Evaluation of rhodamine b photocatalytic degradation over batio3-mno2 ceramic materials

This research was funded by UIDB/50006/2020 with funding from FCT/MCTES through national funds and from the Institute of General and Ecological Chemistry of Lodz University of Technology. Susana L.H. Rebelo and Iwona Kuźniarska-Biernacka thank FCT (Fundação para a Ciência e Tecnologia) for funding through program DL 57/2016–Norma transitória (RE-QUIMTE/EEC2018/30 (SLHR) and REQUIMTE/EEC2018/14 (IKB)).Ferroelectric ceramics (BaTiO3_MnO2 ) with different Mn admixtures were prepared using solid-state synthesis. Elemental analysis, powder X-ray diffraction, scanning electron microscopy, Fourier-transform infrared spectroscopy, and impedance spectroscopy confirmed that the BaTiO3 and MnO2 coexisted in the ceramics. In addition, the high purity and homogeneity of the element distributions in the ceramic samples were confirmed. The adsorptive and photocatalytic properties of the BaTiO3 (reference sample, BTO) and BaTiO3_MnO2 materials (BTO_x, where x is wt.% of MnO2 and x = 1, 2 or 3, denoted as BTO_1, BTO_2 and BTO_3, respectively) were evaluated using Rhodamine B (RhB) as the model dye in a photocatalytic chamber equipped with a UV lamp (15 W) in the absence of additional oxidants and (co)catalysts. No adsorption of RhB dye was found for all the materials during 360 min (dark experiment). All samples were photocatalytically active, and the best results were observed for the BTO_3 material, where RhB was 70% removed from aqueous solution during 360 min of irradiation. The photodegradation of RhB in the presence of MnO2-modified BTO ceramics followed a pseudo-first order model and the rate constant of BTO_3 was about 10 times higher than that of BTO, 2 times that of BTO_2, and 1.5 times that of BTO_1. The photocatalysts could be successfully reused after thermal activation. © 2021 by the authors. Licensee MDPI, Basel, Switzerland. Published under the CC BY 4.0 license.Fundação para a Ciência e Tecnologia RE-QUIMTE/EEC2018/30, REQUIMTE/EEC2018/14; Institute of General and Ecological Chemistry of Lodz University of Technology; Ministério da Ciência, Tecnologia e Ensino Superior; Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART2

Green Aromatic Epoxidation with an Iron Porphyrin Catalyst for One-Pot Functionalization of Renewable Xylene, Quinoline, and Acridine

Sustainable functionalization of renewable aromatics is a key step to supply our present needs for specialty chemicals and pursuing the transition to a circular, fossil-free economy. In the present work, three typically stable aromatic compounds, representative of products abundantly obtainable from biomass or recycling processes, were functionalized in one-pot oxidation reactions at room temperature, using H2O2 as a green oxidant and ethanol as a green solvent in the presence of a highly electron withdrawing iron porphyrin catalyst. The results show unusual initial epoxidation of the aromatic ring by the green catalytic system. The epoxides were isolated or evolved through rearrangement, ring opening by nucleophiles, and oxidation. Acridine was oxidized to mono- and di-oxides in the peripheral ring: 1:2-epoxy-1,2-dihydroacridine and anti-1:2,3:4-diepoxy-1,2,3,4-tetrahydroacridine, with TON of 285. o-Xylene was oxidized to 4-hydroxy-3,4-dimethylcyclohexa-2,5-dienone, an attractive building block for synthesis, and 3,4-dimethylphenol as an intermediate, with TON of 237. Quinoline was directly functionalized to 4-quinolone or 3-substituted-4-quinolones (3-ethoxy-4-quinolone or 3-hydroxy-4-quinolone) and corresponding hydroxy-tautomers, with TON of 61

Biomimetic One-Pot Route to Acridine Epoxides

The first direct epoxidation of acridine on the edge positions is reported. The reaction proceeds under mild conditions using a biomimetic catalytic system based on a Mn­(III) porphyrin. The successive oxyfunctionalization to mono-, di-, and tetraepoxy derivatives is accomplished using hydrogen peroxide as a green oxidant at room temperature. Computed optimized geometries showed only slight shifts to the base planarity upon dearomatization by epoxidation, which is an important feature for DNA intercalation and bioactivity. NMR studies and comparison with theoretical values allowed the assignment of the stereochemistry of the <i>anti</i>- and <i>syn</i>-diepoxy and -tetraepoxy derivatives as well as compounds resulting from epoxide ring opening, exemplified by epoxydiol. The diepoxide is formed in an <i>anti</i>:<i>syn</i> ratio of ∼4, and the attack by nucleophiles, exemplified by ethylaniline, occurs selectively and with full conversion, using a microwave process with acetonitrile reflux for 10 min. Finally, studies of the electrostatic potential allowed the mechanisms of the formation of 4-hydroxyacridine and the regioselective reaction of diepoxyacridine with nucleophiles to be rationalized

Microwave-assisted silylation of graphite oxide and iron(III) porphyrin intercalation

