Kinetics and mechanism of the hexacyanomanganate(IV)–arsenic(III) redox reaction in acidic medium

1988 ◽  
Vol 66 (11) ◽  
pp. 2855-2859 ◽  
Author(s):  
Guillermo López-Cuetoa ◽  
Carlos Ubide
Keyword(s):  
Sulfuric Acid ◽  
Ionic Strength ◽  
Rate Constant ◽  
Redox Reaction ◽  
Acidic Medium ◽  
Absorption Maximum ◽  
Cyanide Complex ◽  
Acidic Media ◽  
Acid Media ◽  
First Order

The reaction between hexacyanomanganate(IV) and arsenic(III), in acidic media, proceeds with a stoichiometry Δ[Mn(IV)]/Δ[As(III)] = 1. The reaction in sulfuric acid media has been followed spectrophotometrically at 387 nm, where the Mn(IV) cyanide complex has an absorption maximum, and shows a first-order dependence on the hexacyanomanganate(IV) concentration, viz., −d[Mn(IV)]/dt = k[Mn(IV)], the value of k being dependent on the acidity and the arsenic(III) concentration. At As(III), 0.1 M; H+, 0.16 M; ionic strength, 2.0; and T, 30 °C, the value of the rate constant was found to be k = (1.04 ± 0.06) × 10−5 s−1. The proposed mechanism, through three parallel pathways, explains satisfactorily the experimental results observed.

scholarly journals EFFECT OF DIATOMEAOUS EARTH TREATMENT USING HYDROGEN CHLORIDE AND SULFURIC ACID ON KINETICS OF CADMIUM(II) ADSORPTION

2010 ◽  
Vol 2 (2) ◽  
pp. 107-112
Author(s):  
Nuryono Nuryono ◽  
Narsito Narsito
Keyword(s):  
Aqueous Solution ◽  
Sulfuric Acid ◽  
Hydrogen Chloride ◽  
Rate Constant ◽  
Diatomaceous Earth ◽  
Adsorption Rate ◽  
Physical Interaction ◽  
First Order ◽  
Adsorption Rate Constant ◽  
Kinetics Of

In this research, treatment of diatomaceous earth, Sangiran, Central Java using hydrogen chloride (HCl) and sulfuric acid (H2SO4) on kinetics of Cd(II) adsorption in aqueous solution has been carried out. The work was conducted by mixing an amount of grounded diatomaceous earth (200 mesh in size) with HCl or H2SO4 solution in various concentrations for two hours at temperature range of 100 - 150oC. The mixture was then filtered and washed with water until the filtrate pH is approximately 7 and then the residue was dried for four hours at a temperature of 70oC. The product was used as an adsorbent to adsorb Cd(II) in aqueous solution with various concentrations. The Cd(II) adsorbed was determined by analyzing the rest of Cd(II) in the solution using atomic absorption spectrophotometry. The effect of treatment was evaluated from kinetic parameter of adsorption rate constant calculated based on the simple kinetic model. Results showed  that before equilibrium condition reached, adsorpstion of Cd(II) occurred through two steps, i.e. a step tends to follow a reaction of irreversible first order  (step I) followed by reaction of reversible first order (step II). Treatment with acids, either hydrogen chloride or sulfuric acid, decreased adsorption rate constant for the step I from 15.2/min to a range of 6.4 - 9.4/min.  However, increasing concentration of acid (in a range of concentration investigated) did not give significant and constant change of adsorption rate constant. For step II process,  adsorption involved physical interaction with the sufficient low adsorption energy (in a range of 311.3 - 1001 J/mol).     Keywords: adsorption, cdmium, diatomaceous earth, kinetics.

SOME OBSERVATIONS ON CYANIC ACID AND CYANATES

1955 ◽  
Vol 33 (2) ◽  
pp. 426-440 ◽  
Author(s):  
M. W. Lister
Keyword(s):  
Activation Energy ◽  
Ionic Strength ◽  
Rate Constant ◽  
Ionization Constant ◽  
Side Reaction ◽  
Cyanic Acid ◽  
First Order ◽  
Second Stage ◽  
Carbonate Concentration ◽  
Considerable Range

