scholarly journals Grafting of (3-Chloropropyl)-Trimethoxy Silane on Halloysite Nanotubes Surface

2021 ◽  
Vol 11 (12) ◽  
pp. 5534
Author(s):  
Asmaa M. Abu El-Soad ◽  
Giuseppe Lazzara ◽  
Alexander V. Pestov ◽  
Daria P. Tambasova ◽  
Denis O. Antonov ◽  
...  
Keyword(s):  
Active Site ◽  
Chemical Engineering ◽  
Coupling Reaction ◽  
Ammonium Hydroxide ◽  
Halloysite Nanotubes ◽  
Chemical Activity ◽  
Molar Ratio ◽  
New Materials ◽  
Experimental Conditions ◽  
Trimethoxy Silane

Modified halloysite nanotubes (HNTs-Cl) were synthesized by a coupling reaction with (3-chloropropyl) trimethoxysilane (CPTMS). The incorporation of chloro-silane onto HNTs surface creates HNTs-Cl, which has great chemical activity and is considered a good candidate as an active site that reacts with other active molecules in order to create new materials with great applications in chemical engineering and nanotechnology. The value of this work lies in the fact that improving the degree of grafting of chloro-silane onto the HNT’s surface has been accomplished by incorporation of HNTs with CPTMS under different experimental conditions. Many parameters, such as the dispersing media, the molar ratio of HNTs/CPTMS/H2O, refluxing time, and the type of catalyst were studied. The greatest degree of grafting was accomplished by using toluene as a medium for the grafting process, with a molar ratio of HNTs/CPTMS/H2O of 1:1:3, and a refluxing time of 4 h. The addition of 7.169 mmol of triethylamine (Et3N) and 25.97 mmol of ammonium hydroxide (NH4OH) led to an increase in the degree of grafting of CPTMS onto the HNT’s surface.

Reduction of silver nitrate by polyaniline nanotubes to produce silver-polyaniline composites

2009 ◽  
Vol 63 (1) ◽  
Author(s):  
Jaroslav Stejskal ◽  
Miroslava Trchová ◽  
Libuše Brožová ◽  
Jan Prokeš
Keyword(s):  
Silver Nitrate ◽  
Silver Content ◽  
Ammonium Hydroxide ◽  
Molar Ratio ◽  
Reaction Yield ◽  
Experimental Conditions ◽  
Molar Ratios ◽  
Silver Composites ◽  
Silver Flakes ◽  
Polyaniline Composites

AbstractPolyaniline (PANI) nanotubes were prepared by oxidation of aniline in 0.4 M acetic acid. They were subsequently used as a reductant of silver nitrate in 1 M nitric acid, water or 1 M ammonium hydroxide at various molar ratios of silver nitrate to PANI. The resulting PANI-silver composites contained silver nanoparticles of 40–60 nm size along with macroscopic silver flakes. Under these experimental conditions, silver was always produced outside the PANI nanotubes. Changes in the molecular structure of PANI were analyzed by FTIR spectroscopy. Silver content in the composites was determined as a residue by thermogravimetric analysis, and confirmed by density measurements. The highest conductivity of a composite, 68.5 S cm−1, was obtained at the nitrate to PANI molar ratio of 0.67 in water. Also, the best reaction yield was obtained in water. Reductions performed in an acidic medium gave products with conductivity of 10−4–10−2 S cm−1, whereas the reaction in alkaline solution yielded non-conducting products.

