An improved TCF sequence for biobleaching kenaf pulp: Influence of the hexenuronic acid content and the use of xylanase

2014 ◽  
Vol 152 ◽  
pp. 253-258 ◽  
Author(s):  
Glòria Andreu ◽  
Teresa Vidal
Keyword(s):  
Acid Content ◽  
Hexenuronic Acid

Voltammetric analysis of the bleachability of softwood kraft pulps

Holzforschung ◽  
2004 ◽  
Vol 58 (6) ◽  
pp. 581-587 ◽  
Author(s):  
Robert Bourbonnais ◽  
Loredana Valeanu ◽  
Michael G. Paice
Keyword(s):  
Chlorine Dioxide ◽  
Acid Content ◽  
Black Spruce ◽  
Kappa Number ◽  
Western Hemlock ◽  
Kraft Pulps ◽  
Residual Lignin ◽  
Redox Mediators ◽  
Voltammetric Analysis ◽  
Hexenuronic Acid

Abstract Kraft and oxygen delignified pulps with various kappa numbers were prepared from black spruce and western hemlock chips. The bleachability (ratio of kappa number decrease to chlorine dioxide applied) of the different pulps at the same kappa number varied with both wood furnish and delignification process. Thus, unbleached kappa number alone is not a reliable indicator of bleachability for these pulps. This may be due in part to the variable hexenuronic acid content of the pulps; those with higher ratio of hexenuronic acid content to kappa number (HexA/kappa) are harder to bleach. Voltammetric analysis of the same kraft pulps in the presence of redox mediators was found to measure both the content and reactivity of residual lignin. Peak current ratios of redox mediators correlated with pulp bleachability for all pulps. These ratios may therefore provide a more accurate prediction of bleachability than unbleached kappa number.

A study of anthraquinone-fortified green liquor pretreatment of loblolly pine chips

Holzforschung ◽  
2009 ◽  
Vol 63 (3) ◽  
Author(s):  
Weiping Ban ◽  
Qiujuan Liu ◽  
Jiqiang Guo ◽  
Haibo Mao ◽  
Lucian A. Lucia
Keyword(s):  
Carboxylic Acid ◽  
Loblolly Pine ◽  
Acid Content ◽  
Lignin Content ◽  
Chemical Reactivity ◽  
Energy Requirement ◽  
Kraft Pulping ◽  
Specific Level ◽  
Green Liquor ◽  
Hexenuronic Acid

Abstract Green liquor (GL) pretreatment for kraft pulping technologies was modified by applying anthraquinone (AQ) during the pretreatment stage. Analysis of the pulp lignin contents and final pulp yields demonstrated that the addition of AQ improved delignification selectivity. A proposed mechanism for the behavior of AQ during the GL pretreatment is that it amplifies delignification rather than preserves hemicelluloses. An analysis of the pulp carboxylic acid groups indicated that AQ did not affect the total carboxylic acid content in the pulp, but provided a lower hexenuronic acid content at a specific level of lignin content. In general, green liquor pretreatment reduces the energy requirement for pulping and improves chemical reactivity during delignification. As a result, net pulping efficiency for a kraft pulping operation can be improved.

Influence of the hexenuronic acid content on refining and ageing in eucalyptus TCF pulp

2010 ◽  
Vol 101 (10) ◽  
pp. 3554-3560 ◽  
Author(s):  
Edith M. Cadena ◽  
Teresa Vidal ◽  
Antonio L. Torres
Keyword(s):  
Acid Content ◽  
Hexenuronic Acid

scholarly journals Relationship between Hexenuronic Acid Content of Pulp and Brightness Stability in Accelerated Aging

2012 ◽  
Vol 66 (7) ◽  
pp. 743-757 ◽  
Author(s):  
Eiko Kuwabara ◽  
Xin Zhou ◽  
Mitsuko Homma ◽  
Shiho Takahashi ◽  
Mikio Kajiyama ◽  
...  
Keyword(s):  
Acid Content ◽  
Accelerated Aging ◽  
Hexenuronic Acid

Inter-laboratory comparisons of hexenuronic acid measurements in kraft eucalyptus pulps using a UV-Vis spectroscopic method

