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

2003 ◽  
Vol 42 (18) ◽  
pp. 4156-4161 ◽  
Author(s):  
Maria J. M. C. Barroca ◽  
José Almiro A. M. Castro
Keyword(s):  
Chlorine Dioxide ◽  
Kraft Pulp ◽  
Kinetics Of

Modeling of alkaline extraction chemistry and kinetics of softwood kraft pulp

Holzforschung ◽  
2014 ◽  
Vol 68 (7) ◽  
pp. 733-746 ◽  
Author(s):  
Susanna Kuitunen ◽  
Ville Tarvo ◽  
Tiina Liitiä ◽  
Stella Rovio ◽  
Tapani Vuorinen ◽  
...  
Keyword(s):  
Chlorine Dioxide ◽  
Kraft Pulp ◽  
Oxygen Demand ◽  
Alkaline Extraction ◽  
Fiber Wall ◽  
Transfer Equations ◽  
Softwood Kraft Pulp ◽  
Engineering Parameters ◽  
Liquid Mass Transfer ◽  
Kinetics Of

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.

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

BioResources ◽  
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

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

2018 ◽  
Vol 12 (2) ◽  
pp. 218-222 ◽  
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

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.

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.

The Role of Oxalic Acid in the Ozone Bleaching Kinetics of an Xo-Kraft Pulp

2000 ◽  
Vol 20 (2) ◽  
pp. 147-167 ◽  
Author(s):  
M. Blanca Roncero ◽  
José F. Colom ◽  
Teresa Vidal ◽  
M. [Agrave]ngels Queral
Keyword(s):  
Oxalic Acid ◽  
Kraft Pulp ◽  
Kinetics Of ◽  
Ozone Bleaching

Effects and Kinetics of Chlorine Dioxide Removal Microcystin-RR

2009 ◽  
Author(s):  
Ming-Song Wu ◽  
Ying Ji ◽  
Jun-Li Huang ◽  
Jiao Fu ◽  
Yu-Ling Zhang ◽  
...  
Keyword(s):  
Chlorine Dioxide ◽  
Kinetics Of

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

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.

Evidence for the formation of lignin-hexenuronic acid-xylan complexes during modified kraft pulping processes

Holzforschung ◽  
2006 ◽  
Vol 60 (2) ◽  
pp. 137-142 ◽  
Author(s):  
Zhi-Hua Jiang ◽  
Jean Bouchard ◽  
Richard Berry
Keyword(s):  
Acid Hydrolysis ◽  
Kraft Pulp ◽  
Kraft Pulping ◽  
Order Kinetic ◽  
Kraft Pulps ◽  
First Order ◽  
Pseudo First Order ◽  
Hexenuronic Acid ◽  
Kinetics Of ◽  
Hydrolysis Of

Abstract The finding that hexenuronic acid (HexA) groups can be selectively removed from kraft pulps by acid hydrolysis has provided an opportunity to reduce bleaching chemicals. However, there is evidence that the acid hydrolysis is not uniform. In this report, we evaluate the kinetics of acid hydrolysis of HexA in a xylan sample enriched with HexA, a conventional kraft pulp, and three modified kraft pulps: anthraquinone pulp (Kraft-AQ), polysulfide pulp (PS), and polysulfide-anthraquinone pulp (PS-AQ). We found that HexA present in the xylan and conventional kraft pulp behaved similarly toward the acid hydrolysis throughout. On the other hand, HexA present in the Kraft-AQ, PS-AQ and PS pulps was heterogeneous toward acid hydrolysis and the reaction can be separated into two pseudo-first-order kinetic phases, each of which has a different rate constant. The kinetic data provide evidence for the formation of lignin-HexA-xylan complexes during modified kraft pulping processes.

Sign in / Sign up

Export Citation Format

Share Document