Removal of urea from dilute streams using RVC/nano-NiO x -modified electrode

Abstract

Reticulated vitreous carbon (RVC), a high surface area electrode (40 cm²/cm³), has been modified with nickel oxide nanoparticles (nano-NiO_x ) and used for electrochemical oxidation of urea from alkaline solution. For the cyclic voltammetry measurements, the used dimensions are 0.8 cm × 0.8 cm × 0.3 cm. The purpose was to offer high specific surface area using a porous open network structure to accelerate the electrochemical conversion. NiO_x nanoparticles have been synthesized via an electrochemical route at some experimental conditions. The morphological, structural, and electrochemical properties of the RVC/nano-NiO_x are characterized by using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), cyclic voltammetry (CV), and potentiostatic measurements. The fabricated electrode, RVC/nano-NiO_x , demonstrates high electrocatalytic activity towards urea oxidation in an alkaline electrolyte. The onset potential of the RVC/nano-NiO_x compared to that of the planar GC/NiO_x is shifted to more negative value with higher specific activity. The different loadings of the NiO_x have a substantial influence on the conversion of urea which has been evaluated from concentration-time curves. The urea concentration decreases with time to a limit dependent on the loading extent. Maximum conversion is obtained at 0.86 mg of NiO_x per cm³ of the RVC matrix.