Авторы: SHIN M., BARRINGTON S., MARSHALL W.

2005 г.

Soil and Sedim.

         The ligands iodide (I−) and thiocyanate (SCN−), alone or in admixture, in combination with a non-ionic surfactant, Triton X-100, were evaluated as washing agents for heavy metal desorption from a contaminated soil. After seven successive washings, selective sequential extraction (SSE) was performed to determine the heavy metal content that remained associated with each geo-chemical fraction of the soil. The surfactant with 0.336 mol L−1 of ligand I− removed 75% Cd and 23% Cu, whereas the mobilization of Zn and Pb were not significant after 7 washings. At a concentration of 0.286 mol L−1, the ligand SCN− in the presence of surfactant removed 36% Cd, 44% Cu and 77% Zn. Among the washing agents, the combination of I− and SCN− produced the highest desorption efficiencies 95% Cd, 48% Cu, and 3.1% Pb, but not for Zn. The SCN− ligand extracted the most Zn (77%). The SSE procedure indicated that the I− removed metals from the exchangeable, carbonate and oxide fractions whereas SCN− removed metals only from the exchangeable fraction. Both ligands, in the presence of surfactant, removed Cu from all fractions except the exchangeable sites, whereas only SCN− plus surfactant removed Zn from all fractions. The ligand mixture plus surfactant mobilized only limited quantities of Pb from the oxide and residual fractions.

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