scholarly journals Effect of Enzymatic Depolymerization of Cellulose and Hemicelluloses on the Direct Dissolution of Prehydrolysis Kraft Dissolving Pulp

2021 ◽  
Author(s):  
Sara Ceccherini ◽  
Marina Ståhl ◽  
Daisuke Sawada ◽  
Michael Hummel ◽  
Thaddeus C. Maloney
Keyword(s):  
Dissolving Pulp ◽  
Direct Dissolution ◽  
Prehydrolysis Kraft ◽  
Enzymatic Depolymerization

scholarly journals PENGGUNAAN XILANASE PADA PEMUTIHAN DISSOLVING PULP Acacia crassicarpa

2015 ◽  
Vol 5 (02) ◽  
Author(s):  
Susi Sugesty ◽  
Teddy Kardiansyah ◽  
Wieke Pratiwi
Keyword(s):  
Chlorine Dioxide ◽  
Dissolving Pulp ◽  
Raw Material ◽  
National Standard ◽  
Cellulose Content ◽  
Pulp Bleaching ◽  
Elemental Chlorine ◽  
Free Process ◽  
Acacia Crassicarpa ◽  
Prehydrolysis Kraft

The use of xylanase in pulp bleaching process is intended to reduce chemicals consumption in pulp industry that still using chlorine compounds (chlorine dioxide), so the bleaching stage needs to be modified without reducing the quality of dissolving pulp. Dissolving pulp was produced from six-year-old Acacia crassicarpa as raw material by the Prehydrolysis-Kraft process, then the pulp was bleached with the ECF (elemental chlorine free) process using xylanase (X) and oxygen (O) as comparison at the early stage of bleaching. The sequences of process include X/ODEDED (xylanase or oxygen; chlorine dioxide; extraction-1; chlorine dioxide-1; extraction-2; chlorine dioxide -2). Results showed that the dissolving pulp with active alkali of 22%, sulphidity of 30%, the temperature of 165oC, and the ratio of 1:4 is the optimal condition. Cellulose content, viscosity and brightness were above 94%, 6.2 cP and 88% ISO, respectively.The dissolving pulp produced with the application of xylanase has better quality than the oxygen one, and meets the requirement according to Indonesia National Standard (SNI 0938:2010, pulp rayon).Keywords: Acacia crassicarpa, xylanase, Prehydrolysis-Kraft, dissolving pulp, rayon pulpABSTRAKPenggunaan xilanase pada proses pemutihan pulp dimaksudkan untuk mengurangi konsumsi bahan kimia yang digunakan selama ini di industri pulp, yang masih menggunakan senyawa klorin (klorin dioksida), untuk itu perlu dilakukan modifikasi pada tahap pemutihannya tanpa mengurangi kualitas dissolving pulp yang dihasilkan. Pembuatan dissolving pulp dilakukan menggunakan bahan baku kayu Acacia crassicarpa berumur 6 tahun dengan proses Prahidrolisa–Kraft, selanjutnya pulp diputihkan dengan proses ECF (Elemental Chlorine Free) menggunakan xilanase (X) dan oksigen (O) sebagai pembanding pada awal pemutihan dengan 6 tahapan proses, yaitu X/ODEDED (xilanase atau oksigen; klorin dioksida; ekstraksi-1; klorin dioksida-1; ekstraksi-2; klorin dioksida-2) dengan perlakuan oksigen sebagai pembanding. Hasil pembuatan dissolving pulp dengan alkali aktif 22%, sulfiditas 30%, suhu 165oC, rasio 1:4 adalah kondisi yang optimal. Kandungan selulosa, viskositas dan derajat cerah yang diperoleh masing-masing yaitu di atas 94%, 6,2 cP dan 88% ISO. Kualitas dissolving pulp hasil pemutihan dengan penambahan xilanase lebih tinggi daripada menggunakan oksigen dan memenuhi persyaratan spesifikasi SNI 0938:2010, pulp rayon. Kata kunci : Acacia crassicarpa, xilanase, Prahidrolisa-Kraft, dissolving pulp, pulp rayon

scholarly journals Understanding the effect of severity factor of prehydrolysis on dissolving pulp production using prehydrolysis kraft pulping and elemental chlorine-free bleaching sequence

BioResources ◽  
2020 ◽  
Vol 15 (2) ◽  
pp. 4323-4336
Author(s):  
Wei Wei ◽  
Zhongjian Tian ◽  
Xingxiang Ji ◽  
Qiang Wang ◽  
Jiachuan Chen ◽  
...  
Keyword(s):  
Fiber Quality ◽  
Degree Of Polymerization ◽  
Kraft Pulping ◽  
Dissolving Pulp ◽  
Quality Analysis ◽  
X Ray Diffraction ◽  
Severity Factor ◽  
Elemental Chlorine ◽  
Prehydrolysis Kraft ◽  
Temperature Time

