Adsorption of heavy metals on Na-montmorillonite. Effect of pH and organic substances

Clays (especially montmorillonite and bentonite) are widely used as barriers in landfills to prevent contamination of subsoil and groundwater by leachates containing heavy metals. For this reason it is important to study the adsorption of metals by these clays. The sorption of seven metals (Cd, Cr,...

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Bibliographic Details
Published in:Water research (Oxford) 2003-04, Vol.37 (7), p.1619-1627
Main Authors: Abollino, O., Aceto, M., Malandrino, M., Sarzanini, C., Mentasti, E.
Format: Article
Language:English
Subjects:
Adsorption
Aluminum Silicates
barriers
Bentonite - chemistry
Breakthrough
Heavy metals
Hydrogen-Ion Concentration
Metal complexes
Metals, Heavy - chemistry
montmorillonite
Na-montmorillonite
Organic Chemicals
Sodium - chemistry
Water Pollutants - analysis
Water Purification - methods
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Summary:Clays (especially montmorillonite and bentonite) are widely used as barriers in landfills to prevent contamination of subsoil and groundwater by leachates containing heavy metals. For this reason it is important to study the adsorption of metals by these clays. The sorption of seven metals (Cd, Cr, Cu, Mn, Ni, Pb and Zn) on Na-montmorillonite was studied as a function of pH and in the presence of ligands, forming complexes of different stabilities with the metals of interest. The continuous column method was used as it better simulates natural conditions. The total capacity of Na-montmorillonite towards these metals was determined. The pH variations influence to a higher extent the concentrations of Cu, Pb and Cd in the effluent. Moreover the results suggest that complex formation hinders the sorption of the metals on the clay, with an increasing influence in the order: Mn ⩽ Pb ⩽ Cd ⩽ Zn < Ni < Cu < Cr. The evaluation of the total capacity of Na-montmorillonite shows that this clay is a good sorbent towards all examined metals.
ISSN:0043-1354
1879-2448
DOI:10.1016/S0043-1354(02)00524-9