Degradation of Hardwood Sulfate Pulp in Aqueous Dioxane

2005 ◽  
Vol 78 (8) ◽  
pp. 1333-1336 ◽  
Author(s):  
E. V. Udoratina ◽  
V. A. Demin
Keyword(s):  
Aqueous Dioxane ◽  
Sulfate Pulp

scholarly journals Kinetics and Mechanism of the Change of the 4-Nitrobenzylthio-System into 4,4′-Diformylazoxybenzene in Alkaline Dioxane-Water Media

1985 ◽  
Vol 40 (11) ◽  
pp. 1128-1132
Author(s):  
Y. Riad ◽  
Adel N. Asaad ◽  
G.-A. S. Gohar ◽  
A. A. Abdallah
Keyword(s):  
Acetic Acid ◽  
Sodium Hydroxide ◽  
Rate Constants ◽  
Main Product ◽  
Reaction Medium ◽  
Aqueous Dioxane ◽  
Proton Abstraction ◽  
First Order ◽  
Water Media ◽  
Different Temperatures

Sodium hydroxide reacts with α -(4-nitrobenzylthio)-acetic acid in aqueous-dioxane media to give 4,4'-diformylazoxybenzene as the main product besides 4,4'-dicarboxyazoxybenzene and a nitrone acid. This reaction was kinetically studied in presence of excess of alkali in different dioxane-water media at different temperatures. It started by a fast reversible a-proton abstraction step followed by two consecutive irreversible first-order steps forming two intermediates (α -hydroxy, 4-nitrosobenzylthio)-acetic acid and 4-nitrosobenzaldehyde. The latter underwent a Cannizzaro's reaction, the products of which changed in the reaction medium into 4,4'-diformylazoxybenzene and 4,4'-dicarboxyazoxybenzene. The rate constants and the thermodynamic parameters of the two consecutive steps were calculated and discussed. A mechanism was put forward for the formation of the nitrone acid.Other six 4-nitrobenzyl, aryl sulphides were qualitatively studied and they gave mainly 4,4'-diformylazoxybenzene beside 4,4'-dicarboxyazoxybenzene or its corresponding azo acid.

THE ALKALINE CLEAVAGE OF o-NITROBENZYLTRIMETHYLSILANE SOLVENT EFFECTS IN THE DIOXANE–WATER SYSTEM

1963 ◽  
Vol 41 (6) ◽  
pp. 1525-1530 ◽  
Author(s):  
H. R. Allcock
Keyword(s):  
Transition State ◽  
Solvent Effects ◽  
Water System ◽  
Solvent Polarity ◽  
High Water ◽  
Aqueous Dioxane ◽  
Alkaline Cleavage ◽  
Rate Of Reaction ◽  
Kinetics Of

The kinetics of alkaline cleavage of o-nitrobenzyltrimethylsilane were examined in aqueous dioxane media. At high water concentrations, increases in solvent polarity retard the cleavage, as required by a mechanism involving charge dispersion in the transition state. At high dioxane concentrations, solvent polarity increases are accompanied by increases in the rate of reaction, a result which may reflect association between the solvent components.

Structure of aqueous dioxane solutions of alkali metal hydroxides according to PMR data

1980 ◽  
Vol 21 (2) ◽  
pp. 162-167
Author(s):  
N. G. Dovbysh ◽  
Yu. A. Volokhov ◽  
V. B. Lebedev ◽  
V. M. Sizyakov ◽  
V. E. Mironov
Keyword(s):  
Alkali Metal ◽  
Aqueous Dioxane ◽  
Metal Hydroxides ◽  
Alkali Metal Hydroxides

