Determination of Cu2+ Ions Concentration by Electrochemical Methods

Abstract

The possibility of determining the concentration of heavy metal ions, i.e., Cu2+ ions in an aqueous solution of CuSO4 ∙ 5H2O, was tested by electrochemical means. For this purpose, polarisation curves were recorded on a Pt electrode in solutions of known (0.1, 0.5, 1.0, 2.5, 5.0, 7.5, 10.0, 50.0, and 100.0 mM) and unknown concentrations of Cu2+ ions with the reading of the limiting diffusion current. Polarisation measurements were performed in the potential range from open circuit potential to −3.0 V with different potential scan rates (1, 5, 10, 20, and 50 mV s–1). By cathodic deposition on the Pt surface, a reddish-brown copper coating was deposited, the thickness of which increased as the concentration of Cu2+ ions in the solution increased. Furthermore, the limiting diffusion current id increased linearly with the increase in Cu2+ ion concentration, c. The id = f(c) plot was constructed and the unknown concentrations of Cu2+ ions in three randomly prepared CuSO4 ∙ 5H2O solutions were determined. Heavy metal ions from polluted waters (Cu2+ ions) can be successfully removed by electrochemical means, and their concentration determined.

Keywords

• heavy metal ions
• copper
• polarisation measurements
• electrodeposition
• limiting diffusion current