scholarly journals The Effects ofCassia SiameaLam. Root Extract on the Corrosion and Kinetics of Corrosion Process of Copper in Alkaline Solutions

2011 ◽  
Vol 8 (4) ◽  
pp. 1708-1713
Author(s):  
A. I Onen ◽  
B. T. Nwufo ◽  
E. E. Ebenso
Keyword(s):  
Copper Surface ◽  
Alkaline Solutions ◽  
Root Extract ◽  
Adsorption Model ◽  
Free Energy Of Adsorption ◽  
First Order Kinetics ◽  
Absorbance Difference ◽  
Increasing Temperature ◽  
Kinetics Of ◽  
Kinetic Treatment

The effect ofCassia siamealam. (CSL) root extract as a corrosion inhibitor of copper in 0.50 M NaOH solutions was investigated using absorbance difference technique at 30 °C and 40 °C. CSL root extract inhibited the corrosion of copper in 0.50 M NaOH solutions and the inhibition efficiency (% IE) increased to a maximum of 78.3±2.3% with increasing concentration of the extract but decreased with increasing temperature. The adsorption of CSL root extract on copper surface followed the Langmuir adsorption model with the average heat of adsorption, Qadsand free energy of adsorption, ΔGadsof -8.98 kJmol-1and -8.70 kJmol-1respectively. A kinetic treatment of the data revealed a first order kinetics with respect to copper in the presence and absence of the extract.

The catalysis of the para -hydrogen conversion by the solid free radical αα -diphenyl- β -picryl hydrazyl

1953 ◽  
Vol 220 (1140) ◽  
pp. 77-90 ◽  
Keyword(s):  
Free Radical ◽  
Adsorbed Layer ◽  
Inhomogeneous Magnetic Field ◽  
Langmuir Adsorption ◽  
First Order ◽  
Heterogeneous Catalytic ◽  
Hydrogen Molecules ◽  
First Order Kinetics ◽  
Increasing Temperature ◽  
Kinetics Of

A detailed study of the kinetics of the heterogeneous catalytic ortho - para -hydrogen conversion on the solid free radical αα -diphenyl- β -picryl hydrazyl, shows that this conversion follows the usual first-order kinetics and that the rate is independent of pressure. Examination of the rate at 90, 190 and 290° K indicates that it decreases with increasing temperature. This type of behaviour has been observed for other paramagnetic heterogeneous conversions, and the ‘negative activation energy' has been assumed to indicate that the catalysis takes place in a physically adsorbed layer of hydrogen molecules. Some evidence that this is the true explanation of the phenomenon is shown by the results of studies of the adsorption of hydrogen on the free radical. Experiments carried out at 77 and 90° K indicate that hydrogen is physically adsorbed by the free radical to form a weakly sorbed layer which obeys the Langmuir adsorption isotherm for the case when the surface is only sparsely covered. A theoretical discussion is given for a heterogeneous conversion occurring during the collision of the hydrogen molecule with the catalyst surface both in the absence, and in the presence, of a physically adsorbed layer. It is shown that only the theory based on the latter model is in agreement with experimental results, and so it is concluded that in the present case the catalysis is due to the interaction between the hydrogen molecules in a physically adsorbed layer, and the inhomogeneous magnetic field at the surface of the catalyst, which enables the otherwise forbidden ortho - para transitions to take place.

scholarly journals Temperature Effects Associated with the Adsorption of Neodymium Ions onto Activated Charcoal

2005 ◽  
Vol 23 (5) ◽  
pp. 399-406 ◽  
Author(s):  
Riaz Qadeer
Keyword(s):  
Activation Energy ◽  
Activated Charcoal ◽  
Temperature Effects ◽  
Adsorption Process ◽  
First Order ◽  
First Order Kinetics ◽  
Charcoal Adsorption ◽  
Increasing Temperature ◽  
Kinetics Of ◽  
Activated Charcoal Adsorption

The temperature dependence of the kinetics of the adsorption of neodymium ions from aqueous solution onto activated charcoal has been studied. The results obtained indicate that a form of equilibration appears to be attained after ca. 30 min although further very slow changes may occur over a much longer period. The adsorption process is controlled by the diffusion of neodymium ions into the pores of the activated charcoal. Adsorption follows first-order kinetics with an activation energy of 13.09 kJ/mol. Values of the equilibrium constant for the adsorption of neodymium ions onto activated charcoal increase with increasing temperature, thereby indicate the endothermic nature of the process.

