Simultaneous Washing Removal of Copper and Phenanthrene from Contaminated Soil with Sodium N-Lauroyl Ethylenediamine Triacetate

Abstract

This study investigated the effectiveness of using a novel chelating surfactant, sodium N-lauroyl ethylenediamine triacetate (LED3A), on the removal of copper (Cu) and phenanthrene (Phe) simultaneously from artificially contaminated soil. The effects of operating conditions, such as the contact time, initial LED3A concentration, solution pH value and Cu/Phe combination of contaminated soil on the removal efficiencies were extensively examined by a series of batch tests. The results indicated that the equilibrium time (12 h) for Cu desorption was consistent with that of Phe, and the desorption processes of Cu and Phe could be well described by the Elovich and two-constant rate equations. Increasing the LED3A concentration improved effectively both Cu and Phe removal efficiencies, and at the optimum concentration of 18 g/L LED3A, the removal percentages of Cu and Phe were 60.40% and 52.27%, respectively. A wide pH value range from 5.0 to 9.0 was suitable for simultaneously removing of Cu and Phe from the co-contaminated soil. The removals of Cu and Phe were constrained each other in different degrees. The speciation analysis of contaminants in soil demonstrated that LED3A washing resulted in the decrease of the mobile fractions of Cu and Phe, and an increase in the fractions strongly bonded to the soil matrix, compared to their levels before washing. The use of LED3A as an extractant to enhance the removal of heavy metals and hydrophobic organic contaminants (HOCs) from co-contaminated soils appears as a promising remediation method.