Simultaneous transport of seven heavy metal cations across a bulk liquid membrane using phosphoric tri (4-chloro aniline) as ion carrier and their determination by flame atomic absorption spectrometry

The fluxes and selectivity for competitive of Co2+, Ni2+, Cu2+, Zn2+, Ag+, Cd2+ and Pb2+ metal cations transport across bulk liquid membranes by phosphoric tri(4-chloro aniline) ligand were determined using some organic solvents as membranes. The membrane solvents include chloroform (CHCl3), dichloromethane (DCM), 1,2-dichloroethane (1,2-DCE) and nitrobenzene (NB). The transport process was driven by a back flux of protons maintained by the buffering the source and receiving phase with pH 4.9 and 3.0, respectively. The selectivity order and the transport rates for competitive bulk liquid membrane transport of cations are strongly sensitive to the nature and also the type of the organic membrane phases [1,2]. The obtained results show that, in most cases, among the different used organic solvents as liquid membranes, the most transport rate was dedicated for Zn2+ ion in the presence of tri (4-chloro aniline) ligand in comparison with other cations. The competitive transport rate of Zn2+ metal cation was also studied in the optimum solvent of DCM at different times and showed that optimum time is 18 hour. Also, in order to facilitate the transition of ions, the effect of fatty acids as surfactant on the transfer percent of Zn2+ cation was studied in presence of the several fatty acids such as: palmitic acid (P.A), stearic acid (S.A), terephethalic acid (T.A) and fumaric acid (F.A) in DCM organic solvents.In addition to, the complexation reaction between a numeral these metal cations with phosphoric tri(4-chloro aniline) were studied in pure acetonitrile (AN) at different temperatures of 15℃,25℃,35℃ and 45℃ using the conductometric method [3]. The conductance data show that the complexes with stoichiometry of 1:1 (L:M) were formed between phosphoric tri(4-chloro aniline) ligand and these metal cations. Also, the values of complex formation constants and thermodynamic parameters(∆G_c^°,∆H_c^°, ∆S_c^°) for these complexes in pure AN solvent were obtained from temperature dependence of stability constants.