A capillary electrophoretic determination of the kinetics of tetradecanedisulfate hydrolysis

1999 ◽  
Vol 77 (2) ◽  
pp. 227-231 ◽  
Author(s):  
Richard A Walker ◽  
D Gerrard Marangoni ◽  
Truis Smith-Palmer
Keyword(s):  
Activation Energy ◽  
Capillary Electrophoresis ◽  
Sulfuric Acid ◽  
Acid Solution ◽  
Acid Hydrolysis ◽  
First Order ◽  
Entropy Of Activation ◽  
Capillary Electrophoretic ◽  
Kinetics Of

Capillary electrophoresis was used to follow the decrease in concentration of tetradecanedisulfate as a function of time during its hydrolysis in 0.5 M sulfuric acid solution at 60, 75, and 90°C. The hydrolyses were mostly carried out at premicellar concentrations of surfactant, from 1 to 7.5 mM. Large increases of rate occurred at higher concentrations (at least 15 mM). The reaction was found to be first order in tetradecanedisulfate. The activation energy and entropy of activation were calculated to be 97 kJ mol-1 and -55 J K-1 mol-1, respectively.Key words: capillary electrophoresis, surfactant, acid hydrolysis, tetradecanedisulfate, activation energy, entropy of activation.

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 STUDIES ON THE PERVANADIUM COMPLEX

1961 ◽  
Vol 39 (6) ◽  
pp. 1174-1183 ◽  
Author(s):  
G. A. Dean
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Acid Solution ◽  
Anionic Complex ◽  
Cationic Complex ◽  
Kcal Mole ◽  
Decomposition Products ◽  
First Order ◽  
Discrete Variations ◽  
Kinetics Of

The 'pervanadium complex' is investigated in a general manner. The kinetics of its thermal decomposition in acid solution are shown to be first order with respect to pervanadium, the apparent activation energy is 26.5 ± 1.0 kcal/mole, and possible mechanisms are suggested. The effect of various acids upon the nature of the decomposition products is determined: almost quantitative yields of vanadium (V) or vanadium (IV) are obtained in very dilute or concentrated acid, respectively. Spectrophotometric studies indicate that in acid solution two separate complexes exist: a red (1:1) cationic complex and a yellow (1:2) anionic complex. The stoichiometry of the equilibrium between the two complexes in solutions of sulphuric acid is investigated by a method of 'discrete variations'. The equilibrium could be described by[Formula: see text]where Kr/y = 2.2 ± 0.2 at 22 °C. The anion is shown to play an important part in determining the nature of the pervanadium complex.

Vulcanization of Elastomers. 23. The Chemical Kinetics of Vulcanization Reactions and The Physical Properties of The Vulcanizates. I

1960 ◽  
Vol 33 (2) ◽  
pp. 335-341
Author(s):  
Walter Scheele ◽  
Karl-Heinz Hillmer
Keyword(s):  
Activation Energy ◽  
Physical Properties ◽  
Chemical Kinetics ◽  
Kcal Mole ◽  
First Order ◽  
Equilibrium Swelling ◽  
Kinetics Of ◽  
Kinetics Of Vulcanization ◽  
Limiting Value ◽  
Good Agreement

Abstract As a complement to earlier investigations, and in order to examine more closely the connection between the chemical kinetics and the changes with vulcanization time of the physical properties in the case of vulcanization reactions, we used thiuram vulcanizations as an example, and concerned ourselves with the dependence of stress values (moduli) at different degrees of elongation and different vulcanization temperatures. We found: 1. Stress values attain a limiting value, dependent on the degree of elongation, but independent of the vulcanization temperature at constant elongation. 2. The rise in stress values with the vulcanization time is characterized by an initial delay, which, however, is practically nonexistent at higher temperatures. 3. The kinetics of the increase in stress values with vulcanization time are both qualitatively and quantitatively in accord with the dependence of the reciprocal equilibrium swelling on the vulcanization time; both processes, after a retardation, go according to the first order law and at the same rate. 4. From the temperature dependence of the rate constants of reciprocal equilibrium swelling, as well as of the increase in stress, an activation energy of 22 kcal/mole can be calculated, in good agreement with the activation energy of dithiocarbamate formation in thiuram vulcanizations.

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.

scholarly journals Improvement of recovered activity and stability of the Aspergillus oryzae β-galactosidase immobilized on duolite A568 by combination of immobilization methods

2017 ◽  
Vol 23 (4) ◽  
pp. 495-506 ◽  
Author(s):  
Larissa Falleiros ◽  
Bruna Cabral ◽  
Janaína Fischer ◽  
Carla Guidini ◽  
Vicelma Cardoso ◽  
...  
Keyword(s):  
Activation Energy ◽  
Aspergillus Oryzae ◽  
Physical Adsorption ◽  
Cross Linking ◽  
Thermal Deactivation ◽  
Order Model ◽  
First Order ◽  
Immobilized Biocatalyst ◽  
The Stability ◽  
Kinetics Of

The immobilization and stabilization of Aspergillus oryzae ?-galactosidase on Duolite??A568 was achieved using a combination of physical adsorption, incubation step in buffer at pH 9.0 and cross-linking with glutaraldehyde and in this sequence promoted a 44% increase in enzymatic activity as compared with the biocatalyst obtained after a two-step immobilization process (adsorption and cross-linking). The stability of the biocatalyst obtained by three-step immobilization process (adsorption, incubation in buffer at pH 9.0 and cross-linking) was higher than that obtained by two-steps (adsorption and cross-linking) and for free enzyme in relation to pH, storage and reusability. The immobilized biocatalyst was characterized with respect to thermal stability in the range 55-65 ?C. The kinetics of thermal deactivation was well described by the first-order model, which resulted in the immobilized biocatalyst activation energy of thermal deactivation of 71.03 kcal/mol and 5.48 h half-life at 55.0 ?C.

