The paper shows the results from a number of lab-scale washing treatments using the four chelating agents EDTA, NTA, citric acid and [S,S]-EDDS aiming at the remediation of a real heavy metal-contaminated sediment. Investigation of the influence of chelant type and concentration as well as solution pH was the major focus of the work. The analysis of speciation of metals and chelating agents in solution was carried out through geochemical speciation modelling in order to identify the optimal conditions for the washing process as well as to evaluate the competition phenomena of metal-chelant complexes in solution. The major competing cations were found to be Ca above all and Mg under specific conditions. Among the investigated chelating agents, EDDS appeared to be less affected by competition by major cations while ensuring adequate heavy metal extraction efficiencies. For a 1:1 chelant/metal ratio, the following ranking was observed: EDDS > Cit > NTA > EDTA for As, EDDS > NTA congruent to EDTA >> Cit for Cu, EDDS congruent to EDTA congruent to NTA > Cit for Zn, EDTA > NTA > EDDS > Cit for Pb at pH 5 and EDTA congruent to EDDS congruent to NTA >> Cit for Pb at pH 8. For a 10:1 chelant/metal ratio geochemical modelling indicated that at the equilibrium the extracting solutions were dominated by the free form of the chelating agents, indicating the inability of such species to complex trace metals due the strong interactions existing between heavy metal ions and sediment constituents. (c) 2006 Elsevier Ltd. All rights reserved.

The effect of operating variables on chelant-assisted remediation of contaminated dredged sediment / Polettini, Alessandra; Pomi, Raffaella; Rolle, Enrico. - In: CHEMOSPHERE. - ISSN 0045-6535. - 66:5(2007), pp. 866-877. [10.1016/j.chemosphere.2006.06.023]

The effect of operating variables on chelant-assisted remediation of contaminated dredged sediment

POLETTINI, Alessandra;POMI, Raffaella;ROLLE, Enrico
2007

Abstract

The paper shows the results from a number of lab-scale washing treatments using the four chelating agents EDTA, NTA, citric acid and [S,S]-EDDS aiming at the remediation of a real heavy metal-contaminated sediment. Investigation of the influence of chelant type and concentration as well as solution pH was the major focus of the work. The analysis of speciation of metals and chelating agents in solution was carried out through geochemical speciation modelling in order to identify the optimal conditions for the washing process as well as to evaluate the competition phenomena of metal-chelant complexes in solution. The major competing cations were found to be Ca above all and Mg under specific conditions. Among the investigated chelating agents, EDDS appeared to be less affected by competition by major cations while ensuring adequate heavy metal extraction efficiencies. For a 1:1 chelant/metal ratio, the following ranking was observed: EDDS > Cit > NTA > EDTA for As, EDDS > NTA congruent to EDTA >> Cit for Cu, EDDS congruent to EDTA congruent to NTA > Cit for Zn, EDTA > NTA > EDDS > Cit for Pb at pH 5 and EDTA congruent to EDDS congruent to NTA >> Cit for Pb at pH 8. For a 10:1 chelant/metal ratio geochemical modelling indicated that at the equilibrium the extracting solutions were dominated by the free form of the chelating agents, indicating the inability of such species to complex trace metals due the strong interactions existing between heavy metal ions and sediment constituents. (c) 2006 Elsevier Ltd. All rights reserved.
2007
chelating agents; heavy metals; sediment; washing
01 Pubblicazione su rivista::01a Articolo in rivista
The effect of operating variables on chelant-assisted remediation of contaminated dredged sediment / Polettini, Alessandra; Pomi, Raffaella; Rolle, Enrico. - In: CHEMOSPHERE. - ISSN 0045-6535. - 66:5(2007), pp. 866-877. [10.1016/j.chemosphere.2006.06.023]
File allegati a questo prodotto
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/235537
 Attenzione

Attenzione! I dati visualizzati non sono stati sottoposti a validazione da parte dell'ateneo

Citazioni
  • ???jsp.display-item.citation.pmc??? 0
  • Scopus 89
  • ???jsp.display-item.citation.isi??? 82
social impact