Improving the Diffusion Controlled Cementation of Cadmium Ions Using Reciprocating Fixed Bed of Zinc Rings

2011 ◽  
Vol 312-315 ◽  
pp. 694-699 ◽  
Author(s):  
A.H. El-Shazly ◽  
Ashraf A. Mubarak ◽  
Hesham S. Bamufleh
Keyword(s):  
Arrhenius Equation ◽  
Fixed Bed ◽  
Effect Of Temperature ◽  
Vibration Velocity ◽  
Kcal Mole ◽  
Cadmium Ions ◽  
Bed Height ◽  
Diffusion Controlled ◽  
Ring Diameter ◽  
Kinetics Of

The aim of the present work is to investigate the effect of pulsation on improving the rate of the diffusion controlled cementation of cadmium ions using reciprocating fixed bed of zinc rings. The kinetics of the cementation reaction was investigated under different conditions of initial concentration of cadmium ions, frequency and amplitude of oscillation (vibration velocity), zinc ring diameter, bed diameter, bed height and temperature. The effect of temperature was found to fit the Arrhenius equation with an activation energy of 7.58 kcal/mole which confirms the diffusion controlled nature of the reaction. A dimensionless correlation in the form of Sh = 6.9 Re0.45 Sc0.33 (Bd/Bh)0.89 was deduced. The industrial application of the obtained results was discussed.

Improving the Diffusion Controlled Cementation of Copper Ions on a Fixed Bed of Zinc Raschig Rings Using Flow Pulses in a Batch Reactor

2014 ◽  
Vol 353 ◽  
pp. 153-158 ◽  
Author(s):  
Ahmed H. El-Shazly ◽  
Ashraf A. Mubarak ◽  
Hesham S. Bamufleh
Keyword(s):  
Copper Ions ◽  
Batch Reactor ◽  
Fixed Bed ◽  
Effect Of Temperature ◽  
Vibration Velocity ◽  
Bed Height ◽  
Diffusion Controlled ◽  
Ring Diameter ◽  
Kinetics Of ◽  
Perforated Disc

This work investigates the possibility of improving the kinetics of the diffusion controlled cementation of copper on a fixed bed of zinc Raschig rings in a batch reactor by using flow pulses induced through the bed by a pulsating perforated disc. The kinetics of the cementation reaction was investigated under different conditions of initial concentration of copper ions, frequency and amplitude of oscillation (vibration velocity), zinc ring diameter, bed height and temperature. The effect of temperature was found to fit the Arrhenius equation with an activation energy of 5.5 kcal/mole which confirms the diffusion controlled nature of the reaction. A dimensionless correlation in the form that: Sh = 6.9 Re0.55 Sc0.33 (Pd/Bh)0.49 was deduced. Industrial application of the results obtained was discussed.

A STUDY OF THE MECHANISM AND KINETICS OF THE SULPHITE PROCESS

1939 ◽  
Vol 17b (4) ◽  
pp. 121-132 ◽  
Author(s):  
J. M. Calhoun ◽  
F. H. Yorston ◽  
O. Maass
Keyword(s):  
Temperature Coefficient ◽  
Arrhenius Equation ◽  
Practical Interest ◽  
Effect Of Temperature ◽  
Wood Meal ◽  
Spruce Wood ◽  
Mechanism And Kinetics ◽  
Kinetics Of

The rate of delignification of resin extracted spruce wood-meal has been determined in calcium-base sulphite liquor at temperatures from 130 °C. down to 50 °C. No break was found in the temperature coefficient curve at the lower temperatures, the reaction following the Arrhenius equation closely. Possible mechanisms of the reaction are discussed in the light of existing theories, and the effect of temperature on the yield of pulp is pointed out for its practical interest.

