sulfonated Lignin

Production and Application of Lignosulfonates and Sulfonated Lignin

Partial circuit closure of filtrate in an ECF bleaching plant

Characterization of a dusting lime kiln – A mill study

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