THE POTENTIAL COMPLEXING IMPACT OF SOME ORGANIC COMPOUNDS AMINE AND CARBOXYL GROUPS ON TRANSITION METALS

Environmental water chemistry is substantially aided by modern electrochemical research. Sensitive voltammetric techniques are much more useful for metal species in natural waters, where complexation with organic molecules predominates. Many environmental electrochemists are still interested in determining the stability constants of metal ion complexes with various ionic species found in natural waterways. The aim of this work is to investigate the possible influence of complexation of amine and carboxyl groups of some organic molecules (with EDTA, NTA and aniline, using differential pulse polarography). The Differential Pulsed Polarography (DPP) is experimental technique that consist on three-electrode electrochemical cell of: working electrode (SMDE "Static Mercury Drop Electrode"), reference electrode (Ag/AgCl electrode) and auxiliary electrode (graphite electrode). In our research we have followed the polarographic waves of metal ions (Men+), in constant concentration (C=1x10-4 mol/dm3) titrating in perchlorate solution with complexing agents: aniline, NTA and EDTA, in concentrations from C 1x10-5 to 1x0-3 mol.dm-3, at two pH values (pH = 4 and pH = 6). To prove the competition of organic ligands in the complexion of metal ions (Men+) we have prepared solutions by completely complexing the metal ions with aniline and then we have gradually added the strongest complexing agents NTA and EDTA.