Degradation of PFOA in a modified-cathode flow-through reactor

Abstract

The widespread use of poly- and perfluorinated alkyl substances (PFAS) has led to global contamination of drinking water, and these persistent and harmful organic contaminants can accumulate inside the human body and pose health risks and environmental hazards. Several methods have been used to remove PFAS from water, such as activated carbon sorption, ion exchange, advanced oxidation and reduction processes, and thermal and nonthermal destruction. Indirect cathodic electro-Fenton reactions in advanced oxidation processes are some of the most popular technologies. The limited yield of hydrogen peroxide in conventional flow-through reactors results in inefficient electro-Fenton reactions. In this study, the degradation of PFOA, one of the most common PFAS, was studied for the first time in a cathode-modified flow-through reactor using electro-Fenton reaction in a stable high yield hydrogen peroxide environment. The degradation efficiency of PFOA was investigated by applying currents of 60 mA, 90 mA and 120 mA in the flow-through reactor at an initial PFOA concentration of 4 mg/L and a flow rate of 3 ml/min. The experimental results showed that the flow-through reactor achieved the degradation of PFOA at the laboratory level. The degradation was mainly due to the electro-Fenton reaction occurring on the cathode rather than to the adsorption to the reactor. Overall degradation ranged from 32% to 46%. The degradation efficiency of PFOA in 4 mg/L PFOA solution increased linearly with current and reaction time, reaching a maximum of 46% at 120 mA current and 120 min reaction time. This establishes a stable and dependable degradation device as well as a research direction for future electrochemical PFOA degradation. Additionally, it adds to the body of knowledge regarding the electrochemical degradation of PFOA and facilitates future research on the degradation of other PFAS pollutants, thereby improving the aquatic environment.--Author's abstract