The mechanism of d-metal ion sorption from aqueous media and chelating sites structures of modified heterocyclic biopolymers

Abstract

Sorption of d-metal ions (Cu2+, Fe2+, and Ni2+) from aqueous media using modified heterocyclic biopolymers takes place with the participation of sorption sites, with the following acidic groups: α-hydroxycarboxylic (monobasic, bidentate), hydroxamic (monobasic, bidentate), and aldehyde bisulphite (dibasic) in the form of chelate metal complexes, whose structures were determined through the use of computational quantum chemistry on some modeled compounds. Ion exchange mechanism of the components of hetero-phase system in electroneutral, molecular form reflects the implementation of the general laws of thermodynamics: Gibbs’ phase rule, law of mass action, law of equivalent proportions, and law of conservation of charge at electroneutrality of phases. Sorbents functional groups act as sorption sites whose filling goes in accordance with their amount, denticity, basicity and ability of metal cations to complex formation and solvation. The amount and the nature of acid sorption sites of sorbents permits the comparison of their initial and maximum sorption abilities.