Characteristics of prehydrolysis-kraft pulp fibers from Scots pine

Holzforschung ◽  
2012 ◽  
Vol 66 (7) ◽  
pp. 801-808 ◽  
Author(s):  
Esa Saukkonen ◽  
Jesse Kautto ◽  
Irina Rauvanto ◽  
Kaj Backfolk
Keyword(s):  
Scots Pine ◽  
Chlorine Dioxide ◽  
Kraft Pulp ◽  
Kraft Pulping ◽  
Hot Water ◽  
Wood Chips ◽  
Pulp Fibers ◽  
Fiber Dimensions ◽  
End Use ◽  
Prehydrolysis Kraft

Abstract To clarify the influence of prehydrolysis on fiber characteristics, Scots pine (Pinus sylvestris L.) wood chips were subjected to pressurized hot-water and dilute-acid prehydrolysis (0.5% H2SO4) prior to kraft pulping to partially remove hemicelluloses as hydrolyzate. After the prehydrolysis, the wood chips were submitted to kraft pulping and the pulp was fully bleached in oxygen (O), chlorine dioxide (D), alkaline extraction (E) and chlorine dioxide (D)-sequence. Measurements with an automated optical fiber analyzer showed that prehydrolysis prior to kraft pulping caused significant changes in the fiber dimensions and morphology of the final bleached pulp. Especially, a decrease in fiber width and an increase in fiber deformations were observed compared to a reference kraft pulp. The scanning electron microscopy of handsheets supported the morphology analyses and revealed alterations also in the fiber ultrastructure. The changes in both chemical and physical fiber characteristics require attention when considering the correct processing and end-use of prehydrolysis-kraft pulp fibers.

Semi-bleached paper and fermentation products from a larch biorefinery

TAPPI Journal ◽  
2012 ◽  
Vol 11 (10) ◽  
pp. 31-39 ◽  
Author(s):  
HANNA HÖRHAMMER ◽  
OKSANA BEREZINA ◽  
EERO HILTUNEN ◽  
TOM GRANSTRÖM ◽  
ADRIAAN VAN HEININGEN
Keyword(s):  
Kraft Pulp ◽  
Siberian Larch ◽  
Kraft Pulping ◽  
Larix Sibirica ◽  
Wood Chips ◽  
Paper Properties ◽  
Fermentation Products ◽  
Kraft Paper

This study was focused on the products from a larch biorefinery, specifically bleached paper and different fermentation products. Siberian larch (Larix sibirica Lebed.) wood chips were treated with water in a pre-extraction (PE) stage. The larch extract was removed by drainage and fermented into different products. Eight different bacteria strains were tested. The extracted wood chips were mildly washed before kraft pulping with polysulfide (PS) and anthraquinone (AQ). The PE-PSAQ pulps were bleached to about 80% brightness. Laboratory paper sheets were made and tested for different paper properties, and a conventional larch kraft pulp was also prepared as reference. The larch PE-PSAQ paper and the larch kraft paper had similar properties. The removal of a significant amount of hemicelluloses from the wood chips before pulping was not a detriment to the paper properties.

Enhancement of eucalypt pulp yield through extended impregnation cooking

2018 ◽  
Vol 33 (2) ◽  
pp. 175-185 ◽  
Author(s):  
Gustavo B. de Souza ◽  
Jorge Luiz Colodette ◽  
Fernando José Borges Gomes ◽  
Danila Morais de Carvalho
Keyword(s):  
Chlorine Dioxide ◽  
Kraft Pulp ◽  
Strength Properties ◽  
Kraft Pulping ◽  
Kappa Number ◽  
Pulp Yield

