Comparison of acid sulfite (AS)- and prehydrolysis kraft (PHK)-based dissolving pulps

Cellulose ◽  
2015 ◽  
Vol 22 (6) ◽  
pp. 4017-4026 ◽  
Author(s):  
Chao Duan ◽  
Jianguo Li ◽  
Xiaojuan Ma ◽  
Chunxia Chen ◽  
Yishan Liu ◽  
...  
TAPPI Journal ◽  
2019 ◽  
Vol 18 (5) ◽  
pp. 287-293 ◽  
Author(s):  
JANNATUN NAYEEM ◽  
M. SARWAR JAHAN ◽  
RAZIA SULTANA POPY ◽  
M. NASHIR UDDIN ◽  
M.A. QUAIYYUM

Jute cutting, jute caddis, and cutting-caddis mixtures were prehydrolyzed by varying time and temperature to get about 90% prehydrolyzed yield. At the conditions of 170°C for 60 min of prehydrolysis, the yield for 100% jute cutting was 76.3%, while the same for jute caddis was only 67.9%. But with prehydrolysis at 150°C for 60 min, the yield was 90% for jute cutting, where 49.94% of original pentosan was dissolved and prehydrolysis of jute caddis at 140°C in 60 min yielded 86.4% solid residue. Jute cutting-caddis mixed prehydrolysis was done at 140°C for 30 min and yielded 92% solid residue for 50:50 cutting-caddis mixtures, where pentosan dissolution was only 29%. Prehydrolyzed jute cutting, jute caddis, and cutting-caddis mixtures were subsequently kraft cooked. Pulp yield was only 40.9% for 100% jute cutting prehydrolyzed at 170°C for 60 min, which was 10.9% lower than the prehydrolysis at 140°C. For jute cutting-caddis mixed prehydrolysis at 140°C for 45 min followed by kraft cooking, pulp yield decreased by 3.3% from the 100% cutting to 50% caddis in the mixture, but 75% caddis in the mixture decreased pulp yield by 6.7%. The kappa number 50:50 cutting-caddis mixture was only 11.3. Pulp bleachability improved with increasing jute cutting proportion in the cutting-caddis mixture pulp.


Cellulose ◽  
2021 ◽  
Author(s):  
Isabel Carrillo-Varela ◽  
Regis Teixeira Mendonça ◽  
Miguel Pereira ◽  
Pablo Reyes-Contreras ◽  
David Contreras

1983 ◽  
Vol 22 (3) ◽  
pp. 506-508 ◽  
Author(s):  
Mohamed A. Abou-State ◽  
Fouad F. Abd El-Megeid ◽  
Refaat I. Nesseem

Holzforschung ◽  
2017 ◽  
Vol 71 (7-8) ◽  
pp. 625-631 ◽  
Author(s):  
Jordan Perrin ◽  
Dominique Lachenal ◽  
Christine Chirat

Abstract The factors governing the brightness reversion (BR) of dissolving pulps under heat exposure are investigated. Carbonyl (CO) groups were artificially introduced on fully bleached pulp by sodium hypochlorite (NaClO) oxidation. It was demonstrated that the CO groups are responsible for loss of brightness stability (BS). These groups were partly eliminated by an alkaline extraction stage (E), which improved BS. However, an alkaline peroxide stage (P) was more efficient than E to improve BS, but without any additional CO loss. Moreover, an unbleached dissolving pulp was bleached in the laboratory by elemental chlorine free (ECF) and totally chlorine free (TCF) [ozone-based] sequences to the same brightness. The very low CO content was about the same in both cases. The ECF-bleached pulp showed substantially lower BS than the TCF pulp. These results are interpreted such that the chemistry of chromophores in the unbleached pulp also governs BS. In situ detection of phenolic and quinone chromophores in bleached dissolving pulp was performed by electron paramagnetic resonance (EPR) spectroscopy and ultraviolet resonance Raman (UVRR) spectroscopy. The content of these groups was bleaching-sequence-dependent, which may be related to the BS differences.


Holzforschung ◽  
2002 ◽  
Vol 56 (1) ◽  
pp. 60-66 ◽  
Author(s):  
S. Abad ◽  
B. Saake ◽  
J. Puls ◽  
J. C. Parajó

Summary Eucalyptus globulus wood samples were delignified in two-stage treatments carried out in media made up of formic acid, water and hydrogen peroxide under selected operational conditions. The pulps were subjected to Totally Chlorine Free (TCF) bleaching sequences. Alkaline treatments, oxygen delignification, ozone stages and treatments with peroxyacids were assayed in order to reach the target values for dissolving pulps. Under the best conditions, a fully bleached pulp (91.6% ISO brightness) with SCAN viscosity of 649 ml/g and favourable molar mass distribution was obtained.


2011 ◽  
Vol 233-235 ◽  
pp. 1479-1484
Author(s):  
Ke Xin Hu ◽  
Guang Ming Zeng ◽  
Hai Chao Zhang

The possibilities of dissolving grade pulp production from reed were investigated in this paper. Two – stage prehydrolysis – kraft pulping and CEHA bleaching process of reed for preparation of dissolving grade pulp were studied in laboratory. The optimum cooking and bleaching conditions were found out. The mechanism and its kinetics of reed in prehydrolysis process were also discussed. The results showed that under the laboratory conditions the rate for removal of materials at about 175°C follow approximately a pseudo first order law with two distinct phrases: the bulk removal and the residual removal of the materials. The prehydrolysis-factor (P-factor) was established. The advantage of using P-factor is predict compensating adjustments in cooking time and/or temperature to give the same degree of pulping and to produce pulp with predetermined characteristics. It is found that three distinct delignification rate stages about 75% of pentosans and about 50% of lignin were removed. A CEHA four stage bleaching is used for dissolving grade pulp. Total chlorine charge in bleaching is 6% (to oven-dry pulp). The results show that all of the indices fitted the quality standards of dissolving grade pulp.


Holzforschung ◽  
2016 ◽  
Vol 70 (7) ◽  
pp. 611-617 ◽  
Author(s):  
Benoît Arnoul-Jarriault ◽  
Raphaël Passas ◽  
Dominique Lachenal ◽  
Christine Chirat

Abstract The swelling of dissolving pulps has been investigated by a new method based on the MorfiR analyser, which is measuring the width variation of thousands of fibres in a cupriethylenediamine (CUEN) solution in a few minutes. Pulps from various origins were analysed coming from softwood, birch wood, eucalyptus wood, kraft pulps, sulphite pulps and ECF and TCF bleached pulps, which were modified by several treatments including chemical (cold caustic extraction, hypochlorite) or enzymatic (cellulase) methods. The swelling was much affected by the crystalline form of cellulose and the hemicellulose content but did not depend neither on the cellulose DP nor on the fibre structure (hardwood vs. softwood). The dissolving pulp reactivity in the viscose process was also assessed by swelling in dilute solutions of cupriethylenediamine (CUEN) instead of the Fock’s method.


Cellulose ◽  
2004 ◽  
Vol 11 (1) ◽  
pp. 73-83 ◽  
Author(s):  
H. Sixta ◽  
H. Harms ◽  
S. Dapia ◽  
J.C. Parajo ◽  
J. Puls ◽  
...  

2015 ◽  
Vol 61 (3) ◽  
pp. 292-298 ◽  
Author(s):  
Andri Taufick Rizaluddin ◽  
Qiang Liu ◽  
Posma R. Panggabean ◽  
Hiroshi Ohi ◽  
Keiichi Nakamata

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