Sorption of Cu on a Fe-deformed montmorillonite complex: Effect of pH, ionic strength, competitor heavy metal, and inorganic and organic ligands

The sorption of Cu as affected by pH, ionic strength, competitor heavy metal, and inorganic and organic ligands on a Fe-deformed montmorillonite complex was observed in the current study. The results showed that the sorption of Cu was pH dependent and insensitive to a change of ionic strength, indicating that the formation of an inner-sphere complex was the primary sorption mechanism, and it was probably due to the high surface coverage of Fe (oxyhydr)oxides as nanoparticles on deformed montmorillonite. Copper was less effective than Pb in competitive sorption. Phosphate, sulfate and oxalate showed different characteristics in affecting Cu sorption. Phosphate inhibited Cu sorption at a relatively low ligand concentration while a facilitating effect was observed when the concentration of phosphate was relatively high. The sorption of Cu was generally promoted by sulfate but the extent was less than that by phosphate. Oxalate promoted Cu sorption at a relatively low pH (pH 3.5) and a relatively low oxalate concentration, while a significant diminution of Cu sorption was found at higher pHs (pH 4.5 and 5.5) or a relatively high ligand concentration. The results obtained in the current study are of significant importance for evaluating the mobility of Cu in polluted environment.