Removal of urea from dilute streams using RVC/nano-NiOx-modified electrode.

Reticulated vitreous carbon (RVC), a high surface area electrode (40 cm2/cm3), has been modified with nickel oxide nanoparticles (nano-NiOx) 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. NiOx nanoparticles have been synthesized via an electrochemical route at some experimental conditions. The morphological, structural, and electrochemical properties of the RVC/nano-NiOx 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-NiOx, demonstrates high electrocatalytic activity towards urea oxidation in an alkaline electrolyte. The onset potential of the RVC/nano-NiOx compared to that of the planar GC/NiOx is shifted to more negative value with higher specific activity. The different loadings of the NiOx 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 NiOx per cm3 of the RVC matrix.