Analysis of Synthetic Antioxidant in Food by Capillary Electrophoresis

2011 ◽  
Vol 361-363 ◽  
pp. 1855-1858 ◽  
Author(s):  
Qian Xiang ◽  
Ying Gao
Keyword(s):  
Capillary Electrophoresis ◽  
Amperometric Detection ◽  
Peak Height ◽  
Butylated Hydroxyanisole ◽  
Applied Potential ◽  
Synthetic Antioxidant ◽  
Separation Potential ◽  
Relative Standard ◽  
Capillary Electrophoretic

A capillary electrophoretic assay for determining synthetic antioxidant butylated hydroxyanisole in food has been developed. The extraction with 70% (v/v) methanol quantitatively extracted synthetic antioxidant. The separation was carried out by CZE using phosphate at a separation potential of 18 kV. Amperometric detection was achieved with an applied potential of 0.60 V. A linear relationship between the peak height and the concentration of the analyte was found in the range 1.8-180 µg/mL for BHA, with correlation coefficient of 0.994. The relative standard deviations of migration time and peak height were 0.19 and 5.3 %, respectively. The method developed was successfully applied for the determination of synthetic antioxidant butylated hydroxyanisole in food. Recovery of butylated hydroxyanisole was 93%.

Kinetics of the Reaction Between S2O3-- and I3- in Aqueous Solution

1974 ◽  
Vol 29 (1) ◽  
pp. 141-144
Author(s):  
T. S. Rao ◽  
S. I. Mali
Keyword(s):  
Aqueous Solution ◽  
Reduction Potential ◽  
Frequency Factor ◽  
Effective Concentration ◽  
Specific Rate ◽  
Platinum Foil ◽  
First Order ◽  
Entropy Of Activation ◽  
Kinetics Of ◽  
Foil Electrode

The kinetics of the reaction between has been studied under conditions of production of iodine at a known rate by the persulfate-iodide reaction and its consumption by S2O3-- . The effective concentration of iodine during the steady state is measured from its reduction potential at a bright platinum foil electrode. The reaction is of first order with respect to I3- and S2O3-- individually and hence of over all second order. The specific rate is 1.51 X 105 M -1 sec-1 and the frequency factor is 1.69 × 1012 M -1 sec-1 at 25 °C. The energy of activation for the reaction is 9.58 × 103 cal/mole and the entropy of activation is -2.55 cal/mole deg.

Kinetics and Activation Parameters for the Alkaline Aqueous Rearrangement of Trichorfon [O,O-Dimethyl-(2,2,2-Trichloro-1-Hydroxyethyl) Phosphonate] to Dichlorvos [O,O-Dimethyl-O-(2,2-Dichloroethenyl)Phosphate]

2001 ◽  
Vol 36 (3) ◽  
pp. 589-604 ◽  
Author(s):  
Julian M. Dust ◽  
Christopher S. Warren
Keyword(s):  
Activation Energy ◽  
High Pressure ◽  
Activation Parameters ◽  
Base Catalysis ◽  
Rearrangement Product ◽  
Exponential Factor ◽  
First Order ◽  
Pseudo First Order ◽  
Order Plot ◽  
Kinetics Of

Abstract The kinetics of the alkaline rearrangement of O,O-dimethyl-(2,2,2-trichloro-1- hydroxyethyl)phosphonate, (trichlorfon, 1), the active insecticidal component in such formulations as Dylox, was followed at 25±0.5°C by high pressure liquid chromatography (UV-vis detector, 210 nm). The rearrangement product, O,Odimethyl- O-(2,2-dichloroethenyl)phosphate (dichlorovos, 2), which is a more potent biocide than trichlorfon, undergoes further reaction, and the kinetics, consequently, cannot be treated by a standard pseudo-first-order plot. A two-point van't Hoff (initial rates) method was used to obtain pseudo-first-order rate constants (kѱ) at 25, 35 and 45°C: 2.6 × 10-6, 7.4 × 10-6 and 2.5 × 10-5 s-1, respectively. Arrhenius treatment of this data gave an activation energy (Ea) of 88 kJ·mol-1 with a pre-exponential factor (A) of 5.5 × 109 s-1. Kinetic trials at pH 8.0 using phosphate and tris buffer systems show no buffer catalysis in this reaction and indicate that the rearrangement is subject to specific base catalysis. Estimates are reported for pseudo-first-order half-lives for trichlorfon at pH 8.0 for environmental conditions in aqueous systems in the Corner Brook region of western Newfoundland, part of the site of a recent trichlorfon aerial spray program.

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