Facile synthesis of mesoporous black N–TiO2 photocatalyst for efficient charge separation and the visible-driven photocatalytic mechanism of ibuprofen degradation

Abstract

The present study aimed to investigate the photodegradation of ibuprofen (IPF) by using black N–TiO2 under visible LED illumination. The as-synthesized black N–TiO2 nanoparticles were characterized by field emission scanning electron microscope (FESEM) equipped with energy dispersive X-ray spectrometer (EDS) detector, transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), UV visible diffuse reflectance spectroscopy (UV-DRS), and Brunauer–Emmett–Teller (BET) techniques. The potential photocatalytic activity of the synthesized nanoparticles was assessed by degradation and mineralization of IPF under visible LED light irradiation. Compared to N–TiO2, the black N–TiO2 exhibited higher degradation (96%) and mineralization (81%) efficiency for IPF under selected operational conditions. We observed that codoping of N and Ti3+ narrowed the band gap (2.1 eV) and decreased the recombination of photogenerated carriers. Pseudo-first order kinetic model was best fitted with the experimental results (R2 > 0.99 for different IPF concentrations). Radical-scavenging tests showed that hydroxyl radicals (•OH), holes (h+), and superoxide radicals (•O2−) are involved in the photocatalytic degradation of IPF, however •OH and •O2− played more important roles. The energy consumption of the system for different initial IPF concentrations was around 16.6–38.7 kWh/m3, indicating that the LED-black N–TiO2 process is energy-efficient. The results revealed that the photocatalytic activity of the black N–TiO2 is not changed much, even after 5 cycles, demonstrating its excellent photocatalytic stability and reusability. According to the findings, LED-black N–TiO2 process has the potential to be applied for facile removal of contaminants of emerging concern (CECs) such as IPF from water resources.