Improved electrical driving current of electrochemical treatment of Per- and Polyfluoroalkyl Substances (PFAS) in water using Boron-Doped Diamond anode

Abstract

Emerging Per- and Polyfluoroalkyl Substances (PFAS) in water resources is toxic contaminants, which has negative impacts on human health and the environment. Electrochemical Oxidation (EO) is a promising treatment technology to manage water pollutants. The purpose of this study is to develop an efficient EO system to remove PFAS with reducing physical resistance of titanium connector using Boron-Doped Diamond (BDD) and titanium (Ti) electrodes All experiments were performed in a batch reactor through a polypropylene vessel containing 350 mL of Milli-Q water spiked with Perfluorooctanoic Acid (PFOA), Perfluorohexane sulfonate (PFHxS), and Perfluorooctane Sulfonate (PFOS) at concentrations of 1 mg L−1. Two types of electrolytes called sodium sulfate (Na2SO4) and sodium chloride (NaCl) were mixed into the solution. Reactions were performed with a BDD anode as a working electrode and a titanium cathode. The electrode surface area was 78.5 cm 2 with a plate distance of 3 cm. The electrical connectors (Ti wire) physically reduced the resistance from 9 Ohm to 7 Ohm which improved the driving capability of electric current. Results show that the electrochemical oxidation system with low resistance demonstrated higher removal efficiency for PFOS, PFHxS, and PFOA increased by 89.1%, 88.1%, and 94.0%, respectively, with low energy consumption. The decomposition efficiency of PFAS was higher because the electron transfer magnitude of current affects the rate of electrolysis oxidation. Meanwhile, the conductivity with low resistance increased approximately 1.3 times when compared with resistance at 9 Ohm. In addition, the Dimond electrode and titanium electrode present high efficiency in PFAS removal in water. Although BDD anode service life was not the focus of this study, no decreasing trend, determined for PFAS, was observed throughout the approximately 10 batch experiments (50 h) performed with a BDD anode.