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Главная страница Новости науки Journal of Photochemistry and Photobiology A: Chemistry
Новости науки
ScienceDirect Publication: Journal of Photochemistry and Photobiology A: Chemistry
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  • Preparation of magnetic photocatalysts from TiO2, activated carbon and iron nitrate for environmental remediation

    Publication date: 1 September 2019

    Source: Journal of Photochemistry and Photobiology A: Chemistry, Volume 382

    Author(s): Leydiane de Oliveira Pereira, Isabela Marques Sales, Luana Pereira Zampiere, Sara Silveira Vieira, Iara do Rosário Guimarães, Fabiano Magalhães

    Abstract

    In this study different magnetic photocatalysts were prepared. Activated carbon (AC) and iron nitrate were used for the preparation of a magnetic support (Fe/AC). Different TiO2 contents were supported on the surface of Fe/AC to obtain the photocatalyst Ti/Fe/AC. Results obtained by XRD showed that the photocatalysts have Fe3O4, which confers magnetic property. The presence of carbon and TiO2 was confirmed by Raman and XRD. Scanning Electron Microscopy images showed clusters of TiO2 particles on the surface of Fe/AC. Results of X-ray fluorescence allowed the obtention of the levels of carbon, iron and titanium in the photocatalysts, which followed the expected trend. The results of reactions carried out in the presence of ultraviolet radiation showed that the magnetic photocatalysts removed from 50 to 96% of color ratio of Reactive Black (RB) in aqueous medium. The best efficiency for removal of total organic carbon (TOC) reached 90%. Sedimentation kinetics tests performed in the presence of magnetic field showed that nearly 92% of the photocatalysts could be rapidly separated from the aqueous medium, while pure TiO2 does not sediment efficiently. Results for the recovery and reuse of the photocatalysts for four consecutive reactions showed that they can be separated from the reaction medium in a simple and fast way, without significant losses of photocatalytic efficiency. These results showed that the prepared magnetic photocatalysts have excellent photocatalytic activity and can be easily recovered and reused, which implies the reduction of costs and increases the potential for scale up application.

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  • A revised experimental protocol for implementing the actinometry method with the Reinecke’s salt

    Publication date: 1 September 2019

    Source: Journal of Photochemistry and Photobiology A: Chemistry, Volume 382

    Author(s): Robbie Radjagobalou, Jean-François Blanco, Victoria Dias da Silva Freitas, Caroline Supplis, Fabrice Gros, Odile Dechy-Cabaret, Karine Loubière

    Abstract

    The present short note aims at proposing a revised experimental protocol to implement the actinometry method with Reinecke’s salt. It consists in substituting, for the dosing of the thiocyanate anions produced, perchloric acid (HClO4) by nitric acid (HNO3), the latter being carefully chosen regarding the chemical equilibria occurring in the aqueous medium and the moderate risks of HNO3. This substitution has been rigorously validated by carrying out the experiments in a dedicated torus batch photoreactor enabling simple treatment of experimental results from a one-dimensional model.

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    Actinometry using the Reinecke’s salt: switching the perchloric acid with a less hazardous acid.

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  • Synthesis of carbon nanohoops containing thermally stable cis azobenzene

    Publication date: 1 September 2019

    Source: Journal of Photochemistry and Photobiology A: Chemistry, Volume 382

    Author(s): Paul J. Evans, Lev N. Zakharov, Ramesh Jasti

    Abstract

    Cycloparaphenylenes (CPPs) have been praised for their size-tunable HOMO/LUMO gap and associated electronic and optical properties, and have generated significant interest for small-molecule electronics. Another fascinating but less-explored prospect for CPPs involves exploiting their hollow geometry. With a rigid pore of tunable size and high electron density arising from the inward facing π-orbitals, CPPs are ideal for electron-poor guests. [10]CPP in particular has shown very high binding affinity for fullerene C60. The ability to reverse this encapsulation by external stimuli is an important next step. Herein we report the design and synthesis of two CPPs containing thermally stable cis azobenzene moieties in the conjugated framework, their behavior upon irradiation, and computational results evaluating their potential as photoswitchable fullerene hosts.

