Kinetics and mechanism of the thermal decomposition of the thiosulphatopentaamminecobalt(III) ion in dilute aqueous acid

1986 ◽  
Vol 64 (2) ◽  
pp. 311-313
Author(s):  
Anthony Martin Newton
Keyword(s):  
Thermal Decomposition ◽  
Acetic Acid ◽  
Sodium Acetate ◽  
Major Product ◽  
Order Kinetic ◽  
Sodium Acetate Buffer ◽  
Reaction Products ◽  
First Order ◽  
Aqueous Acid ◽  
Reactive Complex

In acetic acid – sodium acetate buffer of pH 5.6 (25 °C) the Co(NH3)5S2O3+ ion undergoes redox decomposition rather than aquation. First-order kinetic are observed and the reaction products Co2+, NH3, and S4O62− are due to internal reduction of Co(III) by coordinated S2O32−. In dilute perchloric acid of pH < 4 the rate is retarded, first-order plots are not linear, and S4O62− is not a major product of the reaction. It is proposed that, in dilute HClO4, protonation of Co(NH3)5S2O3+ depletes the concentration of the reactive complex and that decomposition of coordinated HS2O3− occurs. Conversion of O-bonded S2O32− to S-bonded S2O32− in the reactive complex is also considered.

Thermal processing of sewage sludge by drying, pyrolysis, gasification and combustion

2001 ◽  
Vol 44 (10) ◽  
pp. 333-339 ◽  
Author(s):  
P. Stolarek ◽  
S. Ledakowicz
Keyword(s):  
Thermal Decomposition ◽  
Sewage Sludge ◽  
Kinetic Parameters ◽  
Thermal Processing ◽  
Combustion Process ◽  
Order Kinetic ◽  
Municipal Sludge ◽  
Pyrolysis Kinetics ◽  
Exponential Factor ◽  
First Order

Thermal processing of sewage sludge including drying, pyrolysis and gasification or combustion may be an alternative to other ways of utilising it. In this paper thermogravimetric analysis (TGA) was employed in the investigation of thermal decomposition of sewage sludge. The kinetic parameters of drying, pyrolysis and gasification or combustion of sewage sludge have been determined in an inert-gas (argon) and additionally some series of the sludge decomposition experiments have been carried out in air, in order to compare pyrolysis and combustion. The pyrolysis char has been gasified with carbon dioxide. A typical approach to the kinetics of thermal decomposition of a solid waste is to divide the volatile evolution into a few fractions (lumps), each of which is represented by a single first-order reaction. If these lumps are assumed to be non-interacting and evolved by independent parallel reactions the first-order kinetic parameters such as activation energy Ei and pre-exponential factor Ai can be determined from mathematical evaluation of TG or DTG curves. The object of our investigations was a municipal sludge from the two wastewater treatment plants (WTP) in Poland. The experiments have been carried out in the thermobalance Mettler-Toledo type TGA/SDTA851 LF, in the temperature range 30-1,000°C. Five different values of heating rate have been applied β = 2, 5, 10, 15 and 20 K/min. The values of Ei and Ai have been determined for all recognised lumps of gaseous products. The method employed has also revealed its usefulness for the determination of kinetic parameters for municipal sludge, that possess an undefined content. An alternative route to combustion of sewage sludge is its gasification, which significantly increases the gaseous product (pyrolytic gas + syngas). Besides pyrolysis kinetics, gasification or combustion process kinetics have also been determined.

The thermal decomposition of t-butyl methyl ether

1968 ◽  
Vol 21 (11) ◽  
pp. 2711 ◽  
Author(s):  
NJ Daly ◽  
C Wentrup
Keyword(s):  
Thermal Decomposition ◽  
Methyl Ether ◽  
Arrhenius Equation ◽  
Reaction Products ◽  
First Order ◽  
Comparison Of The Results ◽  
Butyl Methyl Ether ◽  
Kinetic Form

The rates of the thermal decomposition of t-butyl methyl ether have been measured in the range 433-495�. The reaction products are isobutene and methanol, and the kinetic form is first order. The Arrhenius equation K1 = 1014.38exp(-61535/RT) sec-1 describes the variation of rate with temperature. The reaction behaviour is consistent with a unimolecular mechanism. Comparison of the results with those obtained for the production of isobutene from various t-butyl compounds indicates that the reaction has some degree of heterolytic character.

The Thermal Decomposition of Boron Trimethyl

1962 ◽  
Vol 15 (4) ◽  
pp. 744 ◽  
Author(s):  
AS Buchanan ◽  
F Creutzberg
Keyword(s):  
Thermal Decomposition ◽  
Activation Energies ◽  
Major Product ◽  
Main Reaction ◽  
Static System ◽  
Hydrogen Formation ◽  
First Order ◽  
Rate Expression

The thermal decomposition of boron trimethyl has been studied in a static system in the range 468-513 �C and was found to be first order with a rate expression������������� k1=1.2 x 1012e-[56 000/RT] sec-1. The activation energies for methane and hydrogen formation were found to be 76 and 75 kcal, respectively. The stoicheiometry for the main reaction was found to be ���������������� 2B(CH3)3 → 2CH4 + H2 + [B(CH2)2]2. Preliminary experiments on the photolysis of boron trimethyl indicated that methane was the major product.

