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

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.

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ECF Bleaching of Pre-Hydrolyzed Larix Kraft Pulp for Production of Dissolving Pulp

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.634-638.386 ◽

2013 ◽

Vol 634-638 ◽

pp. 386-390

Author(s):

Zhi Li ◽

Jun Li ◽

Jun Xu

Keyword(s):

Hydrogen Peroxide ◽

Chlorine Dioxide ◽

Kraft Pulp ◽

Kappa Number ◽

Alkaline Extraction ◽

Polymerization Degree ◽

Oxygen Delignification ◽

Elemental Chlorine ◽

Pulp Properties ◽

Ecf Bleaching

Elemental Chlorine Free (ECF) bleaching sequence of O1/O2D0EOPD1D2 was adopted to bleach the pro-hydrolyzed Larix kraft pulp, where O1/O2 was two-stage oxygen delignification without interstage treatment, D was chlorine dioxide bleaching, EOP was pressurized alkaline extraction strengthened by hydrogen peroxide. Keeping bleaching temperature and time unchanged, sodium hydroxide charge(NaOH) in O1 stage, chlorine dioxide(ClO2) charge in D0 stage and D2 stage were studied, pulp properties such as brightness, kappa number, alpha-cellulose, pentosan and polymerization degree were measured and compared to establish optimal bleaching conditions. Results show that the optimal charge of NaOH in O1 stage is 2.5%, ClO2 in D0 and D2 stage are 2.5%, 0.6%, and the pulp gained at the optimal bleaching conditions has the properties of 93.9% of alpha-cellulose, 2.60% of pentosan, 375.5 ml/g of viscosity and 86.6%ISO of brightness.

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Enzymes improve ECF bleaching of pulp

BioResources ◽

10.15376/biores.1.1.34-44 ◽

2006 ◽

Vol 1 (1) ◽

pp. 34-44 ◽

Cited By ~ 4

Keyword(s):

Chlorine Dioxide ◽

Acid Treatment ◽

Kraft Pulp ◽

Elemental Chlorine ◽

Eucalyptus Kraft Pulp ◽

Mediator System ◽

Pulp Properties ◽

Laccase Enzyme ◽

Ecf Bleaching ◽

Appreciable Reduction

The delignification efficiency of different laccase enzymes was examined on the eucalyptus Kraft pulp. The laccase enzyme from Trametes versicolor showing the highest delignification efficiency was selected and used in the elemental chlorine-free bleaching sequence for improving the pulp bleachability. A n appreciable reduction in chlorine dioxide consumption was also obtained. Further reduction in chlorine dioxide consumption was obtained when the same laccase treated pulp was subjected to an acid treatment after the extraction stage followed by the DE P D sequence. Elemental-chlorine free bleaching was also performed using the xylanase-laccase treated pulp. Xylanase treatment was incorporated to the laccase mediator system in the elemental-chlorine free bleaching both sequentially and simultaneously. The bleaching sequence DE P D followed and in both the cases, the reduction in chlorine dioxide consumption was greater in comparison to the control. The chlorine dioxide consumption was reduced further when xylanase-laccase treated pulp was given an additional acid treatment. The final pulp properties of the treated pulps were comparable to the control pulp.

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Modification of chlorine dioxide bleaching of Gmelina arborea (gamar) pulp

Bangladesh Journal of Scientific and Industrial Research ◽

10.3329/bjsir.v52i4.34812 ◽

2017 ◽

Vol 52 (4) ◽

pp. 247-252 ◽

Cited By ~ 1

Author(s):

M Sarwar Jahan ◽

MM Uddin ◽

MA Kashem

Keyword(s):

