Kinetic Studies of Gold Recovery from Diluted Chloride Aqueous Solutions Using Activated Carbon Organosorb 10 CO

2016 ◽  
Vol 69 (3) ◽  
pp. 254 ◽  
Author(s):  
Marek Wojnicki ◽  
Ewa Rudnik ◽  
Magdalena Luty-Błocho ◽  
Robert P. Socha ◽  
Zbigniew Pędzich ◽  
...  
Keyword(s):  
Activated Carbon ◽  
Acidic Solution ◽  
Activation Parameters ◽  
Kinetic Studies ◽  
Reaction Model ◽  
Surface Functional Groups ◽  
Complex Ions ◽  
First Order ◽  
Material Theory

The kinetic studies of gold(iii) chloride complex ions recovery from acidic solution using activated carbon (AC) were carried out using spectrophotometry. AC samples were characterized in terms of surface area, porosity, and zeta potential. The surface functional groups were also identified. It was found that adsorption of AuCl4– onto AC was followed by reduction of the ions to the metallic form. The process obeyed the first order reaction model, but the reaction was controlled by diffusion. Arrhenius and Eyring–Polanyi equations were used for determination of the activation parameters. Distribution of gold across the AC pellets was also determined and discussed according to the porous material theory.

Platinum(IV) Chloride Complex Ions Adsorption on Activated Carbon Organosorb 10CO

2017 ◽  
Vol 70 (7) ◽  
pp. 769 ◽  
Author(s):  
Marek Wojnicki ◽  
Ewa Rudnik ◽  
Robert P. Socha ◽  
Krzysztof Fitzner
Keyword(s):  
Activated Carbon ◽  
Photoelectron Spectroscopy ◽  
Kinetic Studies ◽  
Reaction Model ◽  
Chloride Complex ◽  
Complex Ions ◽  
Spectrophotometric Methods ◽  
The Individual ◽  
Adsorption Desorption ◽  
Platinum Recovery

Kinetic studies on the recovery of platinum(iv) chloride complex ions from acidic solutions using commercially available activated carbon (AC) were carried out using spectrophotometric methods. The overall process obeyed first-order reaction model. The overall process is complex and consists of two steps: the first one is related to the reversible adsorption–desorption of PtIV complex and the second one is related to the reduction of PtIV complex on the AC surface. The first step of the overall process was limited by diffusion, whereas the second step ran under kinetic control. The activation energies of the individual reactions in both steps were determined and corresponded to 18.27, 7.85, and 31.2 kJ mol–1 for the adsorption, desorption, and reduction reactions, respectively. X-ray photoelectron spectroscopy results confirmed that the chemical reaction was related to the reduction of PtIV to PtII on the AC surface. The results show that the investigated AC can be applied for platinum recovery from highly diluted aqueous systems.

Kinetic Studies of Condensation of Aromatic Aldehydes with Meldrum’s Acid

2002 ◽  
Vol 57 (11) ◽  
pp. 1320-1326 ◽  
Author(s):  
H. A. A. Medien
Keyword(s):  
Condensation Reaction ◽  
Activation Parameters ◽  
Kinetic Studies ◽  
Aromatic Aldehydes ◽  
Isokinetic Temperature ◽  
Meldrum's Acid ◽  
Meldrum’S Acid ◽  
First Order ◽  
A Value

The condensation reaction of Meldrum’s acid with aromatic aldehydes in the presence of a catalyst has been investigated spectrophotometrically at 25-50 °C. The reaction follows overall second order kinetics, first order in each of the reactants. Electron-withdrawing groups accelerate and electron-releasing groups retard the rate of condensation. From the dependence of the rate constants on temperature, the activation parameters have been calculated and also the isokinetic temperature with a value of 403.5 K. Based on this reaction, determination of eight aromatic aldehydes in a concentration range of 1.49 - 91 μg/ml is proposed. On the other hand, determination of some aromatic aldehydes with Meldrum’s acid is performed in water at 75 °C for 2 h, without adding any catalyst.

