Analysis of Mercury (II) ions detection under Redox based magnetohydrodynamically driven fluid convection

Y. M. Panta

Department of Mechanical Engineering , Leonard C. Nelson College of Engineering and Sciences, West Virginia University Institute of Technology (WVU Tech), WVU Beckley, WV 25801

Abstract
Application of Redox-based magnetohydrodynamics to enhance the detection of mercury (II) ions has been experimentally investigated. Hg²⁺ ions at concentrations ranging from 0.375 nM to 1 mM in the presence and absence of Redox species, potassium ferric/ferrocyanide, under various magnetic flux densities were measured with linear sweep stripping voltammetry (LSSV) technique. When a voltage is applied across the working and reference electrodes in an electrochemical cell, a current density transmitted through the electrolyte solution results. In the presence of a magnetic field, the interaction between the resulting current density and the magnetic field induces Lorentz forces. The induced MHD convection enhances the ionic mass transport during the deposition and stripping steps, leading to larger stripping signals and thus higher detection sensitivities. The experimental results demonstrated that the stripping signals of the Hg²⁺ ions ranging from 1 nM to 1 mM are enhanced, respectively, by about 10-12% and 22-27 0n the absence and presence of 1 mM Redox species K₄Fe(CN)₆/K₃Fe(CN)₆ under the magnetic flux density B ≈ 0.71 T if compared to other identical conditions in the absence of the magnetic field. The detection limit for the mercury (II) ions using the LSSV technique in the absence of both the Redox species and the magnetic field is 0.875 nM, which is further reduced to 0.375 nM by adding 1 μM Redox species under the magnetic flux density B ≈ 0.71 T. The presence of a supporting electrolyte, potassium chloride, shifts the positions of the peak currents corresponding to the mercury (II) ions. The research work presented is still ongoing to precisely locate the peak current of the Hg(II) ions vs. voltage and also to establish a functional relationship of the peak current as a function of the concentration of Hg²⁺ ions to quantify the mercury content in unknown samples. Thus, the usage of Redox-based MHD convection may enhance the sensitivities for the detection of heavy metal ions avoiding the use of traditional mechanical stirrers. Figs 13, Refs 30.