Phase-Pure Brookite TiO2 as a Highly Active Photocatalyst for the Degradation of Pharmaceutical Pollutants

Spherical-shaped brookite TiO2 nanoparticles, average size of about ∼ 10 nm, have been prepared by a hydrothermal method at 175°C for 7 h using HCl acid medium at a concentration of 3.0 M and amorphous TiO2 as precursor that was synthesized by the sol–gel method. Under the sunlight equivalent ultraviolet A (UV-A) irradiation, this brookite acts as an efficient photocatalyst for the photodegradation of recalcitrant pharmaceuticals (e.g., cinnamic acid, ibuprofen, and diatrizoic acid). The photocatalytic assay was conducted using a high pharmaceutical load and a low photocatalyst amount, corresponding to a fixed photocatalyst/pharmaceutical mass ratio of 4. The photodegradation of the pharmaceuticals was followed by a combination of ultraviolet/visible (UV/Vis) absorption spectroscopic, total organic carbon (TOC), and electrospray ionisation time-of-flight mass (ESI–TOF–MS) measurements. Scavenger experiments were carried out to confirm the importance of active species including holes and superoxide radicals acting as “door openers” in the photodegradation of pharmaceuticals in terms of aromatic ring opening, thus facilitating complete mineralization.