Square wave anodic stripping voltammetric measurement of cadmium and lead ions using antimony trioxide modified carbon nanotube paste electrode

Heavy metal ions are the hazardous pollutants in the environment around us [1]. Some electrochemical methods have been applied to determine these metal ions [2]. In this study, an antimony trioxide modified multi-walled carbon nanotube paste electrode (Sb2O3/CNTPE) was employed for square wave anodic stripping voltammetric (SWASV) measurement of Cd2+ and Pb2+ ions. For estimating the morphology and properties of the modified electrode, the field emission-scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS) and electrochemical impedance spectroscopy (EIS) methods were applied. SWASV measurement were done in 0.01 M HCl at -1.2 V vs. Ag|AgCl|KCl (3 M) for 130 s as deposition step. After equilibrium time of 15 s, an SWASV signals appeared at -0.7 for Cd2+ and -0.5 V for Pb2+ vs. Ag|AgCl|KCl (3 M) as stripping step. The Sb2O3/CNTPE revealed a good linear operation in the examined concentration range of 10-100 ppb Cd2+ and Pb2+ with appropriate detection limits of about 1.7 ppb for Cd2+ and 1.2 ppb for pb2+, respectively. The stability of the modified electrode during 7 weeks and its behavior in the presence of some other metal ions were evaluated. Finally, the method was successfully tested via measuring Cd2+ and Pb2+ in tap water.