Prehydrolysis kraft pulping is an effective approach to produce dissolving pulp, which can be used for viscose application. The prehydrolysis process using hot liquid water could remove hemicellulose and loosen the compact cell wall, thus facilitating subsequent pulping and bleaching processes. In this study, the composite severity factor (CSF) was used to reveal the intensity of prehydrolysis treatment and its effect on the pulping and bleaching process by combining the temperature, time, and pH variables. Results showed that the optimum CSF was 6.61, which produced a pulp with α-cellulose of 92.3%, degree of polymerization (DP) of 1081, brightness of 85.1% ISO, and Kappa number of 0.61. In addition, the fiber quality, crystalline structure, and microstructure of pulps were characterized by FQA (fiber quality analysis), XRD (X-ray diffraction), and SEM (scanning electron microscopy).

scholarly journals Effect of the Dissolving Method on the Dissolution of Dissolving Pulp Cellulose Fibers with Different Dried-States in Different NaOH/additives Aqueous Solutions

2021 ◽  
Author(s):  
Weiwei Kong ◽  
Guangrong Yu ◽  
Jiong xing ◽  
Rui Kong ◽  
Meihua Liu ◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
Cellulose Fibers ◽  
Solvent System ◽  
Degree Of Polymerization ◽  
Dissolving Pulp ◽  
Pulp Fiber ◽  
Dissolution Method ◽  
Pure Cellulose ◽  
Thiourea Solution ◽  
Direct Dissolution

Abstract A NaOH/urea (or thiourea) solvent system capable of dissolving cellulose at lower temperatures is a breakthrough in cellulose chemistry, and it was reported that cellulose rapidly dissolved when it was added to a precooled aqueous solution of sodium hydroxide (NaOH) and additives. Therefore, this work compared the effectiveness of the direct dissolution method and freezing-thaw method in dissolving pulp fiber and pure cellulose. Three aqueous solutions were examined: 7% NaOH/12% urea, 9.5% NaOH/4.5% thiourea, and 8% NaOH/8% urea/6.5% thiourea. The dissolving capacity of three NaOH/additives aqueous solutions was analyzed by polarized optical microscopy and the dissolved cellulose proportion was determined. The results showed that the never-dried softwood dissolving pulp and bamboo dissolving pulp achieved better dissolution using freezing-thaw method than using direct dissolution method in the three aqueous solutions. The dissolving method had a negligible effect on the dissolution of each dissolving pulp in the 8% NaOH/8% urea/6.5% thiourea solution. It seems that the direct dissolution method was more suitable for oven-dried microcrystalline cellulose with a low degree of polymerization (DP) and the freezing-thaw method was more suitable for never-dried pulp cellulose fibers with a higher DP.

High consistency cellulase treatment of hardwood prehydrolysis kraft based dissolving pulp

2015 ◽  
Vol 189 ◽  
pp. 413-416 ◽  
Author(s):  
Qiang Wang ◽  
Shanshan Liu ◽  
Guihua Yang ◽  
Jiachuan Chen ◽  
Yonghao Ni
Keyword(s):  
Dissolving Pulp ◽  
Cellulase Treatment ◽  
High Consistency ◽  
Prehydrolysis Kraft

Process modifications to obtain a prehydrolysis kraft dissolving pulp with low limiting pulp viscosity

2020 ◽  
Vol 35 (3) ◽  
pp. 332-341
Author(s):  
Elisabet Brännvall ◽  
Karin Walter
Keyword(s):  
Molecular Weight ◽  
Additional Treatment ◽  
Dissolving Pulp ◽  
Oxygen Delignification ◽  
Peroxide Bleaching ◽  
Low Viscosity ◽  
Pulp Viscosity ◽  
Lower Temperature ◽  
Prehydrolysis Kraft ◽  
Hydrolysis Of

AbstractCellulose can be directly dissolved in cold alkali without derivatization. However, this requires low cellulose molecular weight, i. e. low pulp viscosity, preferably below 300 mL g−1. This can be achieved by for example acid or enzymatic hydrolysis of the dissolving pulp. However, it would be beneficial to manufacture pulp with sufficiently low viscosity without an additional treatment stage prior to dissolution. Unit processes in pulping can be operated in such a way as to reduce the molecular weight of cellulose. The approach of the study was to modify the conditions in unit pulping processes in order to obtain a low pulp viscosity of fully bleached prehydrolysis kraft pulp. A high charge of alkali in the oxygen delignification reduced the cellulose molecular weight significantly. Increased temperature, 120 °C compared to 98 °C, had also a significant effect on viscosity. By performing peroxide bleaching at acidic pH, the viscosity could be sufficiently reduced even when oxygen delignification was performed at lower temperature. However, for high brightness, a chlorine dioxide stage is needed.

