Comparative study on photocatalytic degradation of the antidepressant trazodone using (Co, Fe and Ru) doped titanate nanowires: Kinetics, transformation products and in silico toxicity assessment.

Titanate nanomaterials have been outstanding in the removal of emerging contaminants by the photocatalysis process. These photocatalysts, when modified through techniques such as doping with metals, they have advantages over TiO2, especially in the region of visible light. In this work, the photocatalytic performance of four recent reported catalysts, pristine titanate nanowires, cobalt-doped titanate nanowires, iron-doped titanate nanowires and ruthenium-doped titanate nanowires, for the removal of the antidepressant trazodone under visible light radiation was compared. The iron-doped titanate nanowires presented the best catalytic activity by the catalyst surface area. Additionally, thirteen transformation products (TPs) were identified by high-resolution mass spectrometry and, to the best of our knowledge, nine of them have never been described in the literature. It was shown that for each catalyst different TPs were formed with distinct time profiles. Finally, toxicity assessment by computational methods showed that TPs were not readily biodegradable and they presented toxicity to aquatic organisms with mutagenic potential. These findings reinforce the importance of taking into consideration the TPs formed during the removal of pollutants since many of them may be toxic and can be produced during photocatalysis.

Degradation of duloxetine: Identification of transformation products by UHPLC-ESI(+)-HRMS/MS, in silico toxicity and wastewater analysis.

Duloxetine (DUL), an antidepressant drug, has been detected in surface water and wastewater effluents, however, there is little information on the formation of its transformation products (TPs). In this work, hydrolysis, photodegradation (UV irradiation) and chlorination experiments were performed on spiked distillated water, under controlled experimental conditions to simulate abiotic processes that can occur in the environment and wastewater treatment plants (WWTPs). Eleven TPs, nine from reaction with UV light and two from chlorine contact, were formed and detected by ultra-high performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry, and nine of them had their chemical structures elucidated upon analyses of their fragmentation patterns in MS/MS spectra. The formation and degradation of the TPs were observed. The parent compound was completely degraded after 30 min in photodegradation and after 24 hr in chlorination. Almost all TPs were completely degraded in the experiments. The ecotoxicity and mutagenicity of the TPs were predicted based on several in silico models and it was found that a few of these products presented more ecotoxicity than DUL itself and six TPs showed positive mutagenicity. Finally, wastewater samples were analyzed and DUL and one TP, possibly formed by chlorination process, were detected in the effluent, which showed that WWTP not only did not remove DUL, but also formed a TP.

Transformation products of citalopram: Identification, wastewater analysis and in silico toxicological assessment.

The objective of this study was to identify transformation products (TPs) of citalopram (CIT), an antidepressant drug, in laboratory experiments. Moreover, toxicity predictions and analyzes in wastewater samples were performed. For the formation of TPs, raw water was used for the processes of hydrolysis; photodegradation under ultraviolet (UV) irradiation and chlorination. The toxicities were predicted by computational toxicity assessment. The TPs were identified by liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QTOF/MS) in broadband collision induced dissociation (bbCID) acquisition mode and product ion scan mode (MS/MS). The probable structures of the TPs under study were established based on accurate mass, fragmentations observed in the MS spectra and prediction tools software. The experiments resulted in seventeen possible identified TPs and their stability and formation was monitored over time in the experiments. Two of these TPs were identified in wastewater samples It was also observed that most of TPs formed were either less toxic then CIT or had a similar toxicity.