Determination of conditional stability constants of cadmium-humic acid complexes in freshwater by use of a competitive ligand equilibration-solvent extraction technique

2000 ◽  
Vol 19 (2) ◽  
pp. 283-292 ◽  
Author(s):  
Luc Van Ginneken ◽  
Ronny Blust
Keyword(s):  
Humic Acid ◽  
Solvent Extraction ◽  
Stability Constants ◽  
Extraction Technique ◽  
Conditional Stability ◽  
Conditional Stability Constants ◽  
Solvent Extraction Technique ◽  
Competitive Ligand

Determination of Co(II) and Ni(II)-humate stability constants at high ionic strength NaCl solutions

2000 ◽  
Vol 88 (9-11) ◽  
Author(s):  
D.N. Kurk ◽  
Gregory R. Choppin
Keyword(s):  
Humic Acid ◽  
Ionic Strength ◽  
Solvent Extraction ◽  
Potentiometric Titration ◽  
Stability Constants ◽  
Dissociation Constants ◽  
High Ionic Strength ◽  
Extraction Technique ◽  
Solvent Extraction Technique

Complexation of Ni(II) and Co(II) by unfractionated humic acid (HA) was measured in 0.3 to 5.0 m NaCl solutions at pH 6 and 20 °C, using a solvent extraction technique. The dissociation constants and capacities of the humic acid were investigated in 0.1 to 5.0 m NaCl solutions at 25 °C using potentiometric titration methods.

Reactions of gallocyanine methyl ester with gallium(III) and indium(III) ions

1982 ◽  
Vol 47 (7) ◽  
pp. 1950-1963 ◽  
Author(s):  
Milan Kotouček ◽  
Josef Růžička ◽  
Pavla Vaculíková
Keyword(s):  
Methyl Ester ◽  
Stability Constants ◽  
Equilibrium Constants ◽  
Photometric Determination ◽  
Conditional Stability ◽  
Conditional Stability Constants

Reactions of gallocyanine methyl ester with gallium(III) and indium(III) ions in solutions in 15% (m/m) ethanol were studied spectrophotometrically. At pH 1.7-6.5, the GaL, GaL2, and Ga(OH)L3 complexes are formed; in the case of indium, the In(OH)2L2 and In(OH)L3 complexes appear at pH 4-6.5, and InL3B2 in tartrate solutions. The conditional stability constants and the equilibrium constants of the coordination equilibria were calculated, and procedures were worked out for a photometric determination of gallium and for a chelatometric determination of gallium and indium using gallocyanine methyl ester as metallochromic indicator.

scholarly journals Determination of complex formation constants of neptunium(V) with propionate and lactate in 0.5–2.6 m NaCl solutions at 22–60°C using a solvent extraction technique

2019 ◽  
Vol 107 (7) ◽  
pp. 623-634
Author(s):  
Aleksandr N. Vasiliev ◽  
Nidhu L. Banik ◽  
Rémi Marsac ◽  
Stepan N. Kalmykov ◽  
Christian M. Marquardt
Keyword(s):  
Solvent Extraction ◽  
Complex Formation ◽  
Nuclear Waste ◽  
Equilibrium Constants ◽  
Extraction Technique ◽  
Nuclear Waste Repository ◽  
Clay Rock ◽  
Complex Formation Constants ◽  
Solvent Extraction Technique

Abstract Natural clay rocks like Opalinus (OPA) and Callovo-Oxfordian (COx) clay rock are considered as potential host rocks for deep geological disposal of nuclear waste. However, small organic molecules such as propionate and lactate exist in clay rock pore water and might enhance Np mobility through a complexation process. Therefore, reliable complex formation data are required in the frame of the Safety Case for a nuclear waste repository. A solvent extraction technique was applied for the determination of ${\rm{NpO}}_2^ + $ complexation with propionate and lactate. Extraction was conducted from isoamyl alcohol solution containing 10−3 M TTA and 5 · 10−4 M 1,10-phenanthroline. Experiments were performed in 0.5–2.6 m NaCl solutions at temperatures ranging from 22 to 60 °C. Formation of 1:1 Np(V) complexes for propionate and lactate was found under the studied conditions. The SIT approach was applied to calculate equilibrium constants β°(T) at zero ionic strength from the experimental data. Log β°(T) is found linearly correlated to 1/T for propionate and lactate, evidencing that heat capacity change is near 0. Molal reaction enthalpy and entropy ( ${\Delta _{\rm{r}}}H_{\rm{m}}^ \circ $ and ${\Delta _{\rm{r}}}S_{\rm{m}}^ \circ $ ) could therefore be derived from the integrated van’t Hoff equation. Data for log β° (298.15 K) are in agreement with literature values for propionate and lactate. Np(V) speciation was calculated for concentrations of acetate, propionate and lactate measured in clay pore waters of COx. In addition, the two site protolysis non-electrostatic surface complexation and cation exchange (2SPNE SC/CE) model was applied to quantitatively describe the influence of Np(V) complexation on its uptake on Na-illite, a relevant clay mineral of OPA and COx.

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