Strongly Coupled Redox-Linked Conformational Switching at the Active Site of the Non-Heme Iron-Dependent Dioxygenase, TauD

2019 ◽  
Author(s):  
Christopher John ◽  
Greg M. Swain ◽  
Robert P. Hausinger ◽  
Denis A. Proshlyakov
Keyword(s):  
Active Site ◽  
Structural Model ◽  
Heme Iron ◽  
Chemical Transformations ◽  
Experimental Conditions ◽  
Strongly Coupled ◽  
Non Heme Iron ◽  
Reversible Redox ◽  
Wide Range ◽  
Complex Structural

2-Oxoglutarate (2OG)-dependent dioxygenases catalyze C-H activation while performing a wide range of chemical transformations. In contrast to their heme analogues, non-heme iron centers afford greater structural flexibility with important implications for their diverse catalytic mechanisms. We characterize an <i>in situ</i> structural model of the putative transient ferric intermediate of 2OG:taurine dioxygenase (TauD) by using a combination of spectroelectrochemical and semi-empirical computational methods, demonstrating that the Fe (III/II) transition involves a substantial, fully reversible, redox-linked conformational change at the active site. This rearrangement alters the apparent redox potential of the active site between -127 mV for reduction of the ferric state and 171 mV for oxidation of the ferrous state of the 2OG-Fe-TauD complex. Structural perturbations exhibit limited sensitivity to mediator concentrations and potential pulse duration. Similar changes were observed in the Fe-TauD and taurine-2OG-Fe-TauD complexes, thus attributing the reorganization to the protein moiety rather than the cosubstrates. Redox difference infrared spectra indicate a reorganization of the protein backbone in addition to the involvement of carboxylate and histidine ligands. Quantitative modeling of the transient redox response using two alternative reaction schemes across a variety of experimental conditions strongly supports the proposal for intrinsic protein reorganization as the origin of the experimental observations.

scholarly journals Photocatalytic Treatment of Wastewater Containing Simultaneous Organic and Inorganic Pollution: Competition and Operating Parameters Effects

Catalysts ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 855
Author(s):  
Ahmed Amine Azzaz ◽  
Salah Jellali ◽  
Nasser Ben Harharah Hamed ◽  
Atef El Jery ◽  
Lotfi Khezami ◽  
...  
Keyword(s):  
Ultra Violet ◽  
Degradation Process ◽  
Molar Ratio ◽  
Experimental Conditions ◽  
Retention Capacity ◽  
Isotherm Study ◽  
Related Data ◽  
Ph Values ◽  
Pseudo Second Order ◽  
Maximum Retention

In the present study, methylene blue (MB) removal from aqueous solutions via the photocatalytic process using TiO2 as a catalyst in the presence of external ultra-violet light (UV) was investigated. The results of adsorption in the absence of UV radiation showed that adsorption reached an equilibrium state at 60 min. The experimental kinetic data were found to be well fitted by the pseudo-second-order model. Furthermore, the isotherm study suggested that dye uptake by TiO2 is a chemisorption process with a maximum retention capacity of 34.0 mg/g. The photodegradation of MB was then assessed under various experimental conditions. The related data showed that dye mineralization decreased when dye concentrations were increased and was favored at high pH values and low salt concentrations. The simultaneous presence of organic and inorganic pollution (Zinc) was also evaluated. The effect of the molar ratio Zn2+/MB+ in the solution at different pH values and NaCl concentrations was also monitored. The corresponding experimental results showed that at low values of Zn2+ in the solution (30 mg/L), the kinetic of the MB removal became faster until reaching an optimum at Zn2+/MB+ concentrations of 60/60 mg/L; it then slowed down for higher concentrations. The solutions’ carbon contents were measured during the degradation process and showed total mineralization after about 5 h for the optimal Zn2+/MB+ condition.

scholarly journals Reaktive E=C(p–p)π Systeme, XXXIV Addition von Alkoholen oder primären Aminen an Phosphaalkene F3CP=C(F)OR. Neue Trifluormethylphosphane und -phosphaalkene/Reactive E = C( p – p ) π-Systems, XXXIV Addition of Alcohols or Primary Amines to Phosphaalkenes F3CP= C(F)OR . Novel Trifluoromethylphosphanes and Phosphaalkenes

1993 ◽  
Vol 48 (1) ◽  
pp. 58-67 ◽  
Author(s):  
Joseph Grobe ◽  
Duc Le Van ◽  
Gudrun Lange
Keyword(s):  
High Resolution Mass Spectrometry ◽  
Molar Ratio ◽  
Primary Amines ◽  
The Novel ◽  
Experimental Conditions ◽  
Pull System ◽  
Fragment Ions ◽  
New Compounds ◽  
C Nmr

