Photodegradation of metoprolol using a porphyrin as photosensitizer under homogeneous and heterogeneous conditions


Porphyrins are known as effective photosensitizers and can be an interesting key in phototreatment of water contaminated with micropollutants such as pharmaceuticals. They already showed to be efficient photocatalysts for the degradation of dyes, chlorophenols and other pollutants. This work demonstrates the applicability of 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin (H2TF5PP) as photosensitizer for treatment of water contaminated with metoprolol, a highly prescribed beta-blocker, which is not completely removed in sewage treatment plants. Studies were firstly developed under homogeneous conditions with simulated solar radiation and porphyrin was found to be efficient in the photodegradation of metoprolol, following a pseudo-first order kinetics with ca. 90% metoprolol degradation after 12 h. Experiments in presence of scavengers confirmed the mechanism of degradation via singlet oxygen. Appearance of several new peaks in HPLC chromatograms indicates the formation of products, identified by HPLC-MSn. Furthermore, the porphyrin was immobilized on a silica support and used as heterogeneous photocatalyst in degradation of metoprolol. Experiments using this heterogeneous photocatalyst under real solar irradiation were also performed, and similar results were obtained. Kinetic comparison of metoprolol photodegradation in buffer solution and in real wastewater treatment plant effluent showed that the efficiency of the immobilized porphyrin was not decreased by the complex matrix of the effluent.



subject category

Engineering; Environmental Sciences & Ecology


Neves, CMB; Filipe, OMS; Mota, N; Santos, SAO; Silvestre, AJD; Santos, EBH; Neves, MGPMS; Simoes, MMQ

our authors


Thanks are due to National Foundation for Science and Technology/Ministerio da Educacao e Ciencia-FCT/MEC (POPH/FSE) for the financial support to QOPNA (UID/QUI/00062/2013), CERNAS (UID/AMB/00681/2013), CESAM (UID/AMB/50017 - POCI-01-0145-FEDER-007638) and CICECO (UID/CTM/50011/2013), through national funds (PIDDAC) and, where applicable, co-financed by the FEDER, within the PT2020 Partnership Agreement and Compete 2020, and also to the Portuguese NMR Network. The authors are also grateful to FCT and POPH/FSE for the PhD Grant to C.M.B. Neves (PD/BD/52531/2014). S.A.O. Santos thanks to AgroForWealth project (CENTRO-01-0145-FEDER-000001) funded by Centro2020. The authors also thank Aguas do Centro Litoral, S.A. (ETAR de Ilhavo) and its responsible, Eng. Milton Fontes, for the collection of the effluent sample and for providing data on its chemical characterization.

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