Kinetics of ion exchange of some complex cations on chromium ferrocyanide gel

1979 ◽  
Vol 57 (10) ◽  
pp. 1214-1217 ◽  
Author(s):  
Ishwari P. Saraswat ◽  
Suresh K. Srivastava ◽  
Ashok K. Sharma
Keyword(s):  
Diffusion Coefficients ◽  
Structural Changes ◽  
Effective Diffusion ◽  
Solution Concentration ◽  
Slow Step ◽  
Kinetic Measurements ◽  
Ammine Complex ◽  
Large Size ◽  
Effective Diffusion Coefficients ◽  
Kinetics Of

The parameters effective diffusion coefficients, activation energies, and entropies of activation are reported for the exchange of the ammine-complex cations of cobalt, viz. [Co(NH3)6]3+ and[Co(en)3]3+ (en = enthylenediamine) on chromium ferrocyanide gel in the H form. The values of these constants throw significant light on the possible structural changes in the exchanger framework caused by the introduction of these large size complex cations. Kinetic measurements have been made as the function of particle size of the exchanger, temperature, and solution concentration of the exchanging ions. The slow step governing the rate of exchange is diffusion of ions through the exchanger particles.

Bromine-Methanol Etching of Cadmium Telluride in a Rotating Disk Reactor

1990 ◽  
Vol 204 ◽  
Author(s):  
Michael B. Gentzler ◽  
Edmond I. Ko ◽  
Paul J. Sides ◽  
Paul T. Bowman
Keyword(s):  
Diffusion Coefficients ◽  
Rotation Rate ◽  
Transport Model ◽  
Effective Diffusion ◽  
Rotating Disk ◽  
One Dimensional ◽  
Effective Diffusion Coefficients ◽  
Rotating Disk Reactor ◽  
Bromine Concentration ◽  
Kinetics Of

ABSTRACTThe kinetics of the bromine-methanol etching of CdTe were studied in a rotating disk reactor as a function of temperature, bromine concentration, substrate orientation, and rotation rate. The results indicated that the etching process is mass transfer controlled from -20°C to 40°C and to a maximum rotation rate of 1200 RPM. A one-dimensional transport model was used to obtain effective diffusion coefficients for bromine in methanol. The diffusion coefficient of the etchant in methanol is given by 3.7×10-8 (T/η) cm2/s over the range of 2.5°C to 23°C.

Effective Diffusion Coefficients and Thermal Stability of the Structure of Metallic Glass Fe48Co32P14B6

2020 ◽  
Vol 62 (12) ◽  
pp. 2258-2265 ◽  
Author(s):  
S. V. Vasiliev ◽  
V. I. Parfenii ◽  
E. A. Pershina ◽  
A. S. Aronin ◽  
O. V. Kovalenko ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Metallic Glass ◽  
Diffusion Coefficients ◽  
Effective Diffusion ◽  
Effective Diffusion Coefficients ◽  
Thermal Stability Of

scholarly journals Modeling and thermodynamic properties of ‘bacaba’ pulp drying

2019 ◽  
Vol 23 (9) ◽  
pp. 702-708 ◽  
Author(s):  
Maria F. de Morais ◽  
José R. O. dos Santos ◽  
Marisângela P. dos Santos ◽  
Dyego da C. Santos ◽  
Tiago N. da Costa ◽  
...  
Keyword(s):  
Activation Energy ◽  
Thermodynamic Properties ◽  
Diffusion Coefficients ◽  
Effective Diffusion ◽  
Thermal Conditions ◽  
Drying Process ◽  
Experimental Conditions ◽  
Effective Diffusion Coefficients ◽  
Drying Rates ◽  
Increasing Temperature

ABSTRACT This study aimed to dry ‘bacaba’ (Oenocarpus bacaba Mart.) pulp under different thermal conditions, fit different mathematical models to the dehydration curves, and calculate the diffusion coefficients, activation energy and thermodynamic properties of the process. ‘Bacaba’ fruits were meshed to obtain the pulp, which was dried at temperatures of 40, 50 and 60 °C and with thickness of 1.0 cm. Increase in drying temperature reduced the dehydration times, as well as the equilibrium moisture contents, and drying rates of 0.65, 1.04 and 1.25 kg kg min-1 were recorded at the beginning of the process for temperatures of 40, 50 and 60 °C, respectively. The Midilli’s equation was selected as the most appropriate to predict the drying phenomenon, showing the highest R2, lowest values of mean square deviation (MSD) and χ2 under most thermal conditions, and random distribution of residuals under all experimental conditions. The effective diffusion coefficients increased with increasing temperature, with magnitudes of the order of 10-9 m2 s-1, being satisfactorily described by the Arrhenius equation, which showed activation energy (Ea) of 37.01 kJ mol-1. The drying process was characterized as endergonic, in which enthalpy (ΔH) and entropy (ΔS) reduced with the increment of temperature, while Gibbs free energy (ΔG) was increased.

Measurement of effective diffusion coefficients in dairy powders by confocal microscopy and sorption kinetic profiles

2019 ◽  
Vol 20 ◽  
pp. 100108 ◽  
Author(s):  
Valentyn Maidannyk ◽  
Eva Lutjes ◽  
Sharon Montgomery ◽  
Noel McCarthy ◽  
Mark A.E. Auty
Keyword(s):  
Confocal Microscopy ◽  
Diffusion Coefficients ◽  
Effective Diffusion ◽  
Sorption Kinetic ◽  
Effective Diffusion Coefficients ◽  
Dairy Powders
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