Evaluation of Sediments Decontamination by ChelatingAgents using ThermogravimetricAnalysis

This study investigated single-step extraction of heavy metals from contaminated sediments collected in the port of Cádiz. Experimental tests of washing with an aqueous solution of a chelating agent were performed at selected solid/liquid (S/L) ratios. Two chelating agents were chosen: 0.3 M EDTA(pH 3.8 and 8) and sodium citrate (1 M). The objective of the tests was to investigate extractive decontamination by the washing treatment. The study was focused on the extraction of Pb, Cu, Zn, and Cd. The experiments showed that the decontamination efficiencies of the extractants were of the order: EDTA (pH 3.8) > EDTA (pH 8) ~ sodium citrate. EDTAsolution with slightly acid pH was optimal for the extraction of Pb, Cu, Zn and Cd. The data obtained from the thermal analysis of sediments after the decontamination process indicated the success of the extraction procedurewhich is proposed as a technique for controlling the behaviour of the decontamination process.