Evolution of Hydrogen Sulfide from Vulcanized Rubber

1930 ◽  
Vol 3 (3) ◽  
pp. 386-396
Author(s):  
Edward Wolesensky
Keyword(s):  
Thermal Decomposition ◽  
Hydrogen Sulfide ◽  
Sulfur Compound ◽  
Rate Of Evolution ◽  
Vulcanized Rubber ◽  
A Minor ◽  
Temperature Time

Abstract The rubber-sulfur compound in vulcanized rubber splits off hydrogen sulfide at all times and at all temperatures between 25° C. and the temperature of complete thermal decomposition. The rate of evolution of the gas depends upon the temperature, time, the proportion of combined sulfur, and possibly other factors. The reaction affords a new explanation of the formation of hydrogen sulfide during vulcanization, and possibly also, in part at least, of the excess of combined sulfur over that required by the formula C5H8S. It may also be another factor in aging, though, perhaps, only a minor one, and presents a new problem in the regeneration of rubber.

Pyrolysis of ethane in the presence of hydrogen sulfide. Rates of formation of ethylene, hydrogen, and methane

1970 ◽  
Vol 48 (11) ◽  
pp. 1782-1785 ◽  
Author(s):  
P. R. McLean ◽  
D. J. McKenney
Keyword(s):  
Thermal Decomposition ◽  
Hydrogen Sulfide ◽  
Quantitative Data ◽  
Methane Formation ◽  
Partial Product ◽  
Complex Mechanism ◽  
Product Analysis ◽  
Hydrogen Formation

Rates of formation of ethylene, hydrogen, and methane have been measured at 630 °C for the thermal decomposition of ethane at pressures between 100 and 620 Torr, with various pressures (approximately 1 to 100 Torr) of added hydrogen sulfide. The effect of the H2S was to increase the rate of methane formation and to decrease the rate of ethylene and hydrogen formation. Rates of formation of all three of these gases decreased with increasing hydrogen sulfide pressures. The quantitative data obtained and the partial product analysis indicate that a complex mechanism is operative. Possible qualitative explanations for the observations are discussed.

scholarly journals Hydrothermal Synthesis of Hematite Nanoparticles Decorated on Carbon Mesospheres and Their Synergetic Action on the Thermal Decomposition of Nitrocellulose

Nanomaterials ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 968 ◽  
Author(s):  
Abdenacer Benhammada ◽  
Djalal Trache ◽  
Mohamed Kesraoui ◽  
Salim Chelouche
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Analytical Techniques ◽  
Decomposition Reaction ◽  
Decomposition Temperature ◽  
Heating Rates ◽  
Scanning Calorimetry ◽  
Nano Catalyst ◽  
Average Size ◽  
A Minor

In this study, carbon mesospheres (CMS) and iron oxide nanoparticles decorated on carbon mesospheres (Fe2O3-CMS) were effectively synthesized by a direct and simple hydrothermal approach. α-Fe2O3 nanoparticles have been successfully dispersed in situ on a CMS surface. The nanoparticles obtained have been characterized by employing different analytical techniques encompassing Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The produced carbon mesospheres, mostly spherical in shape, exhibited an average size of 334.5 nm, whereas that of Fe2O3 supported on CMS is at around 80 nm. The catalytic effect of the nanocatalyst on the thermal behavior of cellulose nitrate (NC) was investigated by utilizing differential scanning calorimetry (DSC). The determination of kinetic parameters has been carried out using four isoconversional kinetic methods based on DSC data obtained at various heating rates. It is demonstrated that Fe2O3-CMS have a minor influence on the decomposition temperature of NC, while a noticeable diminution of the activation energy is acquired. In contrast, pure CMS have a slight stabilizing effect with an increase of apparent activation energy. Furthermore, the decomposition reaction mechanism of NC is affected by the introduction of the nano-catalyst. Lastly, we can infer that Fe2O3-CMS may be securely employed as an effective catalyst for the thermal decomposition of NC.

THE KINETICS OF THE THERMAL DECOMPOSITION OF VINYL ISOPROPYL ETHER

1953 ◽  
Vol 31 (4) ◽  
pp. 418-421 ◽  
Author(s):  
Arthur T. Blades
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Free Radical ◽  
Ethyl Ether ◽  
Close Agreement ◽  
Flow System ◽  
Isopropyl Ether ◽  
Radical Decomposition ◽  
A Minor ◽  
Kinetics Of

The thermal decomposition of vinyl isopropyl ether in the presence of toluene has been studied in a flow system in the temperature range 447–521 °C. In this range, the data indicate a purely intramolecular decomposition into propylene and acetaldehyde, the activation energy for the reaction being in close agreement with that found for the decomposition of vinyl ethyl ether. At 570 °C. a minor free radical decomposition of the ether becomes apparent. Some qualitative studies of the decomposition of vinyl isobutyl ether are also reported.

