A thermogravimetric study of the solid-state reaction between alumina and strontium carbonate

The kinetics of the solid-state reaction between alumina and strontium carbonate were studied by thermogravimetry. The effects of the structure ( or) and/or doping (with Li⁺ or Cd²⁺) of the alumina on the kinetics of the reaction were examined. The results obtained were correlated with the phase composition and structural changes, followed by a number of physicochemical analyses (DTA, XRA and IRA) throughout the course of the reaction.

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Zusammenfassung Die Kinetik der Festkörperreaktion zwischen Aluminiumoxid und Strontium-carbonat wurde thermogravimetrisch untersucht. Die Effekte der Struktur ( und) und/oder des Dopens des Aluminiumoxids (mit Li⁺ oder Cd²⁺) auf die Kinetik der Reaktion wurde untersucht. Die erhaltenen Ergebnisse wurden mit der Phasenzusammensetzung und mit durch physikalisch-chemische Analysenverfahren (DTA, XRA und IRA) während des Reaktionsverlaufs verfolgten strukturellen Veränderungen in Beziehung gebracht.

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. ( ) Li⁺ Cd²⁺ . , , - .

     

HETEROCYCLES SYNTHESIS THROUGH REACTIONS OF INDOLIN-2-ONE DERIVATIVES WITH ACTIVE METHYLENE AND AMINO REAGENTS,PART 3, NOVEL AND FACILE ONE-STEP SYNTHESIS OF SPIROTHIOPYRAN-4- YL INDOLIDENE DERIVATIVES

Abstract

New spirothiopyran-4-yl indolidene derivatives have been synthesised via a facile one-step method. Structures and reaction mechanisms are also reported and supported by another synthetic route.     

Chemical Preparation,Thermal Behavior,Kinetic, and IR Studies of MnK4(P3O9)2.2H2O,Crystallographic Data of a New Cyclotriphosphate MnK4(P3O9)2, and Quantum Chemical Calculations for the P3O3− 9 Ion

Abstract

Chemical presparation, thermal behavior, and infrared (IR) studies are discussed for the cyclotriphosphate MnK₄(P₃O₉)₂.2H₂O and its anhydrous form MnK₄(P₃O₉)₂. The total dehydration of MnK₄(P₃O₉)₂.2H₂O, between 200 and 550 °C, leads to its anhydrous form MnK₄(P₃O₉)₂. MnK₄(P₃O₉)₂ is a new cyclotriphosphate crystallizing in the rhombohedral system and is stable until its melting point at 560 °C. The thermal behavior of MnK₄(P₃O₉)₂.2H₂O has been investigated and interpreted by comparison with IR absorption spectrometry and X-ray diffraction experiments. Two different methods, Ozawa and KAS (Kissinger-Akahira-Sunose), were selected in studying the kinetics of thermal behavior of the title compound. Quantum chemical calculations were made for the P₃O ^3? ₉ ion.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.

GRAPHICAL ABSTRACT     

Effect of Inorganic Solids,Wax to Asphaltene Ratio,and Water Cut on the Stability of Water-in-Crude Oil Emulsions

The formation of stable water-in-crude oil emulsions during petroleum production and refinery may create sever and costly separation problems. It is very important to understand the mechanism and factors contributing to the formation and stabilization of such emulsions for both great economic and environmental development. This article investigates some of the factors controlling the stability of water-in-crude oil emulsions formed in Burgan oil field in Kuwait. Water-in-crude oil emulsion samples collected from Burgan oil filed have been used to separate asphaltenes, resins, waxes, and crude oil fractions. These fractions were used to prepare emulsion samples to study the effect of solid particles (Fe₃O₄) on the stability of emulsions samples. Results indicate that high solid content lead to higher degree of emulsion stability. Stability of emulsion samples under various waxes to asphaltenes (W/A) ratios have also been tested. These tests showed that at low W/A content, the emulsions were very stable. While at a wax to asphaltene ratio above 1 to 1, the addition of wax reduced emulsion stability. Stability of emulsion samples with varying amount of water cut has also been investigated. Results indicated that stability and hence viscosity of emulsion increases as a function of increasing the water cut until it reaches the inversion point where a sharp decline in viscosity takes place. This inversion point was found to be approximately at 50% water cut for the crude oils considered in this study.     