Kinetic Studies of [4n+2]π-Thermal Cyclodimerization of 1-(3-Pyridazinyl)-3-oxidopyridinium Betaines

1992 ◽  
Vol 57 (9) ◽  
pp. 1951-1959 ◽  
Author(s):  
Madlene L. Iskander ◽  
Samia A. El-Abbady ◽  
Alyaa A. Shalaby ◽  
Ahmed H. Moustafa
Keyword(s):  
Energy Gap ◽  
Activation Parameters ◽  
Kinetic Studies ◽  
Cyclic Transition ◽  
Concerted Mechanism ◽  
First Order ◽  
Thermodynamic Activation Parameters ◽  
Cyclic Transition State ◽  
Complete Dissociation ◽  
Homo Lumo

The reactivity of the base induced cyclodimerization of 1-(6-arylpyridazin-3-yl)-3-oxidopyridinium chlorides in a pericyclic process have been investigated kinetically at λ 380 nm. The reaction was found to be second order with respect to the liberated betaine and zero order with respect to the base. On the other hand dedimerization (monomer formation) was found to be first order. It was shown that dimerization is favoured at low temperature, whereas dedimerization process is favoured at relatively high temperature (ca 70 °C). Solvent effects on the reaction rate have been found to follow the order ethanol > chloroform ≈ 1,2-dichloroethane. Complete dissociation was accomplished only in 1,2-dichloroethane at ca 70 °C. The thermodynamic activation parameters have been calculated by a standard method. Thus, ∆G# has been found to be independent on substituents and solvents. The high negative values of ∆S# supports the cyclic transition state which is in favour with the concerted mechanism. MO calculations using SCF-PPP approximation method indicated low HOMO-LUMO energy gap of the investigated betaines.

scholarly journals Spectrophotometric Analysis of the Kinetic of Pd(II) Chloride Complex Ions Sorption Process from Diluted Aqua Solutions Using Commercially Available Activated Carbon

2017 ◽  
Vol 62 (4) ◽  
pp. 2405-2411 ◽  
Author(s):  
M. Wojnicki
Keyword(s):  
Activated Carbon ◽  
Kinetic Model ◽  
Thermodynamic Parameters ◽  
Kinetic Studies ◽  
Sorption Process ◽  
Spectrophotometric Analysis ◽  
Chloride Complex ◽  
Adsorption Kinetic ◽  
Complex Ions ◽  
Process Kinetic

AbstractIn this paper, results of adsorption kinetic studies of Pd(II) chloride complex ions on activated carbon Organosrob 10 CO are presented. Spectorphotometrical method was applied to investigate the process. Kinetic model was proposed, and fundamental thermodynamic parameters were determined. Proposed kinetic model describes well observed phenomenon in the studied range of concentration of Pd(II) chloride complex ions as well, as concentration of activated carbon.

scholarly journals Determination of surface functional groups on mechanochemically activated carbon cloth by Boehm method

Tehnika ◽  
2014 ◽  
Vol 69 (3) ◽  
pp. 367-372
Author(s):  
Anđelka B. Đukić ◽  
Nikola S. Vukelić ◽  
Bojana M. Paskaš-Mamula ◽  
Nikola B. Novaković ◽  
Radojka T. Vujasin ◽  
...  
Keyword(s):  
Activated Carbon ◽  
Functional Groups ◽  
Carbon Cloth ◽  
Surface Functional Groups ◽  
Activated Carbon Cloth

Kinetic studies of sorption and reduction of gold(III) chloride complex ions on activated carbon Norit ROX 0.8

2015 ◽  
Vol 29 ◽  
pp. 289-297 ◽  
Author(s):  
Marek Wojnicki ◽  
Magdalena Luty-Błocho ◽  
Robert P. Socha ◽  
Krzysztof Mech ◽  
Zbigniew Pędzich ◽  
...  
Keyword(s):  
Activated Carbon ◽  
Kinetic Studies ◽  
Chloride Complex ◽  
Complex Ions

