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

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

BioResources ◽

10.15376/biores.11.4.8820-8830 ◽

2016 ◽

Vol 11 (4) ◽

Author(s):

Huixia Zhu ◽

Shuangquan Yao ◽

Lei Jiang ◽

Shuangfei Wang ◽

Chengrong Qin

Keyword(s):

Chlorine Dioxide ◽

Kraft Pulp ◽

Organic Halogen ◽

Eucalyptus Kraft Pulp ◽

Kinetics Of

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

Journal of Biobased Materials and Bioenergy ◽

10.1166/jbmb.2018.1767 ◽

2018 ◽

Vol 12 (2) ◽

pp. 218-222 ◽

Cited By ~ 3

Author(s):

Shuangquan Yao ◽

Cong Gao ◽

Cheng Wang ◽

Lisheng Shi ◽

Chengrong Qin ◽

...

Keyword(s):

Chlorine Dioxide ◽

Kraft Pulp ◽

Organic Halogen ◽

Eucalyptus Kraft Pulp ◽

Kinetics Of

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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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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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Initiating ECF bleaching sequences of eucalyptus kraft pulps with Z/D and Z/E stages

Holzforschung ◽

10.1515/hf.2010.008 ◽

2010 ◽

Vol 64 (1) ◽

Cited By ~ 6

Author(s):

Juan C. García ◽

Francisco López ◽

Antonio Pérez ◽

M. Angels Pèlach ◽

Pere Mutjé ◽

...

Keyword(s):

Hydrogen Peroxide ◽

Chlorine Dioxide ◽

Ecological Impact ◽

Substantial Reduction ◽

Reference Sequence ◽

Kraft Pulps ◽

Eucalyptus Kraft Pulp ◽

The Impact ◽

Ecf Bleaching ◽

Ozone Bleaching

Abstract Ozone bleaching is a common practice in pulping, and also of eucalyptus, where it is usually applied in combination with bleaching sequences based on oxygen, hydrogen peroxide, or chlorine dioxide. Ozone has been proven to be a highly efficient and competitive bleaching chemical in terms of delignification efficiency, low costs, and reducing ecological impact. The objective of the present work was to evaluate technology with ozone/alkaline extraction (Z/E) and ozone/chlorine dioxide (Z/D) for bleaching of eucalyptus kraft pulp. Primarily, the impact of these bleaching steps on refinability and quality of pulp should be investigated. As reference, the sequence D*(EP)D (hot chlorine dioxide, extraction in presence of hydrogen peroxide, chlorine dioxide) was selected, which is considered as the state-of-the-art bleaching in elemental chlorine free (ECF) bleaching technology. Various bleaching sequences with ozone in their first step (Z/D(EP)DP, Z/D(EP)DD, Z/EDP, Z/EDD and A*Z/EDP) were found to provide kraft pulps of similar brightness and in similar yield as the reference sequence D*(EP)D. The kappa number, viscosity, and the contents of glucose and xylose, and hexenuronic acid of the pulps were also similar. In addition, the Z sequences resulted in a substantial reduction of the total chlorine dioxide consumption (more than 30.3% in all cases). The A*Z/EDP sequence, which proved to be the most efficient, yielded 87.5% ClO2 reduction. The studied bleaching sequences also resulted in substantially improved brightness reversal with regard to the reference sequence. The sequence A*Z/EDP was also the most efficient as regards the removal or organochlorines (OX) from the pulp and their reduction in the effluents (AOX). Ozone bleaching sequences improved paper strength, especially with the A*Z/EDP sequence.

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Method for analysis of ClO2 and Cl2 air emissions from pulp mill

Nordic Pulp & Paper Research Journal ◽

10.1515/npprj-2018-0012 ◽

2019 ◽

Vol 34 (1) ◽

pp. 19-27

Author(s):

Kimona Häggström ◽

Magnus Gunnarsson ◽

Katarina Bremert-Jirholm ◽

Nina Simic

Keyword(s):

Chlorine Dioxide ◽

Analytical Method ◽

Kraft Pulp ◽

Pulp Mill ◽

Air Emissions ◽

Pulp Mills ◽

Limit Of Quantification ◽

Regulatory Standards ◽

Low Concentrations ◽

Kraft Pulp Mills

Abstract Chlorine dioxide is commonly used as a bleaching agent in kraft pulp mills. Scrubbers are required to remove any remaining ClO2 from the plant tail gases. To control the air emissions of chlorine compounds, chlorine dioxide and chlorine contents must be monitored to ensure that the strict regulatory standards are met. However, the currently used analytical method is not suitable for detection of low concentrations of chlorine and chlorine dioxide. A new method for measuring chlorine dioxide and chlorine emissions was developed, which ensures compliance with the stringent requirements imposed by the authorities. The two species could be measured separately with a limit of quantification of 3 ppm. The method was robust and easy to use in the pulp mill environment and it was validated both in the laboratory and the field. The specificity of the method was demonstrated, Cl2 analysis was not sensitive to the presence of ClO2 and vice versa. The uncertainty (±2×RSD) of the analytical method in the field was estimated from duplicate measurements performed in the range of 3–500 ppm for ClO2 and 3–300 ppm for Cl2, and was found to be ±20 % and ±10 %, respectively. Possible interferences in the analytical method are also discussed.

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