Kinetics Research of Wheat Straw Atmospheric Pressure Pulping with Microwave Radiation

2012 ◽  
Vol 610-613 ◽  
pp. 1726-1730
Author(s):  
Hong Zhu ◽  
Hong Xu Qiao
Keyword(s):  
Activation Energy ◽  
Wheat Straw ◽  
Microwave Radiation ◽  
Atmospheric Pressure ◽  
Lignin Content ◽  
Removal Rate ◽  
Black Liquor ◽  
Alkali Concentration ◽  
Paper Pulp ◽  
Lignin Removal

The lignin removal of pulping process is left in black liquor, and with relation to the paper pulp lignin. The higher the black liquor lignin content is, the bigger the lignin of paper pulp is removed. This paper analyzes the delignification mechanism of wheat straw atmospheric pressure pulping with microwave radiation. The relations of black liquor lignin content and alkali concentration to pulping time are described in detail. The results show that delignification process is divided into two stages: quick stage and residual stage. The lignin removal rate in the first stage is much higher than the second stage, that is, lignin has been removed more sufficiently after quick stage. In first stage, reaction order of delignification is 1.0, and 0.7 with respect to OH-, the activation energy is 38.62 kJ • mol-1. The latter delignification also belongs to the first-order reaction and 4.4 with respect to OH-, the activation energy is 75.56 kJ • mol-1. Apparently, residual stage needs to consume large amounts of energy to removal lignin.

Kinetics Analysis of Wheat Straw Pulping Process

2013 ◽  
Vol 860-863 ◽  
pp. 1012-1016 ◽  
Author(s):  
Ming Xian Cui ◽  
Wei Song ◽  
Zong Yu Liu
Keyword(s):  
Activation Energy ◽  
Wheat Straw ◽  
Lignin Content ◽  
Removal Rate ◽  
Black Liquor ◽  
Alkali Concentration ◽  
Slow Stage ◽  
First Order ◽  
Lignin Removal ◽  
Two Stages

This paper analyzes the delignification mechanism of wheat straw pulping process. The lignin removal of pulping process is left in black liquor. The higher the black liquor lignin content is, the bigger the lignin of paper pulp is removed. The relations of black liquor lignin content and alkali concentration to pulping time are described in detail. The results show that delignification process is divided into two stages: quick and slow stage. The lignin removal rate in the first stage is much higher than the second, that is, lignin has been removed more sufficiently after quick stage. In first stage, reaction order of delignification is 1.0, and 0.7 with respect to OH-, the activation energy is 38.62 kJ • mol-1. The latter delignification also belongs to the first-order reaction and 4.4 with respect to OH-, the activation energy is 75.56 kJ • mol-1. Apparently, slow stage needs to consume large amounts of energy to removal lignin.

Combustion properties of reduced-lignin black liquors

TAPPI Journal ◽  
2014 ◽  
Vol 13 (8) ◽  
pp. 81-90 ◽  
Author(s):  
NIKLAS VÄHÄ-SAVO ◽  
NIKOLAI DEMARTINI ◽  
RUFUS ZIESIG ◽  
PER TOMANI ◽  
HANS THELIANDER ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Lignin Content ◽  
Black Liquor ◽  
Nitrogen Atmosphere ◽  
Pulp Mills ◽  
Lignin Removal ◽  
Nitric Oxide Formation ◽  
Combustion Properties ◽  
Black Liquors ◽  
Almost All

