Absorption/desorption of calcium ions on polypyrrole-loaded reticulated vitreous carbon

Polypyrrole/polystyrene sulfonate-loaded reticulated vitreous carbon electrodes RVC/PPy/PSS were studied as electrochemical cation exchangers for the absorption of Ca²⁺ ions from aqueous solutions. Two grades of RVC were used mainly with 20 and 45 PPI. The preparation and characterization of the PPy/PSS layers on RVC are described. The structure and morphology of the porous electrodes were characterized using cyclic voltammetry (CV) and scanning electron microscopy (SEM). The potential dependent absorption and desorption of Ca²⁺ on RVC/PPy/PSS electrodes was studied in 0.1 M CaCl₂ solution using chronoamperometry and atomic adsorption spectroscopy (AAS). The extent of Ca²⁺ ions absorbed into RVC/PPy/PSS was found to increase with decreasing absorption potential, the specific surface area and the extent of polymer loading. Recovery of the RVC/PPy/PSS electrode was performed by anodic polarization at potentials at which Ca²⁺ ions are desorbed. The coulomb efficiency for the Ca²⁺ desorption process was found to be higher than that for the Ca²⁺ absorption process. From these results the feasibility of using RVC/PPy/PSS for water softening was determined under the prevailing experimental conditions.