skip to main content

Title: Competitive adsorption of Cu(II)-EDTA and Cd(II)-EDTA onto TiO{sub 2}

Cu(II), EDTA, Cu(II)-EDTA, Cd(II)-EDTA, and Cu(II)/Cd(II) and Cu(II)-EDTA/Cd(II)-EDTA competitive adsorption onto TiO{sub 2} has been studied with variation of pH and concentration. For Cu(II) and EDTA, typical cationic and anionic types of adsorption are noted, respectively. Ligand-type adsorption is found for Cu(II)-EDTA and Cd(II)-EDTA under both single and competitive conditions. Surface complexation modeling considered inner-sphere complexation and the diffuse layer model employing MINTEQA2; surface complexes used include Ti-(OH{sub 2})O-Cu{sup +}, Ti-(OH)EDTAH{sub 2}{sup {minus}2}, Ti-(OH)EDTA-Cu{sup {minus}2}, and Ti-(OH)EDTA-Cd{sup {minus}2}. Experimental and model predictions suggest no competitive adsorption between Cu(II) and Cd(II) at 5 {times} 10{sup {minus}5} M. On the other hand, adsorption data and model predictions indicate that Cd(II)-EDTA adsorption is favored over that of Cu(II)-EDTA with some competition for adsorption sites. Cd(II)-EDTA Adsorption was only slightly affected by the presence of Cu(II)-EDTA; however, Cu(II)-EDTA adsorption was strongly influenced by the presence of Cd(II)-EDTA, especially as the molar ratio of Cd(II)-EDTA/Cu(II)-EDTA increased. A modified surface complexation constant for Cd(II)-EDTA is required to explain the competitive data, suggesting surface site heterogeneity.
Authors:
;  [1]
  1. Univ. of Maryland, College Park, MD (United States). Dept. of Civil and Environmental Engineering
Publication Date:
OSTI Identifier:
680106
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Colloid and Interface Science; Journal Volume: 216; Journal Issue: 1; Other Information: PBD: 1 Aug 1999
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; COPPER; CADMIUM; ADSORPTION; TITANIUM OXIDES; SORPTIVE PROPERTIES; EDTA; MATHEMATICAL MODELS; ENVIRONMENTAL TRANSPORT