- Hydrothermally Induced Oxygen Doping of Graphitic Carbon Nitride with a Highly Ordered Architecture and Enhanced Photocatalytic Activity
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As an amorphous or semicrystalline material, graphitic carbon nitride (g-C3N4) displays poor photocatalytic activity owing to rapid recombination of the photogenerated charge carriers, which is mainly caused by a high density of defects in the graphitic structure. In this work, a porous O-doped g-C3N4 (P-CNO) nanosheet with a highly ordered architecture is fabricated by introducing a novel hydrothermal treatment to the precursor before the final thermal condensation. The photocatalytic hydrogen evolution rate (HER) and HER per surface area of P-CNO are 13.9 and 1.7 times higher than that of bulk g-C3N4. The improved photocatalytic activity is ascribed to a synergistic effect of O doping, a porous sheet-like morphology, and increased crystallinity. This work also provides a new approach for the synthesis of other polymer-based photocatalysts with high crystallinity and excellent performance.
- Wang, Chao,Fan, Huiqing,Ren, Xiaohu,Ma, Jiangwei,Fang, Jiawen,Wang, Weijia
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- Overturned Loading of Inert CeO2 to Active Co3O4 for Unusually Improved Catalytic Activity in Fenton-Like Reactions
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In the past decades, numerous efforts have been devoted to improving the catalytic activity of nanocomposites by either exposing more active sites or regulating the interaction between the support and nanoparticles while keeping the structure of the active sites unchanged. Here, we report the fabrication of a Co3O4?CeO2 nanocomposite via overturning the loading direction, i.e., loading an inert CeO2 support onto active Co3O4 nanoparticles. The resultant catalyst exhibits unexpectedly higher activity and stability in peroxymonosulfate-based Fenton-like reactions than its analog prepared by the traditional impregnation method. Abundant oxygen vacancies (Ov with a Co???Ov???Ce structure instead of Co???Ov) are generated as new active sites to facilitate the cleavage of the peroxide bond to produce SO4.? and accelerate the rate-limiting step, i.e., the desorption of SO4.?, affording improved activity. This strategy is a new direction for boosting the catalytic activity of nanocomposite catalysts in various scenarios, including environmental remediation and energy applications.
- Song, Chunli,Zhan, Qing,Liu, Fei,Wang, Chuan,Li, Hongchao,Wang, Xuan,Guo, Xuefeng,Cheng, Yingchun,Sun, Wei,Wang, Li,Qian, Jieshu,Pan, Bingcai
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supporting information
(2022/02/23)
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- Preparation method of cyromazine
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The invention discloses a preparation method of cyromazine. Melamine is used as an initial raw material; the preparation method comprises the following steps: carrying out an acidic hydrolysis reaction to obtain 4, 6-diamino-2-hydroxy-1, 3, 5-triazine, carrying out a chlorination reaction on 4, 6-diamino-2-hydroxy-1, 3, 5-triazine to obtain a toluene solution of 4, 6-diamino-2-chloro-1, 3, 5-triazine, and carrying out an amination reaction on 4, 6-diamino-2-chloro-1, 3, 5-triazine and cyclopropylamine so as to generate cyromazine. According to the method, toxic 2-cyclopropylamino-4, 6-dichloro-S-triazine is prevented from being generated, ammoniation pressurizing equipment is prevented from being used, reaction conditions are milder, cheaper materials are used, and the prepared cyclopropylamine is high in yield and good in quality.
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Paragraph 0023-0024; 0027-0028; 0031-0032; 0035-0036; 0039-0
(2020/09/16)
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- Integrated photocatalytic-biological treatment of triazine-containing pollutants
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The degradation of triazine-containing pollutants including simazine, Irgarol 1051 and Reactive Brilliant Red K-2G (K-2G) by photocatalytic treatment was investigated. The effects of titanium dioxide (TiO2) concentration, initial pH of reaction mixture, irradiation time and ultraviolet (UV) intensity on photocatalytic treatment efficiency were examined. Complete decolorization of K-2G was observed at 60 min photodegradation while only 15 min were required to completely degrade simazine and Irgarol 1051 under respective optimized conditions. High-performance liquid chromatography (HPLC), gas chromatography/mass spectrometry (GC/MS) and ion chromatography (IC) were employed to identify the photocatalytic degradation intermediates and products. Dealkylated intermediates of simazine, deisopropylatrazine and deethyldeisopropylatrazine, and Irgarol 1051 were detected by GC/MS in the initial phase of degradation. Complete mineralization could not be achieved for all triazine-containing pollutants even after prolonged (>72 h) UV irradiation due to the presence of a photocatalysis-resistant end product, cyanuric acid (CA). The toxicities of different compounds before and after photocatalytic treatment were also monitored by three bioassays. To further treat the photocatalysis-resistant end product, a CA-degrading bacterium was isolated from polluted marine sediment and further identified as Klebsiella pneumoniae by comparing the substrate utilization pattern (Biolog microplate), fatty acid composition and 16S rRNA gene sequencing. K. pneumoniae efficiently utilized CA from 1 to 2000 mg/L as a good nitrogen source and complete mineralization of CA was observed within 24 h of incubation. This study demonstrates that the biodegradability of triazine-containing pollutants was significantly improved by the photocatalytic pre-treatment, and this proposed photocatalytic-biological integrated system can effectively treat various classes of triazine-containing pollutants.