Chlorine Dioxide ◽

Kraft Pulp ◽

Kappa Number ◽

Side Reactions ◽

Gmelina Arborea ◽

Pulp Bleaching ◽

Bleaching Process ◽

Elemental Chlorine ◽

Extraction Stage ◽

Ecf Bleaching

Elemental Chlorine Free (ECF) pulp bleaching is now the dominant pulp bleaching process in globally. In most bleachery, chlorine dioxide is over-consumed. About two thirds of the chlorine dioxide is wasted in useless side reactions. In the study, kraft pulp from Gmelina arborea (gamar wood) was bleached by ECF bleaching in modified sequences. Oxygen prebleaching was carried out to decrease ClO2 requirement, which reduced kappa number of kraft pulp by 47.6% and increased pulp brightness by 21.7 percent points. Several sequences were tested based on the application of limited charges of ClO2 during successive ClO2and extraction stage. Application of this concept allowed a 33% reduction of ClO2 to reach target brightness. The kraft pulp could not reach target brightness of 80% in DED sequences using even 30 kg ClO2/ton of pulp, while splitting of same amount of ClO2 charge into DEDED sequences reached the pulp brightness to 81.1%. But oxygen delignified kaft pulp reached 79.6% brightness using 25 kg ClO2/ton of pulp in DED sequences. In the splitting of ClO2 charge into DEDED sequences, Oxygen pulp reached to 85% brightness by using only 20 kg ClO2/ton pulp.Bangladesh J. Sci. Ind. Res. 52(4), 247-252, 2017

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

TAPPI Journal ◽

10.32964/tj9.9.47 ◽

2010 ◽

Vol 9 (9) ◽

pp. 47-53 ◽

Cited By ~ 2

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.

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Lipophilic Extractives from Eucalyptus globulus Pulp during Kraft Cooking Followed by TCF and ECF Bleaching

Holzforschung ◽

10.1515/hf.2001.043 ◽

2001 ◽

Vol 55 (3) ◽

pp. 260-264 ◽

Cited By ~ 27

Author(s):

A. Gutiérrez ◽

J. Romero ◽

J.C. del Río

Keyword(s):

Gas Chromatography ◽

Chlorine Dioxide ◽

Eucalyptus Globulus ◽

Gas Chromatography Mass Spectrometry ◽

Chemical Analyses ◽

Wood Extractives ◽

Elemental Chlorine ◽

Kraft Cooking ◽

Ecf Bleaching ◽

Paper Pulps

SummaryThe chemical composition of lipophilic extractives in paper pulps fromEucalyptus globuluswood during kraft cooking followed by TCF (“totally chlorine free”) and ECF (“elemental chlorine free”) bleaching sequences has been determined by gas chromatography and gas chromatography-mass spectrometry. The chemical analyses revealed that the composition of the lipophilic extractives in pulp after kraft cooking and TCF bleaching with hydrogen peroxide was similar to that ofE. globuluswood extractives, sitosterol and sitosterol esters being the predominant compounds. In contrast, the presence of these compounds was almost negligible in pulp after ECF bleaching with chlorine dioxide and only the saturated sterol stigmastanol, in both free and esterified forms, survived the bleaching.

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Optimization of elemental chlorine-free bleaching for a softwood kraft pulp – part 1: impact of oxidative extraction on chlorine dioxide stoichiometry

TAPPI Journal ◽

10.32964/tj9.8.27 ◽

2010 ◽

Vol 9 (8) ◽

pp. 27-35 ◽

Cited By ~ 2

Author(s):

BRIAN N. BROGDON

Keyword(s):

Decision Making ◽

Chlorine Dioxide ◽

Kraft Pulp ◽

Alkaline Extraction ◽

Pulp Bleaching ◽

Elemental Chlorine ◽

Kraft Pulp Bleaching ◽

Softwood Kraft Pulp ◽

Chemical Usage ◽

Minimize Costs

The present investigation meticulously analyzes how oxidative alkaline extraction can be augmented through process changes, and how these augmentations can be leveraged to optimize chlorine dioxide usage with elemental chlorine-free (ECF) sequences for a conventional softwood kraft pulp. Bleaching data from Basta and co-workers (1992 TAPPI Pulping Conference) are re-examined and re-interpreted in this study. We determined that ~60% to 65% of the overall ClO2 charge should be applied in the D0-stage. Peroxide addition to an (EOP) can replace 0.6 to 2.5 Kg. ClO2 per Kg H2O2. Boosting the (EO) temperature to 80°C is equivalent to a 70°C (EOP) with 0.25% to 0.30% H2O2,whereas a 90°C (EO) is equivalent to 0.50% – 0.75% H2O2 in a 70°C (EOP). The stoichiometric bleaching data from this study can guide decision-making for lowering chemical usage and minimize costs to reach target brightness levels with three- and five-stage sequences.

