Electrochemical determination of mercury(II) in ambient water at palladium oxide/graphite composite electrodes

The voltammetric behavior of mercury was investigated using carbon paste electrode modified with a palladium oxide supported onto natural phosphate (PdO/NP-CPE). The aim of this work is to optimize all factors influencing this determination (frequency, amplitude, pulse height, deposition time and potential, heated temperature and charge loading of palladium oxide). The best results were obtained with square wave potential in 0.1 mol/L HCl medium. Linear dependence of current versus mercury(II) concentrations, under optimized conditions, was obtained for the concentration ranges from 2.5 x 10(-7) to 1.0 x 10(-4) mol/L. For 3 min preconcentration, detection limits of 1.93 x 10(-8) mol/L was obtained at the signal noise ratio (SNR) of 3. The repeatability expressed as relative standard deviation (%R.S.D.) was always <4.78%. These results indicate clearly that using square wave voltammetry (SWV) with the PdO-doped natural phosphate-carbon composite electrode provides a real opportunity for detecting mercury(II) in ambient water solutions. (C) 2014 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.