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The methylene blue photosensitization under red light irradiation (MB/Red-light) is a promising and powerful tool for removal of pharmaceuticals from wastewater. To further develop this new technology, the present work aimed at studying the effect of operational parameters on the performance of MB/Red-light pharmaceuticals removal processes. Three...
Citations
... Depending on the excitation wavelength of the chosen photosensitizer molecule, visible light can be efficiently used for water treatment instead of UV sources [3,12,13]. The use of photosensitizers for treatment of waste water was described to exhibit the potential to overcome inhibitory effects of background water constituents in complex water matrices [3]. ...
... The degradation of pharmaceuticals by 1 O 2 and OH radicals was studied in river and waste water and confirmed the possibility and efficiency of 1 O 2 for oxidative elimination [2,12,13]. Consequently, photosensitizers were studied for degradation of pollutants in water [3,[12][13][14][15][16]. ...
... The degradation of pharmaceuticals by 1 O 2 and OH radicals was studied in river and waste water and confirmed the possibility and efficiency of 1 O 2 for oxidative elimination [2,12,13]. Consequently, photosensitizers were studied for degradation of pollutants in water [3,[12][13][14][15][16]. ...
Two different photosensitizer molecules were immobilized on a commercial polyethersulfone membrane by electron beam-mediated grafting. The resulting membrane surface generates singlet oxygen upon activation with light according to the photosensitizer‘s excitation wavelength. Thus, the immobilization procedure results in highly active membrane surfaces. The degradation of different pharmaceuticals (propranolol and ranitidine) by the photoactive membranes was investigated. The activity (singlet oxygen generation rate) and degradation efficiency regarding the two pharmaceuticals was studied next to membrane characteristics (scanning electron microscopy, permeance, contact angle, X-ray photoelectron spectroscopy). The immobilization led to increased surface hydrophilicity and permeance while preserving pore size and morphology. Both photosensitizer membrane systems showed high singlet oxygen generation activity. It was found that propranolol and ranitidine were efficiently converted by singlet oxygen to transformation products, but they were not completely mineralized as monitored by total organic carbon analysis and chromatography.
... Depending on the excitation wavelength of the chosen photosensitizer molecule, visible light can be efficiently used for water treatment instead of UV sources [3,12,13]. The use of photosensitizers for treatment of waste water was described to exhibit the potential to overcome inhibitory effects of background water constituents in complex water matrices [3]. ...
... The degradation of pharmaceuticals by 1 O 2 and OH radicals was studied in river and waste water and confirmed the possibility and efficiency of 1 O 2 for oxidative elimination [2,12,13]. Consequently, photosensitizers were studied for degradation of pollutants in water [3,[12][13][14][15][16]. ...
... The degradation of pharmaceuticals by 1 O 2 and OH radicals was studied in river and waste water and confirmed the possibility and efficiency of 1 O 2 for oxidative elimination [2,12,13]. Consequently, photosensitizers were studied for degradation of pollutants in water [3,[12][13][14][15][16]. ...
Photodynamic treatment is a promising tool for the therapy of multidrug-resistant bacteria. In this study, we highlight photosensitizer-loaded hydrogels as an application system for infected wounds. The poly(ethylene glycol) diacrylate-based and electron beam-polymerized hydrogels were mechanically stable and transparent. They were loaded with two photoactive, porphyrin-based drugs – tetrakis(1-methylpyridinium-4-yl)porphyrin p-toluenesulfonate (TMPyP) and tetrahydroporphyrin – p-toluenesulfonate (THPTS). The hydrogels released a sufficient amount of the photosensitizers (up to 300 mmol l-1), relevant for efficiency. The antimicrobial effectivity of loaded hydrogels was investigated in a tissue-like system as well as in a liquid system against a multiresistant Escherichia coli. In both systems, light induced eradication was possible. In contrast, hydrogels alone showed only minor antimicrobial activity. Furthermore, the loaded hydrogels were successfully tested against seven multidrug-resistant bacterial strains, namely Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumonia, Acinetobacter baumannii, Pseudomonas aeruginosa, Escherichia coli and Achromobacter xylosoxidans.
The eradication of these pathogens, except A. xylosoxidans, was successfully demonstrated. In general, TMPyP-loaded hydrogels were more effective than THPTS-loaded ones. Nevertheless, both photosensitizers displayed effectivity against all investigated bacteria strains. Taken together, our data demonstrate that photosensitizer-loaded hydrogels are a promising new tool to improve the treatment of wounds infected with problematic bacterial pathogens.
