Cu-catalytic generation of reactive oxidizing species from H2 and O2 produced by water electrolysis for electro-fenton degradation of organic contaminants

A novel Pd-based electro-Fenton process has recently been developed to degrade organic contaminants in wastewaters and groundwater. However, the high cost of Pd catalyst limits the application of this process. In this study, Cu supported on bamboo charcoal (Cu/C) was synthesized to evaluate the feasibility of substituting Pd catalysts. Using phenol as a probe organic contaminant, the performance of Cu/C catalyst was evaluated for the electro-Fenton degradation of phenol in a typical undivided electrolytic system. The electrochemical degradation of phenol in the presence of Cu/C was significant, following a pseudo-first-order kinetics with rate constant (k(1)) of 0.008 min(-1). The addition of Fe2+ remarkably enhanced the degradation (k(1) = 0.012 min(-1)). H2O2 and (OH)-O-center dot were validated as the reactive oxidizing species (ROSS), and (OH)-O-center dot was the main ROS contributing to phenol degradation. The as-synthesized Cu/C consisting of Cu, CuO and Cu2O could catalyze the production of H2O2 from chemisorbed H-2 and O-2 as well as the decomposition of H2O2 to (OH)-O-center dot. Particularly, the addition of Fe2+ facilitated the transformation of H2O2 to (OH)-O-center dot. Phenol degradation increased with increasing the current from 5 to 50 mA and decreased with the further increase to 100 mA. The degradation improved with the increase in Cu loadings and the decrease in solution pH. The presence of NaNO3, Na2SO3 or Na2S inhibited the degradation, while the presence of NaCl increased the degradation. Although the activity of Cu/C is much lower than that of Pd/C for phenol degradation, the cost of Cu/C is much lower. (C) 2013 Elsevier B.V. All rights reserved.