Primary products and processes in the γ-radiolysis of 2-methyltetrahydrofuran

1965 ◽  
Vol 285 (1402) ◽  
pp. 319-338 ◽  
Keyword(s):  
Glassy Phase ◽  
Kcal Mole ◽  
Radical Species ◽  
Molecule Reaction ◽  
Positive Ions ◽  
Primary Products ◽  
Diffusion Controlled ◽  
Thermal Bleaching ◽  
The Matrix ◽  
Kinetics Of

From a study of the u. v., visible, near i. r. and e. s. r. spectra induced by γ -irradiation at 77°K in glassy MTHF and in glassy MTHF containing various additives and from a study of controlled temperature increases on these spectra, the following conclusions are drawn. (1) The primary products of the radiolysis are electrons ( e - ) and positive ions ( MTHF + ) which undergo a rapid ion-molecule reaction to give O CH 3 radicals ( R ⋅). (2) e - can either be trapped in the glassy MTHF matrix or can be captured by either napththalene, ferric chloride, carbon tetrachloride, nitrous oxide or trans -stilbene if these substances are present. (3) The e - T are bleachable by light or heat and disappear independently of the radicals R⋅ without either augmentation of R⋅ or the production of any new radical species. (4) e - T and R⋅ disappear thermally and independently by second-order reactions, the rate constants being K e - + e - (M -1 S -1 ) = 10 12⋅4±1⋅1 exp ─ [0⋅85 ± 0⋅10 kcal/mole/ R ( T ─ 75)] and K R˙ + R˙ (M -1 S -1 ) = 10 13⋅3±1⋅4 exp ─ [1⋅20 ± 0⋅15 kcal/mole/ R ( T ─ 75)]. These rate expressions suggest that both reactions are diffusion controlled at low temperatures in the glassy phase. (5) The kinetics of the thermal bleaching of e - T indicate that the electrons migrate distances of about 150 Å from their parent positive ions before being trapped in the matrix. (6) The effect of FeCl 3 in reducing the formation of e - T at 77°K and its lack of effect on the thermal bleaching of e - T suggests that the reaction e - + FeCl 3 → FeCl 2 + Cl - only occurs before the electron is thermalized.

The kinetics of polysulphone formation II. The formation of 1-butene polysulphone in the region of the ceiling temperature

1952 ◽  
Vol 212 (1109) ◽  
pp. 207-220 ◽  
Keyword(s):  
Monomer Concentration ◽  
Effect Of Temperature ◽  
Kcal Mole ◽  
Temperature Dependent ◽  
Chain Polymer ◽  
Free Energy Of Formation ◽  
Ceiling Temperature ◽  
Liquid Sulphur ◽  
State 1 ◽  
Kinetics Of

The effect of temperature on the rate of formation of 1-butene polysulphone from mixtures of liquid sulphur dioxide and 1-butene has been investigated dilatometrically. Three methods of initiation were used: photochemical, silver nitrate and benzoyl peroxide, and the temperature range covered was 0 to 70° C. For appreciable rates of reaction, the photochemical rate may be expressed in the form: rate = k 1 [ B ] [ S ] — k 2 , where [ B ] [ S ] denotes the monomer concentration product and k 1 and k 2 are temperature-dependent constants. For each reaction mixture there is a critical temperature defined as the ceiling temperature T c above which the reaction rate and molecular weight of polymer formed are very small. This temperature is independent of the method and rate of initiation. Previous explanations of the ceiling temperature phenomenon are shown to be unsound. The present results may be interpreted on the assumption that the reverse of the propaga­tion reaction, here designated the depropagation reaction, becomes important as the ceiling temperature is approached. The kinetic data permit the evaluation of both the heat and entropy of polymerization, and for the reaction (l - C 4 H 8 + SO 2 ) liq. mixt → 1/ n (C 4 H 8 SO 2 ) n (solution in monomer mixture), — Δ H = 20.7 ± 1.4 kcal mole -1 , — Δ S ° = 68.2 cal mole -1 ° K -1 (standard state 1 mole l. -1 each reactant). The heat change determined by adiabatic calorimetry is 22.0 ± 0.7 kcal mole -1 . In principle, all polymerization systems should exhibit the ceiling temperature effect under suitable conditions. Possible systems for investigation are suggested. The ceiling temperature is the temperature at which the free energy of formation of long-chain polymer is zero. Above the ceiling temperature the polymer is thermodynamically unstable. Depolymerization experiments on I-butene polysulphone indicate that below 130° C the degradation is random in character, whether effected by light or by heat.

