Voltammetric studies on mercury behavior in different aqueous solutions for further development of a warning system designed for environmental monitoring

Abstract

This article presents some results concerning the electrochemical detection of mercury in different aqueous solutions, using the following electrodes: platinum-disk electrode (PDE), carbon paste electrode (CPE) and glass carbon electrode (GCE). Using the voltam­metric technique applied on the above mentioned electrodes, the experimental conditi­ons were established in order to obtain the maximum current peaks, in terms of the best analytical characteristics for mercury analyses. The dependence equations of cathodic current intensity on the scan rate were established in the case of mercury ion discharge in each prepared solution of 0.984 mM HgCl₂ in different electrolyte background: 0.1 M KCl, 0.1 M H₂SO₄ and 0.9 % NaCl. Among the three investigated electrodes, the carbon paste electrode presented the highest detection sensitivity toward mercury ions in the aqueous solution. It was observed that, at a low scanning rate, the pH had an in­si­gnificant influence over the current peak intensity; however, the quantification of this in­fluence was achieved using a quadratic polynomial equation, which could prevent the er­rors in mercury detection in case of industrial waste stream pH changes. The calibration curves for mercury in 0.9 % NaCl solution and in the tap water respectively were carried out.