3.10. COMPLEXATION AND CHELATION
The properties of metals dissolved in water depend largely upon the nature of
metal species dissolved in the water. Therefore, speciation of metals plays a crucial
role in their environmental chemistry in natural waters and wastewaters. In addition to
the hydrated metal ions, for example, Fe(H2O)6
3+ and hydroxy species such as
FeOH(H2O)5
2+ discussed in the preceding section, metals may exist in water reversibly
bound to inorganic anions or to organic compounds as metal complexes. For
example, a cyanide ion can bond to dissolved iron(II):