Environmentally Benign Sequential Extraction of Heavy Metals from Marine Sediments

Abstract

An environmentally friendly heavy metals remediation process from polluted marine sediments is proposed. The efficiency of three organic and inorganic salts (ammonium acetate, ammonium nitrate, and sodium potassium tartrate) to salt out these pollutants was ascertained in sediment washing waters containing nonionic surfactants. The immiscibility regions were correlated by means of three known models, and the experimental data were interpreted in the light of thermodynamic parameters such as Gibbs free energy of hydration and molar entropy of hydration. The proposed process was applied to model aqueous solutions containing two representative heavy metals (zinc and copper). The viability of the suggested strategy was checked in real contaminated marine sediments by including a sequential treatment: marine sediment washing–contaminant extraction, which led to total remediation values higher than 80% for copper and 90% for zinc.