Ligand I- along with nonionic surfactant, Triton X-100 or anionic surfactant, sodium dodecyl sulfate (SDS) were applied as soil washing agents to desorb Cd from both naturally and artificially contaminated soils. After seven consecutive washings, up to 90% of Cd was desorbed from both soils. Triton X-100 with I- showed a higher capacity to desorbing Cd than did SDS with I-. The increase of ligand concentration was a critical factor for increasing leaching capacity. Without the ligand, surfactant alone could not desorb Cd effectively from either soil. After seven consecutive washings, a sequential extraction experiment was performed for soil residuals to define the soil fraction of Cd removed by the washing agent. Among the washing agents, only Triton X-100/I- could remove Cd from the exchangeable fraction of both soils. / Various ligands including I-, SCN-, and I-/SCN- in combination with Triton X-100 were tested for their efficacy in desorbing heavy metals such as Cd, Zn, Cu, and Pb from a field contaminated soil. Cadmium was preferentially desorbed by Triton X-100/I- whereas Zn and Cu were preferentially desorbed by Triton X-100/SCN-. The mixture of I- and SCN- with Triton X-100 desorbed the most Cd and Cu, but not for Zn, as I- inhibited Zn desorption. Sequential extraction experiments after seven washings showed that metals held in the exchangeable fraction can be desorbed only by a combination of ligand and surfactant. / Nonionic surfactants having different alkyl chain lengths in combination with ligand I- were tested for the desorption of Cd and PCBs from soil. Cadmium desorption was increased at the lower surfactant concentration and higher ligand concentration. The increase in the hydrophilic alkyl chain length of the surfactant adversely affected Cd desorption. Up to 100% of PCBs were successfully removed by most of surfactant-ligand combinations and the desorption was less dependent, compared to heavy metals, on the concentration of washing agents and length of alkyl chain. The linear relationships between number of washings and Cd desorption, and between alkyl chain length and Cd desorption was defined. (Abstract shortened by UMI.)
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.85096 |
| Date | January 2004 |
| Creators | Shin, Mari |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Bioresource Engineering.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 002172745, proquestno: AAINR06341, Theses scanned by UMI/ProQuest. |
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