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Extension of a steady-state chlorine dioxide brightening model for Z-ECF bleaching of softwood kraft pulps

TAPPI Journal ◽

10.32964/tj20.3.186 ◽

2021 ◽

Vol 20 (3) ◽

pp. 186-197

Author(s):

BRIAN N. BROGDON ◽

LUCIAN A. LUCIAN

Keyword(s):

Steady State ◽

Linear Relationship ◽

Chlorine Dioxide ◽

Current Model ◽

Kappa Number ◽

Kraft Pulps ◽

Current Investigation ◽

Elemental Chlorine ◽

Steady State Model ◽

Ecf Bleaching

Earlier studies developed a steady-state model to predict the brightness and/or bleach consumption during the chlorine dioxide brightening (D1) of softwood pulps produced by conventional elemental-chlorine-free (ECF) sequences. This model relates the chlorine dioxide consumed to the brightness gains predicated upon an asymptotic D1 brightness limit, an incoming D1 pulp brightness, and an equation parameter (β11). The current investigation examines the application of this model to ECF sequences that use ozone delignification (Z-ECF). Literature D1 data from various Z-ECF bleaching studies, which investigated OZ, OD0/Z, and OZ/D0 delignification, were fitted to the model. The β11 parameter was found to be linearly correlated to the entering kappa number. Interestingly, this linear relationship was found to be identical to the relationships observed when modeling the D1 stage for conventional ECF and chlorine-based bleach sequences. Subtle differences in D1 brightening response in the model among the various bleach sequences are reflected by incoming pulp brightness (at the same kappa number). The current model is used to illustrate how alterations to Z-ECF delignification affect D1 brightening and chlorine dioxide consumption.

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Effects of D0-stage temperature, pH, and kappa factor on chlorine dioxide decomposition and D0-(EP)-D1 bleaching performance for eucalypt pulps

TAPPI Journal ◽

10.32964/tj15.4.285 ◽

2016 ◽

Vol 15 (4) ◽

pp. 285-295 ◽

Cited By ~ 2

Author(s):

UMIT SEZGI ◽

JANAINA RESENDE ◽

LEWIS SHACKFORD ◽

JORGE COLODETTE ◽

MARCELA ANDRADE

Keyword(s):

Chlorine Dioxide ◽

Kraft Pulp ◽

Significant Variable ◽

Optimum Conditions ◽

Pulp Bleaching ◽

Elemental Chlorine ◽

Kraft Pulp Bleaching ◽

Eucalyptus Kraft Pulp ◽

Hexenuronic Acid ◽

Proper Operation

Mills have largely used chlorine dioxide (ClO2) for eucalyptus kraft pulp bleaching. Different mills have observed significant variation in ClO2 demand to reach full brightness (≥90 ISO). These large differences in ClO2 consumption derive from many factors. The most significant include differences in carryover loads and hexenuronic acid (HexA) contents and the level of chlorate formation across bleaching. Handling of pulp with high HexA content and ClO2 losses to chlorate can be minimized by proper operation of the ClO2 stages across the bleach plant. An oxygen delignified eucalyptus kraft pulp with a kappa of 10-12 units contains only 4-6 units actually derived from lignin. This scarce amount of lignin (0.6%-0.9%) is not able to consume high ClO2 doses and, as a consequence, the excess ClO2 applied can end up being converted into chlorate. Hence, proper optimization of ClO2 bleaching stages can save significant amounts of this oxidant. This study focused on optimizing ClO2 bleaching for a typical oxygen delignified eucalyptus kraft pulp of kappa number 11.7. Elemental chlorine free bleaching was carried out with the D0-(EP)-D1 sequence. The following conditions were varied in the D0 stage: temperature, end pH, and kappa factor. The results indicated that maximum ClO2 bleaching efficiency is achieved when minimum chlorate is formed, especially when ClO2 bleaching is adjusted in such a way that residual active chlorine is maintained to a minimum. The most significant variable affecting chlorate formation is pH; however, ClO2 doses (ClO2 concentration) also play a very important role. Chlorate formation is more intense in the D1 stage in relation to the D0 stage. Optimum conditions to run the D0 stage were 90°C, 3.5 pH, and 0.22 kappa factor.