- Chan, Cho Yin,Chan, Ho Shing,Wong, Po Keung
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p. 371 - 380
(2019/02/07)
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- Oxidation of atrazine by photoactivated potassium persulfate in aqueous solutions
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General laws of the photochemical oxidation of atrazine by inorganic peroxo compounds under the impact of solar radiation are studied. It is found that almost complete conversion of atrazine can be achieved via photochemical oxidation with persulfate afte
- Khandarkhaeva,Aseev,Sizykh,Batoeva
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p. 2177 - 2182
(2016/10/24)
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- A proof of the direct hole transfer in photocatalysis: The case of melamine
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The photoinduced transformation of 2,4,6-triamino-1,3,5-triazine (melamine) was studied by using different advanced oxidation technologies under a variety of experimental conditions. The systems involving homogeneous hydroxyl radicals, as generated by H2O2/hν, Fenton reagent, and sonocatalysis are ineffective. However, melamine is degraded under photocatalytic conditions or by SO4- (S2O82-/hν). The time evolution of long-living intermediates, such as 2,4-diamino-6-hydroxy-1,3,5-triazine (ammeline) and 2-amino-4,6-dihydroxy-1,3,5-triazine (ammelide), has been followed, being 2,4,6-trihydroxy-1,3,5-triazine (cyanuric acid) the final stable product. During both photocatalytic and S2O82-/hν experiments, in the early steps, a fairly stable intermediate evolving to ammelide is observed in a large extent. This intermediate was identified as 2,4-diamino-6-nitro-1,3,5-triazine. This indicates that the primary photocatalytic event is the oxidation of the amino-group to nitro-group through several consecutive fast oxidation steps, and that a hydrolytic step leads to the release of nitrite in solution. To elucidate the nature of the oxidant species hole scavengers such as methanol and bromide ions were added to the irradiated TiO2. They completely stop the degradation, whereas chloride and fluoride ions decrease the degradation rate. The study of the photocatalytic degradation rate of melamine at increasing concentrations using two different commercial titanium dioxides, such as P25 and Merck TiO2, showed an intriguing behavior. A drastic abatement of the melamine transformation rate was observed when coagulation of the P25 slurry occurs due both to the pH change and melamine concentration effect that increase melamine adsorption. In the presence of TiO2 (Merck) the melamine initial degradation rates are significantly lower than those observed in the presence of P25 but are not depressed at larger concentrations. The experimental evidences (e.g.; absence of melamine adsorption onto TiO2 surface at low concentrations or at acidic pH or due to the catalyst surface texture, and the lack of reactivity toward OH free and bound) suggest that the effective photocatalytic mechanism is based on an outer sphere direct hole transfer to the melamine. Its formal potential lies in the range 1.9-2.3 V vs NHE. Then, the photodegradation of melamine is an efficient tool to evaluate the direct hole transfer ability of a photocatalyst.
