Metal Extraction From Contaminated Soils by EDDS Washing Under EDDS Excess Conditions

Biodegradable EDDS(S,S-ethylenediaminedisuccinic acid)is an emerging chelant for enhancing heavy metal extraction from contaminated soils.EDDS excess is often en- countered at soil washing.In this study,an empirical model,which utilized the initial metal distribution in soils and a set of parameter values independently determined from sequential ex- traction,was developed for estimating the time-dependent heavy metal extraction by EDDS from multi-metal contaminated soils.The model simulation provided a satisfactory description of the experimental results of the 7-d extraction kinetics of Cu,Zn and Pb in both artificially contaminated and field-contaminated soils under excess EDDS concentration in batch kinetic experiments.Thus,independent and prior assessment of extraction efficiency would be availa- ble to facilitate the engineering applications of EDDS.Furthermore,a simple empirical equa- tion using the initial metal distribution was also proposed to estimate the extraction efficiency at equilibrium.