scholarly journals Simultaneous Spectrophotometric Determination of Chromium(VI) and Vanadium(V) by using 3,4-Dihydroxybenzaldehyde isonicotinoyl hydrazone (3,4-DHBINH)

2009 ◽  
Vol 6 (s1) ◽  
pp. S459-S465 ◽  
Author(s):  
Lakshmi Narayana ◽  
Suvarapu ◽  
Adinarayana Reddy Somala ◽  
Prathima Bobbala ◽  
Hwang Inseong ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Metal Ions ◽  
Sodium Acetate ◽  
Atomic Absorption Spectrophotometry ◽  
Photometric Method ◽  
Sodium Acetate Buffer ◽  
Absorption Spectrophotometry ◽  
Chromium Vi ◽  
Highly Sensitive

A simple, rapid, highly sensitive and new simultaneous spectro- photometric method is proposed for the analysis of chromium(VI) and vanadium(V) without separation by using 3,4-dihydroxybeznaldehyde isonicotinoyl hydrazone (3,4-DHBINH). The reagent reacts with the two metal ions in acetic acid-sodium acetate buffer of pH 5.5 and gives maximum absorbances at 400 nm and 360 nm for chromium(VI) and vanadium(V), respectively. Both the metal ions gives 1: 1 (M:L) complexes with the reagent. Effect of various diverse ions also studied. The instability constants for the two complexes were also evaluated. This method was successfully applied for the determination of chromium(VI) and vanadium(V) in various spiked samples. The validity of the method was checked by comparing with the results obtained by atomic absorption spectrophotometry.

The thermal decomposition of diethyl ether. III. The action of inhibitors and the mechanism of the reaction

1958 ◽  
Vol 245 (1240) ◽  
pp. 49-67 ◽  
Keyword(s):  
Nitric Oxide ◽  
Thermal Decomposition ◽  
Diethyl Ether ◽  
Rate Constant ◽  
Initial Pressure ◽  
Direct Analysis ◽  
Reaction Products ◽  
First Order ◽  
Molecular Decomposition ◽  
Induced Reaction

Small quantities of nitric oxide reduce the rate of thermal decomposition of diethyl ether at 525 °C to about one-quarter. Much larger amounts accelerate the decomposition, but the concentration ranges in which the ‘ maximally inhibited ’ reaction and the ‘ nitric-oxide-induced’ reaction can be studied are so widely separated that these reactions can be treated as two distinct entities. The ‘uninhibited’ reaction constitutes a third. Reaction products and kinetics are recorded for all three, and nitric oxide consumption is measured for the first two. In all three the major products are the same, with secondary differences which are discussed. In the presence of nitric oxide small amounts of cyanides and other compounds are formed. In the nitric-oxide-induced reaction 1.4 molecules of ether are decomposed for each molecule of nitric oxide used up: in the maximally inhibited reaction the ratio, which is dependent on the ether pressure, is very much greater. The rate of the maximally inhibited reaction is independent of the concentration of nitric oxide, or of propylene, and the same for the two inhibitors (as is now proved by direct analysis). The first-order rate constant varies with the initial pressure of ether according to the equation k inhib. = ( A [ether])/(1 + B [ether]) + C [ether]. The rate constant of the uninhibited reaction varies with ether pressure according to an expression which, although probably of different algebraical form, is empirically similar to the above over a considerable range. The nitric-oxide-induced reaction is nearly of the first order with respect both to ether pressure and to nitric oxide pressure. The maximally inhibited reaction is shown to be most probably a molecular decomposition of the ether. The uninhibited reaction is predominantly a chain reaction, the mechanism of which is discussed. The nitric-oxide-induced reaction, it is suggested on the basis of the experimental evidence, is largely initiated by a generation of radicals in an attack of nitric oxide on ether. It is possibly also in part a molecular decomposition of ether caused by collision with nitric oxide.

Real-Time Monitoring of Hydrogen Elimination Processes in Pulsed-Gas PECVD Using in Situ Mass Spectroscopy

1996 ◽  
Vol 452 ◽  
Author(s):  
Easwar Srinivasan ◽  
Jeremy S. Bordeaux ◽  
Gregory N. Parsons
Keyword(s):  
Mass Spectroscopy ◽  
Order Kinetic ◽  
Elimination Reaction ◽  
Reaction Products ◽  
First Order ◽  
Thermally Activated ◽  
Hydrogen Elimination ◽  
Abstraction Reaction ◽  
Elimination Mechanism

AbstractIn situ mass spectroscopy is used to monitor and analyze the hydrogen elimination reaction products during cyclical exposure of thin films of amorphous silicon to a flux of atomic deuterium. Mass spectroscopy results that atomic deuterium etches deposited silicon forming SiD4 and abstracts hydrogen bonded to silicon in the film to form HD. The relative signal intensities show that abstraction is the primary hydrogen elimination mechanism. The energy of activation for the abstraction reaction is obtained from the mass spectroscopy signals through a first order kinetic analysis and is found to be approximately zero, indicating that abstraction is not thermally activated.

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