A new analytical method for selective pre-concentration of free silver in estuarine waters using liquid membranes

Silver is recognized as an important pollutant of natural waters. This element is a selective tracer of anthropogenic pollution related to sewage. Studying its bio-availability requires the application of specific separation of the free ion. A liquid membrane is proposed for separating Ag(+) from estuarine water samples. A bulk liquid membrane (BLM) has been selected. Free silver is transported from the sample to a receiving solution through an organic membrane containing tri-isobutylphosphine sulfide (TIBPS). Effects of formation of chlorinated and organic complexes on silver pertraction have been evaluated. The extent of formation of the aforementioned complexes has been based on the decrease of silver transport to the receiving phase, measured as enrichment factor (EF), because only Ag(+) is assumed to be transported. Finally, after quantifying the effects of the employed ligands on EF, total concentration of silver can be estimated from the experimental data of Ag(+) analyzed by the proposed BLM system.