Synthesis, Properties and Application of Novel Ethylenediamine Triacetate Chelating Surfactants

Novel ethylenediamine triacetate (ED(3)A) chelating surfactants containing a flexible spacer whose general formula are of CH3(CH2)(x)CH2OCH2CH(OH)CH2N(CH2COONa)CH2CH2N(CH2 center dot COONa)(2) (D1: x = 10, D2: x = 12) have been synthesized. The structures of their carboxylic acid derivatives (Cl and C2) were characterized with electrospray ionization mass spectrometry (ESI-MS), H-1-NMR and C-13-NMR. The values of the critical micelle concentration (CMC) of the two surfactants (D1 and D2) are at level 10(-4) mol L-1 and the surface tension of the surfactant D1 solution at CMC is only 28.6 mN m(-1), which indicates a high surface activity of the D1 surfactant. The surfactants have good foaming, foam stabilizing and emulsifying properties for toluene. When eluting heavy metal contaminated soils with surfactant solution at a concentration of 0.1 mol L-1, where the metals (Pb, Cu and Zn) are mainly in the presence of residual fraction, D1 and D2 can obtain the metal removal efficiencies of 27.82% and 28.19% for Pb, 24.73% and 24.00% for Cu, 9.12% and 8.61 % for Zn, respectively. It is suggested that the two chelating surfactants can be used as elution agents to remediate heavy metal contaminated soils.