KINETICS OF ADSORPTION OF ORGANIC AND INORGANIC PHOSPHATES BY SHORT-RANGE ORDERED PRECIPITATE OF ALUMINUM

1990 ◽  
Vol 70 (3) ◽  
pp. 461-470 ◽  
Author(s):  
C. SHANG ◽  
P. M. HUANG ◽  
J. W. B. STEWART
Keyword(s):  
Short Range ◽  
Kinetics Of Adsorption ◽  
Temperature Range ◽  
First Order Kinetics ◽  
Initial Ph ◽  
Two Stages ◽  
Relationship Of ◽  
Kinetics Of ◽  
Inorganic Phosphates ◽  
Phosphate Groups

The kinetics of the adsorption of orthophosphate (Pi), inositol hexaphosphate (IHP), inositol monophosphate (IMP) and glucose 6-phosphate (G6P) by short-range ordered precipitate of Al were studied at the initial pH 4.50 and in the temperature range of 278–308 K. This information is essential for understanding the rate and energy relationship of the adsorption of phosphates by short-range ordered Al precipitate. The amounts of Pi and IHP adsorbed by the Al precipitate were much higher than those of IMP and G6P adsorbed in the temperature range and reaction periods studied. The adsorption can be divided into two stages, a fast adsorption before 1 h and a slow adsorption between 1 and 24 h. The adsorption at both stages obeyed the first-order kinetics. Among all the phosphates studied, the adsorption of Pi proceeded most rapidly. The rate constants for the adsorption of IHP were much greater than those of G6P and IMP at the same temperature; this was attributed to the functionality of multiple phosphate groups of IHP. The Arrhenius activation energies for the adsorption of Pi, IHP, IMP and G6P, which were estimated from the slow reaction, were 48 ± 2, 89 ± 4, 100 ± 8 and 108 ± 10 KJ/mol P adsorbed, respectively. Key words: Organic phosphate, precipitate of aluminum, adsorption, rate constant, Arrhenius activation energy

scholarly journals On the Mechanism of Methane Conversion in the Nonсatalytic Processes of Its Thermal Pyrolysis and Steam and Carbon Dioxide Reforming

2021 ◽  
Author(s):  
E. Busillo ◽  
V. I. Savchenko ◽  
V. S. Arutyunov
Keyword(s):  
Carbon Dioxide ◽  
Methane Conversion ◽  
Carbon Dioxide Reforming ◽  
Temperature Range ◽  
Thermal Pyrolysis ◽  
First Order Kinetics ◽  
Initial Stage ◽  
Conversion Of Methane ◽  
Exponential Factors ◽  
Kinetics Of

Abstract A detailed kinetic modeling of the noncatalytic processes of thermal pyrolysis and steam and carbon dioxide reforming of methane revealed almost completely identical kinetics of the methane conversion in these processes. This suggests that, in the temperature range 1400–1800 K, the initial stage of conversion of methane in all these processes is its thermal pyrolysis. The modeling results agree well with the experimental data on methane pyrolysis. For the temperature range examined, the Arrhenius expressions (pre-exponential factors and activation energy) were obtained in the first-order kinetics approximation for the rate of methane conversion in the processes studied. The expressions derived may be useful for making preliminary estimates and carrying out engineering calculations.

Correlation Between Resistivity Characteristics and Electronic Structure Parameters of the Ni-Pd-P Amorphous Alloys

2000 ◽  
Vol 644 ◽  
Author(s):  
Mykola Babich ◽  
Olesya Nakonechna ◽  
Mykhailo Semen'ko ◽  
Mykola Zakharenko ◽  
Gennagy Yeremenko ◽  
...  
Keyword(s):  
Amorphous Alloys ◽  
Crystallization Process ◽  
Level Shift ◽  
Relaxation Processes ◽  
Temperature Range ◽  
Temperature Coefficients ◽  
Localized State ◽  
P Content ◽  
Two Stages ◽  
Kinetics Of

AbstractThe temperature dependencies of resistivity of the Ni-Pd-P-based amorphous alloys (P content was varied from 14 to 23 at. %) have been measured in a wide temperature range using the standard four-probe method. The temperature coefficients of resistivity (TCR) have been calculated. TCR value is decreased with P content increasing and becomes negative for Ni46Pd31P23 alloy. On the other hand, TCR value is increased with Pd content increasing while P content is not changed. Such behavior could be attributed to the electronic transfer effect from Ni to Pd and from P to Ni. These lead to the Fermi level shift to d-band edge and to the increasing influence of the Mott's localized state. The peculiarities caused by structural relaxation processes have been observed at the temperature range of 550 – 620 K. The relaxation process was shown to consist at least of two stages. The kinetics of the crystallization process has been analyzed using the Kissinger method.

