Enhanced Degradation of Carbamazepine from Constructed Wetlands with a PEC System Based on an Anode of N-TiO2 Nanocrystal-Modified TiO2 Nanotubes and an Activated Carbon Photocathode

Abstract

We used the Vienna ab initio Simulation Package (VASP), X-ray photoelectron spectroscopy (XPS) and diffuse reflectance (DRS) to optimize anode material for a photoelectric catalytic system. After screening how the doping of TiO2 by N and S affects its photoelectric properties, N-doped TiO2 was selected to fabricate the photoelectron catalytic (PEC) system. TiO2 nanotubes modified by N-doped TiO2 nanocrystals and activated carbon were used as an anode and as a photocathode, respectively, to decompose carbamazepine in water samples from the constructed wetlands. The calculations showed that the N-TiO2 NCs/TNTAs-AC/PTFE system had the highest content of •OH. The highest carbamazepine removal rate under the N-TiO2 NCs/TNTAs-AC/PTFE composite presence was at pH = 8, and 69% of carbamazepine was removed within 180 min of the constructed wetland water treatment at pH = 7.8. The PEC system containing modified (with nano N-TiO2) TiO2 nanotubes as an anode and activated carbon as a photocathode can effectively decompose carbamazepine in the constructed wetlands.