Removal of Lead and Zinc From Contaminated Soil by a Novel Chelating Surfactant

Abstract

In the present study, the focus was to explore the feasibility of using a chelating surfactant, sodium N-lauroyl ethylenediamine triacetate (LED3A), as an effective washing reagent for lead (Pb)-and zinc (Zn)-contaminated soils. The total content of Pb and Zn was equal to 949.6 and 936.4 mg kg À1 , respectively. A series of batch washing experiments was conducted. The results showed that the washing experiments reached equilibrium within 17 h, at >3 g L À1 LED3A. The desorption processes of Pb and Zn could be best described by the pseudo-second-order equation. The intra-particle diffusion model implied that the desorption processes included three continuous stages, and that intra-particle diffusion was not the only rate-limiting step. Results from the effect of the LED3A concentration and temperature indicated that desorption of Pb and Zn was an endothermic process, and the optimum concentration of LED3A was 7 g L À1 . Data from sequential extractions showed that LED3A washing resulted in the decrease of the Pb and Zn percentage in the mobile fractions, and an increase in fractions strongly bonded to the soil matrix. LED3A showed a significant potential for chelating extensive amounts of the used heavy metals from contaminated soil.

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

“…It was observed that LED3A readily extracted metal from the acid extractable fraction, and partially also from the reducible, the oxidizable and the residual one. Qiao et al [41] also reported that LED3A had the ability to remove various forms of heavy metals in the soils. However, the difference in this study was that the proportion of Cu in the oxidizable fraction of washed soil decreased markedly, which possibly attribute to the enhanced solubilizing effect of surfactant on PAH in metal-PAH-soil bond [7].…”

“…Based on the kinetics parameters of Table 2, the decrease in the k di value of Cu or Phe reveals that the second stage of the multi-linear plot is the rate-limiting step. The increase in the c i value reflects the expanding in the thickness of the boundary layer surrounding the particle, which decreases the change in the external mass diffusion and increases the change of the internal mass transfer [41]. Such a multi-linearity curve with nonzero intercept demonstrated that intra-particle diffusion was not the only rate controlling step for the system [40,42].…”

Remediation of Heavy Metal-Contaminated Soils with Soil Washing: A Review

“…Chen et al found that the best removal efficiencies of Cd in artificially contaminated soil were obtained with 1 h washing time, and the Cd removal rate was achieved at 81.2% [55]. SDS can bind with metals and prompt their desorption from soil particles [56]. Other commonly used surfactants include DPC, DDAC, SDBS, Ammonyx KP, CATB, etc.…”