The course of the reactions o f fluorophosphaalkenes F3CP = C (F)OR [R = Me (1), Et (2)] with methanol or ethanol strongly depends on the experimental conditions. Thus at 70 °C a mixture of the 2-phosphapropionic acid ester F3CP (H )CO2R [R = Me (3), Et (4)] and trifluoromethylphosphane H2PCF3 is formed [molar ratio: 3 or 4 /H2 CF3 ≈1/1]. If the precursors F3CP (H )CO2R [R = Me (3), Et) are used as starting materials, the reaction with ROH under the same conditions affords 3 and 4, respectively, (90 to 95% yield) with only traces of H2PCF 3. In the presence o f iPr2NH these precursors react with R′OH to give the novel trifluoromethylphosphaalkenes F3CP = C (OR )OR [R /R′: Me/Me (6); E t/E t (7); Me/Et (8)]. With Et2NH , 3 undergoes an addition/elimination process yielding the interesting push/pull system Et2N(F)C = P-CO2Me (5). 1 and 2 react with primary amines R′NH2 (R′= tBu, Me) with stereoselective formation of the fairly labile phosphaalkenes F3CP = C(OR)NHR′ [R /R′: Me/tBu (9), Et/tBu(10), Me/Me (11)] with trans-positions for CF3 and NHR′.The new compounds 3 -11 were characterized by spectroscopic investigations (1H , 19F, 31P, 13C NMR ; IR, MS) and determination of M+ or typical fragment ions [M+ -OR ] by high resolution mass spectrometry.

scholarly journals Phosphorus extracted by ion exchange resins and mehlich-1 from oxisols (latosols) treated with different phosphorus rates and sources for varied soil-source contact periods

2013 ◽  
Vol 37 (3) ◽  
pp. 667-677 ◽  
Author(s):  
Irio Fernando de Freitas ◽  
Roberto Ferreira Novais ◽  
Ecila Mercês de Albuquerque Villani ◽  
Sarah Vieira Novais
Keyword(s):  
Sandy Loam ◽  
Extraction Methods ◽  
Available P ◽  
Molar Ratio ◽  
P Availability ◽  
Triple Superphosphate ◽  
Experimental Conditions ◽  
Reactive Phosphate ◽  
Exchange Resins ◽  
P Sources

Despite the large number of studies addressing the quantification of phosphorus (P) availability by different extraction methods, many questions remain unanswered. The aim of this paper was to compare the effectiveness of the extractors Mehlich-1, Anionic Resin (AR) and Mixed Resin (MR), to determine the availability of P under different experimental conditions. The laboratory study was arranged in randomized blocks in a [(3 x 3 x 2) + 3] x 4 factorial design, with four replications, testing the response of three soils with different texture: a very clayey Red Latosol (LV), a sandy clay loam Red Yellow Latosol (LVA), and a sandy loam Yellow Latosol (LA), to three sources (triple superphosphate, reactive phosphate rock from Gafsa-Tunisia; and natural phosphate from Araxá-Minas Gerais) at two P rates (75 and 150 mg dm-3), plus three control treatments (each soil without P application) after four contact periods (15, 30, 60, and 120 days) of the P sources with soil. The soil acidity of LV and LVA was adjusted by raising base saturation to 60 % with the application of CaCO3 and MgCO3 at a 4:1 molar ratio (LA required no correction). These samples were maintained at field moisture capacity for 30 days. After the contact periods, the samples were collected to quantify the available P concentrations by the three extractants. In general, all three indicated that the available P-content in soils was reduced after longer contact periods with the P sources. Of the three sources, this reduction was most pronounced for triple superphosphate, intermediate for reactive phosphate, while Araxá phosphate was least sensitive to the effect of time. It was observed that AR extracted lower P levels from all three soils when the sources were phosphate rocks, while MR extracted values close to Mehlich-1 in LV (clay) and LVA (medium texture) for reactive phosphate. For Araxá phosphate, much higher P values were determined by Mehlich-1 than by the resins, because of the acidity of the extractor. For triple superphosphate, both resins extracted higher P levels than Mehlich-1, due to the consumption of this extractor, particularly when used for LV and LVA.

