The present work aims at impregnating copper oxide nanoparticles (Cu NPs) on activated carbon by means of green synthesis with Moringa oleifera leaf extract to develop a material to remove contaminants from water. The produced materials were characterized by means of their textural (specific surface area), morphological (Transmission Electron Microscopy), and structural (X-ray Diffraction) properties. Particles size was estimated by Scherrer equation and the elemental copper concentrations were estimated by Total Reflection X-ray Fluorescence (TXRF). Adsorption experiments, as well as pH, kinetics, and adsorption isotherms studies were carried out with the intent of evaluating the efficiency of nitrate (NO3-) removal from water. The impregnation efficiency of Cu NPs on activated carbon after the adsorption process was measured by means of TXRF analyses. Characterization results confirmed the formation, impregnation, and stability of copper oxide nanoparticles supported on activated carbon, whose crystallite average size ranged between 6 and 61nm. The proposed method for the nanoparticles synthesis and impregnation were demonstrated to be simple and eco-friendly. Impregnated carbons presented significant nitrate removal (about 60%) thus indicating their potential application in water treatment.