Micellar catalysis of organic reactions. XIV. Hydrolysis of some 1,4-Benzodiazepin-2-one drugs in acidic solution

1984 ◽  
Vol 37 (9) ◽  
pp. 1895 ◽  
Author(s):  
TJ Broxton ◽  
T Ryan ◽  
SR Morrison
Keyword(s):  
Acid Concentration ◽  
Acidic Solution ◽  
Sodium Dodecyl ◽  
Kinetic Studies ◽  
Micellar Catalysis ◽  
Amide Bond ◽  
First Order ◽  
Amide Hydrolysis ◽  
Hydrolysis Of ◽  
Azomethine Bond

Kinetic studies of the acidic hydrolysis of diazepam and nitrazepam were carried out in the presence of micelles of sodium dodecyl sulfate (sds). The hydrolysis of diazepam was shown to occur with biphasic kinetics. This is consistent with initial hydrolysis of the azomethine bond followed by very slow hydrolysis of the amide bond as found for hydrolysis in aqueous solution. Nitrazepam, however, was found to decompose with monophasic kinetics consistent with initial amide hydrolysis. Reactions involving the hydrolysis of the azomethine bond were shown to be independent of acid concentration and subject to inhibition by micelles of sds. Reactions involving amide hydrolysis were shown to be first order in acid concentration and subject to micellar catalysis. The mechanistic change for the hydrolysis of nitrazepam on transfer from water (initial azomethine cleavage) to micelles of sds (initial amide cleavage), was presumably the result of the inhibition of azomethine hydrolysis and the catalysis of amide hydrolysis by the micelles.

scholarly journals Kinetic Isotope Effects in the Chromium(VI) Oxidation of Bicyclic Alcohols

1999 ◽  
Vol 23 (2) ◽  
pp. 146-147
Author(s):  
J. Hodge Markgraf ◽  
Jordan S. Dubow ◽  
Jessica A. Charland ◽  
Elliott H. Sohn
Keyword(s):  
Rate Constants ◽  
Acidic Solution ◽  
Isotope Effects ◽  
Activation Parameters ◽  
Kinetic Isotope Effects ◽  
Secondary Alcohols ◽  
First Order ◽  
Chromium Vi ◽  
Kinetic Isotope ◽  
Pseudo First Order

Pseudo first-order rate constants are determined for the oxidation of a series of secondary alcohols and their monodeutero analogues by ammonium chromate in aqueous acidic solution at several temperatures; the relative rates and activation parameters are consistent with a cyclic, symmetrical transition state.

scholarly journals Kinetics and Mechanism of Micellar Catalyzed Oxidation of Dextrose by N-Bromosuccinimide in H2SO4 Medium

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Minu Singh
Keyword(s):  
Fractional Order ◽  
Activation Parameters ◽  
Kinetic Studies ◽  
Kinetics And Mechanism ◽  
Stoichiometric Ratio ◽  
Product Analysis ◽  
Experimental Conditions ◽  
First Order ◽  
Order Dependence ◽  
Wide Range

Kinetics and mechanism of micellar catalyzed N-bromosuccinimide oxidation of dextrose in H2SO4 medium was investigated under pseudo-first-order condition temperature of 40°C. The results of the reactions studied over a wide range of experimental conditions show that NBS shows a first order dependence, fractional order, on dextrose and negative fractional order dependence on sulfuric acid. The determined stoichiometric ratio was 1 : 1 (dextrose : N-bromosuccinimide). The variation of Hg(OAC)2 and succinimide (reaction product) has insignificant effect on reaction rate. Effects of surfactants, added acrylonitrile, added salts, and solvent composition variation have been studied. The Arrhenius activation energy and other thermodynamic activation parameters are evaluated. The rate law has been derived on the basis of obtained data. A plausible mechanism has been proposed from the results of kinetic studies, reaction stoichiometry, and product analysis. The role of anionic and nonionic micelle was best explained by the Berezin’s model.

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