Various reactions of cyanic acid and the cyanate ion have been examined. Cyanic acid, in the presence of added hydrochloric or nitric acid, decomposes quantitatively according to the equation: HNCO + H3O+ → CO2 + NH4+. The rate constant for this reaction was measured over a range of temperature and ionic strength, and was found to be 0.86 mole liter−1 min.−1 at unit ionic strength and 1.5 °C. The activation energy is [Formula: see text] The effect of ionic strength on the reaction with hydrochloric acid closely parallels that on the activity coefficients of the acid itself. Without added acid cyanic acid decomposes by a first order reaction: HNCO + 2H2O → NH4HCO3, followed by a rapid second stage: NH4HCO3 + HNCO → NH4NCO + H2CO3. This reaction has a rate constant of 0.011 min.−1 at 0 °C. and an activation energy of 16 kcal. There is also a few per cent of some side reaction. Cyanate ions in alkaline solution decompose thus: OCN− + 2H2O → NH4+ + CO3−−. This reaction was examined over a range of temperature and ionic strength: it is first order with k = 3.0 × 10−3 min.−1at 100 °C. (0.3 ionic strength) and [Formula: see text] activation energy. The rate is somewhat dependent on hydroxide concentration, when this is fairly low. The reaction is catalyzed by carbonate, but not by a number of other anions that were examined. The rate of the catalyzed reaction is proportional to the carbonate concentration, but independent of cyanate, at least over a considerable range. The ionization constant of cyanic acid has been measured by a method that avoids errors from hydrolysis; the value obtained was 2.0 × 10−4. The oxidation of cyanate by hypochlorite and by chlorine was examined more briefly.

scholarly journals Kinetics and Mechanism of Oxidation of Glutamic Acid byN-Bromophthalimide in Aqueous Acidic Medium

2011 ◽  
Vol 8 (4) ◽  
pp. 1472-1477
Author(s):  
N. M. I. Alhaji ◽  
S. Sofiya Lawrence Mary
Keyword(s):  
Dielectric Constant ◽  
Ionic Strength ◽  
Glutamic Acid ◽  
Acidic Medium ◽  
Reaction Medium ◽  
Kinetics Of Oxidation ◽  
First Order ◽  
Mechanism Of Oxidation ◽  
Kinetics Of ◽  
Aqueous Acidic Medium

The kinetics of oxidation of glutamic acid (Glu) withN-bromophthalimide (NBP) was studied in perchloric acid medium at 30°C by potentiometric method. The reaction is first order each in NBP and glutamic acid and is negative fractional order in [H+]. Addition of KBr or the reaction product, phthalimide had no effect on the rate. Similarly variation of ionic strength of the medium did not affect the rate of the reaction. Also the rate increased with decrease in dielectric constant of the reaction medium. The thermodynamic parameters were computed from Arrhenius and Eyring plots. A suitable mechanism consistent with the kinetic results has been proposed.

Kinetics of the Ce3+/BrO2-Reaction in Sulfuric Acid Medium

1985 ◽  
Vol 40 (4) ◽  
pp. 368-372 ◽  
Author(s):  
H. D. Försterling ◽  
H. J. Lamberz ◽  
H. Schreiber
Keyword(s):  
Sulfuric Acid ◽  
Acid Solution ◽  
Acid Medium ◽  
Rate Constant ◽  
Constant Concentration ◽  
First Order ◽  
Sulfuric Acid Medium ◽  
First Order Kinetics ◽  
Belousov Zhabotinsky Reaction ◽  
Kinetics Of

The reaction of Ce3+ with BrO2 in sulfuric acid solution (which is the starting step in the inorganic reaction subset of the Belousov-Zhabotinsky-reaction) is followed spectroscopically in a reaction mixture containing BrO2 at constant concentration. From first order kinetics (Br02 in excess) the rate constant for this reaction is evaluated.

scholarly journals Belousov-Zhabotínsky oscillatory reaction. Kinetics of malonic acid decomposition

2000 ◽  
Vol 65 (10) ◽  
pp. 709-713 ◽  
Author(s):  
Slavica Blagojevic ◽  
Natasa Pejic ◽  
Slobodan Anic ◽  
Ljiljana Kolar-Anic
Keyword(s):  
Sulfuric Acid ◽  
Reaction Kinetics ◽  
Rate Constant ◽  
Malonic Acid ◽  
Oscillatory Reaction ◽  
Acid Decomposition ◽  
First Order ◽  
First Order Kinetics ◽  
Pseudo First Order ◽  
Kinetics Of