TAPPI Journal ◽  
2014 ◽  
Vol 13 (1) ◽  
pp. 57-61 ◽  
Author(s):  
J.Y. ZHU ◽  
H.F. ZHOU ◽  
X.S. CHAI ◽  
DONNA JOHANNES ◽  
RICHARD POPE ◽  
...  
Keyword(s):  
Acid Content ◽  
Spectroscopic Method ◽  
The Other ◽  
Kraft Pulps ◽  
Chemical Pulp ◽  
Three Samples ◽  
Hexenuronic Acid ◽  
Replicate Measurements ◽  
The Comparative Study ◽  
Measurement Repeatability

An inter-laboratory comparison of a UV-Vis spectroscopic method (TAPPI T 282 om-13 “Hexeneuronic acid content of chemical pulp”) for hexeneuronic acid measurements was conducted using three eucalyptus kraft pulps. The pulp samples were produced in a laboratory at kappa numbers of approximately 14, 20, and 35. The hexeneuronic acid contents of the three pulps were approximately 55–65 μmol/g, or with a variation of approximately 15%. Five laboratories from four different countries participated in this round-robin study as part of the evaluation of the TAPPI provisional method for upgrading to a TAPPI standard method. The comparative study showed that the orders of hexeneuronic acid content from low to high among the three pulp samples produced by four laboratories were in agreement. Replicate measurements were not conducted at the laboratory that produced an inconsistent order of hexeneuronic acid among the three pulp samples compared with the other four laboratories. The differences in hexeneuronic acid contents from different laboratories were systematic and consistent; that is, some laboratories consistently produced high values of hexeneuronic acid for all three samples. The comparative data of three pulp samples concluded that the measurement repeatability (within a laboratory) was less than 3% and reproducibility (among laboratories) was less than 16%.

Effect of light intensity on the ultrastructure of the filamentous cyanobacterium, Anabaena variabilis

1988 ◽  
Vol 46 ◽  
pp. 300-301
Author(s):  
C. S. Bricker ◽  
S. R. Barnum ◽  
B. Huang ◽  
J. G. Jaworskl
Keyword(s):  
Fatty Acid ◽  
Light Intensity ◽  
Acid Content ◽  
Fatty Acid Content ◽  
Anabaena Variabilis ◽  
Chloroplast Envelope ◽  
Major Constituent ◽  
Filamentous Cyanobacterium ◽  
Photosynthetic Membrane ◽  
Effect Of Light

Cyanobacteria are Gram negative prokaryotes that are capable of oxygenic photosynthesis. Although there are many similarities between eukaryotes and cyanobacteria in electron transfer and phosphorylation during photosynthesis, there are two features of the photosynthetic apparatus in cyanobacteria which distinguishes them from plants. Cyanobacteria contain phycobiliproteins organized in phycobilisomes on the surface of photosynthetic membrane. Another difference is in the organization of the photosynthetic membranes. Instead of stacked thylakolds within a chloroplast envelope membrane, as seen In eukaryotes, IntracytopIasmlc membranes generally are arranged in three to six concentric layers. Environmental factors such as temperature, nutrition and light fluency can significantly affect the physiology and morphology of cells. The effect of light Intensity shifts on the ultrastructure of Internal membrane in Anabaena variabilis grown under controlled environmental conditions was examined. Since a major constituent of cyanobacterial thylakolds are lipids, the fatty acid content also was measured and correlated with uItrastructural changes. The regulation of fatty acid synthesis in cyanobacteria ultimately can be studied if the fatty acid content can be manipulated.

129: Sialic Acid Content of Urinary TAMM-Horsfall Protein is Reduced in Interstitial Cystitis Patients

2007 ◽  
Vol 177 (4S) ◽  
pp. 44-45
Author(s):  
C. Lowell Parsons ◽  
Mahadevan Rajasekaran ◽  
Marianne Chenoweth ◽  
Paul Stein
Keyword(s):  
Sialic Acid ◽  
Interstitial Cystitis ◽  
Acid Content ◽  
Sialic Acid Content
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