5-hydroxymethyl furfural formation and reaction kinetics of different pekmez samples: effect of temperature and storage

2012 ◽  
Vol 8 (4) ◽  
Author(s):  
Rasim Alper Oral ◽  
Mahmut Dogan ◽  
Kemal Sarioglu ◽  
Ömer Said Toker
Keyword(s):  
Reaction Kinetics ◽  
Arrhenius Equation ◽  
Storage Period ◽  
Effect Of Temperature ◽  
Temperature Changes ◽  
Juniperus Communis ◽  
Hydroxymethyl Furfural ◽  
Different Temperatures ◽  
And Storage ◽  
Kinetics Of

Abstract Pekmez (molasses) is a traditional food commonly produced from grape and other kind of fruit juices by evaporation processes. In this study, 5-Hydroxymethylfurfural (HMF) level of various pekmez samples was investigated during storage at different temperatures. HMF content of apricot, mulberry, carob, grape, Juniperus communis pekmez changed from 133.0 ppm to 1060.5 ppm, from 88.2 to 1921.5 ppm, from 11.1 to 1153.6 ppm, from 75.5 to 2077.0 ppm, from 19.9 to 280.1 ppm throughout eight months storage period, respectively. Samples of pekmez from the Juniperus communis had the minimum k values for each temperature that means HMF formation in these samples were slower than other pekmez types. The kinetic data analysis for HMF formation during storage was performed and an Arrhenius equation was used to determine the effect of temperature on reaction kinetics of 5-HMF formation in pekmez samples. Ea values were found between 10.58–37.73 (kcal/mol). Apricot pekmez was found as the least sensitive sample to HMF formation resulted from temperature changes.

The Reaction Kinetics of Liquid 60/40 Sn/Pb Solder With Copper and Nickel: A High Temperature X-Ray Diffraction Study

1984 ◽  
Vol 40 ◽  
Author(s):  
Patrick W. Dehaven
Keyword(s):  
High Temperature ◽  
Reaction Kinetics ◽  
X Ray Diffraction ◽  
Kcal Mole ◽  
Nickel Metal ◽  
X Ray ◽  
Diffusion Controlled ◽  
Solder Reaction ◽  
Kinetics Of

AbstractWith proper sample preparation, high temperature x-ray diffraction can be used to study in-situ the reactions occurring at a solder/metal interface. We have applied this technique to an investigation of the reaction kinetics between copper and nickel metal and 60/40 Sn/Pb solder. The copper and nickel are shown to follow similar pathways, each having a complex reaction profile that involves an initial “hold” of little reactivity, followed by a two-step diffusion controlled reaction. Activation energies were obtained from Arrhenius-type plots, and result in values of 6.8 kcal/mole for the nickel/solder reaction, and 13 kcal/mole for the copper/solder reaction. These results are compared with those obtained by previous investigators, and discussed in terms of the growth of the different intermetallic phases.

Study on Mass-Transfer Kinetics of Nd by 2-Ethylhexylphosphonic Acid Mono-(2-Ehylhexyl) Ester in the Presence of a Complexing Agent

2012 ◽  
Vol 461 ◽  
pp. 647-651
Author(s):  
Hong Tao Chang ◽  
Mei Li ◽  
Zhao Gang Liu ◽  
Yan Hong Hu ◽  
Fu Shun Zhang
Keyword(s):  
Interfacial Area ◽  
Extraction Process ◽  
Effect Of Temperature ◽  
Complexing Agent ◽  
Extraction Kinetics ◽  
Specific Interfacial Area ◽  
Diffusion Controlled ◽  
Mass Transfer Kinetics ◽  
Kinetics Of ◽  
Rate Of Extraction

The Nd(III) extraction kinetics by 2-ethylhexylphosphonic acid mono-(2-ethylhexyl) ester (HEH/EHP) in the presence of a complexing agent acetic acid(HAc) has been investigated using constant interfacial cell. The kinetics mechanism and extraction rate equation were achieved by the studies on the effect of stirring rate, temperature and specific interfacial area on the rate of extraction. The effect of temperature on the kinetics was analyzed, the value of the apparent activation energy was calculated as 9.24 kJ/mol, and it was found that the extraction process was a diffusion-controlled kinetics process.