The Compressibility of Rubber

1930 ◽  
Vol 3 (4) ◽  
pp. 555-562 ◽  
Author(s):  
L. H. Adams ◽  
R. E. Gibson
Keyword(s):  
High Pressures ◽  
Sulfur Compound ◽  
Reliable Estimate ◽  
Total Sulfur ◽  
Tetramethylthiuram Disulfide ◽  
Three Samples ◽  
Inorganic Fillers ◽  
A Minor ◽  
Low Pressures ◽  
Minor Correction

Abstract Although many of the elastic properties of rubber have been investigated with very interesting results, no measurements have been made, so far as we know, of its cubic compressibility at high pressures. Those measurements which have been made at low pressures yield results varying from 93×10−6 obtained by Clapeyron to an estimate of the order of the compressibility of bronze (about 1×10−6) given by Amagat. As the compressibility of rubber enters as a minor correction into most compressibility measurements at high pressures, it is very desirable to have a reliable estimate of its value. In this communication we propose to give the results of experimental determinations of the compressibility at 25° of three samples of rubber which were furnished to us by H. L. Curtis and A. H. Scott of the U. S. Bureau of Standards. The samples are described as follows: Sample A.—Hard rubber from panel made by the Goodrich Company. It is a rubber-sulfur compound containing no inorganic fillers. The total sulfur amounts to 27.4 per cent, of which 0.21 per cent, is free sulfur. The density is 1.149 at 27° C. Sample B.—A rubber-sulfur compound containing 90 per cent. smoked rubber and 10 per cent. sulfur and vulcanized 105 minutes at 300° F. Density = 0.990 at 25°. Sample C consists of pale crepe rubber 90.75 per cent., zinc oxide 5 per cent., sulfur 4 per cent., tetramethylthiuram disulfide 0.25 per cent. It was vulcanized for 30 minutes at 260° F. Density = 0.990 at 27°.

Kinetics and Mechanism of the Thermal Decomposition of Hexaamminecobalt(III) and Aquopentaamminecobalt(III) Ions in Acidic Aqueous Solution

1974 ◽  
Vol 52 (15) ◽  
pp. 2751-2759 ◽  
Author(s):  
Anthony Martin Newton ◽  
Thomas Wilson Swaddle
Keyword(s):  
Aqueous Solution ◽  
Thermal Decomposition ◽  
Rate Coefficient ◽  
Initial Step ◽  
Hydrogen Ion ◽  
Minor Amount ◽  
Acidic Aqueous Solution ◽  
First Order ◽  
Independent Path ◽  
A Minor

The initial step in the thermal decomposition of Co(NH3)63+ in acidic aqueous solution is the replacement of NH3 by H2O, which occurs by a hydrogen-ion independent path, first order in complex, with rate coefficient k1 = 7.9 × 10−5 s−1 (140.4°), ΔH* = 36.6 kcal mol−1 and ΔS* = 10.7 cal deg−1 mol−1 in 0.1 M HClO4. For Co(NH3)5OH23+, there is a similar initial aquation path with k1 = 12.6 × 10−5 s−1 (140.6°), ΔH* = 41.9 kcal mol−1 and ΔS* = 24 cal deg−1 mol−1 and also a path first order in complex but inverse first order in [H+] with k2′ = 6.2 × 10−1 M s−1 (140.6°), ΔH* = 43.5 kcal mol−1 and ΔS* = 26.7 cal deg−1 mol−1 in perchlorate media of ionic strength 1.0 M. The effects of electrolyte type and concentration on the rates of these reactions have been examined. Subsequent aquation steps are relatively rapid because of the predominance of inversely [H+]-dependent pathways and are followed by redox to Co(H2O)62+, NH4+, N2, N2O, and a minor amount of O2. A mechanism involving OH and NH2 radicals is proposed for the redox step.

Experiments on the Causes of the Deterioration of Ebonite when Exposed to Light and Air

1930 ◽  
Vol 3 (4) ◽  
pp. 618-625
Author(s):  
D. M. Webster ◽  
B. D. Porritt
Keyword(s):  
Heat Treatment ◽  
Hydrogen Sulfide ◽  
Experimental Error ◽  
Surface Film ◽  
Rate Of Evolution ◽  
Long Period ◽  
Volatile Organic ◽  
Oxidation Of Hydrogen ◽  
Increasing Temperature ◽  
Free Sulfur