α-DEUTERIUM KINETIC ISOTOPE EFFECTS IN SOLVOLYSES OF endo-NORBORNYL p-BROMOBENZENESULFONATE

1965 ◽  
Vol 43 (8) ◽  
pp. 2254-2258 ◽  
Author(s):  
C. C. Lee ◽  
Edward W. C. Wong
Keyword(s):  
Acetic Acid ◽  
Formic Acid ◽  
Isotope Effects ◽  
Kinetic Isotope Effects ◽  
Aqueous Dioxane ◽  
Kinetic Isotope ◽  
Different Temperatures

endo-Norbornyl-2-d p-bromobenzenesulfonate was synthesized and the isotope effects, as measured by kH/kD, were determined over a range of temperatures for solvolyses in 30% water – 70% dioxane, acetic acid, and formic acid. Values of kH/kD are of the order of 1.20. The data appear to indicate slightly higher isotope effects as the solvents are changed from aqueous dioxane to acetic acid to formic acid, as well as somewhat higher isotope effects at lower temperatures. Possible mechanistic implications of these results are presented. Relative titrimetric acetolysis rates, kexo/kendo, at different temperatures, and enthalpies and entropies of activation for these acetolyses are evaluated and discussed.

Copper(II) Chloride Catalyzed Carboxydediazoniation of Arenediazonium Tetrafluoroborates with Carbon Monoxide in Aqueous Dioxane Solution to Arenecarboxylic Acids1

Synlett ◽  
1990 ◽  
Vol 1990 (10) ◽  
pp. 596-598 ◽  
Author(s):  
George A. Olah ◽  
An-hsiang Wu ◽  
Alessandro Bagno ◽  
G. K. Surya Prakash
Keyword(s):  
Carbon Monoxide ◽  
Aqueous Dioxane ◽  
Dioxane Solution

Reactivity of α-amino acids in the N-acylation with benzoic acid esters in aqueous dioxane

2010 ◽  
Vol 80 (5) ◽  
pp. 964-967 ◽  
Author(s):  
N. R. Ishkulova ◽  
L. E. Oparina ◽  
L. B. Kochetova ◽  
T. P. Kustova ◽  
N. V. Kalinina ◽  
...  
Keyword(s):  
Amino Acids ◽  
Benzoic Acid ◽  
Aqueous Dioxane ◽  
Acid Esters

Treatability of kraft pulp bleaching wastewater by biochemical and photocatalytic oxidation

1999 ◽  
Vol 40 (1) ◽  
pp. 281-288 ◽  
Author(s):  
Işıl Akmehmet Balcıoǧlu ◽  
Ferhan Çeçen
Keyword(s):  
Biological Treatment ◽  
Kraft Pulp ◽  
Photocatalytic Oxidation ◽  
Treated Wastewater ◽  
Oxidation Reactions ◽  
Pulp Bleaching ◽  
Kraft Pulp Bleaching ◽  
Activated Sludge Reactor ◽  
Sulfate Pulp ◽  
Biological Treatability

In this study the biological treatability and TiO2 photocatalyzed oxidation characteristics of sulfate pulp bleaching effluents were investigated. The original wastes had a low biodegradability as determined by BOD5/COD ratios. Biological treatment was conducted in a batch activated sludge reactor. The non-biodegradable fraction amounted to 60% of the initial COD and compounds specific to these wastes were not removed during biotreatment. In order to enhance the biodegradability of these wastes, mixed raw effluent, C/E-H stage effluent, D/E-D stage effluent and biologically pretreated wastes were subjected to TiO2 photocatalyzed oxidation. Photocatalytic oxidation led to an increase in the BOD5/COD ratio of D/E-H stage raw and biologically treated wastewater, while chloride formation was observed in both cases in a five-hour reaction period in the presence of 1g 1−1 TiO2 and 15×10−3 M H2O2 at pH=6.5. The specific absorption values (A272nm/CODs, A254nm/CODs, A346nm/CODs, A436nm/CODs) exhibited parallel decreases during photocatalytic oxidation which indicate that oxidation reactions were nonspecific with respect to the organics present in these wastes. As a conclusion it can be suggested that biological treatment should be placed before the photocatalytic oxidation method. Even in this scheme, the application of photocatalytic oxidation could only then be favored when the COD and chloride concentrations in the wastewater were below certain values or when wastewater was diluted.

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