Brightness reversion of eucalyptus kraft pulp: Effect of carbonyl groups generated by hypochlorous acid oxidation

Holzforschung ◽  
2011 ◽  
Vol 65 (3) ◽  
Author(s):  
Zhen Zhou ◽  
Anna-Stiina Jääskeläinen ◽  
Immanuel Adorjan ◽  
Antje Potthast ◽  
Paul Kosma ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Kraft Pulp ◽  
Hypochlorous Acid ◽  
Weight Fraction ◽  
Acid Oxidation ◽  
Carbonyl Groups ◽  
Carbonyl Content ◽  
Brightness Reversion ◽  
Eucalyptus Kraft Pulp ◽  
The Impact

Abstract The impact of hypochlorous acid (HOCl) treatment on a fully bleached eucalyptus kraft pulp was studied with respect to the final brightness as well as the brightness reversion under humid ageing conditions. The carbonyl contents in the pulps were determined by the CCOA method where carbazole-9-carboxylic acid [2-(2-aminooxethoxy)-ethoxy] amide (CCOA) was applied as the carbonyl-selective fluorescence label. The molecular weight distribution of cellulose and hemicelluloses was analyzed as well. The amount of carbonyl groups in pulp was observed to increase significantly after the HOCl treatment, and the carbonyl distribution in pulp to shift towards the low molecular weight fraction. Plotting the carbonyl content against the post color number (PCN) of the pulps revealed a linear correlation. Additionally, the effect of the hemicellulose content was investigated, and alkaline extraction was applied to partially remove the hemicelluloses in pulp. These hemicellulose-poor samples showed a lower reactivity with hypochlorous acid and less brightness reversion at equal carbonyl content.

Effect of UV radiation on the carbonyl distribution in different pulps

Holzforschung ◽  
2004 ◽  
Vol 58 (6) ◽  
pp. 597-602 ◽  
Author(s):  
Antje Potthast ◽  
Sonja Schiehser ◽  
Thomas Rosenau ◽  
Herbert Sixta ◽  
Paul Kosma
Keyword(s):  
Molecular Weight ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Kraft Pulp ◽  
Cellulose Degradation ◽  
Minor Effect ◽  
Carbonyl Groups ◽  
Eucalyptus Kraft Pulp ◽  
Prehydrolysis Kraft ◽  
Ccoa Method

Abstract The effect of UV irradiation on unbleached and TCF-bleached dissolving pulp samples of different provenience, a beech sulphite and an eucalyptus prehydrolysis kraft pulp, has been analyzed according to the CCOA method, evaluating the changes in the molecular weight distribution, the total number of carbonyl groups and the carbonyl group profiles of each pulp. In the case of TCF bleached material, slightly more carbonyl groups were introduced into the kraft pulp as compared to the sulfite pulp. Cellulose degradation was relatively low in both pulps. In the case of unbleached sulfite pulps, the residual lignin had only a minor effect on the molecular weight distribution and the oxidation state of the cellulose, whereas for eucalyptus kraft pulp a pronounced introduction of carbonyl groups accompanied by severe degradation of cellulose was observed. The presence of hemicelluloses governed the photochemical behavior and the carbonyl profiles of the low molecular weight region of the cellulose.

Behavior of Eucalyptus Kraft Pulp Extractives Components across ECF Bleaching and Their Impact on Brightness Reversion

2011 ◽  
Vol 31 (2) ◽  
pp. 103-120 ◽  
Author(s):  
Célia R. A. Maltha ◽  
Luiz C. A. Barbosa ◽  
Marco A. B. Azevedo ◽  
Jorge L. Colodette
Keyword(s):  
Kraft Pulp ◽  
Brightness Reversion ◽  
Eucalyptus Kraft Pulp ◽  
Ecf Bleaching

Impact of dissolved oxygen concentration on membrane filtering resistance and soluble organic matter characteristics in membrane bioreactors

2008 ◽  
Vol 57 (2) ◽  
pp. 161-165 ◽  
Author(s):  
Kyung-Nan Min ◽  
Sarina J. Ergas ◽  
Anna Mermelstein
Keyword(s):  
Molecular Weight ◽  
Organic Matter ◽  
Dissolved Oxygen ◽  
Weight Fraction ◽  
Total Resistance ◽  
Soluble Organic Matter ◽  
Aerobic Conditions ◽  
Do Concentration ◽  
The Impact ◽  
Molecular Weight Fractions

