Removal of Pb by EDTA-washing in the presence of hydrophobic organic contaminants or anionic surfactant

Weihua Zhang, Daniel C.W. Tsang, Irene M C Lo

Research output: Journal article publicationJournal articleAcademic researchpeer-review

47 Citations (Scopus)

Abstract

Heavy metals and organic contaminants often coexist in contaminated soils, of which the remediation requires a combined or sequential use of surfactant and chelant in chemical-enhanced soil washing. This study investigated the Pb removal by EDTA-washing in the presence of the coexisting hydrophobic organic contaminants (marine diesel fuel, MDF) or anionic surfactant (sodium dodecyl sulfate, SDS). The results of batch experiments indicated a negative impact of MDF on Pb removal, whereas a positive or negative influence of SDS depending on the molar ratio of [EDTA]:[Pb]. The surface of MDF-contaminated soil was partially covered by free-phase MDF limiting the interaction between EDTA and sorbed Pb, especially at [EDTA]:[Pb] = 1:1. Despite the ability of SDS itself for extracting Pb to some extent, probably through electrostatic interaction and dissolution of soil organic matter (SOM), the addition of SDS into EDTA solution only slightly enhanced Pb removal at [EDTA]:[Pb] = 1:1 but inhibited at [EDTA]:[Pb] = 2:1. This may be attributed to the SOM dissolution and the potential formation of ternary surface complexes, respectively. Along the same line of reasoning, it was not surprising that the optimal sequence for Pb removal was EDTA- followed by SDS-washing rather than the reverse sequence or simultaneous EDTA- and SDS-washing.
Original languageEnglish
Pages (from-to)433-439
Number of pages7
JournalJournal of Hazardous Materials
Volume155
Issue number3
DOIs
Publication statusPublished - 15 Jul 2008
Externally publishedYes

Keywords

  • EDTA
  • Lead
  • Organics
  • SDS
  • Soil washing

ASJC Scopus subject areas

  • Chemical Health and Safety
  • Process Chemistry and Technology
  • Safety, Risk, Reliability and Quality
  • Environmental Engineering

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