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.

Fibre strength in relation to molecular weight distribution of hardwood kraft pulp

2000 ◽  
Vol 15 (4) ◽  
pp. 326-332 ◽  
Author(s):  
Elisabeth Sjöholm ◽  
Kristina Gustafsson ◽  
Erik Norman ◽  
Torbjörn Reitberger ◽  
Anders Colmsjö
Keyword(s):  
Molecular Weight ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Kraft Pulp ◽  
Fibre Strength

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.

Studies on oxidative modifications of cellulose in the periodate system: Molecular weight distribution and carbonyl group profiles

Holzforschung ◽  
2007 ◽  
Vol 61 (6) ◽  
pp. 662-667 ◽  
Author(s):  
Antje Potthast ◽  
Mirjana Kostic ◽  
Sonja Schiehser ◽  
Paul Kosma ◽  
Thomas Rosenau
Keyword(s):  
Molecular Weight ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Periodate Oxidation ◽  
Gel Permeation Chromatography ◽  
Fluorescence Labeling ◽  
Carbonyl Groups ◽  
Oxidation Degree ◽  
Multiple Detection ◽  
Low Degrees

Abstract The effects of periodate oxidation on cellulose were studied by means of gel permeation chromatography (GPC) using multiple detection and carbonyl-selective fluorescence labeling according to the CCOA methodology profiling of carbonyl groups. At low degrees of oxidation, the molecular weight distribution was fully maintained. Upon more pronounced oxidation the molecular weight even increased due to cross-linking effects. More condensed structures were identified by means of light scattering. Periodate oxidation also affects crystalline regions of cellulose, as demonstrated by comparison of homogeneous and heterogeneous carbonyl labeling. Highly ordered regions in cellulose were affected by oxidation even below an oxidation degree of 2%. Two different phases for the oxidation kinetics were identified in the early stages of periodate treatments.

Extraction and Partial Purification of Protease from Bilimbi (Averrhoa bilimbi L.)

2013 ◽  
Vol 10 (2) ◽  
pp. 29
Author(s):  
Normah Ismail ◽  
Nur' Ain Mohamad Kharoe
Keyword(s):  
Molecular Weight ◽  
Protein Content ◽  
Ammonium Sulfate ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Protease Activity ◽  
Protein Concentration ◽  
Temperature Stability ◽  
Partial Purification ◽  
Ammonium Sulfate Precipitation

Unripe and ripe bilimbi (Averrhoa bilimbi L.) were ground and the extracted juices were partially purified by ammonium sulfate precipitation at the concentrations of 40 and 60% (w/v). The collected proteases were analysed for pH, temperature stability, storage stability, molecular weight distribution, protein concentration and protein content. Protein content of bilimbi fruit was 0.89 g. Protease activity of both the unripe and ripe fruit were optimum at pH 4 and 40°C when the juice were purified at 40 and 60% ammonium sulfate precipitation. A decreased in protease activity was observed during the seven days of storage at 4°C. Molecular weight distribution indicated that the proteases protein bands fall between IO to 220 kDa. Protein bands were observed at 25, 50 and 160 kDa in both the unripe and ripe bilimbi proteases purified with 40% ammonium sulfate, however, the bands were more intense in those from unripe bilimbi. No protein bands were seen in proteases purified with 60% ammonium sulfate. Protein concentration was higher for proteases extracted with 40% ammonium sulfate at both ripening stages. Thus, purification using 40% ammonium sulfate precipitation could be a successful method to partially purify proteases from bilimbi especially from the unripe stage. 

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