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Title: Adsorption of Pb(II), EDTA, and Pb(II)-EDTA onto TiO{sub 2}

Abstract

The adsorption of aqueous Pb(II), EDTA, and Pb(II)-EDTA complexes onto TiO{sub 2} were studied at both stoichiometric and non-stoichiometric Pb(II)/EDTA concentrations. For Pb(II)-TiO{sub 2} and ECTA-TiO{sub 2}, a typical cationic and anionic-type of adsorption was noted, respectively. For 10{sup {minus}3} and 10{sup {minus}4} M Pb(II)-EDTA systems, near-equal adsorption of Pb(II) and EDTA indicated that the complex adsorbs as a single species. Also, a ligand-type Pb(II)-EDTA adsorption, i.e., decreasing adsorption with an increase in the pH, was noted. Systems with EDTA greater than Pb(II) showed near-zero lead removal; competitive adsorption of EDTA and Pb(II)-EDTA onto TiO{sub 2} was suggested to cause this effect. For Pb(II) concentrations (5 {times} 10{sup {minus}4} and 10{sup {minus}3} M) higher than EDTA (10{sup {minus}4} M), significantly higher EDTA adsorption at high pH as compared to individual 10{sup {minus}4} EDTA and 10{sup {minus}4} M Pb(II)-EDTA systems was noted. Adsorption modeling was completed employing the geochemical speciation model MINTEQA2 employing the diffuse layer model. Inner-sphere complexation was considered to occur between Pb(II), EDTA, Pb(II)-EDTA, and the TiO{sub 2} surface sites. Surface complexes used in the modeling included Ti-O-Pb{sup +}, Ti-EDTAH{sup 2{minus}}, Ti-EDTA-Pb{sup {minus}}, and Ti-O-Pb-EDTA{sup 3{minus}}. The cationic-type complexation, Ti-O-Pb-EDTA{sup 3{minus}}, was postulated to explain and model themore » anomalous EDTA adsorption as noted for Pb(II) > EDTA studies. Results from the present study show that the adsorption behavior in aqueous metal/EDTA systems will change with any variation in the contaminant concentration ratios.« less

Authors:
;  [1]
  1. Univ. of Maryland, College Park, MD (United States). Dept. of Civil Engineering
Publication Date:
OSTI Identifier:
605717
Resource Type:
Journal Article
Journal Name:
Journal of Colloid and Interface Science
Additional Journal Information:
Journal Volume: 198; Journal Issue: 1; Other Information: PBD: 1 Feb 1998
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; LEAD; EDTA; ADSORPTION; TITANIUM OXIDES; SORPTIVE PROPERTIES; AQUEOUS SOLUTIONS; MATHEMATICAL MODELS; M CODES; LEAD COMPLEXES; TITANIUM COMPLEXES; WATER TREATMENT; GROUND WATER

Citation Formats

Vohra, M S, and Davis, A P. Adsorption of Pb(II), EDTA, and Pb(II)-EDTA onto TiO{sub 2}. United States: N. p., 1998. Web. doi:10.1006/jcis.1997.5264.
Vohra, M S, & Davis, A P. Adsorption of Pb(II), EDTA, and Pb(II)-EDTA onto TiO{sub 2}. United States. https://doi.org/10.1006/jcis.1997.5264
Vohra, M S, and Davis, A P. 1998. "Adsorption of Pb(II), EDTA, and Pb(II)-EDTA onto TiO{sub 2}". United States. https://doi.org/10.1006/jcis.1997.5264.
@article{osti_605717,
title = {Adsorption of Pb(II), EDTA, and Pb(II)-EDTA onto TiO{sub 2}},
author = {Vohra, M S and Davis, A P},
abstractNote = {The adsorption of aqueous Pb(II), EDTA, and Pb(II)-EDTA complexes onto TiO{sub 2} were studied at both stoichiometric and non-stoichiometric Pb(II)/EDTA concentrations. For Pb(II)-TiO{sub 2} and ECTA-TiO{sub 2}, a typical cationic and anionic-type of adsorption was noted, respectively. For 10{sup {minus}3} and 10{sup {minus}4} M Pb(II)-EDTA systems, near-equal adsorption of Pb(II) and EDTA indicated that the complex adsorbs as a single species. Also, a ligand-type Pb(II)-EDTA adsorption, i.e., decreasing adsorption with an increase in the pH, was noted. Systems with EDTA greater than Pb(II) showed near-zero lead removal; competitive adsorption of EDTA and Pb(II)-EDTA onto TiO{sub 2} was suggested to cause this effect. For Pb(II) concentrations (5 {times} 10{sup {minus}4} and 10{sup {minus}3} M) higher than EDTA (10{sup {minus}4} M), significantly higher EDTA adsorption at high pH as compared to individual 10{sup {minus}4} EDTA and 10{sup {minus}4} M Pb(II)-EDTA systems was noted. Adsorption modeling was completed employing the geochemical speciation model MINTEQA2 employing the diffuse layer model. Inner-sphere complexation was considered to occur between Pb(II), EDTA, Pb(II)-EDTA, and the TiO{sub 2} surface sites. Surface complexes used in the modeling included Ti-O-Pb{sup +}, Ti-EDTAH{sup 2{minus}}, Ti-EDTA-Pb{sup {minus}}, and Ti-O-Pb-EDTA{sup 3{minus}}. The cationic-type complexation, Ti-O-Pb-EDTA{sup 3{minus}}, was postulated to explain and model the anomalous EDTA adsorption as noted for Pb(II) > EDTA studies. Results from the present study show that the adsorption behavior in aqueous metal/EDTA systems will change with any variation in the contaminant concentration ratios.},
doi = {10.1006/jcis.1997.5264},
url = {https://www.osti.gov/biblio/605717}, journal = {Journal of Colloid and Interface Science},
number = 1,
volume = 198,
place = {United States},
year = {Sun Feb 01 00:00:00 EST 1998},
month = {Sun Feb 01 00:00:00 EST 1998}
}