The growing interest in production of green chemicals and biofuels from biomass provides an incentive for pulp mills to identify new possibilities in recovering more wood components from the pulping process. One possibility is to use lignin, separated from black liquor. We undertook this work to determine the combustion properties of reduced-lignin black liquors—two kraft liquors and one soda liquor—in a laboratory-scale, singleparticle furnace. The combustion times, maximum swollen volume, nitric oxide formation, cyanate formation, and sulfur release were measured for the original liquors, the filtrates, and intermediate levels of lignin reduction. Combustion experiments were conducted at 900°C in 10% oxygen. Cyanate formation experiments were carried out by pyrolyzing the droplets at 800°C in 100% nitrogen to form a char. The chars were then gasified at 800°C in a 13% carbon dioxide/87% nitrogen atmosphere to obtain the smelt. Sulfur release was studied by pyrolyzing the samples at temperatures ranging from 300°C to 900°C. Liquors with the lowest lignin content had a smaller maximum swollen volume than the original sample. The devolatilization time was not affected by the lignin removal to any great extent, but lignin removal did have a clear effect on the char burning time. The amount of formed nitric oxide (g N/kg black liquor solids) remained constant or decreased slightly with increasing lignin removal in the kraft liquor samples, while for the soda samples the amount of nitric oxide formed increased. The amount of cyanate decreased clearly when comparing the samples with lowest lignin content to the original liquor samples. The peak sulfur release occurred at 500°C for both kraft liquors. In almost all experiments, the share of sulfur released was highest for the original samples and lowest for the sample with lowest lignin content. These results provide new data on combustion properties for reduced-lignin black liquors and indicate that for lignin removal levels up to about 20%, no significant changes are expected in the combustion behavior.

Temperature and effective alkali effect on brown pulp kraft cooking

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Jaqueline Silveira Comelato Favaro ◽  
Gustavo Ventorim ◽  
Iliane Rodrigues de Oliveira ◽  
Cláudia Rodrigues de Oliveira
Keyword(s):  
Lignin Content ◽  
Removal Rate ◽  
Linear Trend ◽  
Total Yield ◽  
Eucalyptus Grandis ◽  
Kappa Number ◽  
Factor H ◽  
Pulp Yield ◽  
Lignin Removal ◽  
Kraft Cooking

Abstract One way to obtain high quality pulp production is to improve selectivity delignification of step, maximize yield. Brown pulp yield and chemical composition were studied, with variation of temperature and effective alkali in Kraft cooking. Considering that these variables directly affect lignin removal rate and final product quality. Industrial wood chips from Eucalyptus grandis x Eucalyptus urophylla hybrids were used in this study. The cooking was performed to obtain pulps with kappa number 13, 15 and 17 for temperatures 155 °C, 160 °C and 165 °C, using the same Factor H (695). Yields were analyzed according to: total yield, rejects content and screened pulp yield. Klason lignin content, wood and pulp sugars, levels of hexenuronic acids in pulp were also determined. Results indicate that lower cooking temperatures are beneficial in relation to cooking performance, selectivity and preservation of xylans. With a screened pulp yield of 57.1 % for KN 17 at the lowest temperature 155 ºC and 55.3 % at the same KN at 165 ºC. The lowest screened pulp yield obtained, 51 %, was for KN 13 at 165 ºC, with 54.1 % with the same KN at 155 ºC. Evidencing a decreasing linear trend of screened pulp yield with temperature increase and kappa number reduction.

Changes in wheat straw cell walls during ozone pretreatment

Holzforschung ◽  
2020 ◽  
Vol 74 (12) ◽  
pp. 1157-1167
Author(s):  
Elena M. Ben’ko ◽  
Dmitriy G. Chukhchin ◽  
Valeriy V. Lunin
Keyword(s):  
Cell Wall ◽  
Wheat Straw ◽  
Plant Biomass ◽  
Lignin Content ◽  
Cellulose Microfibrils ◽  
Primary Cell Wall ◽  
Residual Lignin ◽  
Intercellular Substance ◽  
Lignin Removal ◽  
Wall Stiffness

