Kinetic, mechanism and mass transfer impact on electrochemical oxidation of MIT using Ti-enhanced nanotube arrays/SnO2-Sb anode

Abstract

In this study, a novel Ti-enhanced nanotube arrays/SnO2-Sb electrode was prepared by the sol-gel method on enhanced TiO2 nanotube arrays (ENTA). The characterization, degradation performance, oxidation mechanism and mass transfer impact of the novel electrode was investigated. Compared with the conventional Ti/SnO2-Sb electrode, our novel electrode has higher oxygen evolution potential and electrochemical stability, due to the fabrication of ENTA structure. Its application for the destruction of a common biocide of MIT (2-methyl-4-isothiazolin-3-one), the first-order rate constants were determined from 0.01 min−1 to 0.505 min−1 during the electrochemical process. The radical oxidation and non-radical oxidation of the MIT degradation contribution were quantitatively identified as 87.8% and 12.1%, respectively. Furthermore, the second-rate constant between hydroxyl radical and MIT was estimated at 3.72×109M−1S−1. The mass transfer impact was investigated with a differential column batch reactor (DCBR) under the conditions of various electrode spacing and fluid velocities. It indicated that reducing the electrode spacing and increasing the fluid velocity would enhance the mass transfer process and increase the overall oxidation rate. Meanwhile, the EE/O decreased from 17.7 kWh m−3 to 9.7 kWh m−3, and the mass transfer coefficients increased dramatically from 0.52 × 10−6 m s−1 to 2.48 × 10−6 m s−1.