METAL-FULVIC ACID CHELATION EQUILIBRIUM IN AQUEOUS NaNO3 SOLUTION. Hg(II), Cd(II), AND Cu(II) FULVATE COMPLEXES

Abstract

Conditional stability constants of some metal fulvate complexes have been determined at 25 C using specific ion electrodes. In aqueous 0.1 M NaNO₃, solution, the log K values are: 4.86 and 5.08 at pH 3 and 4 for mercury complexes; 3.04 and 3.64 at pH 4.9 and 5.95 for cadmium complexes; and 3.22, 3.72, and 4.35 at pH 3, 4, and 5 for copper complexes. In 0.04 M NaNO₃ solution, the log K value for mercury–fulvic acid system is 5.12 at pH 3.1. The order of metal affinity toward fulvic acid Hg > Cu > Cd is in general agreement with the literature for complexing of these metals with similar type donors.