AbstractThe improvement caused by eucalypt chip impregnation on kraft pulping performance was assessed for terminating the cook at kappa in the range of 15–27 and at controlled residual effective alkali (REA) of 6–8 g/L NaOH. Extended impregnation cooking of eucalypt chips (EIC) increased about 1 %lignin- and HexA-freescreen yield gains in relation to conventional cooking (CC), regardless of kappa number in the range of 15–27. The EIC technology allows for cooking eucalypt wood to kappa number up to 27, without rejects production, but without significant improvement inlignin- and HexA-freescreen yield and with larger chlorine dioxide (ClO2) consume during bleaching. The optimum kappa number for both CC and EIC cooking was about 19 with similar refinability and strength properties for both technologies, CC and EIC. It was concluded that extended impregnation cooking is an attractive technique for enhancing bleached eucalypt Kraft pulp yield.

scholarly journals Effect of mechanical and chemical pulping on ionic liquid fractionation of wood chips

2019 ◽  
Author(s):  
◽  
Nhlanhla Hlongwa
Keyword(s):  
Ionic Liquid ◽  
Kraft Pulp ◽  
Thermo Gravimetric Analysis ◽  
Wood Chip ◽  
Kraft Pulping ◽  
Wood Chips ◽  
Regenerated Cellulose ◽  
Gravimetric Analysis ◽  
Mechanical Pulp ◽  
G Ratio

In this study, a comparison of two pulping methods namely mechanical and chemical, on the dissolution of Eucalyptus grandis (E. grandis) wood chips was undertaken. The wood chip pulp was treated with an ionic liquid (IL): 1-allyl-3-methylimidazolium chloride to extract the cellulose. The IL was mixed with unbleached mechanical pulp (UBMP), bleached mechanical pulp (BMP), unbleached kraft pulp (UBKP) and bleached kraft pulp (BKP) in ratios of 10%, 20%, 30%. Each solution contained IL, wood pulp and 2-mL of 16 v/v % of dimethyl sulfoxide (DMSO). The 30 % IL pretreatment was the most effective IL pretreatment. The cellulose yield at 30 % IL pretreatment for UBMP, BMP, UBKP and BKP was 65.12%, 63.82%, 67.43%, 67.15%, respectively. This indicated that the kraft pulping method was more effective than the mechanical pulping method for the yield of cellulose after the IL pretreatment. The Crl value at 30 % IL pretreatment was highest for UBMP (72.03%) indicating that the pretreatment used was the least effective in reducing the cellulose crystallinity. The fractions of E. grandis wood chip namely, lignin, regenerated cellulose and hemicelluloses before and after the IL pretreatment, were characterized by a variety of analytical techniques such as High-Performance Liquid Chromatography (HPLC) (carbohydrates), Fourier Transform Infra-Red Attenuated Total Reflection (FTIR-ATR) (functional groups), Pyrolysis-Gas Chromatography /Mass Spectroscopy (Py-GC/MS) (lignin fractions), Ultraviolet/Visible spectroscopy (UV/Vis) (acid soluble lignin), Thermo Gravimetric Analysis (TGA) (degradation of pulp), X-Ray Diffraction (XRD) (crystallinity) and high resolution Scanning Electron Microscopy (SEM) (morphology). Kraft pulping was the most effective method for the yield of cellulose after the [AMIM][Cl]/DMSO pretreatment. The 30% [AMIM][Cl]/DMSO pretreatment gave the highest S/G ratio indicating that minimal bleaching was required.

scholarly journals Effect of xylanase pretreatment on the kraft pulping of poplar

BioResources ◽  
2020 ◽  
Vol 16 (1) ◽  
pp. 979-986
Author(s):  
Mehmet Akgül ◽  
Mehmet Onurhan Gücüş ◽  
Birol Üner ◽  
Celil Atik
Keyword(s):  
Mechanical Properties ◽  
Optical Properties ◽  
Kraft Pulp ◽  
Lignin Content ◽  
Kraft Pulping ◽  
Wood Chips ◽  
Populus X Euramericana ◽  
Cooking Conditions

This study aimed to determine the influence of prehydrolysis of wood chips on the kraft pulping of Populus x euramericana. Optimum cooking conditions were determined by evaluating different alkali concentrations and cooking periods. Xylanase was used to hydrolyze chips before cooking. Prehydrolysis process increased the yield and viscosity of pulp. Consequently, the mechanical properties of paper changed remarkably. In contrast, the optical properties of the unbleached kraft pulp declined due to lignin content.

