BACKGROUND: In this study, highly visible-light photoactive nitrogen and sulfur co-doped TiO 2 (N,S-TiO 2 ) nanoparticles and nanosheets were synthesized via facile sol-gel and hydrothermal methods, respectively. The photocatalytic activities of N,S-TiO 2 catalysts were evaluated by degradation of non-steroidal anti-inflammatory drugs, ibuprofen (IBP) and naproxen (NPX), under simulated solar irradiation. RESULTS:The N,S-TiO 2 nanoparticle is a well-developed mesoporous structure that contains both anatase and rutile phases and a large BET surface area (132 m 2 g −1 ). N,S-TiO 2 nanosheets contain a complete anatase phase with a larger mesoporous structure and a smaller BET surface area (64 m 2 g −1 ). The results showed that at catalyst loading of 2.0 g L −1 and pH 6, N,S-TiO 2 nanoparticles can degrade 85% and 99.3% of IBP and NPX. At the same conditions, 71.6% of IBP and 99.1% of NPX were degraded by N,S-TiO 2 nanosheets in this study. CONCLUSION:The high photocatalytic activity of N,S-TiO 2 may be due to synergistic effects of nitrogen and sulfur co-doping into TiO 2 , resulting in better separation of photogenerated electrons and holes and higher-visible light adsorption. Reusability tests of N,S-TiO 2 showed that it could retain its catalytic activity even after six cycles.

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Pharmaceuticals are becoming widely distributed in waters and wastewaters and pose a serious threat to public health. The present study aimed to analyze non-steroidal anti-inflammatory drugs (NSAIDs) in surface waters, drinking water, and wastewater in Tehran, Iran. Thirty-six samples were collected from surface waters, tap water, and influent and effluent of municipal and hospital wastewater treatment plants (WWTP). A solid-phase extraction (SPE) followed by liquid chromatography-tandem mass spectrometry method was used for the determination of pharmaceuticals, namely ibuprofen (IBP), naproxen (NPX), diclofenac (DIC), and indomethacin (IDM). IBP was found in most of the samples and had the highest concentration. The highest concentrations of NSAIDs were found in the municipal WWTP influents and hospital WWTP effluents. In the municipal WWTP influent samples, the concentrations of IBP, NPX, DIC, and IDM were 1.05, 0.43, 0.23, and 0.11 μg/L, respectively. DIC was found only in one river sample. All NSAIDs were detected in tap water samples. However, their concentration was very low and the maximum values for IBP, NPX, DIC, and IDM were 47, 39, 24, and 37 ng/L, respectively, in tap water samples. Results showed that the measured pharmaceuticals were detected in all rivers with low concentrations in nanograms per liter range, except DIC which was found only in one river. Furthermore, this study showed that the aforementioned pharmaceuticals are not completely removed during their passage through WWTPs. A potential environmental risk of selected NSAIDs for the urban wastewater has been discussed. However, given their low measured concentrations, no ecotoxicological effect is suspected to occur.