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  • Application of pyrrolo[2,3-b]quinoxaline with an N,N-bis(pyridin-2-ylmethyl)ethylenediamine chain for Zn(II) detection in Candida albicans and fibroblast cells

    Publication date: 1 September 2019

    Source: Journal of Photochemistry and Photobiology A: Chemistry, Volume 382

    Author(s): Majka Duda, Maria Rąpała-Kozik, Katarzyna M. Stadnicka, Bogdan Musielak, Piotr Goszczycki, Łukasz J. Witek, Marcin Zawrotniak, Miriam González-González, Katarzyna Ostrowska

    Abstract

    In the present study, a new 'turn on' fluorescent sensor, (E/Z)-enaminone containing a pyrrolo[2,3-b]quinoxaline group as the fluorophore and a N,N-bis(pyridin-2-ylmethyl)ethylenediamine group as a specific chelator capable of selective detection of Zn2+ is reported. The structure of the ligand was determined by IR, MS, and 1D and 2D NMR, including 1H-15N HMBC correlations. X-ray analysis for (E/Z)-2 confirmed the presence of 90.3% E-diastereoisomer and 9.7% Z-one in the structure of the crystals obtained from acetonitrile. The mechanism of zinc ion recognition is related to the restriction of E/Z-isomerisation of enaminone occurring upon Zn2+ binding that alters the electronic structure of the ligand. Sensing of Zn2+ was confirmed in detail using UV–vis, fluorescent, and 1H NMR titrations, which allowed us to propose the binding mode for complexes formed in the solution during the zinc ion recognition. The ligand functions under physiological conditions and retains its activity in buffer solutions over a wide pH range 2.4–10.6. The developed sensor allowed for intracellular sensing of Zn2+ in human (fibroblast) and fungal (Candida albicans) cells through fluorescence imaging studies.

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  • Black carbon-doped TiO2 films: Synthesis, characterization and photocatalysis

    Publication date: 1 September 2019

    Source: Journal of Photochemistry and Photobiology A: Chemistry, Volume 382

    Author(s): Sarunas Varnagiris, Arturs Medvids, Martynas Lelis, Darius Milcius, Andris Antuzevics

    Abstract

    Black colour TiO2 films were synthesized on amorphous fused silica substrates by DC magnetron sputtering technique with carbon powders placed at the working magnetron surface. Comprehensive sample analysis by X-ray diffraction, energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy showed that the rutile/anatase heterostructure TiO2 films were successfully formed. Moreover, observation of OTiC bonds confirmed that TiO2 phase was doped by carbon additives. Scanning electron microscopy, atomic force microscopy and X-ray diffraction were used to identify the effect of deposition time and TiO2 film thickness on the surface morphology, roughness and crystallite size. Results of electron spin resonance showed that oxygen vacancies were generated on the surface with trapped unpaired electrons. Optical analysis by UV–vis light spectrophotometer showed that TiO2 films with carbon additives improve its capability to absorb visible light. Accordingly, methylene blue bleaching experiments under UVA and visible light irradiation showed that black colour TiO2 films are capable to decompose methylene blue solution at both UVA and visible light irradiation.

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  • Impact of the absolute rutile fraction on TiO2 visible-light absorption and visible-light-promoted photocatalytic activity

    Publication date: 1 September 2019

    Source: Journal of Photochemistry and Photobiology A: Chemistry, Volume 382

    Author(s): D.M. Tobaldi, L. Lajaunie, N. Rozman, A.P.F. Caetano, M.P. Seabra, A. Sever Škapin, R. Arenal, J.A. Labrincha

    Abstract

    Titanium dioxide is by far the most used semiconductor material for photocatalytic applications. Still, it is transparent to visible-light. Recently, it has been proved that a type-II band alignment for the rutile − anatase mixture would improve visible-light absorption. In this research paper we thoroughly characterised the real crystalline and amorphous phases of synthesised titanias – thermally treated at different temperatures to get distinct ratios of anatase-rutile-amorphous fraction – as well as that of three commercially available photocatalytic nano-TiO2.

