Heterogeneous Photocatalytic Degradation of Selected Pharmaceuticals and Personal Care Products (PPCPs) Using Tungsten Doped TiO2: Effect of the Tungsten Precursors and Solvents

Pharmaceuticals and personal care products (PPCPs) which include antibiotics such as tetracycline (TC) and ciprofloxacin (CIP), etc., have attracted increasing attention worldwide due to their potential threat to the aquatic environment and human health. In this work, a facile sol-gel method was developed to prepare tungsten-doped TiO₂ with tunable W⁵⁺/W⁶⁺ ratio for the removal of PPCPs. The influence of solvents in the synthesis of the three different tungsten precursors doped TiO₂ is also taken into account. WCl₆, ammonium metatungstate (AMT), and Na₂WO₄●2H₂O not only acted as the tungsten precursors but also controlled the tungsten ratio. The photocatalyst prepared by WCl₆ as the tungsten precursor and ethanol as the solvent showed the highest photodegradation performance for ciprofloxacin (CIP) and tetracycline (TC), and the photodegradation performance for tetracycline (TC) was 2.3, 2.8, and 7.8 times that of AMT, Na₂WO₄●2H₂O as the tungsten precursors and pristine TiO₂, respectively. These results were attributed to the influence of the tungsten precursors and solvents on the W⁵⁺/W⁶⁺ ratio, sample crystallinity and surface properties. This study provides an effective method for the design of tungsten-doped TiO₂ with tunable W⁵⁺/W⁶⁺ ratio, which has a profound impact on future studies in the field of photocatalytic degradation of PPCPs using an environmentally friendly approach.