scholarly journals Optimization of the Effect of Temperature and Bed Height on Cr (VI) Bioadsorption in Continuous System

2020 ◽  
Vol 29 (54) ◽  
pp. e10477
Author(s):  
Angel Villabona-Ortíz ◽  
Candelaria Tejada-Tovar ◽  
Erika Ruiz-Paternina ◽  
Jesús David Frías-González ◽  
Gerlyn David Blanco-García
Keyword(s):  
Electrostatic Interactions ◽  
Fixed Bed ◽  
Continuous System ◽  
Extraction Process ◽  
Operating Conditions ◽  
Effect Of Temperature ◽  
X Ray Diffraction ◽  
Residual Concentration ◽  
Bed Height ◽  
Vis Spectroscopy

In the present paper, the residues of the plantain starch extraction process are proposed as an adsorbent to remove Cr (VI) in a continuous fixed bed-system, varying the temperature in 33, 40, 55, 70 y 76 °C and bed height in the range of 15.5, 30, 65, 100, 114.5 mm. The adsorbent material was characterized by Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and X-ray Diffraction Analysis (XRD). The Cr (VI) solution at 100 ppm had contact with the column by gravity, with a flow rate of 0.75 mL/s at the different working conditions. At the end of the process, the residual concentration of the metal was measured by UV-Vis spectroscopy using the standard method for the determination of Cr (VI) in water ASTM D1687-17. From the results, it was established that the bioadsorbent has the presence of hydroxyl, carboxyl and methyl functional groups and that the adsorption process is controlled by electrostatic interactions; the variables evaluated had a significant influence on the process because applying the RSM methodology it was observed that the optimal operating conditions are 81.49 mm of bed height and temperature of 68 ºC. Based on the behavior of the rupture curve, it was found that the bio-material has the potential to be used as a filler in an adsorption column with the purpose of remove Cr (VI).

The kinetics of oxidation of benzaldehyde. II. The kinetics of the uncatalyzed reaction in solution

1953 ◽  
Vol 216 (1124) ◽  
pp. 30-44 ◽  
Keyword(s):  
Arrhenius Equation ◽  
Initial Rate ◽  
Benzene Solution ◽  
Kcal Mole ◽  
Widespread Occurrence ◽  
Kinetics Of Oxidation ◽  
Kinetic Behaviour ◽  
Uncatalyzed Reaction ◽  
Kinetics Of ◽  
Reaction In Solution

The initial rate of oxidation of benzaldehyde in benzene solution in the absence of catalysts and inhibitors is given by the relation (-d[O 2 ]/d t ) = ([ R H] 2 [O 2 ])/( b [ R H] 2 + c [O 2 ]). The reciprocals of the constants b and c vary with temperature according to the Arrhenius equation, the corresponding activation energies being 6.0 ± 0.5 and 17.5 ± 1.0 kcal/mole respectively. The difficulty of interpreting the relation in terms of the mechanism proposed by Bolland & Gee (1946) for photochemical and peroxide catalyzed oxidations is pointed out. It is suggested that this kinetic behaviour is of widespread occurrence in uncatalyzed oxidations.

Kinetics of acid dissolution of an orthochlorite mineral

1967 ◽  
Vol 45 (24) ◽  
pp. 3031-3034 ◽  
Author(s):  
G. J. Ross
Keyword(s):  
Activation Energy ◽  
Effect Of Temperature ◽  
Kcal Mole ◽  
Acid Dissolution ◽  
Kinetics Of

Measurements were made of the effect of temperature on the rate at which Mg, Fe, and Al were dissolved from clinochlore, a Mg-rich orthochlorite mineral, by acid. The Mg, Fe, and Al were dissolved at the same rate with the same activation energy of 21 kcal/mole. The data indicated that the reaction proceeded from the particle edges inwards and was controlled by diffusion.

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