Investigation of electrocatalytic activity of nanostructure Ce-doped MnO x sol–gel coating deposited on porous Ti membrane electrode

Ce-doped MnOx/Ti electrocatalytic membrane electrodes were prepared by doping rare earth element Ce into manganese oxide (MnOx) via sol–gel method, and coated on the porous Ti substrate membrane electrode. In order to evaluate electrocatalytic activity of the Ce–MnOx/Ti electrode, a functional electrocatalytic membrane reactor (ECMR), which assembled a Ce–MnOx/Ti electrode as an anode and a stainless steel mesh as a cathode, has been employed for phenolic wastewater treatment. The results revealed that a new crystal form Ce2O3 appeared after doping Ce into the system, and the urchinlike morphology and smaller grain size of Ce–MnOx led the catalytic activity of the composite membrane electrode to improve. Moreover, the 25 mol% Ce–MnOx/Ti (C25MT) composite membrane electrode represented the best activity in the degradation of phenolic wastewater. During ECMR with C25MT operation under the conditions of 450 mg/L phenolic wastewater (500 mL), residence time of 5 min, pH of 1–13 and current density of 0.3–1.2 mA/cm2, the highest degradation efficiency of phenolic wastewater achieved in current density of 0.9 mA/cm2 and pH of 7, that is, the achieved remove rate of phenol, COD and TOC were 99.61, 93.12, and 84.23%, respectively. Finally, the effective reusability of C25MT composite membrane electrode was assessed, and a proposed reaction mechanism has been analyzed in the ECMR operation.