Chelating extraction of copper from soil using s-carboxymethylcysteine

Heavy metal contamination of soil frequently occurs at hazardous waste sites. The use of chelating agents to extract heavy metals from contaminated soils is seen as a treatment method. This research investigated the use of the chelator S-carboxymethylcysteine (SCMC) to extract copper from a spiked soil. Batch equilibration experiments over 24-hour periods tested the hypotheses that through a proper choice of chelator extraction could be made more selective toward heavy metals, and extracted metals could be readily recovered as precipitates by increasing the solution pH. The results showed that SCMC could extract and release copper reversibly and that SCMC prefers complexing with copper over competing Fe and Ca ions. Chemical equilibrium modeling was useful for selecting suitable chelating agents for the extraction and subsequent treatment conditions for metals recovery.