Electrochemical Degradation of 4-Fluorophenol in a Moveable Pd-Polypyrrole Catalyst-Mediated Reactor

Electrochemical redox is an effective method to degrade halogenated organic pollutants (HOPs). Herein, highly dispersed Pd-polypyrrole (Pd-PPy) catalysts were synthesized by a facile one-step polymerization method. The morphology and phase structure of the catalysts were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The electrochemical redox of 4-fluorophenol (4-FP) was conducted in a single-chamber reactor with Pd-PPy as a moveable catalyst. The effects of the initial solution pH, constant current, and supporting electrolyte on the degradation of 4-FP were investigated. The removal efficiency of 4-FP was 84.6% after 2 h under an initial solution pH of 2.5 and an applied current density of 2.0 mA/cm2. The mechanism of 4-FP degradation was inferred, including the defluorination of 4-FP on the cathode and oxidation of 4-FP and phenol on the anode. The degradation of 4-FP in the Pd-PPy-mediated reactor showed lower energy consumption and higher removal efficiency. The degradation efficiency of 4-FP had almost no change after 20 cycles of experiments, which indicates the good durability of the prepared Pd-PPy catalysts.