AbstractTreatment of plant biomass with ozone is a promising delignification method. It was shown that lignin removal from the cell wall during ozonation was limited by topochemical reactions and toke place in the secondary rather in the primary cell wall. The separation of cellulose microfibrils, the loss of cell wall stiffness and complete removal of intercellular substance during the delignification process were visualized by SEM. The dependence of the average diameter of the cellulose microfibril aggregates in the cell wall of ozonized straw on ozone consumption was studied. Lignin removal caused an increase of size of cellulose microfibrils aggregates. It was demonstrated that there was an optimal degree of delignification, at which cellulose became more accessible to enzymes in the subsequent bioconversion processes. The data on the ozone consumption, residual lignin content, and sugars yield in the enzymatic hydrolysis of ozonized wheat straw were obtained. It was also found that the optimum delignification degree for sugars yield was ≈10% of residual lignin content and optimum ozone consumption was 2 mol·О3/mol C9PPU (phenylpropane structural unit) of lignin in raw straw.

Black Liquor Treating of Wheat Straw Pulping Using Microwave Radiation

2014 ◽  
Vol 997 ◽  
pp. 279-283
Author(s):  
Ming Xian Cui ◽  
Wei Song
Keyword(s):  
Activated Carbon ◽  
Reaction Mechanism ◽  
Wheat Straw ◽  
Microwave Radiation ◽  
Organic Pollutants ◽  
Microwave Power ◽  
Black Liquor ◽  
Effective Factors ◽  
Wheat Straw Pulp ◽  
Combined Action

This paper describes the method of treating wheat straw pulp black liquor with microwave radiation. The granular activated carbon and CuO are used as a catalyst.Effects of effective factors such as the total amount, ratio, microwave power, time on treating process are studied. The reaction mechanism is also researched. The results indicate that the oxidative decomposition process of lignin or organic pollutants is combined action of activated carbon and CuO absorption-degradation with microwave induced oxidization. This approach is easy to operate, quickly to treat, completely to react and no new pollutants. So it is used to treat black liquor of containing organic pollutes which is hardly degraded.

Kinetic Study on Lignin Extraction by Ionic Liquid

2013 ◽  
Vol 864-867 ◽  
pp. 477-481
Author(s):  
Yu Deng ◽  
Zhi Min Zhang
Keyword(s):  
Atmospheric Pressure ◽  
Black Liquor ◽  
Order Reaction ◽  
Pulp Yield ◽  
Residual Lignin ◽  
Yield Increase ◽  
First Order ◽  
Lignin Removal ◽  
Lignin Extraction ◽  
Cooking Temperature

This paper has studied the dynamics of delignification in ionic liquids pulping for straw at atmospheric pressure. The date showed that the concentration of the residual lignin in the pulp obviously decreased with the extension of steaming time, pulp yield increase, and the hexose and pentose content in the black liquor was gradually increasing, and at the same time, the amount of the hexose was higher than the pentyl. The concentration of the residual lignin reduced gradually with the cooking temperature increased,the pulp yield increase slowly. The lignin removal reaction is first order reaction, the activation energy is 42.117kJ/mol.

Evaporation of lignin-lean black liquor

TAPPI Journal ◽  
2015 ◽  
Vol 14 (7) ◽  
pp. 441-450
Author(s):  
HENRIK WALLMO, ◽  
ULF ANDERSSON ◽  
MATHIAS GOURDON ◽  
MARTIN WIMBY
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Black Liquor ◽  
Salt Content ◽  
Solubility Limit ◽  
Lignin Removal ◽  
Kraft Black Liquor ◽  
Black Liquors ◽  
The Heat Transfer Coefficient