- Maurino, Valter,Minella, Marco,Sordello, Fabrizio,Minero, Claudio
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- Photocatalytic degradation of the herbicide terbuthylazine: Preparation, characterization and photoactivity of the immobilized thin layer of TiO2/chitosan
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The aim of this study was to immobilize a photocatalytic TiO2 layer on a suitable support material for potential use in a variety of photoreactor designs. The immobilized TiO2/chitosan thin film was used for the photocatalytic treatment of a triazine herbicide, terbuthylazine as representative agrochemical pollutant in the wastewater. The method of preparation was based on the use of a chitosan as binder and glass fiber woven roving material as a support. The employed method was found to be very simple, low cost and quite effective. Several methods of the photocatalyst characterization, such as FE-SEM/EDX, AAS, ICP-MS, TOC and nitrogen adsorption/desorption at 77 K were employed to correlate structural and morphological properties of immobilized TiO2-chitosan/glass fiber woven roving and its photocatalytic properties under UV irradiation. Reaction was performed in a self-constructed batch mode and annular type of the photoreactor. Comparison of thermal, photolytic and photocatalytical degradation of treated terbuthylazine at different reaction conditions was performed in order to get more insight into the photocatalytic performance and reaction mechanism. It was observed that there is no decay in photocatalytic efficiency over a long period of reaction time using for the photocatalytic degradation of terbuthylazine.
- Le Cunff, Jér?me,Toma?i?, Vesna,Wittine, Ozren
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- Design, synthesis, and biological evaluation of unconventional aminopyrimidine, aminopurine, and amino-1,3,5-triazine methyloxynucleosides
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Herein we describe a class of unconventional nucleosides (methyloxynucleosides) that combine unconventional nucleobases such as substituted aminopyrimidines, aminopurines, or aminotriazines with unusual sugars in their structures. The allitollyl or altritollyl derivatives were pursued as ribonucleoside mimics, whereas the tetrahydrofuran analogues were pursued as their dideoxynucleoside analogues. The compounds showed poor, if any, activity against a broad range of RNA and DNA viruses, including human immunodeficiency virus (HIV). This inactivity may be due to lack of an efficient metabolic conversion into their corresponding 5′-triphosphates and poor affinity for their target enzymes (DNA/RNA polymerases). Several compounds showed cytostatic activity against proliferating human CD4+ T-lymphocyte CEM cells and against several other tumor cell lines, including murine leukemia L1210 and human prostate PC3, kidney CAKI-1, and cervical carcinoma HeLa cells. A few compounds were inhibitory to Moloney murine sarcoma virus (MSV) in C3H/3T3 cell cultures, with the 2,6-diaminotri-O-benzyl-D-allitolyl- and -D-altritolyl pyrimidine analogues being the most potent among them. This series of unconventional nucleosides may represent a novel family of potential antiproliferative agents.
- Fernndez-Cureses, Gloria,De Castro, Sonia,Jimeno, Mara-Luisa,Balzarini, Jan,Camarasa, Mara-Jos
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p. 321 - 335
(2015/02/05)
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- Biomimetic simazine oxidation catalyzed by metalloporphyrins
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The metalloporphyrin-mediated simazine oxidation was investigated, in order to evaluate whether metalloporphyrins were good biomimetic models for the oxidation of this herbicide. The commercially available second-generation metalloporphyrins: 5,10,15,20-tetrakis(2,6-dichlorophenyl)porphyrin metal(III) chloride, [M(TDCPP)]Cl; 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin metal(III) chloride, [M(TFPP)]Cl; and 5,10,15,20-tetrakis(N-methyl-4-pyridyl) porphyrin metal(III) chloride, [M(TMPyP)]Cl5 (metal = Fe or Mn), and the oxidants iodosylbenzene (PhIO), hydrogen peroxide, and 3-chloroperoxy benzoic acid (m-CPBA) were employed in this study. Results demonstrated that these metalloporphyrins can mimic both the in vivo and in vitro action of cytochrome P450 for simazine oxidation, with formation of the dechlorinated metabolites OEET and OEAT mainly, as well as production of two other unknown compounds, identified by HPLC/mass spectrometry as ODET and ODDT. Among the systems, [Fe(TDCPP)]Cl/m-CPBA was the most efficient for simazine oxidation, giving up to 49% total conversion. Although hydrogen peroxide did not afford the best results (about 14% simazine conversion), it can be considered the most efficient oxidant from the point of view of toxicity, because it leads to less toxic products, namely OAAT and OEAT. The effect of some reaction conditions was investigated, and product evolution as a function of time was also monitored. Based on these results, simplified reaction mechanisms have been proposed.