... The degradation efficiency of synthesized TiO 2 NPs@C nanocomposite is about 90% when extending the irradiation time to 40 min, the efficiency is much higher than the bare TiO 2 NPs which is about 39% shown in Fig. 6(d). Reactions followed pseudo-first order kinetics and rates of kinetic resolute from the linear portion of the reaction profiles ( Fig. 6(e)) [58,59]. The rate constant (k) of the synthesized TiO 2 NPs@C nanocomposite is ca. ...
As an efficient photocatalytic titanium dioxide [email protected] carbon (TiO2[email protected]) nanocomposite and bright fluorescent with good biocompatible nitrogen-doped carbon dots (N-CDs) were synthesized at once by an affordable hydrothermal method. Physicochemical properties of the synthesized materials were examined by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, field emission scanning electron microscopy (FESEM) with energy dispersive X-ray (EDX) and elemental mapping analysis, high resolution transmission electron microscopy (HRTEM), atomic force microscopy (AFM), ultraviolet–visible (UV–vis) spectroscopy and fluorescence spectroscopy. The photocatalytic efficiency of synthesized TiO2[email protected] nanocomposite was evaluated in the degradation of methylene blue (MB) under UV-light irradiation. The degradation efficiency of TiO2[email protected] nanocomposite is about 90% when extending the irradiation time to 40 min, the rate constant is 5 times higher than that of bare TiO2 NPs. The augmentation of photocatalytic activity of TiO2[email protected] nanocomposite was attributed to the synergistic effect between TiO2 NPs and graphene-like carbon within the nanocomposite. The recycling studies were conducted and the photodegradation efficiency of TiO2[email protected] nanocomposite did not show any significant changes up to three cycles, suggesting that the synthesized photocatalyst has good repeatability and the considerable stability. In addition, the carbon derived from a natural green source possesses the hydroxyl and nitrogen-containing functional groups on the surface which resulting TiO2 NPs @C nanocomposite with high photocatalytic activity. Also, the obtained N-CDs displays almost zero toxicity towards the Candida albicans cells even at high concentrations which can be utilized as a powerful in-vitro label-free fluorescent probe for live cell imaging. Based on their bright with stable fluorescence and cellular imaging with good biocompatibility, N-CDs would offer a great potential for a wide range of applications in the biomedical and clinical applications in the near future.
L’objectif de ce travail est de développer un procédé de photodégradation de contaminants organiques de l’eau par l’intermédiaire la phénalénone (PN). Une mise en oeuvre du photosensibilisateur a été recherchée pour une réaction optimale et une séparation aisée de l’effluent traité. L’utilisation de la PN dans un contexte de traitement de l’eau, a été validé dans un premier temps, en phase homogène pour la photodégradation de deux molécules modèles en solution aqueuse, le phénol, et un fongicide, le tébuconazole (TEB). Cette étude a été menée dans un réacteur annulaire de 0,4 L avec une irradiation dans l’UV ou le visible dont l’émission couvre en partie le spectre d’absorbance de la PN. La PN a été associée à deux supports inorganiques, une halloysite naturelle par voie d’adsorption pour la dégradation du phénol et un sable par greffage chimique pour la dégradation du TEB. L’étude des mécanismes de photodégradation du phénol en solution a révélé que le mécanisme principal était un mécanisme de type II à travers l’oxygène singulet avec la participation du mécanisme de type I via l’intervention de la PN.. Lors de la photodégradation du tébuconazole en utilisant la PN supportée, l’oxygène singulet est la principale espèce oxydative responsable de la photodégradation avec principalement un mécanisme de type II avec une très faible contribution du mécanisme de type I. Ce mécanisme est précédé d’une phase de sorption importante sur le support (50% de l’abattement initial). Le greffage de la PN sur le sable, élargissait sa bande d’absorbance dans la région du visible, améliorant ainsi sa performance dans cette région du spectre avec une constante cinétique du même ordre que celle obtenue sous irradiation UV (1.3 × 10-3 min-1). Une étude à l’échelle du laboratoire a permis de valider l’utilisation d’une irradiation par des LEDs bleu (435nm à 465 nm). Les cinétiques de photodégradation du TEB dans le réacteur à lit fluidisé (38,7 L) sont similaires à celles obtenues dans l’unité de laboratoire. Un modèle de réaction d’ordre 1 dans un réacteur parfaitement agité permet de décrire le fonctionnement du lit fluidisé malgré une perte d’efficacité peut être due à une perte de molécules photosensibilisatrices.
