The technology of SLM's for the facilitated extraction of chromium ions from acidic medium: Comparison of extraction parameters and complexation mechanism

The technology of supported liquid membranes (slm's) was used to achieve the facilitated extraction of chromium ions (cr(vi) and cr(iii)),using methyl cholate (mc) and resorcinarene (reso) as carriers,widely used for a facilitated extraction of carbohydrates. for our (slm's),we use toluene as an organic phase and pvdf microporous film as support. a kinetic model as well as an extraction mechanism have been developed and tested,in the first time,for the facilitated extraction of cr ions from different acidic solutions. the macroscopic parameters,permeabilities p and initial fluxes j0 were determined and related to microscopic parameters,the association constant kass,and apparent diffusion coefficient d*,relating to the stability of the complex (carrier-substrate ts),formed at the membrane interface,and its diffusion through the slm organic phase. the obtained results are important and used to determine the complexation nature of cr ions in the organic phase of the studied slm and to explain the high permeability of such membranes for facilitated extraction of these species. these studies show that these parameters kass and d* are changing significantly with different used carriers so the better extraction of these substrates is possible.