Suchergebnisse

[EN] Photocatalytic degradation of three highly chlorinated contaminants, namely 2,4,6-trichlorophenol (TCP), 2,4,6-trichloroanisole (TCA) and 5-chloro-2-(2,4-dichlorophenoxy)phenol (triclosan, TCS) has been investigated in the presence of N-methylquinolinium tetrafluoroborate (NMQ(+)), a photocatalyst able to act via Type I or Type II mechanism. Photodegradation of contaminants under aerobic conditions was achieved within hours; and it was accompanied by mineralization, as demonstrated by trapping of the evolved carbon dioxide as barium carbonate. Moreover, a high degree of detoxification, based on % inmobilization of daphnids (Daphnia magna bioassay), was reached after 70 h of irradiation. Quenching of the NMQ(+) fluorescence by the pollutants was evidenced by a decrease in the emission intensity and lifetime. Detection of the reduced NMQ. by laser flash photolysis in the presence of the pollutants provided an unambigous evidence of the electron transfer process. Quenching of singlet oxygen by the contaminants showed the typical singlet oxygen quenching constants (10(5)-10(6) M-1 s(-1)). Evaluation of the relative contribution of both pathways (Type I vs Type II) point to the photodegradation occurring via a Type I mechanism, being the contribution of Type II mechanism negligible at any concentration range. ; Financial support from Spanish Government (Grant SEV-2016.0683 and CTQ2015-69832-C4) and generous contribution from Generalitat Valenciana (Prometeo Program) are gratefully acknowledged. We also thank support from VLC/Campus. R Martinez-Haya thanks financial support from Spanish Government (Grant SEV-2012-0267). ; Martínez-Haya, R.; Sabater Marco, C.; Castillo López, M.; Miranda Alonso, MÁ.; Marín García, ML. (2018). A mechanistic study on the potential of quinolinium salts as photocatalysts for the abatement of chlorinated pollutants. Journal of Hazardous Materials. 351:277-284. https://doi.org/10.1016/j.jhazmat.2018.03.010 ; S ; 277 ; 284 ; 351

[EN] The degradation of enrofloxacin (ENR) by direct photolysis, Fenton and solar photo-Fenton processes has been studied in different water matrices, such as ultra-pure water (MQ), tap water (TW) and highly saline water (SW). Reactions have been conducted at initial pH 2.8 and 5.0. At pH = 2.8, HPLC analyses showed a fast removal of ENR by (solar photo)-Fenton treatments in all studied water matrices, whereas a 40% removal was observed after 120 min of photolysis. However, TOC measurements showed that only solar photo-Fenton was able to produce significant mineralization (80% after 120 min of treatment); differences between ENR removal and mineralization can be attributed to the release of important amounts of reaction by-products. Excitation-emission matrices (EEMs) combined with parallel factor analysis (PARAFAC) were employed to gain further insight into the nature of these by-products and their time-course profile, obtaining a 5-component model. EEM-PARAFAC results indicated that photolysis is not able to produce important changes in the fluoroquinolone structure, in sharp contrast with (solar photo)-Fenton, where decrease of the components associated with fluoroquinolone core was observed. Agar diffusion tests employing E. toll and S. aureus showed that the antibiotic activity decreased in parallel with the destruction of the fluoroquinolone core. ; This paper is part of a project that has received funding from the European Union's Horizon 2020 - Research and Innovation Framework Programme under the H2020 Marie Sklodowska-Curie Actions grant agreement No 765860. The paper reflects only the authors' view and the Agency is not responsible for any use that may be made of the information it contains. ; Sciscenko, I.; García-Ballesteros, S.; Sabater Marco, C.; Castillo López, M.; Escudero-Oñate, C.; Oller, I.; Arqués Sanz, A. (2020). Monitoring photolysis and (solar photo)-Fenton of enrofloxacin by a methodology involving EEM-PARAFAC and bioassays: Role of pH and water matrix. Science of The Total Environment. ...