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.