The kinetics of the Belousov-Zhabotinsky (BZ) oscillatory reaction was analyzed. With this aim, the tune evolution of a reactionmixture composedof malonic acid, bromate, sulfuric acid and cerium(III) was studied at 298 K. Pseudo-first order kinetics with respect to malonic acid as the species undergoing decomposition with a corresponding rate constant, k = 7.5x10-3 min-1, was found.

scholarly journals Kinetic and Mechanism of Uncatalytic Oxidation of Dl-Threonine by Cerium (Iv) in Aqueous Acid Medium

2021 ◽  
pp. 51-63
Author(s):  
Gajanand Sahu ◽  
Sanjay Ghosh
Keyword(s):  
Thermodynamic Parameters ◽  
Acid Medium ◽  
Rate Constant ◽  
Acidic Medium ◽  
Order Reaction ◽  
First Order Reaction ◽  
First Order ◽  
Aqueous Acid ◽  
Rate Of Reaction ◽  
Different Temperatures

Kinetic of uncatalyzed oxidation of DL-Threonine has been studied by Ce (IV) in acidic medium has been investigatigated by spectrophotometer technique.  The rate of reaction determined at three different temperatures ranging from 298 K to 318 K at the interval of 10 K. The reaction has been found to be a first order reaction in presence or in absence of KCl, CTAB, and SDS. The rate constant, decreases with increasing the concentration of [HSO4-] and [H+] ion. The various thermodynamic parameters were calculated at 298 K, 308 K and 318 K. The proposed mechanism and results is discussed.

scholarly journals Application of polymer-coated Macadamia integrifolia nutshell biomass impregnated with palladium for chromium(VI) remediation

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Malvin Moyo ◽  
Sekomeng Johannes Modise ◽  
Vusumzi Emmanuel Pakade
Keyword(s):  
Formic Acid ◽  
Rate Constant ◽  
Redox Reaction ◽  
Order Rate Constant ◽  
First Order ◽  
Order Rate ◽  
Chromium Vi ◽  
Relative Standard ◽  
Pseudo First Order ◽  
Catalyst Dosage

AbstractFreely suspended and porous basket restrained granules of palladium nanoparticles supported on polymer-grafted Macadamia nutshell biomass (Pd@Polym-MNS) composite were used for the treatment chromium(VI)-containing water. In the presence of formic acid, the Pd@Polym-MNS demonstrated its activity in the adsorption-reduction-based conversion of noxious chromium(VI) to less toxic chromium(III) with a low activation energy of 13.4 kJ mol–1, ΔH0 (+ 10.8 kJ mol–1), ΔS0 (−270.0 J mol–1 K–1), and ΔG0 (+ 91.3 to + 98.0 kJ mol–1) indicated the exothermic, endergonic and non-spontaneous nature of the catalytic redox reaction. In addition to facilitating easy recovery, rinsing, and reuse, restraining the Pd@Polym-MNS in the basket reactor helped maintain the integrity of the catalysts by preventing violent collisions of suspended granules with the mixing apparatus and the walls of the reaction vessel. Whereas the pseudo-first-order rate constant was recorded as 0.157 min–1 upon initial use, values of the mean and relative standard deviation for the second, third and fourth consecutive uses were found to be 0.219 min–1 and 1.3%, respectively. According to a response surface methodological approach to batch experimentation, the initial concentration of chromium(VI) and catalyst dosage had the greatest impact on the redox reaction rate, accounting for 85.7% and 11.6% of the variability in the value of the pseudo-first-order rate constant, respectively. Mutually beneficial effects of the combinations of high formic acid and low chromium(VI) concentration, high temperature and catalyst dosage as well as high formic acid and catalyst dosage were recorded.

scholarly journals Kinetics Mechanism and Thermodynamic Study of the Oxidation of Iodide Ion by Dichromate Ion in Acidic Medium

2020 ◽  
Vol 24 (5) ◽  
pp. 821-826
Author(s):  
B.E. Nyong ◽  
F.E. Abeng ◽  
O.A. Ushie ◽  
B.J. Bassey ◽  
M.M. Edim
Keyword(s):  
Ionic Strength ◽  
Thermodynamic Parameters ◽  
Redox Reaction ◽  
Acidic Medium ◽  
Kinetic Mechanism ◽  
Thermodynamic Study ◽  
Ion Concentration ◽  
Effect Of Temperature ◽  
Hydrogen Ion Concentration ◽  
Iodide Ion

