Nitrate is the inorganic contaminant of concern in water that can cause serious human health problems such as cancer and methemoglobinemia due to its conversion to nitrite. Thus, suitable treatment methods are needed for its removal from contaminated water, such as electrodialysis, membrane filtration and biological treatment. However, adsorption is the most viable method for treatment of this pollutant. In this study, granular activated carbon (GAC) of babassu coconut was used as adsorbent and it was developed a green synthesized method for the impregnation of copper nanoparticles into its surface using Hibiscus Sabdariffa flower extract. The impregnated carbon was characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD) and Total Reflection X-ray fluorescence (TRXF). After the characterization, the prepared carbon was evaluated in water nitrate removal. For the batch adsorption studies, solutions containing 100 mg/L of nitrate were prepared and the study was conducted to investigate the influence of pH, mass of adsorbent and temperature parameters in nitrate percentage removal. The characterization confirmed the successful synthesis of copper nanoparticles since peaks related to the copper oxides were detected by XRD and copper quantity was determined by TRXF. Also, SEM confirmed the difference between the surface of both pure and impregnated GAC, suggesting the presence of some nanoparticles. For adsorption results, the influence of pH showed that at pH 2 the adsorption process is favorable, since at acidic pH the concentration of H3O+ increases and this ion will interact with nitrate ions. For the influence of mass of adsorbent, results showed that the percentage removal increases proportionally with the increase of the mass, which is attributed to major availability of active sites. Finally yet importantly, the increase of temperature from 15 to 45ºC results in the decrease of nitrate removal. This indicates that NO3- adsorption on impregnated GAC is exothermic process and favorable at lower temperature. The present work indicated that the impregnated GAC is a promising material for removal of nitrate, where the impregnation of copper oxide increased the efficiency of nitrate removal by more than 240%, compared with the pure GAC, at same experimental conditions.