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.

scholarly journals Empirical Validation of a Biogas Plant Simulation Model and Analysis of Biogas Upgrading Potentials

Energies ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2424
Author(s):  
Jan Martin Zepter ◽  
Jan Engelhardt ◽  
Tatiana Gabderakhmanova ◽  
Mattia Marinelli
Keyword(s):  
Simulation Model ◽  
Biogas Production ◽  
Biogas Plant ◽  
Raw Material ◽  
Biogas Upgrading ◽  
Integrated Energy Systems ◽  
First Order Kinetics ◽  
Biogas Plants ◽  
Plant Simulation ◽  
Kinetics Of

Biogas plants may support the transformation towards renewable-based and integrated energy systems by providing dispatchable co-generation as well as opportunities for biogas upgrading or power-to-X conversion. In this paper, a simulation model that comprises the main dynamics of the internal processes of a biogas plant is developed. Based on first-order kinetics of the anaerobic digestion process, the biogas production of an input feeding schedule of raw material can be estimated. The output of the plant in terms of electrical and thermal energy is validated against empirical data from a 3-MW biogas plant on the Danish island of Bornholm. The results show that the model provides an accurate representation of the processes within a biogas plant. The paper further provides insights on the functioning of the biogas plant on Bornholm as well as discusses upgrading potentials of biogas to biomethane at the plant from an energy perspective.

scholarly journals Comparative Study of Chemical Stability of Two H1Antihistaminic Drugs, Terfenadine and ItsIn VivoMetabolite Fexofenadine, Using LC-UV Methods

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Anna Gumieniczek ◽  
Anna Berecka-Rycerz ◽  
Rafał Pietraś ◽  
Izabela Kozak ◽  
Karolina Lejwoda ◽  
...  
Keyword(s):  
Comparative Study ◽  
Chemical Stability ◽  
First Order ◽  
First Order Kinetics ◽  
Kinetics Of Degradation ◽  
Effects Of Temperature ◽  
High Doses ◽  
Antihistaminic Drugs ◽  
Kinetics Of

A comparative study of chemical stability of terfenadine (TER) and itsin vivometabolite fexofenadine (FEX) was performed. Both TER and FEX were subjected to high temperature at different pH and UV/VIS light at different pH and then quantitatively analyzed using new validated LC-UV methods. These methods were used to monitor the degradation processes and to determine the kinetics of degradation for both the compounds. As far as the effects of temperature and pH were concerned, FEX occurred more sensitive to degradation than TER. As far as the effects of UV/VIS light and pH were concerned, the both drugs were similarly sensitive to high doses of light. Using all stress conditions, the processes of degradation of TER and FEX followed the first-order kinetics. The results obtained for these two antihistaminic drugs could be helpful in developing their new derivatives with higher activity and stability at the same time.

scholarly journals Kinetics of drying of basil leaves (Ocimum basilicum L.) in the infrared

2012 ◽  
Vol 16 (12) ◽  
pp. 1346-1352 ◽  
Author(s):  
Renata C. dos Reis ◽  
Ivano A. Devilla ◽  
Diego P. R. Ascheri ◽  
Ana C. O. Servulo ◽  
Athina B. M. Souza
Keyword(s):  
Experimental Data ◽  
Ocimum Basilicum ◽  
Coefficient Of Determination ◽  
Chisquare Test ◽  
The Mean ◽  
Drying Curves ◽  
The One ◽  
Increasing Temperature ◽  
Air Circulation ◽  
Kinetics Of

