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|Title:||Influence of organic ligands on kinetics of adsorption of lead(II) by kaolin under various pH conditions|
|Authors:||Abraham, Beena T|
Anirudhan, T S
|Abstract:||Adsorption of lead(II) from aqueous solution in presence of nitrilotriacetic acid(NTA) and ethylenediaminetetraacetic acid(EDTA) by kaolin has been studied using the batch equilibrium method. The study shows that Pb(II) adsorption by kaolin at different concentrations of NTA and EDTA obeys multiple first-order kinetics. The rate constants of Pb(II) adsorption for both fast and slow processes in presence and absence of organic ligands at different pH values have also been determined. With increase in pH the adsorption of NTA and EDTA decreases. In the absence of organic ligands the rate constants of initial fast process were 18-27 times higher than the slow process in the pH range of 2.0 to 9.0. Maximum adsorption of organic ligands takes place at pH 2.0. NTA and EDTA have a significant promoting effect on the adsorption of Pb on to kaolin at pH 2.0 whereas the ligands have a significant retarding effect on the adsorption at pH 4.0 and 9.0. The kaolin surface carries a net positive charge at pH 2.0, thus negatively charged Pb-NT A or Pb-EDTA complexes can be readily adsorbed. Adsorbed NTA and EDTA at kaolin surface provide new adsorption sites for Pb(II) ions.|
|Appears in Collections:||IJC-A Vol.38A(10) [October 1999]|
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