Barite Nucleation and Inhibition at 0 to 200°C With and Without Thermodynamic Hydrate Inhibitors

SPE Journal ◽  
2010 ◽  
Vol 16 (02) ◽  
pp. 440-450 ◽  
Author(s):  
Chunfang Fan ◽  
Amy T. Kan ◽  
Ping Zhang ◽  
Mason B. Tomson
Keyword(s):  
High Temperatures ◽  
Inhibition Efficiency ◽  
Saturation Index ◽  
Pressure Change ◽  
Accurate Method ◽  
Nucleation Kinetics ◽  
Temperature Range ◽  
Mineral Scale ◽  
Relationship Of ◽  
Kinetics Of

Summary In this study, we modified the commonly employed dynamic-tube-blocking methodology and built an apparatus to study the nucleation kinetics of barite-scale formation at high temperatures in the presence and absence of scale inhibitors. Barite formation was detected by monitoring pressure change over a micrometer-sized in-line filter, and this has been proved to be an easy and accurate method to study mineral-scale-nucleation kinetics at high temperatures. Additionally, we investigated the nucleation kinetics of barite at 0–25°C with and without thermodynamic hydrate inhibitors. By using this modified dynamic-tube-blocking technique, we successfully measured the nucleation kinetics of barite in 1M NaCl solutions over a temperature range from 25 to 200°C and at various supersaturation conditions. We also evaluated the inhibition efficiency of barite precipitation at this high temperature range. On the basis of the experimental results, the relationship of precipitation kinetics of barite as a function of temperature and saturation index was established. The inhibition efficiency of the phosphonate inhibitor [bis-hexamethylenetriamine-penta (methylene phosphonic) acid (BHPMP)] on barite precipitation has been evaluated over the same range of conditions. The Ca2+ effect on the inhibition efficiency of BHPMP at a low temperature (4°C) and at high temperatures (175–200°C) was investigated also. Results of this study have been incorporated into the scale-prediction software ScaleSoftPitzer.

Deposition of Functionalized Polyethylenimine-Dye onto Cotton and Wool Fibres

2014 ◽  
Vol 18 (1) ◽  
pp. 36-49 ◽  
Author(s):  
A.G. Hassabo ◽  
A. Mendrek ◽  
C. Popescu ◽  
H. Keul ◽  
M. Möller
Keyword(s):  
Deposition Process ◽  
Good Alternative ◽  
Kinetics Of Adsorption ◽  
First Order ◽  
Ph Values ◽  
First Order Kinetics ◽  
Colour Strength ◽  
Equilibrium Data ◽  
Amine Groups ◽  
Kinetics Of

Functionalized polyethylenimine–dye (FPEI) is prepared by mixing branched polyethyleneimine (PEI), in which its primary amine groups are modified at different ratios with a quaternary ammonium coupler (QI), and reactive dyestuff (RD) (QI/RD = 0/100, 20/80, 40/60, 60/40 and 80/20 mole/mole %). The deposition of FPEI from an aqueous solution onto the surface of cotton and wool fibres is studied. The adsorption of a charged polymer from an aqueous medium by cotton and wool fibres is investigated at different pH values, and the uptake of colour on fibres is measured by Datacolor and UVVIS spectrophotometers. The study of the kinetics of adsorption shows that pseudo-first-order kinetics provide the best correlation of the experimental data. The equilibrium data indicate that the deposition process onto both cotton and wool follows the Langmuir isotherm. In terms of colour strength (K/S value) the coated fibres compare well with those dyed with a commercial dyestuff, C.I. Basic Red 51, which suggests that the coating is a good alternative to classical dyeing.

Domain coarsening by grain boundary migration in ordered Ni4Mo

1986 ◽  
Vol 44 ◽  
pp. 560-561
Author(s):  
K. Vasudevan ◽  
H. P. Kao ◽  
C. R. Brooks ◽  
E. E. Stansbury
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Short Range ◽  
Boundary Migration ◽  
Grain Boundary Migration ◽  
Rapid Cooling ◽  
Temperature Range ◽  
Fee Structure ◽  
Domain Coarsening ◽  
Boundary Reaction

The Ni4Mo alloy has a short-range ordered fee structure (α) above 868°C, but transforms below this temperature to an ordered bet structure (β) by rearrangement of atoms on the fee lattice. The disordered α, retained by rapid cooling, can be ordered by appropriate aging below 868°C. Initially, very fine β domains in six different but crystallographically related variants form and grow in size on further aging. However, in the temperature range 600-775°C, a coarsening reaction begins at the former α grain boundaries and the alloy also coarsens by this mechanism. The purpose of this paper is to report on TEM observations showing the characteristics of this grain boundary reaction.

DOPING KINETICS OF POLYACETYLENE IN THE SHORT RANGE

1983 ◽  
Vol 44 (C3) ◽  
pp. C3-167-C3-170
Author(s):  
E. Cernia ◽  
L. D'Ilario ◽  
E. Ferretti ◽  
G. Nencini
Keyword(s):  
Short Range ◽  
Kinetics Of

Kinetic of oxidation of methyl orange by vanadium(V) under conditions VO2+ and decavanadates coexist: Catalysis by Triton X-100 micellar medium

2019 ◽  
Author(s):  
Chem Int
Keyword(s):  
Methyl Orange ◽  
Solution Ph ◽  
Vanadium Concentration ◽  
Limiting Behavior ◽  
First Order ◽  
First Order Kinetics ◽  
Ph Range ◽  
Kinetic Pattern ◽  
Triton X ◽  
Kinetics Of

The kinetics of oxidation of methyl orange by vanadium(V) {V(V)} has been investigated in the pH range 2.3-3.79. In this pH range V(V) exists both in the form of decavanadates and VO2+. The kinetic results are distinctly different from the results obtained for the same reaction in highly acidic solution (pH < 1) where V(V) exists only in the form of VO2+. The reaction obeys first order kinetics with respect to methyl orange but the rate has very little dependence on total vanadium concentration. The reaction is accelerated by H+ ion but the dependence of rate on [H+] is less than that corresponding to first order dependence. The equilibrium between decavanadates and VO2+ explains the different kinetic pattern observed in this pH range. The reaction is markedly accelerated by Triton X-100 micelles. The rate-[surfactant] profile shows a limiting behavior indicative of a unimolecular pathway in the micellar pseudophase.

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