Long-term Interaction Between Clay Minerals And Heavy Metal Ions

Clay minerals are a kind of layered alumosilicate whose particles are very fine, possesses strong absorbability, ion exchangeability and expansibility.The mechanism of adsorption of heavy metals by clay minerals is studied from the long-term interaction of them in this paper, and the long-term interaction is observed, while the stability and conversion of its products are also analyzed.The long-term interaction between clay minerals and heavy metal ions is a two-phase process which has a rapid reaction first, then a slow reaction. The mechanism of removal of heavy metal ions by clay minerals is electrostatic force between hydrolysis of heavy metal ions induced by hydration on surface of clay minerals and hydrocolloid particles.Desorption of heavy metal ions is also a two-phase process like that of long-term interaction between clay minerals and heavy metal ions. Process of adsorption and desorption are not totally reversible.Under the general experimental condition, dissolution of Mg²⁺ and Al³⁺ in clay mineral octahedron can induce coprecipitation of 2 and 3 valence heavy metal ions and Mg²⁺-M³⁺-double hydroxides or Al³⁺-M²⁺- double hydroxides forms on the surface of clay mineral in the long-term interaction. And, under the given condition there is a tendency of conversion from these double hydroxides to layer silicate, which changes migration activity of heavy metal ions distinctly.