Publisher: Chemical Society of Nigeria

Remediation of Metal Polluted Sediments Using A Chelating Agent: Fractionation Pattern of Metals Before and After Remediation

A. O Oyeyiola, K. O Olayinka, C. M Davidson, B. I. Alo
KEYWORDS: metals, Sequential extraction, batch extraction, column leaching, sediments, remediation

ABSTRACT:

Four sediment samples from rivers in Lagos state Nigeria were collected and pseudototal metal concentration of Cd, Cr, Cu, Pb and Zn as well as their fractionation pattern was determined, using the modified BCR method. Possible remediation of the sediment with Ethylenediaminetetraacetic acid (EDTA) was investigated using batch extraction and column leaching respectively. The removal of Cd, Cr, Cu, Pb and Zn, were 48-87%, 3-7%, 18-48%, 8-73% and 8-80% for the batch extraction, and 46-66%, 3-7%, 15-57%, 10-59%, and 9-47% for column leaching. EDTA effectively removed metals in the acid exchangeable and the reducible fractions, and also from the oxidisable fraction (in the case of Cu). The efficiency of batch extraction was found to be comparable to the column leaching. The quality of the data was checked with the certified reference materials BCR CRM 143, BCR 701 and good agreement (results within two standard deviations of target values) was obtained between the found and the certified/indicative values. The results proved that heap leaching is a promising approach in the remediation of metal polluted sediments after dredging and metals are removed mainly from the non-detrital fractions (acid exchangeable and reducible fractions)


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