Simulation of copper(II) cations sorption on goethite from aqueous solutions of complexons

Resumo

Effect of complexons of polyaminopolycarboxylic acid series (IDA, NTA, EDTA, and DTPA) and polyphosphonic acid series (HEDP, NTP, and EDTP) on Cu(II) cations sorption on goethite (α-FeOOH) from aqueous solutions has been studied. Obtained results have been considered in the context of complexation reactions in bulk solution and on sorbent surface. It has been found that all complexons (except for EDTA), depending on nature, produce on goethite surface (≡FeOH) triple complexes of type A (surface–metal–complexon) of composition ≡FeOCuLH_i¹⁺ⁱ⁻ⁿ and ≡FeOCuL(OH)_j^1−j−n or type B (surface–complexon–metal) of composition ≡FeLH_iCu^3+i-n and ≡FeLCu(OH)_j^3−j−n. pH-Ranges for complex existence and stability constants for the surface complexes have been determined. Factors affecting the character of complexon effect (immobilization/remobilization) on the sorbed metal have been analyzed.