Effect of Hot Water Extraction on Hardwood Kraft Pulp fibers (Acer saccharum, Sugar Maple)

2011 ◽  
Vol 50 (17) ◽  
pp. 9949-9959 ◽  
Author(s):  
Gustavo V. Duarte ◽  
Bandaru V. Ramarao ◽  
Thomas E. Amidon ◽  
Paulo T. Ferreira
Keyword(s):  
Acer Saccharum ◽  
Kraft Pulp ◽  
Sugar Maple ◽  
Hot Water ◽  
Water Extraction ◽  
Pulp Fibers ◽  
Hot Water Extraction

Brownstock washing: A review of the literature

TAPPI Journal ◽  
2014 ◽  
Vol 13 (1) ◽  
pp. 9-19 ◽  
Author(s):  
RICARDO B. SANTOS ◽  
PETER W. HART
Keyword(s):  
High Efficiency ◽  
Black Liquor ◽  
Material Balance ◽  
Kraft Pulping ◽  
Wash Water ◽  
Pulp Fibers ◽  
Kraft Process ◽  
Cooking Process ◽  
Materials Used ◽  
Entrapped Air

Brownstock washing is a complex, dynamic process in which dirty wash water or weak black liquor (dissolved organic and inorganic material obtained from the pulp cooking process) is separated from pulp fibers. The use of material balance techniques is of great importance to identify potential problems and determine how well the system is operating. The kraft pulping industry was the first known to combine pulp washing with the recovery of materials used and produced in the wood cooking process. The motivation behind materials recovery is economic, and more recently, environmentally driven. The chemicals used in the kraft process are expensive as compared to those used in the sulfite process. For the kraft process to be economically viable, it is imperative that a very high percentage of the cooking chemicals be recovered. To reach such high efficiency, a variety of washing systems and monitoring parameters have been developed. Antifoam additives and processing aids have also played an important role in increasing washing effectiveness. Antifoam materials help attain washing effectiveness by preventing entrapped air from forming in the system, which allows for an easier, unimpeded flow of filtrate through the screens and washers.

Application of pure, thermostable, alkali-tolerant xylanase in bleaching of oxygen-delignified pine kraft pulp

TAPPI Journal ◽  
2015 ◽  
Vol 14 (11) ◽  
pp. 689-694
Author(s):  
QINGZHI MA ◽  
QI WANG ◽  
CHU WANG ◽  
NIANJIE FENG ◽  
HUAMIN ZHAI
Keyword(s):  
Intrinsic Viscosity ◽  
Chlorine Dioxide ◽  
High Purity ◽  
Kraft Pulp ◽  
Alkaline Media ◽  
Industrial Scale ◽  
Elemental Chlorine ◽  
Effect Of Oxygen ◽  
Alkaline Tolerant ◽  
Ecf Bleaching

The effect of oxygen (O2)-delignified pine kraft pulp pretreatment by high-purity, thermostable, and alkaline-tolerant xylanases on elemental chlorine free (ECF) bleaching of O2-delignification kraft pulp was studied. The study found that xylanase pretreatment preserved the intrinsic viscosity and yield of O2-delignified pulp while causing about 7% of delignification with high delignification selectivity. The xylanases with high purity, higher thermostability (75°C~80°C) in highly alkaline media (pH 8.0~9.5) could be applied on an industrial scale. Pulp pretreatment by the high-purity, thermostable, and alkaline tolerant xylanases could improve pulp brightness or reduce the chlorine dioxide (ClO2) consumption. In a D0ED1D2 bleaching sequence using the same amount of ClO2, the xylanase-pretreated pulp obtained a higher brightness (88.2% vs. 89.7% ISO) at the enzyme dose of 2 U/g pulp; or for the same brightness as control (88.2% ISO), the ClO2 dosage in the D0 stage was reduced by 27%, which represents a 16% savings in total ClO2 used for bleaching.