This study investigated the impact of dissolved oxygen (DO) concentration on membrane filtering resistance, soluble organic matter (SOM) and extracellular polymeric substance (EPS) characteristics in a membrane bioreactor (MBR). A laboratory-scale MBR was operated under DO limited (0.2 mg L−1 DO) and fully aerobic (3.7 and 5.4 mg L−1 DO) conditions. Membrane filtering resistance was determined for the mixed liquor suspended solids (MLSS) and for resuspended microbial biomass after removing SOM. Regardless of the DO concentration, the cake resistance (Rc) was approximately 95 percent of the total resistance (Rt). The membrane cake resistance was found to decrease significantly after removing the SOM. The total resistance caused by the resuspended biomass was 29 percent of that caused by the MLSS under DO limited conditions, while the total resistance caused by resuspended biomass was 41 to 48 percent of that caused by the MLSS under fully aerobic conditions. Under DO limited conditions, SOM in the MLSS contained a larger amount of high molecular weight compounds, leading to higher cake resistance than under fully aerobic conditions. There was significant variation in the molecular weight fractions of the EPS, with no clear relationship with DO concentration. There was also no distinct relationship between membrane filtering resistance and molecular weight fraction of the EPS.

The impact of xylanases on bleaching of eucalyptus kraft pulp

1994 ◽  
Vol 38 (1) ◽  
pp. 1-6 ◽  
Author(s):  
P. Bajpai ◽  
N.K. Bhardwaj ◽  
P.K. Bajpai ◽  
M.B. Jauhari
Keyword(s):  
Kraft Pulp ◽  
Eucalyptus Kraft Pulp ◽  
The Impact

scholarly journals Comparative Evaluation of Wound Healing Effect of Cord Blood Low Molecular Weight Fraction (Below 5 kDa) and Actovegin Drug in Skin Cryolesions

2021 ◽  
Vol 31 (2) ◽  
pp. 116-126
Author(s):  
Oleksandr Gulevsky ◽  
◽  
Nataliia Moisieieva ◽  
Olga Gorina ◽  
Yuliya Akhatova ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Wound Healing ◽  
Cord Blood ◽  
Weight Fraction ◽  
Blood Parameters ◽  
Low Molecular Weight ◽  
Healing Effect ◽  
Wound Healing Effect ◽  
Blood Fraction ◽  
The Impact

This paper presents the results of comparative studies of the impact of the low molecular weight (below 5 kDa) cattle cord blood fraction (CBF) and the comparator drug Actovegin on tissue regeneration after skin cryoablation in rats. Here, a local contact cryoexposure was shown to result not only in destruction of all skin layers, but secondary ischemic damage to deeper and adjacent tissues as well. The use of an injection solution of CBF as a therapy for simulated cryolesion proved its pronounced wound healing effect, manifested in accelerated reparation, improved trophicity in an injured area due to hypervascularization and prevention of sclerotic processes. The introduction of CBF and Actovegin to rats accelerated the normalization of clinical blood parameters (RBC and WBC counts, alkaline phosphatase activity) in shorter terms as compared with the control. The obtained effect may be compared with Actovegin action.

scholarly journals The Impact of Combination of Ozonation and Ultrasonication Process on Morphological and Chemical Properties of κ-Carrageenan

REAKTOR ◽  
2019 ◽  
Vol 19 (2) ◽  
pp. 49-53
Author(s):  
Nurfiningsih Nurfiningsih ◽  
Ratnawati Ratnawati ◽  
Aji Prasetyaningrum
Keyword(s):  
Molecular Weight ◽  
Chemical Properties ◽  
Morphological Characteristics ◽  
Weight Fraction ◽  
Sem Analysis ◽  
Low Molecular Weight ◽  
Sulfate Content ◽  
Biomedical Field ◽  
The Impact ◽  
And Chemical Properties

