Quantitative removal of mercury(II) from water by lipophilic polyamines through bulk liquid membranes

Transport of mercury(II) and copper(II) ions through bulk liquid membranes has been studied, the former because of its toxicity and wide distribution in the environment, the latter for comparative purposes. The abilities of two carriers, the known N,N'-bis[2-(hexadecylamino)ethyl]-N,N'-bis(hydroxyethyl) ethylenediamine (bis-HE16ED) and the new N,N'-bis(p-octyloxybenzyl)-3,6-dioxaoctane-1,8-diamine (bispODODA), to complex and transport the selected metal ions are reported. Bis-HE16ED is a good carrier for Cu2+ ions, but the high stability of the carrier/Hg2+ ion complex in the membrane results in a lack of its transport. On the other hand, the new carrier displays a very high efficiency in Hg2+ ion transport, effecting quantitative transfer of the metal ion into the receiving phase within 24 h, despite its chelating region being only slightly different from that in bis-HE16ED. The ability of bis-pODODA to transport 100% of Hg2+ efficiently in consecutive cycles is also reported. This result provides a basis for future development of a decontamination process based on a carrier-mediated transport system.