Use of the Ion Exchange Method for Determination of Stability Constants of Uranyl Ions with Three Soil Humic Acids

Zuyi, Tao; Du, Jinzhou

doi:10.1524/ract.1994.64.34.225

Cited by 14 publications

(8 citation statements)

References 8 publications

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“…Other possible chemical models involving (UO 2 ) 3 (OH) 5 + or (UO 2 ) 4 (OH) 7 + could be ruled out, see end of Sect. 3.2. below for details.…”

Section: Complexation Model For Neutral Ph Conditionsmentioning

confidence: 99%

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Uranium(VI) complexation by humic acid under neutral pH conditions studied by laser-induced fluorescence spectroscopy

Sachs¹,

Brendler²,

Geipel³

2007

Radiochimica Acta

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The complexation of U(VI) with Aldrich humic acid (HA) was studied at pH 7 under exclusion of CO 2 . Using two independent laser-induced spectroscopic methods, timeresolved laser-induced fluorescence spectroscopy (TRLFS) and TRLFS with ultrafast pulses (fs-TRLFS), the formation of the ternary U(VI) mono hydroxo humate complex UO 2 (OH)HA(I) by reaction of UO 2 OH + with HA was studied. Assuming that all proton exchanging functional groups of the HA are able to contribute to the complex formation, a mean stability constant of 6.58 ± 0.24 was derived for UO 2 (OH)HA(I). Alternatively, the analytical data were evaluated based on the metal ion charge neutralization model resulting in a complexation constant of 6.95 ± 0.10 and a loading capacity of 0.76 ± 0.28. An overall complexation constant of log β 0.1 M = 14.89 ± 0.54 was calculated for the total reaction of U(VI) with HA starting from the non-hydrolyzed UO 2 2+ ion. This value agrees very well with literature data. Taking into account the UO 2 (OH)HA(I) complex, the speciation of U(VI) in presence of HA was recalculated. It was found, that the formation of UO 2 (OH)HA(I) can significantly influence the U(VI) distribution in the environmentally relevant pH region. As a consequence, the mobility of U(VI) in natural aquifer systems could be enhanced.

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“…Other possible chemical models involving (UO 2 ) 3 (OH) 5 + or (UO 2 ) 4 (OH) 7 + could be ruled out, see end of Sect. 3.2. below for details.…”

Section: Complexation Model For Neutral Ph Conditionsmentioning

confidence: 99%

“…Thermodynamic complexation data for the interaction of U(VI) with HA (e.g., [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]) have been determined applying different methods and complexation models. These studies *Author for correspondence (E-mail: S.Sachs@fz-rossendorf.de).…”

Section: Introductionmentioning

confidence: 99%

Uranium(VI) complexation by humic acid under neutral pH conditions studied by laser-induced fluorescence spectroscopy

Sachs¹,

Brendler²,

Geipel³

2007

Radiochimica Acta

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“…Therefore the complexation has been rather extensively studied [7][8][9][10][11][12][13][14][15][16]. The nature of the uranium-humic acid complexes was characterized using a number of methods including ion exchange [9,11,[13][14][15][16], dialysis [8], ultrafiltration [8,15], solvent extraction [10], chelating resin [12] and laser spectroscopy [12,15], yielding several stability constants of the complexes. Very little direct information on the charge of the complexes was obtained [15] and virtually no data on their electrophoretic mobilities exist.…”

Section: Introductionmentioning

confidence: 99%

Effect of Humic Acid on the Electrophoretic Mobility of Uranium (VI) in Aqueous Solutions

1999

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Electrophoresis of hexavalent uranium in aqueous solutions containing humic acid (HA) Gohy-573 was studied with the aim to characterize the uranium-humic acid (U-HA) complexes formed. Electrophoretic mobility of uranium towards cathode and anode was determined using a free-liquid electrophoresis, as a function of pH and concentration of humic acid and uranium. Experiments with solutions of 1 X 10~4 mol/1 uranium in absence of humic acid indicated hydrolysis of uranium at pH 3-5. Similar hydrolysis, probably accompanied by the formation of pseudocolloids, was also found for 1 X 10 6 mol/1 uranium. Addition of humic acid in 5.6 X 10~6, 3 X10 5 or 1 X 10 4 mol/1 concentration to 5 X 10" 7 -2 X 10 4 mol/1 solution of uranium at pH 4.0 caused decrease in uranium mobility towards cathode and increase in its mobility towards anode, due to the formation of neutral and/or negatively charged U-HA complexes. The changes were more pronounced at higher ratio [HA]/[U] concentrations. Abundances of U-HA complexes and their mean mobilities towards anode were calculated from the results obtained. It was found that the mobilities decrease with the increasing [U]/HA] ratio due to saturation of negative charge of the humic acid with positively charged uranium species, mainly UO! + .

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“…In previous papers, the stability constants of uranyl ion complexes with three soil humic acids (HA) and of Th with one soil humic acid (HA) and one fulvic acid (FA) extracted from the weathered coal were determined by using the modified Ardakani-Stevenson's method [1,2]. This method was proved to be applicable for the determination of stability constants of complexes with humic substances.…”

Section: Introductionmentioning

confidence: 99%

“…This method was proved to be applicable for the determination of stability constants of complexes with humic substances. In the present paper, these studies were extended to the determination of stability constants of uranyl ion complexes with three soil fulvic acids which are extracted from the same soils as were used in the previous work [1], and a comparison of stability constants and compositions between the uranyl ion complexes with humic and fulvic acids extracted from the same soil was made.…”

Section: Introductionmentioning

confidence: 99%

Use of the Ion Exchange Method for Determination of Stability Constants of Uranyl Ions with Three Soil Fulvic Acids

Zuyi

1996

Radiochimica Acta

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Uranyl ions / Fulvic acid / Ion exchange / Stability constantsperature. The modified calculation method for ß^ was given in the previous papers [1,2]. AbstractThe stabihty constants of uranyl ion complexes with three soil fulvic acids were determined by using the modified ArdakaniStevenson's method at pH = 6, ionic strength 0.1 mol/1 and 25 °C. It was found that 1:1 and 1:2 type complexes, respectively, are formed at different concentration ratios of UO^ to the fulvic acid.

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Use of the Ion Exchange Method for Determination of Stability Constants of Uranyl Ions with Three Soil Humic Acids

Cited by 14 publications

References 8 publications

Uranium(VI) complexation by humic acid under neutral pH conditions studied by laser-induced fluorescence spectroscopy

Uranium(VI) complexation by humic acid under neutral pH conditions studied by laser-induced fluorescence spectroscopy

Effect of Humic Acid on the Electrophoretic Mobility of Uranium (VI) in Aqueous Solutions

Use of the Ion Exchange Method for Determination of Stability Constants of Uranyl Ions with Three Soil Fulvic Acids

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