Polysulfide-borohydride modification of southern pine alkaline pulping integrated with hydrothermal pre-extraction of hemicelluloses

TAPPI Journal ◽  
2011 ◽  
Vol 10 (7) ◽  
pp. 9-16
Author(s):  
SUNG-HOON YOON ◽  
HARRY CULLINAN ◽  
GOPAL A. KRISHNAGOPALAN
Keyword(s):  
Loblolly Pine ◽  
Sodium Borohydride ◽  
Kraft Pulping ◽  
Hot Water ◽  
Pulp Yield ◽  
Paper Strength ◽  
Southern Pine ◽  
Two Stage ◽  
Simultaneous Treatment ◽  
Process Modification

We studied three process modifications to investigate their effects on the property and yield recovery capabilities of kraft pulping integrated with hemicellulose pre-extraction of southern pine. Loblolly pine chips were pre-extracted with hot water until the sugar extraction yield reached the targeted value of 10% and then subjected to conventional and modified kraft pulping. Modification included polysulfide pretreatment; polysulfide-sodium borohydride dual pretreatment, and polysulfide followed by polysulfide-sodium borohydride dual pretreatment two-stage pretreatments prior to kraft pulping. In the first modification, about 5% of the lost pulp yield (total 7%) caused by hemicellulose pre-extraction could be recovered with 15%-20% polysulfide pretreatment. Complete recovery (7%) was achieved with simultaneous pretreatment using 15% polysulfide and 0.5% sodium borohydride with 0.1% anthraquinone in polysulfide-sodium borohydride dual pretreatment. Two-stage pretreatment using recycled 15% polysulfide followed by simultaneous treatment of 6% polysulfide and 0.4%–0.5% sodium borohydride with 0.1% anthraquinone also achieved 100% yield recovery. Continuous recycling of 15% polysulfide employed in the two-stage process modification maintained its yield protection efficiency in a repeated recycling cycle. No significant changes in paper strength were found in handsheets prepared from the three process modifications, except for a minor reduction in tear strength.

Optimization of elemental chlorine-free bleaching for a softwood kraft pulp • part 2: economic analysis of chemical and steam consumption

TAPPI Journal ◽  
2010 ◽  
Vol 9 (9) ◽  
pp. 47-53 ◽  
Author(s):  
BRIAN N. BROGDON
Keyword(s):  
Chlorine Dioxide ◽  
Previous Investigation ◽  
Kraft Pulp ◽  
Energy Costs ◽  
Alkaline Extraction ◽  
Stage Versus ◽  
Kraft Pulps ◽  
Steam Consumption ◽  
Elemental Chlorine ◽  
Softwood Kraft Pulp

Our previous investigation [1] re-analyzed the data from Basta and co-workers (1992 TAPPI Pulping Conference) to demonstrate how oxidative alkaline extraction can be augmented and how these changes affect chlorine dioxide consumption with elemental chlorine-free (ECF) sequences. The current study manipulates extraction delignification variables to curtail bleaching costs with a conventional U.S. Southern softwood kraft pulp. The economic advantages of ~0.35% to 0.65% H2O2 peroxide reinforcement in a 70°C (EOP)-stage versus 90°C (EO)-stage are predisposed to the brightness targets, to short or long bleach sequences, and to mill energy costs. Minimized bleaching costs are generally realized when a 90°C (EO) is employed in D0(EO)D1 bleaching, whereas a 70°C (EOP) is economically advantageous for D0(EOP)D1E2D2 bleaching. The findings we disclose here help to clarify previous ECF optimization studies of conventional softwood kraft pulps.

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.

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