Removal of Cd+2 from aqueous solutions onto polypyrrole coated reticulated vitreous carbon eletrodes

The development of simple methods for removal of heavy metals from aqueous samples is a relevant field of research. In this connection, the electrodeposition of the Cd+2 ion, one of the most toxic species for animals and human beings, was investigated in aerated pH 4.8 sulfuric-sulfate solutions. In potentiostatic conditions, the maximum rate of cadmium deposition at a neutral polypyrrole (PPy0) coated reticulated vitreous carbon (RVC) working electrode occurs at -3.0 V vs. the saturated calomel reference electrode (SCE). Moreover, the conversion rate depends both on the applied potential and on the mass transport regime, and, for solutions containing 10 mg L-1 of Cd2+, the highest removal efficiency achieved is 84% after 90 min of electrolysis. The concentration decay of the Cd+2 ion in the solution was monitored by anodic stripping voltammetry (ASV) at a hanging mercury drop electrode. Besides, metallic cadmium deposited onto the polypyrrole modified RVC electrode was evidenced by Scanning Electron Microscopy (SEM) analysis using the backscattered electron image (BEI) technique and by Energy Dispersive Spectrometry (EDS).