Analytical study of the kinetics of the change in the surface tension accompanying adsorption and diffusion saturation in an electrically conducting solid sphere

1987 ◽  
Vol 22 (6) ◽  
pp. 568-571
Author(s):  
V. N. Yuzevich
Keyword(s):  
Surface Tension ◽  
Analytical Study ◽  
Solid Sphere ◽  
Diffusion Saturation ◽  
Electrically Conducting ◽  
Kinetics Of ◽  
And Diffusion

scholarly journals Biosorption and Diffusion Modeling of Pb(II) by Malt Bagasse

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Klaiani B. Fontana ◽  
Giane Gonçalves Lenzi ◽  
Erica R. L. R. Watanabe ◽  
Ervin Kaminski Lenzi ◽  
Juliana A. M. T. Pietrobelli ◽  
...  
Keyword(s):  
Sorption Process ◽  
Isotherm Models ◽  
Diffusion Modeling ◽  
Biosorption Capacity ◽  
Kinetic And Thermodynamic Parameters ◽  
Pseudo Second Order ◽  
Ph Optimization ◽  
Kinetics Of ◽  
And Diffusion

The removal of Pb(II) from water by biosorption processes onto malt bagasse was investigated and the kinetic and thermodynamic parameters were obtained; additionally a diffusion modeling was proposed. The characterization of malt bagasse was performed by FTIR and SEM/EDS. The experiments were conducted in batch system and an experimental design based response surface methodology was applied for agitation speed and pH optimization. The kinetics of biosorption followed pseudo-second-order model and the temperature of the process affected the biosorption capacity. Isotherm models of Langmuir, Freundlich, and Elovich were applied and the Langmuir model showed better fit and the estimated biosorption capacity was 29.1 mg g−1. The negative values obtained for ΔG° and positive values of ΔH° confirm, respectively, the spontaneous and endothermic nature of the process. The diffusion modeling was performed based on experiments in the absence of agitation to investigate the influence of the biosorbent on the sorption process of Pb(II) ions.

The kinetics of the surface tension of micellar surfactant solutions

1991 ◽  
Vol 60 ◽  
pp. 235-261 ◽  
Author(s):  
C.D. Dushkin ◽  
I.B. Ivanov ◽  
P.A. Kralchevsky
Keyword(s):  
Surface Tension ◽  
Surfactant Solutions ◽  
Micellar Surfactant Solutions ◽  
Kinetics Of

Effect of temperature on cyclic voltammograms during the electrodeposition of lead

1989 ◽  
Vol 67 (1) ◽  
pp. 130-136 ◽  
Author(s):  
Magdy Girgis ◽  
Edward Ghali
Keyword(s):  
Analytical Study ◽  
Ammonium Acetate ◽  
Deposition Process ◽  
Lead Chloride ◽  
Effect Of Temperature ◽  
Cyclic Voltammograms ◽  
Tafel Slopes ◽  
As Adsorption ◽  
And Diffusion ◽  
Potentiostatic Transients

The electrochemical behavior of lead deposition process in a temperature range between 25 and 75 °C was studied in a medium of lead chloride and ammonium acetate by linear and cyclic sweep perturbation. The study was undertaken on four substrates: Pb, Cu, Ag, and C. An increase in temperature resulted in accelerating the deposition process and promoted dendrite formation. Moreover, different kinetic parameters such as adsorption isotherms, Tafel slopes, and diffusion coefficient were affected as a function of temperature elevation. Surface analytical study performed by Auger electron spectroscopy revealed an increase in peak intensities of Cl and Pb as the temperature increased. Keywords: electrodeposition, cyclic voltammetry, potentiostatic transients, underpotential deposition, temperature effect.

Vacancy-Mediated Diffusion and Diffusion-Controlled Processes in Ordered Binary Intermetallics by Kinetic Monte Carlo Simulations

2021 ◽  
Vol 29 ◽  
pp. 95-115
Author(s):  
Rafal Kozubski ◽  
Graeme E. Murch ◽  
Irina V. Belova
Keyword(s):  
Monte Carlo ◽  
Kinetic Monte Carlo ◽  
Simulation Studies ◽  
Self Diffusion ◽  
Monte Carlo Techniques ◽  
Diffusion Controlled ◽  
Kinetic Monte Carlo Simulations ◽  
Kinetic Effects ◽  
Kinetics Of ◽  
And Diffusion

We review the results of our Monte Carlo simulation studies carried out within the past two decades in the area of atomic-migration-controlled phenomena in intermetallic compounds. The review aims at showing the high potential of Monte Carlo methods in modelling both the equilibrium states of the systems and the kinetics of the running processes. We focus on three particular problems: (i) the atomistic origin of the complexity of the ‘order-order’ relaxations in γ’-Ni3Al; (ii) surface-induced ordering phenomena in γ-FePt and (iii) ‘order—order’ kinetics and self-diffusion in the ‘triple-defect’ β-NiAl. The latter investigation demonstrated how diverse Monte Carlo techniques may be used to model the phenomena where equilibrium thermodynamics interplays and competes with kinetic effects.