Many of the pulp mill biorefinery concepts recently presented include removal of lignin from black liquor. In this work, the aim was to study how the change in liquor chemistry affected the evaporation of kraft black liquor when lignin was removed using the LignoBoost process. Lignin was removed from a softwood kraft black liquor and four different black liquors were studied: one reference black liquor (with no lignin extracted); two ligninlean black liquors with a lignin removal rate of 5.5% and 21%, respectively; and one liquor with maximum lignin removal of 60%. Evaporation tests were carried out at the research evaporator in Chalmers University of Technology. Studied parameters were liquor viscosity, boiling point rise, heat transfer coefficient, scaling propensity, changes in liquor chemical composition, and tube incrustation. It was found that the solubility limit for incrustation changed towards lower dry solids for the lignin-lean black liquors due to an increased salt content. The scaling obtained on the tubes was easily cleaned with thin liquor at 105°C. It was also shown that the liquor viscosity decreased exponentially with increased lignin outtake and hence, the heat transfer coefficient increased with increased lignin outtake. Long term tests, operated about 6 percentage dry solids units above the solubility limit for incrustation for all liquors, showed that the heat transfer coefficient increased from 650 W/m2K for the reference liquor to 1500 W/m2K for the liquor with highest lignin separation degree, 60%.

scholarly journals Kinetics and thermodynamic properties related to the drying of 'Cabacinha' pepper fruits

2016 ◽  
Vol 20 (2) ◽  
pp. 174-180 ◽  
Author(s):  
Hellismar W. da Silva ◽  
Renato S. Rodovalho ◽  
Marya F. Velasco ◽  
Camila F. Silva ◽  
Luís S. R. Vale
Keyword(s):  
Experimental Data ◽  
Activation Energy ◽  
Free Energy ◽  
Thermodynamic Properties ◽  
Gibbs Free Energy ◽  
Removal Rate ◽  
Effective Diffusion ◽  
Drying Time ◽  
Three Samples ◽  
Different Temperatures

ABSTRACT The objective of this study was to determine and model the drying kinetics of 'Cabacinha' pepper fruits at different temperatures of the drying air, as well as obtain the thermodynamic properties involved in the drying process of the product. Drying was carried out under controlled conductions of temperature (60, 70, 80, 90 and 100 °C) using three samples of 130 g of fruit, which were weighed periodically until constant mass. The experimental data were adjusted to different mathematical models often used in the representation of fruit drying. Effective diffusion coefficients, calculated from the mathematical model of liquid diffusion, were used to obtain activation energy, enthalpy, entropy and Gibbs free energy. The Midilli model showed the best fit to the experimental data of drying of 'Cabacinha' pepper fruits. The increase in drying temperature promoted an increase in water removal rate, effective diffusion coefficient and Gibbs free energy, besides a reduction in fruit drying time and in the values of entropy and enthalpy. The activation energy for the drying of pepper fruits was 36.09 kJ mol-1.

scholarly journals Test of Anderson-Stuart model in sodium silicate glasses and the general Arrhenian conductivity rule in wide composition range

Cerâmica ◽  
2006 ◽  
Vol 52 (321) ◽  
pp. 22-30 ◽  
Author(s):  
M. L. F. Nascimento ◽  
E. Nascimento ◽  
W. M. Pontuschka ◽  
M. Matsuoka ◽  
S. Watanabe
Keyword(s):  
Activation Energy ◽  
Ionic Conductivity ◽  
Sodium Silicate ◽  
Composition Range ◽  
Absolute Temperature ◽  
Alkali Concentration ◽  
Relative Dielectric Permittivity ◽  
Silicate System ◽  
Wide Composition Range ◽  
Sigma E

We collected and analyzed literature data on ionic conductivity sigma and activation energy E A in the binary sodium silicate system in a wide composition range. The Anderson and Stuart model has been considered to describe the decreasing tendency of activation energy E A with alkali concentration in this system. In this analysis were considered experimental parameters, such as shear modulus G and relative dielectric permittivity epsilon. A general conductivity rule is found in 194 of 205 glasses, when one plots log sigma vs. E A/kB T, where kB is the Boltzmann constant and T is the absolute temperature. This fact means that the arrhenian relation has universal uniqueness of form sigma = sigma (E A,T) in wide Na2O composition range. The results also show that there is strong correlation by more than 19 orders of magnitude on conductivity with E A/kBT. An explanation for this behavior links ionic conductivity and microscopic structure. The problem of phase separation in this system is also considered.

Sign in / Sign up

Export Citation Format

Share Document