Improvement in the Fock test for determining the reactivity of dissolving pulp

TAPPI Journal ◽  
2013 ◽  
Vol 12 (11) ◽  
pp. 21-26 ◽  
Author(s):  
CHAO TIAN ◽  
LINQIANG ZHENG ◽  
QINGXIAN MIAO ◽  
CHRIS NASH ◽  
CHUNYU CAO ◽  
...  
Keyword(s):  
Moisture Content ◽  
Sodium Hydroxide ◽  
Constant Temperature ◽  
Carbon Disulfide ◽  
Testing Procedure ◽  
Dissolving Pulp ◽  
Water Bath ◽  
Testing Conditions ◽  
Pulp Sample ◽  
Fock Reactivity

The Fock test is widely used for assessing the reactivity of dissolving pulp. The objective of this study was to modify the method to improve the repeatability of the test. Various parameters that affect the repeatability of the Fock test were investigated. The results showed that Fock reactivity is dependent on testing conditions affecting the xanthation between cellulose and carbon disulfide, such as the moisture content of the pulp sample, sodium hydroxide (NaOH) concentration, xanthation temperature, carbon disulfide dosage, and xanthation time. The repeatability of the test was significantly improved using the following modified testing procedure: air dried sample in the constant temperature/humidity room, xanthation temperature of 66°F (19°C) in a water bath, xanthation time of 3 h, NaOH concentration of 9% (w/w), and 1.3 mL carbon disulfide.

Prehydrolysis kraft pulping of jute cutting and caddis mixture for rayon production

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
Keyword(s):  
Kraft Pulping ◽  
Kappa Number ◽  
Pulp Yield ◽  
Solid Residue ◽  
Rayon Production ◽  
Kraft Cooking ◽  
Prehydrolysis Kraft

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.

Preparation and Characterization of the High Molecular Weight [3H]Hyaluronic Acid

1992 ◽  
Vol 57 (10) ◽  
pp. 2151-2156 ◽  
Author(s):  
Peter Chabreček ◽  
Ladislav Šoltés ◽  
Hynek Hradec ◽  
Jiří Filip ◽  
Eduard Orviský
Keyword(s):  
Molecular Weight ◽  
Hyaluronic Acid ◽  
High Molecular Weight ◽  
Methyl Bromide ◽  
High Performance ◽  
Hydrogen Atoms ◽  
Isolation And Characterization ◽  
Labelling Procedure ◽  
Enzymatic Depolymerization

Two methods for the preparation of high molecular weight [3H]hyaluronic acid were investigated. In the first one, hydrogen atoms in the molecule were replaced by tritium. This isotopic substitution was performed in aqueous solution using Pd/CaCO3 as the catalyst. In the second method, the high molecular weight hyaluronic acid was alkylated with [3H]methyl bromide in liquid ammonia at a temperature of -33.5 °C. High-performance gel permeation chromatographic separation method was used for the isolation and characterization of the high molecular weight [3H]hyaluronic acid. Molecular weight parameters for the labelled biopolymers were Mw = 128 kDa, Mw/Mn = 1.88 (first method) and Mw = 268 kDa, Mw/Mn = 1.55 (second method). The high molecular weight [3H]hyaluronic acid having Mw = 268 kDa was degraded further by specific hyaluronidase. Products of the enzymatic depolymerization were observed to be identical for both, labelled and cold biopolymer. This finding indicates that the described labelling procedure using [3H]methyl bromide does not induce any major structural rearrangements in the molecule.

scholarly journals Optimization of Lignin Recovery from the Pre-Hydrolysate of Kraft-Based Dissolving Pulp Production Processes

2021 ◽  
Vol 11 (1) ◽  
pp. 454
Author(s):  
Adil Mazar ◽  
Naceur Jemaa ◽  
Waleed Wafa Al Dajani ◽  
Mariya Marinova ◽  
Michel Perrier
Keyword(s):  
Molecular Weight ◽  
Lignin Content ◽  
Sulfuric Acid Concentration ◽  
Dissolving Pulp ◽  
Potential Candidate ◽  
Lignin Extraction ◽  
Dissolved Organic Matters ◽  
Lignin Recovery ◽  
Total Lignin ◽  
Total Lignin Content

A pre-hydrolysate is an aqueous stream obtained during the production of hardwood kraft dissolving pulp. It is rich in sugars and contains dissolved organic matters. The purpose of this study is to investigate the optimization of lignin recovery from wood pre-hydrolysates and to characterize the extracted lignin. The optimal conditions for lignin extraction have been determined to be (a) a filtration temperature of 40 °C, (b) a sulfuric acid concentration of 8.5 kg·m−3, and (c) a coagulation time of 180 min. Using these conditions, high filtration rates have been obtained and the extracted lignin has a low content of impurities (8.3%), a low molecular weight (1270 Da), and a very low polydispersity (Mw/Mn = 1.22). Compared to kraft lignin, the pre-hydrolysate lignin has a much lower molecular weight and could be a potential candidate for niche applications. A high lignin recovery rate is possible (52% of the total lignin content in the pre-hydrolysate).

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