    Optical spectroscopy showed that even a small fraction of rutile (2 wt%) is able to shift to lower energies the apparent optical band gap of an anatase-rutile mixed phase. But is this enough to attain a real photocatalytic activity promoted by merely visible-light? We tried to give an answer to that question.

    Photocatalytic activity was assessed in the liquid- and gas-solid phase (employing rhodamine B and 4-chlorophenol, and isopropanol, respectively, as the organic substances to degrade) using a light source irradiating exclusively in the visible-range.

    Photocatalytic activity results in the liquid-solid phase showed that a high surface hydroxylation led to specimen with superior visible light-promoted catalytic activity – i.e. dye and ligand-to-metal charge transfer complexes sensitisation effects, not photocatalysis sensu-strictu.

    On the other hand, the gas-solid phase results showed that a higher amount of the absolute rutile fraction (around 10 wt%), together with less recombination of the charge carriers, were more effective for both visible-light absorption and a “real” visible-light promoted photocatalytic oxidation of isopropanol.

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  • A coumarin-based near-infrared fluorescent probe with a large stokes shift for the sequential recognition of Ni2+ and CN: Performance research and quantum calculation

    Publication date: 1 September 2019

    Source: Journal of Photochemistry and Photobiology A: Chemistry, Volume 382

    Author(s): Kai Wang, Chengxi Zhao, Shaohua Guo, Yunxiang Lu, Yongjia Shen, Chengyun Wang

    Abstract

    The design and synthesis of bifunctional probes have gradually become a new research focus in the field of fluorescent probes. In this work, a reversible colorimetric and NIR fluorescent probe (Ni−3) for the sequential detection of Ni2+ and CN was developed based on 3-benzothiazolyl-7-hydroxycoumarin. This probe featured a large Stokes shift (145 nm) and excellent anti-fatigue performance for the sequential detection of Ni2+ and CN. Ni−3 showed a highly colorimetric response to Ni2+ and the selectivity could be distinguished by naked eyes. Besides, Ni−3 also exhibited selective NIR fluorescence response toward Ni2+ due to the paramagnetic effect and the chelation-enhanced quenching (CHEQ) effect. Additionally, the in situ generated complex [2 Ni−3 + Ni2+] showed highly sensitive and selective sensing ability for CN via Ni2+ displacement approach. The limit of detection toward CN (1.29 μM) was lower than the maximum acceptable concentration level of cyanide in drinking water (1.9 μM) set by WHO. Furthermore, a “paralleled-coordination” mode between Ni−3 and Ni2+ was proposed and demonstrated with the aid of quantum calculations.

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    A coumarin-based reversible colorimetric and near-infrared fluorescent probe (Ni−3) for the sequential detection of Ni2+ and CN.

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  • Eco-friendly synthesis of Mg0.5Ni0.5AlxFe2-xO4 magnetic nanoparticles and study of their photocatalytic activity for degradation of direct blue 129 dye

