Defect State Modulation of TiO2 Nanostructures for Photocatalytic Abatement of Emerging Pharmaceutical Pollutant in Wastewater Effluent

Abstract

Rapid industrialization has resulted in a significant presence of pharmaceutical compounds in aqueous effluents, and therefore, effluents must be effectively treated before discharging them to water bodies. The removal of emerging pharmaceutical pollutants in wastewater using TiO2 via photocatalysis technique is limited because of its wide bandgap (≈3.2 eV). Herein, defect state modulation of TiO2 for degradation of pharmaceutical pollutant “antipyrine” under visible light irradiation is investigated. A simple hydrothermal technique for synthesis of TiO2 microspheres (average diameter ≈2.94 μm), followed by chemical reduction method for formation of defective‐TiO2 microspheres using NaBH4 under an inert atmosphere for different durations (3, 5, and 8 h) is used. Defective‐TiO2 microspheres are utilized for photocatalytic degradation of antipyrine under visible light illumination. Improved photocatalytic activity for the defective‐TiO2 samples is observed due to a reduction in bandgap as well as incorporation of Ti3+, acting as a trap site and resulting in reduced electron‐hole recombination. For practical application, a continuous prototype reactor comprising defective‐TiO2 particles immobilized over glass beads is developed and efficient photocatalytic degradation of antipyrine under continuous operation is observed. Excellent recyclability and efficient photocatalytic degradation indicate a promising future for the developed defective‐TiO2 particles toward real‐world wastewater treatment applications.