Kinetic model for disposition of 6-mercaptopurine in monkey plasma and cerebrospinal fluid

1985 ◽  
Vol 248 (2) ◽  
pp. R147-R156 ◽  
Author(s):  
D. G. Covell ◽  
P. K. Narang ◽  
D. G. Poplack
Keyword(s):  
Cerebrospinal Fluid ◽  
Brain Parenchyma ◽  
Lymphocytic Leukemia ◽  
Bolus Administration ◽  
Significant Barrier ◽  
Maintenance Of Remission ◽  
Kinetics Of ◽  
And Diffusion ◽  
Monkey Plasma ◽  
Csf Turnover

The antipurine 6-mercaptopurine (6-MP) is effective in the induction and maintenance of remission in patients with acute lymphocytic leukemia. This report presents a compartmental model that describes the kinetics of 6-MP in the plasma and cerebrospinal fluid (CSF) of the monkey. Analysis is based on simultaneously measured plasma and CSF 6-MP concentrations after intravenous and intraventricular bolus administration. Results indicate that 6-MP administered intraventricularly remains largely in the CSF. Disappearance of 6-MP from CSF is principally due to convective losses at a rate equivalent to CSF turnover. Diffusion of 6-MP across the ependymal surface accounts for only 7% of the 6-MP appearing in the plasma. Conversely the dominant route for entry of 6-MP into the CSF from the plasma is entrainment in choroidally formed CSF. Only 12% of 6-MP in the CSF after intravenous administration can be accounted for by permeation of cerebral capillaries and diffusion through brain parenchyma and across the ependymal surface into CSF. These results indicate that the choroid plexus is not a significant barrier for the transfer of molecules like 6-MP from plasma to CSF.

Refinement of Size Distributions for Primary Crystallizations

1997 ◽  
Vol 481 ◽  
Author(s):  
E. Pineda ◽  
T. Pradell ◽  
D. Crespo ◽  
N. Clavaguera ◽  
J. ZHU ◽  
...  
Keyword(s):  
Grain Size ◽  
Metastable Phase ◽  
Primary Crystallization ◽  
Controlled Growth ◽  
Diffusion Controlled ◽  
Average Grain Size ◽  
Soft Impingement ◽  
Single Grain ◽  
Kinetics Of ◽  
And Diffusion

ABSTRACTThe microstructure developed in primary crystallizations is studied under realistic conditions. The primary crystallization of an amorphous alloy is modeled by considering the thermodynamics of a metastable phase transition and the kinetics of nucleation and crystal growth under isothermal annealing. A realistic growth rate, including an interface controlled growth at the beginning of the growth of each single grain and diffusion controlled growth process with soft impingement afterwards is considered. The reduction in the nucleation rate due to the compositional change in the remaining amorphous matrix is also taken into account. The microstructures developed during the transformation are obtained by using the Populational KJMA method, from the above thermodynamic and kinetic factors. Experimental data of transformed fraction, grain density, average grain size, grain size distribution and other related parameters obtained from annealed metallic glasses are modeled.

Oxidation of Copper Sulfides in Aqueous Ammonia. III. Kinetic Characteristics

1979 ◽  
Vol 32 (12) ◽  
pp. 2597 ◽  
Author(s):  
AO Filmer ◽  
AJ Parker ◽  
BW Clare ◽  
LGB Wadley
Keyword(s):  
Aqueous Ammonia ◽  
Sulfide Oxidation ◽  
Metal Sulfide ◽  
Diffusion Control ◽  
Sulfate Ions ◽  
Kinetics Of Oxidation ◽  
Copper Sulfides ◽  
Shrinking Core ◽  
Kinetics Of ◽  
And Diffusion

The kinetics of oxidation with oxygen of chalcocite, Cu2S, to CuS in buffered aqueous ammonia at pH 10.5 at 30� can be modeled approximately by a shrinking core of Cu2S within a thickening shell of CuxS (x ≥ 1). The Cu2S core offers partial cathodic protection to the CuxS and diffusion of Cu+ through CuxS controls the rate of reaction. The kinetics of oxidation of covellite, CuS, to Cu2+, sulfur and sulfate ions in the same solvent can be modeled by a shrinking core of CuS surrounded by a shrinking sphere of CuyS (y < 1) which is much less effectively protected cathodically by the CuS core. Oxidation of CuS is subject to mixed chemical and diffusion control. Rates of oxidation of NiS and of CuS, in the presence and absence of tetrachloroethene and ammonium sulfate, show that, whether sulfur is a major oxidation product or not, the presence of sulfur has very little, if any, influence on the rate or mechanism of oxidation. This is contrary to current ideas on metal sulfide oxidation.

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