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Iron(III)‐Complexes Engaged in the Biochemical Processes in Seawater. I. Voltammetry of Fe(III)‐Succinate Complexes in Model Aqueous Solution
Author(s) -
Cmuk Petra,
Piantanida Ivo,
Mlakar Marina
Publication year - 2009
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/elan.200900238
Subject(s) - aqueous solution , chemistry , stability constants of complexes , stoichiometry , ligand (biochemistry) , cyclic voltammetry , seawater , adsorption , redox , inorganic chemistry , succinic acid , equilibrium constant , voltammetry , analytical chemistry (journal) , electrochemistry , chromatography , organic chemistry , electrode , biochemistry , oceanography , receptor , geology
Abstract Fe 3+ complexes with succinic acid, a ligand naturally present in seawater, were investigated in aqueous solutions by square‐wave and cyclic voltammetry. [Fe(suc) 2 (OH) 2 ] and [Fe(suc) 3 ] were detected at potentials −0.22 and −0.37 V, depending on C suc in the ranges from 0.01 to 0.07 and 0.1 to 0.5 mol L −1 , respectively. Redox processes were irreversible, first with reactant adsorption and second diffusion controlled, both accompanied by chemical step. By UV/Vis spectra formation of these complexes was confirmed and equilibrium constant Fe(suc) 2 (OH) 2 ⇌Fe(suc) 3 calculated (log K 2−3 =(1.14±0.15) mol −1 L), as well as their perceptible stoichiometry. With NTA as competing ligand, conditional stability constant of [Fe(suc) 2 (OH) 2 ] complex was calculated (β cond Fe(suc) 2 [OH] 2=(3.1±1.3)×10 22 mol −1 L).