Treatability of textile dye-bath effluents by advanced oxidation: preparation for reuse

1999 ◽  
Vol 40 (1) ◽  
pp. 183-190 ◽  
Author(s):  
N. H. Ince ◽  
G. Tezcanlı
Keyword(s):  
Organic Carbon ◽  
Total Organic Carbon ◽  
Azo Dye ◽  
Uv Light ◽  
Advanced Oxidation ◽  
Membrane System ◽  
Molar Ratio ◽  
Textile Dye ◽  
Experimental Conditions ◽  
Solids Content

Treatability of textile dye-bath effluents by advanced oxidation with Fenton and Fenton-like reagents (FeII/H2O2 and FeIII/H2O2), in the presence and absence of UV light was investigated, using a reactive azo-dye (Procion Red HE7B), and typical dye bath constituents. Under the experimental conditions employed, it was found that with 20 min UV irradiation, complete color removal and 79% total organic carbon degradation is possible, when the system is operated at pH=3, and with a H2O2/Fe(II) molar ratio of 20:1. The increased dissolved solids content of the treated solution implies the necessity of an appropriate membrane system to make the effluent reusable in the dye/wash processes.

Zirconium Titanate: Synthesis and Processing of Fine Powders Prepared by Chemical Route

2006 ◽  
Vol 530-531 ◽  
pp. 683-688 ◽  
Author(s):  
Valter Ussui ◽  
Dolores Ribeiro Ricci Lazar ◽  
Nelson Batista de Lima ◽  
Ana Helena A. Bressiani ◽  
José Octavio A. Pascoal
Keyword(s):  
Metal Salt ◽  
Ceramic Powder ◽  
Ammonium Hydroxide ◽  
Molar Ratio ◽  
Precipitation Process ◽  
Zirconium Titanate ◽  
X Ray Diffraction ◽  
Chemical Route ◽  
Synthesis And Processing ◽  
Cylindrical Samples

A process for synthesis of fine zirconium titanate powders by chemical route is described. Zirconium/titanium molar ratio was varied from 0.67 to 1.5 and the powders produced were analyzed. The precipitation process comprises the mixture of zirconium and titanium metal salt solutions to ammonium hydroxide solution, followed by washing of the precipitate, calcination and grinding to result in zirconium titanate. The ceramic powder is then uniaxially pressed as cylindrical samples and sintered at 1400°C for 5 hours. The microstructure of fractured and thermally etched ceramic was observed by scanning electron microscopy, and crystal phase identifications were done by X-ray diffraction. At least two different zirconium titanate phases, ZrTiO4 and Zr5Ti7O24, were identified. Ceramic hardness was measured by Vickers indentation.

scholarly journals Optimization Preparation of Indium Tin Oxide Nanoparticles via Microemulsion Method Using Orthogonal Experiment

Crystals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1387
Author(s):  
Zhucheng Jiang ◽  
Ting Liu ◽  
Xiaoyu Zhai ◽  
Jiaxiang Liu
Keyword(s):  
Calcination Temperature ◽  
Tin Oxide ◽  
Indium Tin Oxide ◽  
Orthogonal Experiment ◽  
Transparent Conducting Oxide ◽  
Molar Ratio ◽  
Experimental Conditions ◽  
Microemulsion Method ◽  
Low Resistivity ◽  
Ito Nanoparticles

