Extraction of Tungsten with Trialkylamine - Effect of pH

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Title:Extraction of Tungsten with Trialkylamine - Effect of pH
Creators:
Procházka, Jaroslav
Heyberger, Aleš
Horáček, Jan
Volaufová, Eva
Voborská, Jitka
Macháčková, Eva
Journal or Publication Title:
Collection of Czechoslovak Chemical Communications, 66, 9, pp. 1407-1419
Uncontrolled Keywords:pH effect, Equilibrium, Liquid-liquid extraction, Ion exchange, Tungsten, Wolfram, Tungstates

Abstract

Extraction equilibrium in the system aqueous solution of sodium tungstate-solution of trialkylamine in a mixed diluent was investigated. A tertiary amine with C<sub>7</sub>-C<sub>9</sub> straight alkyl chains was dissolved in a mixture of tributyl phosphate and kerosene and presaturated with sulfuric acid to give normal trialkylamine sulfate. Extraction isotherms at 25 °C and at several constant values of equilibrium pH were measured in a broad range of aqueous tungstate concentrations. pH 2.0-6.0 was adjusted by addition of sulfuric acid during equilibration. The equilibrium tungstate and sulfate contents in both phases were determined. A typical tungstate isotherm exhibits a steep ascending part in the low concentration range, corresponding to the region of anion exchange, and a flat part in the high concentration range, where the acid content in the organic phase is virtually exhausted. The level of the flat part decreases with growing pH, corresponding to the increasing number of negative charges per tungsten atom in the tungstate polyanions extracted. At pH &gt; 5, also the effect of hydrolysis of amine sulfate could be detected. <p>

Title:Extraction of Tungsten with Trialkylamine - Effect of pH
Creators:
Procházka, Jaroslav
Heyberger, Aleš
Horáček, Jan
Volaufová, Eva
Voborská, Jitka
Macháčková, Eva
Uncontrolled Keywords:pH effect, Equilibrium, Liquid-liquid extraction, Ion exchange, Tungsten, Wolfram, Tungstates
Divisions:Life and Chemical Sciences > Institute of Organic Chemistry and Biochemistry > Collection of Czechoslovak Chemical Communications
Journal or Publication Title:Collection of Czechoslovak Chemical Communications
Volume:66
Number:9
Page Range:pp. 1407-1419
ISSN:0010-0765
E-ISSN:1212-6950
Publisher:Institute of Organic Chemistry and Biochemistry
Related URLs:
URLURL Type
http://dx.doi.org/10.1135/cccc20011407UNSPECIFIED
ID Code:1866
Item Type:Article
Deposited On:06 Feb 2009 17:13
Last Modified:06 Feb 2009 16:13

Citation

Procházka, Jaroslav; Heyberger, Aleš; Horáček, Jan; Volaufová, Eva; Voborská, Jitka; Macháčková, Eva (2001) Extraction of Tungsten with Trialkylamine - Effect of pH. Collection of Czechoslovak Chemical Communications, 66 (9). pp. 1407-1419. ISSN 0010-0765

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