Effect of Residual Effective Alkali on Eucalyptus Kraft Pulp Yield and Chemistry

Ribeiro, Robisnéa A.; Colodette, Jorge Luiz; Júnior, Sílvio Vaz

doi:10.1590/01047760201824042593

Cited by 12 publications

(11 citation statements)

References 19 publications

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“…In this way, the identification of liposoluble extracts after hydrolysis is of extreme importance, because the main current processes of dissolving pulp are extremely favorable for their formation. [30][31][32] These extracts before and after hydrolysis and the residue of the aqueous phase were analyzed by GC-MS to determine the detailed chemical composition of each extract.…”

Section: Ftir Analysismentioning

confidence: 99%

Characterizing the Chemical Composition of Lipophilic Extracts from Acacia mearnsii Wood

Oliveira¹,

Grasel²,

Pinho³

et al. 2020

J. Braz. Chem. Soc.

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The chemical composition of Acacia mearnsii wood extract is described in this paper for the first time. This wood is cultivated in Brazil and has been used to complement the demand for hardwood in the pulp industry. In this study, we performed extractions with acetone (total extracts) and dichloromethane (lipophilic extracts responsible for the pitch formation), with the obtained percentages being 1.68 and 0.68%, respectively. The lipophilic extracts were derivatized and analyzed by Fourier transform infrared spectroscopy (FTIR) and gas chromatographymass spectrometry (GC-MS) before and after alkaline hydrolysis. The results showed that 57 compounds were detected in the lipophilic extracts and these are mainly constituted by fatty acids ca. 32.8 mg kg-1 and sterols 26.9 mg kg-1. These chemical classes have always been present in pitch deposits in the pulp industry. Therefore, these results may be used by pulp mills to establish strategies for pitch control and represent an important advance in the knowledge of A. mearnsii.

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Section: Ftir Analysismentioning

confidence: 99%

Characterizing the Chemical Composition of Lipophilic Extracts from Acacia mearnsii Wood

Oliveira¹,

Grasel²,

Pinho³

et al. 2020

J. Braz. Chem. Soc.

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“…Total yield and screened yield ranged from 34-53% and 27-34%, respectively. Screened yield is overall lower than common hardwood pulp and other studies (Lόpez et al 2000;González et al 2013;Robisnéa et al 2018) because persimmon byproduct chips used in this study were less than 5 cm diameter and the bark was not removed (Macleod 2006). With an increase in the AA of white liquor and cooking time, the total yield decreased because extractives and lignin were more easily removed as the pulping conditions became stronger.…”

Section: Bioresourcescommentioning

confidence: 67%

The manufacture of bleached kraft pulp from persimmon byproducts

Lee

Kim

et al. 2019

BioRes

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The authors explored the possibility of using persimmon byproducts as raw materials for obtaining kraft pulps. Various unbleached and bleached kraft pulps via pulping and bleaching processes were prepared. Then, their characteristics were determined and compared with those of commercial kraft pulps. For the highest screened yield of persimmon byproduct unbleached kraft pulps, the optimal pulping conditions were a liquid ratio of 5:1, an active alkali concentration of 25%, a sulfidity of 30%, and a cooking time of 3 h. Furthermore, the authors obtained persimmon byproduct bleached kraft pulps (PB-BKPs) with an ISO brightness of 73% via three-stage bleaching using 3% ClO2, 1.5% NaOH, and 3.5% ClO2. Moreover, PB-BKP prepared under optimal pulping and bleaching conditions had physical characteristics similar to those of commercial mixed-hardwood bleached kraft pulp, but with relatively low ISO brightness. Therefore, as raw materials, persimmon byproducts can be used for manufacturing a bleached kraft pulp.

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“…Eucalyptus urophylla x Eucalyptus grandis hybrid wood chips were cooked to kappa 14, 22, and 26. Cooking processes were terminated at low (1–2 g L –1 ) and high (8–9 g L –1 ) residual effective alkali . These two cooking approaches are henceforth designated as L-REA and H-REA, respectively.…”

Section: Methodsmentioning

confidence: 99%

Chemical Study of Kraft Lignin during Alkaline Delignification ofE. urophyllaxE. grandisHybrid in Low and High Residual Effective Alkali

Ribeiro

Júnior

Jameel

et al. 2019

ACS Sustainable Chem. Eng.

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Chips from E. urophylla x E. grandis hybrid were subjected to kraft cooking using two different approaches: low and high residual effective alkali. The lignin remaining in the pulps were analyzed for hydroxyl and carboxyl functional groups. For both pulping cases, the kappa number varied between 14 and 26. Significant yield gains were observed when kraft cooking was terminated with low residual effective alkali (L-REA) in contrast to those with high residual effective alkali (H-REA) at a given kappa number. The L-REA pulps also tended to contain higher lignin and lower HexA contents than the H-REA pulps at a given kappa number. Cellulolytic enzyme lignin (CEL) was isolated from the studied pulp’s residual lignins, and their hydroxyl functional group distributions were quantified using a method involving 31P NMR. Analysis of residual lignins isolated from L-REA and H-REA cooking indicated that L-REA had high contents of phenolic hydroxyl groups and carboxylic acid groups in relation to the H-REA pulps. This work demonstrates the varied lignin chemistry one can expect when residual effective alkali levels are varied during kraft pulping and how this parameter can influence downstream unit operations and overall process performance.

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Effect of Residual Effective Alkali on Eucalyptus Kraft Pulp Yield and Chemistry

Abstract: The low-REA cooks showed higher pulp yield, xylan yield, cellulose yield and viscosity. The lignin-HexA free screen yields were about similar in the kappa range of 18-26. The low-REA cooks required about 20% less EA than high-REA ones to achieve the kappa.

Cited by 12 publications

References 19 publications

Characterizing the Chemical Composition of Lipophilic Extracts from Acacia mearnsii Wood

Characterizing the Chemical Composition of Lipophilic Extracts from Acacia mearnsii Wood

The manufacture of bleached kraft pulp from persimmon byproducts

Chemical Study of Kraft Lignin during Alkaline Delignification ofE. urophyllaxE. grandisHybrid in Low and High Residual Effective Alkali

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