Response surface methodology for the removal of nitrate ions by adsorption onto copper oxide nanoparticles

Abstract

Nitrate ions (NO3−) enter water sources through sewage and can cause (in high concentrations) methemoglobinemia, cancer of the lymphatic and blood systems. Therefore, the level of NO3− in water must be controlled and effectively reduced. In the present work, copper oxide nanoparticles (CuONPs) were synthesized by chemical deposition method and their physicochemical properties have been determined by SEM, FTIR, XRD techniques. CuONPs have been used as adsorbents to remove nitrate ions from synthetic effluents. The optimization of nitrate ions removal was performed using response surface modeling (RSM) with parameters (input): initial nitrate concentration (20, 45, 70 mg/L), CuONPs concentration (0.03, 0.06, 0.08 g/L), pH (3, 7, 11) and reaction time (40, 80, 120 min). The optimum conditions found were 70 mg/L as nanoparticles dose, 0.08 g/L as NO3− concentration, pH=3, and 120 min contact time. The analysis of variance for this model confirmed that the model was fitted successfully (R2=0.9987, R2adj=0.9974). The adsorption fitted to Langmuir isotherm (R2L=0.9822) and second-order kinetics (R2s2=0.9999).