The Effect of Dissolved Ligands on the Sorption of Cu(II) by Ca-Montmorillonite

Abstract

Abstract--The effects of three organic ligands on the adsorption of copper on Ca-montmorillonite were studied. The results indicate that these effects include three different processes: l) Enhanced uptake of positively charged copper-ligand complexes by ion-exchange. 2) Formation of ternary surface complexes involving surface aluminol groups.3) Inhibited uptake due to competition between the surface ligands and the dissolved ligands for dissolved copper.Ethylenediamine promotes copper uptake by ion-exchange at low pH but tends to suppress adsorption at aluminol groups by ligand competition at high pH. The same mechanisms are operative for/3-alanine; however, the uptake of Cu(fi-ala) § by ion-exchange is not promoted by the attached ligand. The influence of malonate includes both ligand competition and formation of ternary complexes. A quantitative interpretation based on the surface complexation model using the least-squares programs FITEQL (Westall, 1982) and GRFIT (Ludwig, 1992) is presented. The obtained equilibrium constants are listed in Tables 2b and 3.

Adsorption of heavy metal ions on soils and soils constituents

“…As for surface potentials, good agreement between the measured zeta potential and the calculated diffuse layer potential in a TLM for the sphalerite/water interface has been reported [73], but for other oxide/water and clay/water interfaces such correspondences have not been observed [74][75][76]. As for the determination of adsorbed species at the interface, several spectroscopic methods can be used for the determination of surface reactions and species which are important for the adsorption process [33,77,78].…”

Mid-infrared and infrared emission spectroscopy of Cu-exchanged montmorillonite

“…In this respect, clay minerals may fix metals through ion exchange [13,14] or surface complexation [15]. Clay minerals would be a great choice for use as geochemical barriers against diffuse aquatic pollutions such as observed in:…”

Copper(II) adsorption on Ca-rectorite, and effect of static magnetic field on the adsorption

“…Besides, Juang and Wu investigated the adsorption of copper(II) onto goethite in relation to the changes of ζ potentials [13]. And the effects of organic ligands on the adsorption of copper onto Camontmorillonite were studied [14]. Much work mentioned above was done in order to research better methods for the adsorption of Cu(II).…”