Organic complexing ligands

Gledhill, M., and C. M. G. Van den Berg. 1994. Determination of complexation of iron(III) with natural organic complexing ligands in seawater using cathodic stripping voltammetry. Marine Chemistry 47 41—54. 

Nimmo, M. and Fones, G. (1997) The potential pool of Co, Ni, Cu, Pb and Cd organic complexing ligands in coastal and urban rainwaters. Atmos. Environ., 31, 693-702. 

Influence of organic complexation. Ligands whose lead complexes dissociate only partially Within the diffusion layer during the ASV plating process (i.e., complexes partially labile to ASV) (29) have little effect on k-j- and kg. For example, the presence of 10 M humic acid (21), which is partially labile to ASV, reduces the TAF for lead by 31% and the EAF by 5-25% over the range of diffusion layer thicknesses considered here. The... 

It was mentioned earlier that complexing increases the solubility of minerals and thus the mobility of the species involved. This is evident from Fig. 3.14, which shows the solubility of thorian-ite (Th02) as a function of pH in pure water and in the presence of inorganic and organic complexing ligands. The lower, crosshatched curve is the solubility in pure water. At low pH the curve corresponds to the reaction... 

Salicylate has been included as an example of a strong organic complexing ligand (cf. Sigg 1987). The importance of a given complex is determined by both its formation constant and the relative and absolute amounts of the metal cation and ligand in the water. These principles are illustrated by the examples below. 

Figure 5.3. Effects of various organic complexing ligands on the sorption of Cu by montmorillonite. (Modified from McBride, 1991.)...

Recent studies by Perry and Keeling-Tucker [122] using tris-catecholato silicon (IV) complexes as the source of silica extend the range of influence of silica to include calcium and iron in addition to Al. Some form of silica appears to influence the mineralization of iron oxide and calcium phosphate phases as seen by others. Silica shows an affinity for Al species comparable to organic complexing ligands. 

Uranium geochemistry is controlled by the ambient redox environment, pH and concentrations of inorganic and organic complexing ligands [17, 18]. Constraints on Eh, pH and carbonate concentrations are interpreted below based on hydrochemical and mineralogical data obtained in field studies of the Tono Uranium Deposit and nearby vicinity. Iwatsuki et al. [19] and... 

Fig. 6. Example of low-molecular-mass organic complexing ligands interacting with an Al hydroxide polymer. Hydrolysis of Al may be retarded by soil organic acids...

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