Effective degradation of aqueous carbamazepine on a novel blue-colored TiO2 nanotube arrays membrane filter anode

The effective electrochemical oxidation of aqueous carbamazepine (CBZ) using a novel blue-colored TiO2 nanotube arrays (BC-TiO2NTA) membrane filter anode was studied. The BC-TiO2NTA was characterized using SEM, TEM, BET, mercury intrusion porosimetry, XPS, XRD, CV, and LSV. The BC-TiO2NTA had reserved pore structure, formed mesopores, specific and electroactive surface areas of 2.01 m2 g-1 and 9.32 cm2 cm-2, respectively. The oxygen evolution potential was 2.61 V vs. SCE. CBZ could be degraded by OH, SO4- and O2- on BC-TiO2NTA in accordance to pseudo-first-order kinetic, which was greatly enhanced in flow-through mode. The optimal kinetic rate constant of CBZ degradation of 0.403 min-1 was achieved at 3 mA cm-2, while energy consumption per order was 0.086 kW h m-3. The mineralization efficiency and mineralization current efficiency were 50.8 % and 9.5 % at 180 min, respectively. The presence of Cl- (0.3-3 mM) accelerated electrochemical degradation of CBZ, while NO3- (0.1-2 mM) inhibited the reaction. Based on density functional theory calculation and UPLC-Orbitrap-MS/MS measurement, we found that electrochemical degradation of CBZ was initialized by cleavage of -CONH2 group and attack of OH on the olefinic double bond of the central heterocyclic ring.