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Determination of Some Heavy Metals Using Clay Modified Electrode by Voltametric Method
In this study, trace analysis of Cd(II), Hg(II) and Cu(II) ions were determined by using zeolite modified carbon paste electrode (ZCPE) with differential pulse anodic stripping voltammetry (DPASV). The trace amounts of each metal ions that were preconcentrated at optimum conditions were performed with three electrodes that have different clay/carbon rates and their electrochemical performances were compared.
In all experiments, the parameters such as the composition of the electrodes, choosing of electrolyte, preconcentration times and potentials, rotating speed, pH, the performance of electrodes, were examined and optimum conditions were stated. Linear current-concentration graphics of 2.10-7-1.10-6 M ranges of Cd(II) ions and 2.10-6-1.10-5 M ranges of both Cu(II) and Hg(II) ions were obtained with ZCPEs that are prepared under certain conditions. For the determination of the metal ions at the studied concentration ranges, 0.05 M acetat buffer (pH=4.70), 0.05 M phosphate buffer (pH=6.88) and 0.1 M NaNO3 solutions were used as supporting electrolyte and 0.05 M acetat buffer was stated as the most appropriate electrolyte. During the preconcentration (accumulation) period, metal ion solutions were mixed at stirring speeds of 500 and 650 rpm. The preconcentration potentials of metal ions on modified electrodes were carried out -0.9 V, 5 min. for Cd(II) ions , -0.4 V, 5 min. for Cu(II) ions and -0.1 V, 5 and 10 min. for Hg(II) ions. A series of the experiments could be done without decomposition and many measurements could be obtained with the same electrode. As a result of experiments, it’s shown that the metal ions could be determined at the ranges of 10-7 and 10-6 M as depending on pH and the rates of modified carbon paste electrodes.
Furthermore, by using the MINEQL programme, the species of metal ions was determined as depending on pH and concentration of heavy metals.
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