Water‐in‐Crude Oil Emulsions in the Burgan Oilfield: Effects of Oil Aromaticity,Resins to Asphaltenes Content (R/(R+A)), and Water pH

Asphaltenes and resins separated from emulsion samples collected from Burgan oil field were used with heptane‐toluene mixtures as model oil to study the effect of oil aromaticity, resin content, and pH of the aqueous phase on the stability of water in model emulsions. It was confirmed that, as long as the asphaltenes are completely solubilized, increasing aromaticity leads to less stable emulsions. A consistent correlation between emulsion stability and relative resin mass content (R/(R+A)) was observed for all three of the field samples. There was a sharp decrease in stability when the R/(R+A) value exceeded 0.75. Emulsion stability was enhanced at high pH and possibly at very low pH (<2).     

Synthesis,characterization and antioxidant,antibacterial activity Zn2+, Cu2+, Ni2+ and Co2+, complexes of ligand [2-(thiophen-2-yl)-1-(thiophen-2-ylmethyl)-1H-benzo[d]imidazole]

New metal complexes of (Zn(II), Co(II), Ni(II) and Cu(II)) based on the ligand 2-(thiophen-2-yl)-1-(thiophen-2-ylmethyl)-1H-benzo[d]imidazole] were synthesized, whose structures were determined with the different spectroscopic techniques ¹H NMR,¹³C NMR, FT-IR, UV–Visible and by mass spectrometry. The thermal analysis was performed by TG-DTA. The antioxidant activity of the ligand and its complexes was evaluated by DPPH (2,2-diphenyl-1-picrylhydrazyl) method, in comparison with the synthetic antioxidant, ascorbic acid. The results obtained showed that the antioxidant activity of the ligand and its complexes is moderate and that the copper complex has a high activity that exceeds that of ascorbic acid. Antimicrobial activity of the ligand and its metal complexes was studied against two Gram-positive bacteria: Bacillus subtilis ILP1428B, Staphylococcus aureus CIP543154 and two Gram-negative bacteria: Pseudomonas aeruginosa ATCC27653, Escherichia coli CIP5412 (American Type Culture Collection)the activity data show that the metal complexes are more potent than the free ligand.     

PREDICTION OF PREDOMINANT MECHANISMS IN THE SEPARATION OF SECONDARY DISPERSIONS IN A FIBROUS BED

The different drop capture mechanisms for secondary dispersions in fibrous beds are reviewed. A quantitative analysis showed that interception and sedimentation are the predominant mechanisms in fibrous bed coalescers. The selection of operating parameters, e.g. velocity, fibre size and drop size depends upon these mechanisms. A 3 cm deep fibrous bed of glass wool, with a fibre diameter of 25 pm, was found to capture more than 80% of the dispersed phase from an inlet secondary dispersion of 15 Mm drop size. Almost 70% of these drops were captured due to the interception mechanism.     

A stochastic approximation for fully nonlinear free boundary parabolic problems

We present a stochastic numerical method for solving fully nonlinear free boundary problems of parabolic type and provide a rate of convergence under reasonable conditions on the nonlinearity. © 2013 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 30: 902–929, 2014     

Thermal decomposition and creation of reactive solid surfaces

Three chromia precursors, namely CrO₃, (NH₄)₂Cr₂O₇ and chromia gel, were subjected to thorough thermal analysis by means of TG and DTA. The thermal decomposition products obtained by calcination of these precursors at various temperatures (150–500°) for 5 h were investigated by infrared and X-ray techniques. The results obtained allowed a thorough physicochemical characterization of the intermediate steps and products throughout the thermal decomposition.