Chemical classification of interaction trends between metal ions and natural complexants

1 Chemical classification of interaction trends between metal ions and natural complexants 

The extent of metal complexation for a given set of solution conditions varies widely among metals of interest in aquatic systems, and chemists have sought for many years to develop predictive relationships and a rational basis for understanding metal-to-metal patterns of complexation. Three approaches have been widely used  

On the basis of the above considerations, a scheme for metal-complexant interactions in aquatic systems can be drawn (Buffle, 1988, Chapter 2) (Fig. 8.9). In this model, discrimination is made between metal ion groups I, II and III (from hard to soft, Fig. 8.8) and between the following groups of complexants  

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