Cathodic microenvironment reconstruction boost electrocoagulation treatment of photovoltaic wastewater

Abstract

Electrocoagulation has emerged as a rapidly advancing area in the field of wastewater treatment due to its capability to eliminate pollutants that are typically resistant to filtration or chemical treatment methods, as well as its overall effectiveness, which is often impeded by the formation and growth of flocs. In this study, simulated photovoltaic wastewater was treated using the electrocoagulation method, with cathodic water reduction employed to induce a highly efficient electrocoagulation rate towards the removal of SiO2 and F−. Our results demonstrate that the optimal conditions for this process involved the use of an Al anode, Nickel foam as cathode, an inter-electrode distance of 1.0 cm, a current density of 30 mA cm−2, a stirring speed of 300 rpm, sodium chloride as supporting electrolyte, and an initial pH of 7. Our experimental findings indicated satisfactory performance with respect to EC, as evidenced by the reduction of F− content from 25 mg L−1 to 3.68 mg L−1, and the complete removal of SiO2 from 16 mg L−1. Furthermore, electrochemical analysis and texture characterization revealed that the overall rate of flocculation was dependent on the cathodic material, with in-situ generated OH− in the electrolysis cell influencing the microenvironment of iron hydroxide floc formation and sedimentation. Our study offers conclusive evidence that the optimal cathodic material capable of intensifying OH− concentration from water dissociation is key to achieving superior electrocoagulation performance.