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Improved steady-state models for chlorine dioxide delignification sequences that include washer carryover effects

TAPPI Journal ◽

10.32964/tj14.2.93 ◽

2015 ◽

Vol 14 (2) ◽

pp. 93-103 ◽

Cited By ~ 4

Author(s):

BRIAN N. BROGDON

Keyword(s):

Steady State ◽

Chlorine Dioxide ◽

Control Strategies ◽

Kappa Number ◽

Carryover Effects ◽

Advanced Process Control ◽

Elemental Chlorine ◽

Plant Data ◽

State Models ◽

Ecf Bleaching

In previous studies, generalized steady-state models were proposed to approximate the chlorine dioxide demand needed for the delignification of softwood and hardwood pulps, where the kappa number entering the bleach plant can fluctuate. However, these expressions neglect the effect of dissolved solids with the stock that originate from incomplete pulp washing. In this study, the original elemental chlorine-free (ECF) models are modified to include the effects of carryover from brownstock or post-oxygen washing. The stoichiometric bleach consumption from carryover, based on its composition, was calculated from various literature sources. The majority of the bleach demand (about 70%) results from the dissolved lignin contained in the brownstock carryover, with the remainder resulting from the inorganic sulfur constituents (e.g., sulfide and thiosulfate). When the effect of brownstock carryover was taken into account, the modified models accurately predicted the amount of chlorine dioxide consumed for a given delignification level (about ±0.1% chlorine dioxide) vs. actual bleach plant data. The improved models can be used to gauge the level of washer carryover entering the bleach plant if this parameter is not regularly monitored by the mill. Additionally, these modified expressions could be integrated into advanced process control strategies for ECF bleaching where the washer carryover or dissolved lignin entrainment is measured with online sensors.

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Recombinant manganese peroxidase (rMnP) from Pichia pastoris. Part 2: Application in TCF and ECF bleaching

Holzforschung ◽

10.1515/hf.2010.018 ◽

2010 ◽

Vol 64 (2) ◽

Cited By ~ 9

Author(s):

Haowen Xu ◽

Gary M. Scott ◽

Fei Jiang ◽

Christine Kelly

Keyword(s):

Pichia Pastoris ◽

Manganese Peroxidase ◽

Kraft Pulp ◽

Energy Savings ◽

Strength Properties ◽

Enzymatic Treatment ◽

Peroxide Bleaching ◽

Alkaline Peroxide ◽

Elemental Chlorine ◽

Ecf Bleaching

AbstractThe recombinant manganese peroxidase (rMnP) produced from the yeastPichia pastorishas been investigated in totally chlorine free (TCF) and elemental chlorine free (ECF) bleaching sequences for improving the bleachability of kraft pulps. In TCF bleaching, oxygen delignified hardwood kraft pulp was treated with rMnP, followed by a sequence combining a chelating and alkaline peroxide bleaching stage. The inclusion of the enzymatic treatment significantly improved the pulp brightness to a level that is difficult to obtain by chemical bleaching alone. Furthermore, the treatment with rMnP resulted in energy savings during pulp refining with PFI mill with a slight improvement in pulp strength properties such as tensile index and burst index. In ECF bleaching, a significant reduction in chlorine dioxide consumption was obtained. A three-stage rMnP treatment combined with alkaline extraction, followed by DED bleaching sequence for hardwood kraft pulp (HWKP) or DEDED bleaching sequence for softwood kraft pulp (SWKP), reduced the total effective chlorine by 41% and 32% for HWKP and SWKP, respectively, compared with the conventional bleaching sequences without enzymatic treatment. The strength properties of the enzyme-treated pulp were also slightly better than that of the control pulp. Further reductions in the consumption of total effective chlorine were obtained when a xylanase pretreatment was incorporated into the bleaching sequence before the repeated rMnP treatment.

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