Abstract
Summary It was found by conventional and phase-selective a.c. polarography that the dissolution of mercury in the solution of EDTA consists of at least two steps. The first step is probably the formation of ethylenediaminetetracetatomercurate (HgY 2− ) followed by its adsorption on the electrode surface. The second step corresponds to the dissolution of mercury into the solution as mercury-EDTA complexes. The adsorption of HgY 2− on the electrode makes the dissolution of mercury (the second step) irreversible, and also leads to the complicated behavior of the phase angle in the a.c. measurements. The adsorption kinetics of the product were studied by using a complex plane analysis. At lower pH values, the adsorption is controlled by both diffusion and adsorption kinetics. With increasing pH the adsorption becomes a kinetic-controlled process.
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