This article presents some aspects related to the cathodic discharge of the mercuric ion provided from HgCl2 into an aqueous solution of 0.1 M H2SO4 on different types of electrodes: gold disc electrode (GDE), carbon paste electrode (CPE) and platinum-disk electrode (PDE). Using the rotating disk electrode technique applied on PDE it was established that the cathodic discharge mechanism for the mercuric ion is based on both process types: mass transport, achieved by diffusion and charge transfer, achieved by electron transfer from cathode to mercury ion

Abstract:In the present work voltammetric investigations have been performed on HgCl 2 aqueous solutions prepared from a Cz 9024 reagent. Carbon paste electrode (CPE), eriochrome black T modified carbon paste electrode (MCPE/EBT) and KCl 1M as background electrolyte, were involved within the experimental procedures. Cyclic voltammetry (CV) has been performed in order to compare the behaviour of the two electrodes in both K 3 [Fe(CN) 6 ] and mercury calibration aqueous solution. Differential pulse anodic stripping voltammetry (DPASV) was used to determine the most suitable parameters for mercury determination. All experiments were performed at 25 ± 1 °C, using an electrochemical cell with three-electrodes connected to an Autolab PG STAT 302N (Metrohm-Autolab) potentiostat that is equipped with Nova 1.11 software. The measured potential values were generated by using the silver chloride electrode (AgClE) as reference and a platinum wire electrode as auxiliary. A series of time depending equations for the pre-concentration and concentration steps were established, with the observation that a higher sensitivity can be obtained while increasing the pre-concentration time. DPASV were drawn using the CPE in 11.16 % coriander, as mercury complex, the voltamograms signals indicating mercury oxidation, with signal intensity increasing in time.