Kinetics of Adsorbable Organic Halogen Formation During the First Chlorine Dioxide Bleaching Stage of Eucalyptus Kraft Pulp

Abstract A comprehensive model for alkaline extraction (E) of chlorine dioxide delignified (D0) softwood kraft pulp (KP) is presented. The dynamics of the process is modeled by taking into account both irreversible and reversible chemical reactions and gas-liquid and liquid-liquid mass transfer. Equations linking molecular-scale composition (amounts of monomeric lignin and carbohydrate structures) and general engineering parameters [κ number (KN), brightness, intrinsic viscosity, total organic carbon (TOC), chemical oxygen demand (COD), etc.] are presented. The model is capable of reproducing the development of KN and brightness from the molecular-level kinetics. Reactions responsible for the darkening of chlorine dioxide bleached (D0) pulp in alkali, brightening of pulp due to the action of hydrogen peroxide and oxygen, and reduction in KN were identified. The model predicts the chemical composition of both fiber wall and filtrate. This feature enables studies concerning the interaction of the AE chemistry with upstream (D0 washing) and downstream (D1 stage) processes. Quantitative physicochemical modeling approach also points out shortcoming in the present knowledge.

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Effect of hot acid hydrolysis and hot chlorine dioxide stage on bleaching effluent biodegradability

Water Science & Technology ◽

10.2166/wst.2007.210 ◽

2007 ◽

Vol 55 (6) ◽

pp. 39-46 ◽

Cited By ~ 3

Author(s):

C.M. Gomes ◽

J.L. Colodette ◽

N.R.N. Delantonio ◽

A.H. Mounteer ◽

C.M. Silva

Keyword(s):

Acid Hydrolysis ◽

Chlorine Dioxide ◽

Biological Treatment ◽

Kraft Pulp ◽

Sequencing Batch Reactor ◽

Batch Reactor ◽

Organic Load ◽

Activated Sludge System ◽

Eucalyptus Kraft Pulp ◽

Complete Sequences

The hot acid hydrolysis followed by chlorine dioxide (A/D*) and hot chlorine dioxide (D*) technologies have proven very useful for bleaching of eucalyptus kraft pulp. Although the characteristics and biodegradability of effluents from conventional chlorine dioxide bleaching are well known, such information is not yet available for effluents derived from hot acid hydrolysis and hot chorine dioxide bleaching. This study discusses the characteristics and biodegradability of such effluents. Combined whole effluents from the complete sequences DEpD, D*EpD, A/D*EpD and ADEpD, and from the pre-bleaching sequences DEp, D*Ep, A/D*Ep and ADEp were characterized by quantifying their colour, AOX and organic load (BOD, COD, TOC). These effluents were also evaluated for their treatability by simulation of an activated sludge system. It was concluded that treatment in the laboratory sequencing batch reactor was efficient for removal of COD, BOD and TOC of all effluents. However, colour increased after biological treatment, with the greatest increase found for the effluent produced using the AD technology. Biological treatment was less efficient at removing AOX of effluents from the sequences with D*, A/D* and AD as the first stages, when compared to the reference D stage; there was evidence of the lower treatability of these organochlorine compounds from these sequences.

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Chlorine-free Bleaching of Eucalyptus Kraft Pulp Using a Mixture of Peroxymonosulfuric Acid and a Trace of Chlorine Dioxide

Mokuzai Gakkaishi ◽

10.2488/jwrs.67.217 ◽

2021 ◽

Vol 67 (4) ◽

pp. 217-222

Author(s):

Yinchao Xu ◽

Rong Huang ◽

Ayyoub Salaghi ◽

Guangfan Jin ◽

Akiko Nakagawa-Izumi

Keyword(s):

Chlorine Dioxide ◽

Kraft Pulp ◽

Eucalyptus Kraft Pulp

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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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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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Kinetics of the First Chlorine Dioxide Bleaching Stage (D1) of a Hardwood Kraft Pulp

Industrial & Engineering Chemistry Research ◽

10.1021/ie030126f ◽

2003 ◽

Vol 42 (18) ◽

pp. 4156-4161 ◽

Cited By ~ 3

Author(s):

Maria J. M. C. Barroca ◽

José Almiro A. M. Castro

Keyword(s):

Chlorine Dioxide ◽

Kraft Pulp ◽

Kinetics Of

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Research on the Formation Mechanism of Absorbable Organic Halogen During the Alkali Extraction Stage of Eucalyptus Kraft Pulp

Journal of Biobased Materials and Bioenergy ◽

10.1166/jbmb.2017.1704 ◽

2017 ◽

Vol 11 (5) ◽

pp. 461-465 ◽

Cited By ~ 1

Author(s):

Shuangquan Yao ◽

Cong Gao ◽

Lei Jiang ◽

Shuangxi Nie ◽

Shuangfei Wang ◽

...

Keyword(s):

Formation Mechanism ◽

Kraft Pulp ◽

Alkali Extraction ◽

Organic Halogen ◽

Eucalyptus Kraft Pulp ◽

Extraction Stage

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Kinetics of Ozone Bleaching of Eucalyptus Kraft Pulp and Factors Affecting the Properties of the Bleached Pulp

BioResources ◽

10.15376/biores.13.1.425-436 ◽

2017 ◽

Vol 13 (1) ◽

Cited By ~ 1

Author(s):

Tian He ◽

Mingyou Liu ◽

Xiaofei Tian

Keyword(s):

Kraft Pulp ◽

Factors Affecting ◽

Bleached Pulp ◽

Eucalyptus Kraft Pulp ◽

Kinetics Of ◽

Ozone Bleaching

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

TAPPI Journal ◽

10.32964/tj14.11.689 ◽

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.

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