Simultaneous removal of nitrate and phosphate using aluminum electrode coated by ZnO nanoparticles in electrocoagulation process

The excessive usage of nitrogen fertilizers leads to phosphate and nitrate become as a common inorganic pollutants in groundwater resources. Therefore, an alternative process performance seems to be examined to remove these anions from water resources. This study aims to investigate the effect of two variables, water hardness and electrodes distance on electrocoagulation process for simultaneous phosphate and nitrate removal. For this purpose, initial concentration=100 mg/l, current density=22.5 A/m2, pH=6 and retention time=40 min were considered. Under these conditions, the optimum removal efficiency of phosphate and nitrate were achieved at 2 cm electrode distance with 93.8% and 78%, respectively. While, the water hardness of 65 mg/l CaCO3 was shown 99.3% and 86% removal efficiency, respectively. Then, in order to improve the electrocoagulation process and reduce the passivation rate of the aluminum anode, the electrodes were modified with ZnO nanoparticles by sol-gel method. The accuracy of electrode coating with zinc oxide nanoparticles was determined by SEM, EDX and XRD tests. The effect of coating was investigated by cyclic voltammetry, showing that current intensity at modified electrode has improved 202.44%.