- Santos, Joicy Santamalvina Dos,Palaretti, Vinícius,Faria, André Luiz De,Crevelin, Eduardo José,Moraes, Luiz Alberto Beraldo De,Assis, Marilda Das Dores
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scheme or table
p. 163 - 170
(2012/05/04)
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- Generation of melamine polymer condensates upon hypergolic ignition of dicyanamide ionic liquids
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The reaction of dicyanamide ionic liquids with nitric acid results in hypergolic ignition and the formation of a stable precipitate. The precipitate consists of cyclic triazines, including melamine and its polymers, such as melam and melem (see scheme). This study introduces a novel approach to the synthesis of cyclic azines without resorting to high temperatures and pressures. Copyright
- Chingin, Konstantin,Perry, Richard H.,Chambreau, Steven D.,Vaghjiani, Ghanshyam L.,Zare, Richard N.
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experimental part
p. 8634 - 8637
(2011/11/07)
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- METHOD FOR THE TREATMENT OF TRIAZINE-CONTAINING WATER OF A MELAMINE PLANT
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The invention relates to a method for treating triazine-containing water of a melamine plant. Said method is characterized in that the water containing ionic and non-ionic triazines in a dissolved form is fed to at least one membrane filtration unit (MF), the water is separated into an ionic triazine-rich fraction and a non-ionic triazine-rich fraction in the membrane filtration unit (MF), whereupon the ionic triazine-rich fraction is discharged and the non-ionic triazine-rich fraction is redirected into the melamine plant. The inventive method allows a great portion of the melamine contained in the triazine-containing water to be redirected into the process while the yield is increased along the entire melamine process. Furthermore, the need for fresh water in the wet part of the melamine plant is decreased. The disclosed method can be carried out continuously and in liquid phase.
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Page/Page column 10-14
(2008/06/13)
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- Microwave assisted pyrolysis of urea supported on graphite under solvent-free conditions
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The coupling of graphite (support) with microwaves (energy source) is responsible for a high temperature gradient leading to increased reaction rates as compared to conventional procedures. A rapid one-pot preparation of cyanuric acid is described that proceeds from urea by pyrolysis using microwave heating in the absence of water and organic solvents.
- Chemat, Farid,Poux, Martine
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p. 3693 - 3695
(2007/10/03)
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- Atrazine photolysis: Mechanistic investigations of direct and nitrate- mediated hydroxy radical processes and the influence of dissolved organic carbon from the Chesapeake Bay
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Direct and nitrate-mediated hydroxy radical photoprocesses were examined with respect to atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine) transformation. Irradiation (λ > 290 nm) of aqueous solutions of atrazine in the presence of nitrate, which generates ·OH, yielded 20% of 6-amino-2- chloro-4-isopropylamino-s-triazine (CIAT), 10% of 6-amino-2-chloro-4- ethylamino-s-triazine (CEAT), 6% of 4-acetamide-2-chloro-6-isopropylamino-s- triazine (CDIT), 3% of 4-acetamide-2-chloro-6-ethylamino-s-triazine (CDET), 16% of chlorodiamino-s-triazine (CAAT), and 3% of hydroxy atrazine (OIET, 4- ethylamino-6-isopropylamino-2-hydroxy-s-triazine) at 87% atrazine conversion. Direct photolysis of atrazine was much slower and at 23% atrazine conversion gave rise to 14% OIET and ca. 9% of chloroalkyloxidized or chlorodealkylated compounds with the ratio of the reaction rate constants equal to 0.14 (κ(direct)/κ(indirect)). Results also suggest that DIET was not the product of a hydroxy radical process. The efficiency of the hydroxy radical process decreased more than 85%, with increasing DOC obtained from the surface layer of the Chesapeake Bay. However, only a slight decrease (15%) in efficiency was observed for direct photolysis, suggesting that in the presence of surface layer DOC direct photolysis may become more important relative to the ·OH processes.
- Torrents, Alba,Anderson, Brent G.,Bilboulian, Susanna,Johnson, W. Edward,Hapeman, Cathleen J.
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p. 1476 - 1482
(2007/10/03)
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- Studies of Cyanamide Derivatives. Part 110. A facile Synthesis of 2,4,6-Triureido-1,3,5-triazine and 2-Amino-4,6-diureido-1,3,5-triazine
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2,4,6-Triureido-1,3,5-triazine and 2-amino-4,6-diureido-1,3,5-triazine were readily synthetized in high yields, 94 and 85percent respectively, by the alcoholysis of 2,4,6-tris(cyanoamino)-1,3,5-triazine and 2-amino-4,6-bis(cyanoamino)-1,3,5-triazine in the presence of hydrogen chloride
- Iio, Kokoro,Ichikawa, Eiichi
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p. 2009 - 2010
(2007/10/02)
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