Stripping analysis of mercury(II) ionic solutions under magneto-hydrodynamic convection.

Inorganic mercury(II) ions are ubiquitous contaminants of world water systems and thus their determination and removal from the environment are important. The effects of magnetic field on the stripping analysis of mercury(II) ionic solutions have been experimentally investigated. During the stripping analysis, a potential difference is applied across the working and reference electrodes positioned in the working sample and a current density transmits through the electrolyte solution. When the electrochemical cell is exposed to a magnetic field, provided by a permanent magnet, the interaction between the current density and the magnetic field induces Lorentz forces, which, in turn, induce fluid motion. The induced magneto-hydrodynamic (MHD) convection enhances the ionic mass transport during the deposition and stripping steps, which leads to larger anodic current during the stripping step, thus obtaining higher detection sensitivity during the determination of the mercury(II) ions. The Hg2+ ionic solutions with concentrations ranging from 1 nM to 1 microM in the presence and absence of supporting electrolyte, 30 mM nitric acid (HNO 3) and 0.1 M potassium nitrate (KNO 3), under various magnetic flux densities (B=0,0.27,0.53, and 0.71 T) were measured with a linear sweep stripping voltammetry (LSSV) technique. The experimental results demonstrated that the stripping signals of the Hg2+ ions are enhanced, respectively, more than 10 and 30% in the absence and presence of the supporting electrolyte under a magnetic flux density B=0.71 T as compared to the cases in the absence of the magnetic field with all other identical conditions.