The objective of this paper was to model the drying curves of the leaves of basil (Ocimum basilicum L.) in the infrared at temperatures of 50, 60, 70 and 80 ºC and to evaluate the influence of drying temperature on the color of dried leaves. Drying was conducted in infrared dryer with temperature and greenhouse air circulation. Experimental data were fitted to eight mathematical models. The magnitude of the coefficient of determination (R²), the mean relative error (P), the estimated mean error (SE) and chisquare test (χ2) were used to verify the degree of fitness of the models. From the study it was concluded that: a) the behavior of the drying curves of basil leaves was similar to most agricultural products, the drying times in the infrared were less than the drying times in an oven with air circulation, b) the mathematical drying model proposed by Midilli et al. (2002) was the one which best adjusted to the experimental data, c) the diffusion coefficient ranged from 9.10 x 10-12 to 2.92 x 10-11 m² s-1 and d) the color of the samples was highly influenced by drying, becoming darker due to loss of chlorophyll with increasing temperature.

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.

scholarly journals Mathematical modeling of pequi pulp drying and effective diffusivity determination

2017 ◽  
Vol 21 (7) ◽  
pp. 493-498 ◽  
Author(s):  
Elisabete P. de Sousa ◽  
Rossana M. F. de Figueirêdo ◽  
Josivanda P. Gomes ◽  
Alexandre J. de M. Queiroz ◽  
Deise S. de Castro ◽  
...  
Keyword(s):  
Experimental Data ◽  
Effective Diffusivity ◽  
Drying Kinetics ◽  
Convective Drying ◽  
Drying Time ◽  
Air Speed ◽  
Drying Curves ◽  
Increasing Temperature ◽  
Kinetics Of ◽  
Best Fit

ABSTRACT The aim of this work was to study the drying kinetics of pequi pulp by convective drying at different conditions of temperature (50, 60, 70 and 80 °C) and thickness (0.5, 1.0 and 1.5 cm) at the air speed of 1.0 m s-1, with no addition of adjuvant. The experimental data of pequi pulp drying kinetics were used to plot drying curves and fitted to the models: Midilli, Page, Henderson & Pabis and Newton. Effective diffusivity was calculated using the Fick’s diffusion model for a flat plate. It was found that, with increasing thickness, the drying time increased and, with increasing temperature, the drying time was reduced. The Midilli model showed the best fit to the experimental data of pequi pulp drying at all temperatures and thicknesses, presenting higher coefficients of determination (R2), indicating that this model satisfactorily represents the pequi pulp drying phenomenon. There was a trend of increase in the effective diffusivity with the increase in pulp layer thickness and temperature.

scholarly journals Dye removal abilities of the mesophilic and thermophilic biomass: a kinetics study

2018 ◽  
Vol 20 (2) ◽  
pp. 408-416
Keyword(s):  
Intraparticle Diffusion ◽  
Second Order ◽  
Intraparticle Diffusion Model ◽  
First Order Kinetics ◽  
Different Types ◽  
Pseudo Second Order ◽  
Acidic Conditions ◽  
Red Dye ◽  
Experimental Kinetics ◽  
Kinetics Of

Mesophilic biomass and thermophilic biomass samples were isolated and used to remove Dorasyn Red dye from aqueous solutions. The biosorption kinetics of dye uptake by four different types of biomass at three temperatures (20, 30, and 40 °C) were investigated using pseudo-first order kinetics, pseudo-second order kinetics, intraparticle diffusion, Elovich, and Bangham models. The pseudo-second-order kinetics model and the first stage of the intraparticle diffusion model were effective in describing the experimental kinetics data. The biosorption results showed that the mesophilic biomass samples could be useful for removing dye under acidic conditions.

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