    Publication date: 1 September 2019

    Source: Journal of Photochemistry and Photobiology A: Chemistry, Volume 382

    Author(s): Kobra Atrak, Ali Ramazani, Saeid Taghavi Fardood

    Abstract

    In this research, Mg0.5Ni0.5AlxFe2-xO4 (x = 0.5, 1, 1.5) spinel ferrites were synthesized by facile sol-gel technique. The effects of the aluminum ion as a dopant on structural, morphological, optical, magnetic properties, and photocatalytic activity of spinel ferrites have been investigated using various analytical techniques. The XRD results approve the formation of a single-phase cubic spinel structure. It is also observed that the crystallite size decreases as Al3+ concentration increases. The FESEM and TEM analyses indicate a nanosized particle morphology. According to the VSM results, the saturation magnetization (Ms) decreases by the increase of Al content. Optical band gap energy studies of samples express that Eg value increases from 2.55 to 2.67 eV by increasing Al3+ dopant, which is confirmed by UV–vis DRS. The photocatalytic activity of the catalysts was evaluated for the degradation of DB129 as a model reaction under visible light irradiation. Based on our results, there is a direct correlation between photocatalytic activity and the amount of Al. Hence, the catalyst with x = 1.5 illustrates better degradation than the catalyst with x = 1 and 0.5. The catalyst with x = 1.5 is also capable to degrade the direct blue 129 up to 94%.

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  • Dual sensitization effect and conductive structure of Fe3O4@mTiO2/C photocatalyst towards superior photodegradation activity for bisphenol A under visible light

    Publication date: 1 September 2019

    Source: Journal of Photochemistry and Photobiology A: Chemistry, Volume 382

    Author(s): Xiaoxu Zhao, Run Wang, Ziyang Lu, Weichao Wang, Yongsheng Yan

    Abstract

    In this paper, we prepared Fe3O4@mTiO2/C (the mesoporous TiO2 denoted as mTiO2) photocatalyst via a simple synthetic method, and it exhibits strong light response under visible light region because of the dual sensitization effect of Fe3O4 and carbon. In addition, the composite photocatalyst also has double conductivity, which is beneficial to the transfer and separation of charge carriers due to the synergetic effect of Fe3O4, carbon and mTiO2. As a consequence, the double conductive structure Fe3O4@mTiO2/C photocatalyst displays prominent photocatalytic activity in degradation of BPA under visible light. Furthermore, the photocatalyst not only was recycled easily to reduce the secondary pollution of the environment but also had a superior stability. This work may provide a new inspiration toward constructing dual sensitization and double conductive structure with other semiconductor photocatalyst to effectively improve the photocatalytic activity under visible light for practical application.

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    The Fe3O4@mTiO2/C composite photocatalyst is first constructed by a simple and eco-friendly strategy, which presents the excellent photocatalytic activity for removing bisphenol A in water under visible light due to its the dual sensitization effect and double conductive structure of Fe3O4 and carbon.

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  • Photocatalytic activity of solvothermal prepared BiOClBr with imidazolium ionic liquids as a halogen sources in cytostatic drugs removal

    Publication date: 1 September 2019

    Source: Journal of Photochemistry and Photobiology A: Chemistry, Volume 382

    Author(s): Patrycja Wilczewska, Aleksandra Bielicka-Giełdoń, Agnieszka Fiszka Borzyszkowska, Jacek Ryl, Tomasz Klimczuk, Ewa Maria Siedlecka

    Abstract

    In this work, the BiOClBr, as a new family of bismuth based semiconductors, was successfully applied to remove of cytostatic drugs from water under UV-Vis light irradiation. BiOCl, BiOBr and BiOClBr were synthesized using two steps solvothermal method in glycerol. The inorganic salts (KCl and KBr) and 1-butyl-3-metylimidazolium chloride (BmimCl) and 1-butyl-3-metylimidazolium bromide (BmimBr) ionic liquids (ILs) were used as the source of halides for the photocatalysts synthesis. The as-fabricated samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and UV–vis diffuse reflectance spectroscopy (DRS). The specific surface area was measured by Brauner-Emmett-Teller (BET) technique. Additionally, Fourier-transform infrared spectroscopy was used to evaluate the presence of IL on the photocatalysts surface. The comparison of photocatalytic activity between BiOCl and BiOClBr photocatalysts towards 5-fluorouracil (5-FU), imatinib (IMA) and cyclophosphamide (CP) removal was conducted. The highest photocatalytic activity in the cytostatic drugs degradation and mineralization was found using BiOClBr IL synthetized via ILs as the halogens source. The study showed that BiOClBr IL synthesized in the presence of ILs can be a promising material in the water decontamination methods.

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