Continuous multi-cell electrochemical reactor for pollutant oxidation

Abstract Degradation of organic pollutants using electrochemical method has obtained great attentions in recent years. Up to now, most works have focused on electrode property improving and pollutant degradation efficacy examining, but very few efforts have been paid to the electrochemical reactor investigation. This article presents a novel continuous multi-cell electrochemical reactor, which consists of ten serially connected cells using PbO 2 /Ti anode and stainless steel cathode with a short electrode gap of only 2 mm. Hydraulic characteristics of the reactor were investigated using the residence time distribution (RTD) studies. The low dispersion number, 0.06, and Morrill dispersion index (MDI), 1.91, indicate that the reactor is close to a plug-flow reactor (PFR). Electrolysis of 50 mg/L synthetic phenol wastewater was conducted using the multi-cell reactor at a current density of 10 mA/cm 2 , a retention time of 100 min and an electrolyte conductivity of 2.5 mS/cm, and the chemical oxygen demand (COD) of the effluent was only 16 mg/L. During the electrolysis process, the applied voltage in each cell kept stable at a low value of 3.4 V. A comparison between the multi-cell reactor and the conventional single cell reactor for wastewater treatment under the same operating conditions showed that the multi-cell reactor performed much better than the single-cell reactor. For treating 500 mg/L phenol wastewater, the effluent COD of the single-cell reactor was 534 mg/L, with a current efficiency of only 19.9%. On the contrary, the effluent COD of the multi-cell reactor was 242 mg/L and the current efficiency could reach 71.8%.