Factors Affecting the Extraction of Heavy Metals in Sediments Using Biodegradable [S,S]-ethylene diamine disuccinic acid

A biodegradable chelating agent,[S,S] -stereoisomer of ethylenediamine disuccinate([S,S] -EDDS),has been investigated as a potential washing/leaching agent to replace ethylenediaminetetraacetic acid for the extraction of heavy metals from contaminated soils and sediments in recent years,but few studies have been reported on the controlling factors during the extraction.In this study,factors affecting the extraction of heavy metals in sediments using [S,S] -EDDS was studied through batch extraction experiments.The time required to achieve maximum metal extraction from the sediments was different among extracted heavy metals,however,24 h could get a compromise higher extraction efficiency for the extracted metals.Extraction solution pH was not the dominant factor governing the release of Cu,Zn,Cd and Pb from sediments when chelating agent was used.The extractable percentage of heavy metals under different solid-liquid ratios showed no significant difference at neutral pH.The increase of stoichiometric molar ratios of chelator to extracted heavy metals could improve the metal extraction efficiency at neutral pH.But higher ratio of chelator to metal would leach more mineral elements from sediments.According to the cost efficiency,it was suggested that the compromise experimental conditions were 24 h extraction time,neutral pH,and above 1 of the stoichiometric molar ratios of chelator to extracted heavy metals.