Photocatalytic degradation of four non-steroidal anti-inflammatory drugs in water under visible light by P25-TiO2/tetraethyl orthosilicate film and determination via ultra performance liquid chromatography electrospray tandem mass spectrometry

Photocatalytic degradation of four non-steroidal anti-inflammatory drugs (NSAIDs) - salicylic acid, ibuprofen, naproxen and diclofenac in water has been investigated using a novel P25-TiO2/tetraethyl orthosilicate (TEOS) film on glazed ceramic surface under a visible light incubator. Influences of main parameters, such as adsorption, stir, initial pH, amount of P25-TiO2/TEOS and irradiation time has been studied. Results show that the degradations of four NSAIDs obtained maximum and equilibrium effect within 10 h of irradiation at pH 6.0 condition. The maximum degradation effects of salicylic acid, ibuprofen, naproxen and diclofenac under optimum conditions are 76%, 85%, 94% and 65%, respectively. The photocatalytic degradation reactions follow first order kinetics. Naproxen is selected as the representative to analyze the photocatalytic products, and a probable photocatalytic degradation pathway of naproxen is put forward. To support the degradation kinetics study a rapid, sensitive and accurate ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method has been developed. (C) 2014 Elsevier B.V. All rights reserved.