Indium tin oxide (ITO), an experimentally friendly transparent conducting oxide (TCO), has attracted great attention in the photoelectric field due to its intrinsically low resistivity and high transparency. In this work, the experimental conditions of preparing ITO nanoparticles using the microemulsion method were optimized by an orthogonal experiment. The optimal experimental conditions were obtained: mass ratio of the surfactant (AEO-3, MOA-5), a co-surfactant (n-propyl alcohol) of 5:3, molar ratio of indium and ammonia of 1:20, calcination temperature of 700 °C and calcination time of 4 h. Subsequently, the influence from process variables on the resistivity was researched systematically. The results demonstrated that the calcination temperature had a great effect on the resistivity; the resistivity reduced from 11.28 to 2.72 Ω·cm with the increase in the calcination temperature from 500 to 700 °C. Ultimately, ITO nanoparticles were prepared and systematically characterized under the optimal experimental conditions. The particles with a size of 60 nm were attributed to the cubic ITO crystal phase and showed low resistivity of 0.3675 Ω·cm. Significantly, ITO nanoparticles with low resistivity were obtained using the microemulsion method, which has potential application in the field of ITO nanoparticle preparation.

scholarly journals Crystal structure of 1,4-bis[5-(2-methoxyphenyl)-2H-tetrazol-2-yl]butane

2019 ◽  
Vol 75 (12) ◽  
pp. 1844-1847
Author(s):  
Young Min Byun ◽  
Farwa Ume ◽  
Ji Yeon Ryu ◽  
Junseong Lee ◽  
Hyoung-Ryun Park
Keyword(s):  
Title Compound ◽  
Methoxy Group ◽  
Coupling Reaction ◽  
Major Product ◽  
Molar Ratio ◽  
Dihedral Angles ◽  
X Ray ◽  
Compound C ◽  
Crystallographic Study ◽  
Centrosymmetric Dimers

The title compound, C20H22N8O2, was synthesized by the coupling reaction of a sodium tetrazolate salt and dibromobutane in a molar ratio of 2:1. The reaction can produce several possible regioisomers and the title compound was separated as the major product. The X-ray crystallographic study confirmed that the title compound crystallizes in the monoclinic P21/c space group and possesses a bridging butylene group that connects two identical phenyl tetrazole moieties. The butylene group is attached not to the first but the second nitrogen atoms of both tetrazole rings. The dihedral angles between the phenyl groups and the adjacent tetrazolyl rings are 5.32 (6) and 15.37 (7)°. In the crystal, the molecules form centrosymmetric dimers through C—H...O hydrogen bonds between a C—H group of the butylene linker and the O atom of a methoxy group.

scholarly journals On active chlorine

1934 ◽  
Vol 147 (861) ◽  
pp. 309-332
Keyword(s):  
Acetic Acid ◽  
Electric Discharge ◽  
Closed System ◽  
Surface Characteristics ◽  
Chemical Activity ◽  
Active Chlorine ◽  
Side Chain ◽  
Experimental Conditions ◽  
Electrically Charged ◽  
Atomic Chlorine

Evidence has long been available that a modification of chlorine of abnormal chemical activity is produced by an electric discharge in this gas. The greater part of the earlier work was conducted under very badly defined experimental conditions which render the various researches difficult to correlate, but the properties of this “active chlorine” may be summarized as follows:— ( a ) It possesses abnormal bleaching powers, and can react in the cold and the dark with acetic acid to form the monochlor derivative; with benzene it gives the hexachloride, while with toluene the combination occurs mainly in the side chain. ( b ) They yield of active gas is enhanced by irradiation of the discharge, by cooling, and by the presence of moisture. ( c ) It has a life period of at least 75 secs, but is destroyed by heating, passage through water, and the action of another discharge; it is not electrically charged and does not possess as abnormal density.§ ( d ) Since only very small changes in pressure follow passage of a discharge in a closed system containing chlorine, the active modification does not presumably represent an associated molecule such as Cl 3 .‖ Reference may also be made to papers by Venkataramaiah¶ who gives a number of chemical reactions of chlorine activated in various ways but his results must be treated with reserve (see Germann, idem ., p. 951). In the present experiments we have endeavoured to repeat and extend the earlier studies under better defined conditions, and conclude that the phenomena are very probably due to a trace of atomic chlorine whose behaviour is markedly dependent upon the surface characteristics of the apparatus.

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