Development of an electrochemical oxidation processes model: Revelation of process mechanisms and impact of operational parameters on process performance

We developed a heterogeneous kinetic model for electrochemical advanced oxidation processes (EAOPs), which considers mass transfer involving diffusion and electromigration, adsorption to the anode surface, and direct (oxidation on the anode surface) and indirect oxidation (oxidation in solution). To determine the model parameters, we fit the concentration profiles of metformin (MET) and the model fit was excellent (called the training set of data). We then predicted the remaining experimental data (called the verification set of data) using these model parameters and the model was able to predict the EAOP performance for all of the operating conditions. Direct oxidation played a more essential role in metformin degradation than indirect oxidation. Moreover, our model quantified the reaction rate constants between valence band holes (h(+)) of a boron doped diamond electrode and <middle dot>OH with metformin. We also quantified the reaction rate constants for four reactive oxygenated species derived from h(+) reacting with water, (i.e., O-2, <middle dot>OH, O-3, and H2O2). Overall, our model lays a sound foundation for understanding the impact of EAOP operating parameters on process performance (in decreasing order of impact on process performance: initial concentration > current density > velocity), which will allow us to select process paraments that improve EAOP performance.