Classification of metal ions

Present understanding of Lewis acidity and basicity is based mainly on the A and B type classification of metal ions of Ahrland, Chatt,... 

Table 20.1 Classification of Metal Ions on the Basis of H20 Exchange Rate. ...

Table 1.7 Hard-Soft Acid-Base Classification of Metal Ions and Ligands...

Nieboer, E. Richardson, D. H. S. 1980. The replacement of the nondescript term heavy metal by a biologically and chemically significant classification of metal ions. Environmental Pollution (Ser. B), 1, 3-26. 

Table 10 Classification of metal ions into A and B- type and after the Pearson concept into hard and soft acids with preferred ligands (after Stumm and Morgan 1996)...

Figure 8 Classification of metal ions according to binding preferences ...

Metal Ions in Aqueous Solution Aspects of Coordination Chemistry Table 6.3. Classification of Metal Ions... 

Classification of Metal Ions and the Inoi anic Chemistry of Life 625... 

CLASSIFICATION OF METAL IONS AND THE INORGANIC CHEMISTRY OF LIFE... 

Nieboer, E., and Richardson, H. S. (1980) The Replacement of the Nondescriptive Term Heavy Metals by a Biologically and Chemically Significant Classification of Metal Ions, Environ. Pollution (B) 1, 3-26. 

The general characteristics of each group are summarised in Table 2.1 along with a classification of metal ions and ligands of importance in biological inorganic chemistry. In general, hard acids prefer hard ... 

TABLE 14.6 Ahrland s classification of metal ions and ligands. ... 

Classification of Metal Ions According to Nieboer and Richardson (1980)... 

The relationship between metal ionic characteristics and the maximum biosorption capacity was estabUshed using QSAR models based on the classification of metal ions (soft, hard, and borderhne ions). Ten kinds of metal were selected and the waste biomass of Saccharomyces cerevisiae obtained from a local brewery was used as biosorbent. Eighteen parameters of physiochemical characteristics of metal ions were selected and correlated with Ths suggestion was made that classification of metal ions could improve the QSAR models and different characteristics were significant in correlating with ax, such as polarizing power Z /r or the first hydrolysis constant logRo or ionization potential IP. 

The influence of metal ionic characteristics on their biosorption capacity was analyzed using QSAR models. The waste biomass of Saccharomyces cerevisiae was used as biosotbent to adsorb 10 metal ions, and their maximum biosorption capacity (q was predicted by the models, values were correlated with 22 metal ionic characteristics. Among these, covalent index (X r) was crxrelated well with for all metal ions tested in the following equation q , =0.029 + 0.061 xl,r) (R =0.70). The biomass was shown to preferentially absorb soft ions, then borderline ions, and last hard ions. Classification of metal ions, for divalent ion or for soft-hard ion, could improve the linear relationship (R =0.89). 

This classification of metal ions is based on the biological and chemical availability to organisms as a function of their binding preferences. This classification take into account the atomic weight of the element, specific gravity, ionic radius, thermodynamic equilibrium constant and metal ion electronegativity. ... 

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