EDTA effect on the removal of Cu(II) onto TiO 2

Abstract

The adsorption of Cu(II) and Cu(II)–EDTA onto TiO 2 with variations in the pH, concentration, and molar ratio of Cu(II) to EDTA has been studied. The adsorption of Cu(II) and Cu(II)–EDTA onto TiO 2 showed typical cationic- and anionic-type behavior, respectively. The removal of Cu(II) in an EDTA-excess system was less than that in an equimolar Cu(II)/EDTA system due to the competitive adsorption of EDTA and Cu(II)–EDTA onto the TiO 2. The removal of Cu(II) was favorable at low pH for both the equimolar and EDTA-excess systems, while significant Cu(II) removal was observed over the entire pH range in a copper-excess system. For model predictions, the MINTEQA2 program employing an inner-sphere complexation and a diffuse layer model was used; the surface complexes used included Ti (OH 2)O Cu +, Ti (OH)EDTAH 2− 2, and Ti (OH)EDTA Cu 2−.