Electrochemical removal of pentachlorophenol in a lab-scale platinum electrolyzer

This study is focused on the removal of pentachlorophenol from its aqueous phase by electrochemically induced degradation with Pt electrodes. The objective of this study was to contrast the electrochemical removal of pentachlorophenol at the oxidative and the reductive potentials, and further to understand how to apply the electrochemical treatment on PCP degradation. Lab experiments were conducted in a Pt electrolyzer, and the voltage source was supplied and precisely controlled by an electrochemical analyzer. In these experiments, the variables including electrolyte species, pH, voltage supply, and reaction time were examined to compare the efficiency of pentachlorophenol removal. Experimental results showed that pentachlorophenol was completely degraded after being electrolyzed for 1 h at−1.5 V in a 0.5 M KCl solution, while the removal of pentachlorophenol is negligible under the similar condition when 0.5 M NaNO₃ or Na₂CO₃ was used as the electrolyte. The electrolyte concentration below 0.5 M is unfavourable for the electrochemical removal of pentachlorophenol. The removal efficiency of pentachlorophenol is slightly affected by pH, and the strong basic environment might impede the degradation of pentachlorophenol. Comparing with those under positive potentials, the experiments conducted under negative potentials have shown a better removal of pentachlorophenol with a higher current efficiency. It implies that pentachlorophenol degradation followed the reductive pathway. Based on the analysis of GC/MS, the intermediates of pentachlorophenol degradation were identified as 1,2-dichlorocyclohexane and 2-chlorocyclohexanol.