The hybrid material graphite oxide (GO) intercalated with an iron(III) porphyrin was obtained upon a silylation reaction of GO with 3-bromotrimethoxypropylsilane (BrTMS) followed by metalloporphyrin immobilization. Diverse reaction conditions and microwave versus conventional heating were tested. The materials were characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), thermogravimetry (TGA) and temperature programmed desorption (TPD). Microwave-assisted synthesis allowed functionalization reactions of 1 h instead of 24 h (conventional heating) with equivalent or improved yields on both silylation and metalloporphyrin immobilization reactions. The immobilizations performed in anhydrous solvent and absence of other exfoliation agents led to an increase on the GO interlayer distance of 0.14 nm, in a total space of 7 Å that match the metalloporphyrin thickness.The authors thank the Fundação para a Ciência e a Tecnologia (FCT, Portugal), the European Union, QREN, FEDER, COMPETE, for funding REQUIMTE through projects PEst-C/EQB/LA0006/2013, NORTE-07-0124-FEDER-000067-nanochemistry and PTDC/EQU-ERQ/110825/2009. Authors acknowledge the MICINN of Spain (Projects CTQ-2011-29272-C04-01 and -03) for financial support. Thanks are also due to Joint Project “Acções Luso-Espanholas” E20/11 Acciones Integradas AIB2010PT-00104. Monika E. Lipińka also thanks FCT for a PhD grant SFRH/BD/66297/2009.Peer Reviewe

Biomimetic Oxidation of Benzofurans with Hydrogen Peroxide Catalyzed by Mn(III) Porphyrins

The modelling of metabolic activation of the benzofuran nucleus is important to obtain eco-sustainable degradation methods and to understand the related mechanisms. The present work reports the catalytic oxidation of benzofuran, 2-methylbenzofuran, and 3-methylbenzofuran by hydrogen peroxide, at room temperature, in the presence of different Mn(III) porphyrins as models of cytochrome P450 enzymes. Conversions above 95% were attained for all the substrates. The key step is the formation of epoxides, which undergo different reaction pathways depending on factors, such as the position of the methyl group and the reaction and work-up conditions used

N-doped cnt as a metal-free catalyst for reduction of nitro-benzene derivatives

Trabajo presentado en el 9º Encontro Nacional de Catálise e Materiais Porosos, celebrado en Oporto (Portugal) del 6 al 7 de mayo de 2013.Nitroaromatic compounds are commonly used in many industrial processes, including the preparation of pesticides, explosives, textiles and paper. Therefore, they are often detected as water pollutants as a result of their release in industrial effluents. Wastewaters remediation containing these pollutants is very problematic, since they are usually resistant to conventional degradation treatrnents. The physical- and chemical properties of carbon nanotubes (CNTs), particularly the basic character, can be tailored by the incorporation of nitrogen atoms in their structure. [2] N-doped CNTs have been proposed as supports for metal catalysts. Besides, these materials have been also used as metal-free catalysts for the selective oxidation of H2 S reaction, the oxygen reduction reaction or base-catalysed reactions.Here, we report the first use of CNT-N as a metal-free catalyst for the reduction of 4-nitrophenol (4NP) and 4-nitroaniline (4NA) in the presence of NaBH4 . Carbon nanotubes (CNT-N) were synthesized in a fluidized-bed reactor, over a Fe/Si02 catalyst, by catalytic chemical vapour decomposition of acetonitrile vapour and were characterized by transmission electron microscopy (TEM), N2 adsorption isotherm determination (BET) and X-ray photoelectron spectroscopy (XPS). The catalytic experiments were monitored by UV-Vis and the products of the reactions were characterized by 1HNMR.Support for this work was provided by FCT and FEDER through grant PEst­ C/EQB/LA0006/20l1, A95es Integradas Luso-Espanholas E 20/l l and Acciones Integradas AIB20lOPT-00104. MR, BJ and MA thank FCT for their grants.Peer Reviewe

Photodegradation of atrazine and ametryn with visible light using water soluble porphyrins as sensitizers

Abstract The photodegradation of the herbicides atrazine and ametryn with visible light in aerated neutral aqueous solutions and 5, 10, 15, 20-tetrakis (2,6-dichloro-3-sulfophenyl) porphyrin or 5, 10, 15, 20-tetrakis (4-sulfophenyl) porphyrin as sensitizers are reported for the first time. Our findings show that the degradation percentage reached 30% for atrazine and 63% for ametryn. The final photoproducts were characterized as dealkylated s-triazines. Photolysis of the pesticides in the presence of a singlet oxygen quencher showed only a minor contribution of this type of mechanism, while a bimolecular quenching reaction between the triplet state of the sensitizer and the pesticides is excluded by flash photolysis studies. It is proposed that the mechanism may involve the formation of a superoxide radical anion from the triplet state of the sensitizer and molecular oxygen, followed by a radical decomposition pathway

Oxidation of organosulfur compounds using an iron(III) porphyrin complex: An environmentally safe and efficient approach

Following our approach on the use of metalloporphyrins as catalysts and hydrogen peroxide as oxidant in the oxidation of organosulfur compounds (e.g. sulfides, benzothiophenes and dibenzothiophenes), herein the excellent catalytic performance of a homogeneous iron(III) porphyrin complex is demonstrated. Beyond the better results obtained, when compared with those with manganese(III) complexes, the present procedure involves a cleaner approach because ethanol is used as solvent and a co-catalyst is not required. For all the studied substrates (1-10), conversions higher than 95% were achieved with Fe(TF4NMe2PP)Cl (I). More significantly, catalyst (I) is also efficient in the oxidation of a model fuel, constituted by a mixture of benzothiophene (3), 3-methylbenzothiophene (5), 4-methyldibenzothiophene (8) and 4,6-diethyldibenzothiophene (10) in hexane, affording an overall conversion of 84%. (C) 2014 Elsevier B.V. All rights reserved