Carrageenan application in the biomedical field is influenced by the size of molecular weight. Depolymerization process is needed for changing the high molecular weight (HMW) fraction of κ- carrageenan into low molecular weight fraction (LMW) of κ- carrageenan. Ozone is a powerful oxidant and considered for depolymerization of κ- carrageenan. This research was conducted as an investigation on the influence of the combination of ozonation and ultrasonication (OZ/US) on the chemical and morphological characteristics of κ-carrageenan. FTIR and Scanning electron microscopy (SEM) was used to determine the change of chemical and morphological characteristics of κ-carrageenan. The result of this study showed that there was no change of chemical properties of κ-carrageenan during OZ/US treatment. The sulfate content was obtained after OZ/US treatment tends to be stable.  Nevertheless, the result of SEM analysis showed that there were changes on morphological characteristics of κ-carrageenan after OZ/US treatment.  Keywords: ultrasonication, κ-carrageenan, ozonation, morphological, chemical

Understanding the pulping and bleaching performances of eucalyptus woods affected by physiological disturbance

TAPPI Journal ◽  
2018 ◽  
Vol 17 (11) ◽  
pp. 633-642 ◽  
Author(s):  
Juliana Marangon Jardim ◽  
Carolina Marangon Jardim ◽  
Jorge Luiz Colodette
Keyword(s):  
Kraft Pulp ◽  
Negative Impact ◽  
Low Cost ◽  
Wood Quality ◽  
High Yield ◽  
Kraft Pulps ◽  
Bleached Pulp ◽  
Eucalyptus Kraft Pulp ◽  
The Impact

The wood quality is a factor of extreme importance when the pulping process is targeting high yield, low cost, and high pulp quality. Thus, wood knowledge is crucial for process optimization. In some northeastern Brazilian eucalyptus plantations, a physiological disturbance caused by water stress has been observed. Up to now, there have been no studies concerning the effects of such disturbances on the wood quality or on the pulping and bleaching process performance. The present work is aimed at understanding the impact of the stress on the production of bleached pulp. The wood quality of two clones (one tolerant to the disturbance and another sensitive), cultivated in sites where the disturbance is present and absent, was evaluated. Kraft pulps of kappa number 20 were produced and bleached by the sequence DHT(EP)D1 to a brightness of 90% ISO, which allowed for assessment of the wood pulpability and bleachability. It was concluded that the disturbance affects the wood quality, and overall it showed a negative impact on the production of bleached eucalyptus kraft pulp, with significant potential economical setbacks.

Studies on the Functionality of Newly Synthesized Fibrinogen after Treatment of Acute Myocardial Infarction with Streptokinase, Increase in the Rate of Fibrinopeptide Release

1993 ◽  
Vol 70 (06) ◽  
pp. 0978-0983 ◽  
Author(s):  
Edelmiro Regano ◽  
Virtudes Vila ◽  
Justo Aznar ◽  
Victoria Lacueva ◽  
Vicenta Martinez ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Acute Myocardial Infarction ◽  
Molecular Weight ◽  
Steady State ◽  
High Molecular Weight ◽  
Coronary Arteries ◽  
Risk Index ◽  
Weight Fraction ◽  
High Molecular Weight Fraction ◽  
Fibrinopeptide A

SummaryIn 15 patients with acute myocardial infarction who received 1,500,000 U of streptokinase, the gradual appearance of newly synthesized fibrinogen and the fibrinopeptide release during the first 35 h after SK treatment were evaluated. At 5 h the fibrinogen circulating in plasma was observed as the high molecular weight fraction (HMW-Fg). The concentration of HMW-Fg increased continuously, and at 20 h reached values higher than those obtained from normal plasma. HMW-Fg represented about 95% of the total fibrinogen during the first 35 h. The degree of phosphorylation of patient fibrinogen increased from 30% before treatment to 65% during the first 5 h, and then slowly declined to 50% at 35 h.The early rates of fibrinopeptide A (FPA) and phosphorylated fibrinopeptide A (FPAp) release are higher in patient fibrinogen than in isolated normal HMW-Fg and normal fibrinogen after thrombin addition. The early rate of fibrinopeptide B (FPB) release is the same for the three fibrinogen groups. However, the late rate of FPB release is higher in patient fibrinogen than in normal HMW-Fg and normal fibrinogen. Therefore, the newly synthesized fibrinogen clots faster than fibrinogen in the normal steady state.In two of the 15 patients who had occluded coronary arteries after SK treatment the HMW-Fg and FPAp levels increased as compared with the 13 patients who had patent coronary arteries.These results provide some support for the idea that an increased synthesis of fibrinogen in circulation may result in a procoagulant tendency. If this is so, the HMW-Fg and FPAp content may serve as a risk index for thrombosis.

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