Comparison of Conditional Stability Constants of North Carolina Humic and Fulvic Acids with Co(II) and Fe(III)

1972 ◽  
pp. 79-84 ◽  
Author(s):  
Ronald L. Malcolm
Keyword(s):  
North Carolina ◽  
Stability Constants ◽  
Fulvic Acids ◽  
Conditional Stability ◽  
Humic And Fulvic Acids ◽  
Conditional Stability Constants

Fluorescence Analysis of Cu(II), Pb(II) and Hg(II) Ion Binding to Humic and Fulvic Acids

2016 ◽  
Vol 851 ◽  
pp. 135-140 ◽  
Author(s):  
Vojtěch Enev ◽  
Irena Türkeová ◽  
Jana Szewieczková ◽  
Leos Doskocil ◽  
Martina Klučáková
Keyword(s):  
Humic Substances ◽  
Stability Constants ◽  
Metal Ion ◽  
Fluorescence Analysis ◽  
Fulvic Acids ◽  
Ion Binding ◽  
Conditional Stability ◽  
Metal Ion Binding ◽  
The Stability ◽  
Conditional Stability Constants

Abstract. The aim of this work was to study molecular and quantitative aspects of metal ion binding to humic substances (HS). The object of our study was characterization of two standards of humic substances (Elliott Soil standard HA 1S102H and Elliott Soil standard FA 2S102F). All samples of IHSS standards HS were characterized by elemental analysis (EA), ultraviolet-visible spectroscopy (UV/Vis), Fourier transform infrared spectroscopy (FTIR) and steady-state fluorescence spectroscopy. Chemical parameters on the complexation of Cu (II), Pb(II) and Hg(II), including the conditional stability constants and the percentage of fluorophores participating in the complexation, were estimated by the modified Stern–Volmer equation. The stability constants (log Ka) of Me(II)–ESHS complexes range from 3.70 to 5.15 in the order: Hg–ESHA>Cu–ESHA>Pb–ESHA>Cu–ESFA>Pb–ESFA. With respect to the ESHA, ESFA, which showed the smallest contents of O-containing functional groups (e.g. hydroxyl, carbonyl, ester, especially carboxyl groups on the aromatic ring) and the lowest humification degree, the ESFA was characterized by much smaller stability constants. Our findings suggest that soil HS belongs to class of important organic ligands for complexation with heavy metal ions and may significantly affect the chemical forms, mobility, bioavailability and ecotoxicity of heavy metals in the soil environment.

Complexation of cadmium(II) with water- and soil-derived fulvic acids: effect of pH and fulvic acid concentration

1979 ◽  
Vol 57 (11) ◽  
pp. 1263-1268 ◽  
Author(s):  
Robert A. Saar ◽  
James H. Weber
Keyword(s):  
Stability Constant ◽  
Fulvic Acid ◽  
Stability Constants ◽  
Acid Concentration ◽  
Conformational Changes ◽  
Fulvic Acids ◽  
Conditional Stability ◽  
Conditional Stability Constant ◽  
Weak Binding ◽  
Conditional Stability Constants

We studied the conditional stability constants of cadmium(II) bound to fulvic acid derived from water and soil, and found that (1) stability constants increased with increasing pH, and (2) stability constants decreased as we increased the fulvic acid concentration toward 70 mg/L. The second effect does not occur for the copper(II)–fulvate system. Conformational changes that occur when a fulvic acid solution becomes more concentrated apparently weaken sites that are otherwise more accessible to weak-binding cadmium. From pH 4 to 8, the overall conditional stability constant increases from 1.4 to 12 × 103 for water-derived fulvic acid and from 1.7 to 43 × 103 for soil-derived fulvic acid. Increases in fulvic acid concentration from 20 mg/L to 70 mg/L halve the conditional stability constant at a given pH.

Effect of pH, humus concentration and molecular weight on conditional stability constants of cadmium

1988 ◽  
Vol 22 (11) ◽  
pp. 1381-1388 ◽  
Author(s):  
Jan John ◽  
Brit Salbu ◽  
Egil T. Gjessing ◽  
Helge E. Bjørnstad
Keyword(s):  
Molecular Weight ◽  
Stability Constants ◽  
Conditional Stability ◽  
Effect Of Ph ◽  
Conditional Stability Constants

The Ion-exchange Behaviour of Beryllium Salicylate Complexes

1963 ◽  
Vol 16 (3) ◽  
pp. 376
Author(s):  
HJ de Bruin ◽  
JJ Fardy ◽  
RB Temple
Keyword(s):  
Ionic Strength ◽  
Ion Exchange ◽  
Stability Constants ◽  
Conditional Stability ◽  
Conditional Stability Constants ◽  
Exchange Behaviour ◽  
Chelate Rings

The beryllium/salicylate system has been re-examined by ion-exchange procedures. The results appear to confirm the existence of a neutral 1 : 1 and an anionic 1 : 2 complex, in both of which the salicylate radicals form chelate rings. Conditional stability constants have been measured at 25�C at an ionic strength of 0.15, the values obtained being ������������� β1 = 4.97 x 1012, and β2 = 2.63 x 1022.

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