This work introduces a newly developed kinetic mechanism and thermodynamic study that gives a clear theoretical insight between the iodine and chromium in acid solution. The paper mainly focuses on evaluating kinetic mechanism and thermodynamic properties of the oxidation of iodide by dichromate ion in acidic medium. This study was investigated using iodometric method. The rate has been studied by appropriate choice of concentrated conditions at constant temperature and ionic strength. The kinetic studies revealed half order reaction with respect to dichromate ion, first order for iodide ion and second order for hydrogen ion concentration. The dependence of reaction rate on the temperature was monitored in order to generate some thermodynamic parameters, which can be used in predicting the direction and spontaneity of the reaction. The thermodynamic studies of this reaction revealed negative values for ΔG, ΔS and positive values for ΔH which is an indication that the reaction wasspontaneous and endothermic. The oxidant chromium (vi) exist in acidic media as H2CrO4. The effect of ionic strength on the rate of redox reaction was investigated. The ionic strength was adjusted by varying the concentration of the nitrate to maximum. The effect of temperature was also studied to evaluate the thermodynamic parameters. Transition metals should be use as catalyst for future purpose to monitor the rate of redox reaction. The techniques employed on this research are very useful in determining the rate of a redox reaction. Keywords: Kinetic, thermodynamic, oxidation, iodometric method

Development of Sustained Release Multi-Component Microparticulate System of Diclofenac Sodium and Tizanidine Hydrochloride

1970 ◽  
Vol 1 (1) ◽  
pp. 97-105
Author(s):  
Kamlesh Dashora ◽  
Shailendra Saraf ◽  
Swarnalata Saraf
Keyword(s):  
Particle Size ◽  
Sustained Release ◽  
Cellulose Acetate ◽  
Rate Constant ◽  
Diclofenac Sodium ◽  
Order Rate Constant ◽  
Anomalous Transport ◽  
First Order ◽  
Sem Study ◽  
Transport Type

Sustained released tablets of diclofenac sodium (DIC) and tizanidine hydrochloride (TIZ) were prepared by using different proportions of cellulose acetate (CA) as the retardant material. Nine formulations of tablets having different proportion of microparticles developed by varied proportions of polymer: drug ratio ‘’i.e.’’; 1:9 -1:3 for DIC and 1:1 – 3:1 for TIZ. Each tablet contained equivalent to 100 mg of DIC and 6mg of TIZ. The prepared microparticles were white, free flowing and spherical in shape (SEM study), with  the particle size varying from 78.8±1.94 to 103.33±1.28 µm and 175.92± 9.82 to 194.94±14.28µm for DIC  and TIZ, respectively.  The first order rate constant K1 of formulations were found to be in the range of  K1 = 0.117-0.272 and 0.083- 0.189 %hr-1for DIC and TIZ, respectively. The value of exponent coefficient (n) was found to be in the range of 0.6328-0.9412  and 0.8589-1.1954 for DIC and TIZ respectively indicates anomalous  to  non anomalous transport type of diffusions among different formulations

Kinetics of hydrolysis of peroxodisulphate ions in acidic medium to peroxomonosulphuric acid

1981 ◽  
Vol 46 (5) ◽  
pp. 1229-1236 ◽  
Author(s):  
Jan Balej ◽  
Milada Thumová
Keyword(s):  
Ionic Strength ◽  
Rate Constants ◽  
Acidic Medium ◽  
Measured Data ◽  
Molar Ratios ◽  
Starting Solution ◽  
Kinetics Of Hydrolysis ◽  
Rate Of Hydrolysis ◽  
Kinetics Of ◽  
Hydrolysis Of

The rate of hydrolysis of S2O82- ions in acidic medium to peroxomonosulphuric acid was measured at 20 and 30 °C. The composition of the starting solution corresponded to the anolyte flowing out from an electrolyser for production of this acid or its ammonium salt at various degrees of conversion and starting molar ratios of sulphuric acid to ammonium sulphate. The measured data served to calculate the rate constants at both temperatures on the basis of the earlier proposed mechanism of the hydrolysis, and their dependence on the ionic strength was studied.

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