Abstract (1) The surface film of a sample of ebonite—containing no “free” sulfur—has been shown to develop distinct traces of sulfurous and sulfuric acid after exposure to light in a moist atmosphere for a period of four weeks. (2) The above acids appear to result from the oxidation of hydrogen sulfide formed through the decomposition of the hydrocarbon-sulfur nucleus of the ebonite. (3) The rate of evolution of hydrogen sulfide from ebonite when heated in an atmosphere of hydrogen has been investigated for temperatures ranging from 180° to 250° C., and for three different samples of ebonite. (4) For a given temperature the rate of evolution is rapid at first, but falls off quickly and finally remains uniform over a long period, the latter portion of the time-H2S curve being linear within the limits of experimental error. (5) The rate of evolution increases with increasing temperature. (6) Under the heat treatment the ebonite changes in color, becoming reddish in appearance. At the same time it becomes unsaturated and more and more soluble in acetone and carbon disulfide. (7) The decomposition which takes place on heating ebonite to temperatures not exceeding 250° C. does not appear to give rise to appreciable amounts of either free sulfur or volatile organic compounds. (8) The bearing of the above results on the problem of the electrical deterioration of ebonite has been discussed.

The Determination of Free Sulfur in Soft Vulcanized Rubber by a Volumetric Method

1932 ◽  
Vol 5 (3) ◽  
pp. 360-362 ◽  
Author(s):  
W. D. Guppy
Keyword(s):  
Hydrogen Sulfide ◽  
Sulfuric Acid ◽  
Organic Compounds ◽  
Subsequent Oxidation ◽  
Vulcanized Rubber ◽  
Elementary State ◽  
Previously Treated ◽  
Mineral Sulfides ◽  
Free Sulfur

Abstract The methods so far proposed for the determination of the free sulfur in vulcanized rubber depend upon the removal of the sulfur by extraction of the rubber with hot acetone, and subsequent oxidation to sulfuric acid of the sulfur in the extract. The extract is liable however to contain, in addition to sulfur in the elementary state, organic compounds containing sulfur derived from the rubber resins, accelerator, or antioxidant. In the subsequent oxidation this sulfur will be oxidized to sulfuric acid to an extent which depends on the method of oxidation used. In the present work, a method of analysis has been developed which is more rapid than the existing methods, and in which it is considered that the determination of the sulfur present in the elementary state is less likely to be affected by organic compounds containing sulfur. It has been found that when vulcanized rubber placed in contact with a metal, such as tin or aluminum, is boiled in hydrochloric acid, hydrogen sulfide is generated by the action of the nascent hydrogen produced. This reaction occurred with rubber which had been previously treated with acid alone to decompose metallic sulfides, but no hydrogen sulfide was obtained from rubber which had been previously extracted with acetone and was free from metallic sulfides. As these results showed that the reactions were not due to the presence of mineral sulfides, or of sulfur combined with the rubber, it was concluded that the hydrogen sulfide was formed by the reduction of the free sulfur.

Applying a most probable number method for enumerating planktonic, dissimilatory, ammonium-producing, nitrate-reducing bacteria in oil field waters

2005 ◽  
Vol 51 (8) ◽  
pp. 725-729 ◽  
Author(s):  
Ruth E Eckford ◽  
Phillip M Fedorak
Keyword(s):  
Hydrogen Sulfide ◽  
Water Samples ◽  
Oil Field ◽  
Most Probable Number ◽  
Minor Role ◽  
Probable Number ◽  
A Minor ◽  
Reducing Bacteria ◽  
Nitrate Reducing Bacteria ◽  
Oil Field Water

A most probable number (MPN) method was used to enumerate dissimilatory ammonium-producing, nitrate-reducing bacteria (DAP-NRB) in oil field waters and to determine whether they were stimulated by nitrate addition used to control hydrogen sulfide production. An ammonium production medium with 5 carbon and energy sources (acetate, glucose, glycerol, pyruvate, and succinate) and nitrate was used in a 3-tube MPN procedure to enumerate DAP-NRB. These bacteria were detected in 12 of 18 oil field water samples, but they were seldom detected in wellhead samples. Three oil field water samples were amended with nitrate in serum bottles and the numbers of different NRB were determined over a 38-day incubation time. This amendment stimulated increases in the numbers of heterotrophic NRB and autotrophic nitrate-reducing, sulfide-oxidizing bacteria, but DAP-NRB remained a minor portion of these communities. Overall, DAP-NRB were present in many of the oil field waters that were examined but their numbers were low. It appears that DAP-NRB would play a minor role in the consumption of nitrate injected into oil field waters for the control of hydrogen sulfide production.Key words: heterotroph, nitrate-reducing bacteria, dissimilatory nitrate reduction, ammonium, petroleum.

scholarly journals A Clinically Relevant Variant of the Human Hydrogen Sulfide-Synthesizing Enzyme Cystathionineβ-Synthase: Increased CO Reactivity as a Novel Molecular Mechanism of Pathogenicity?

2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
João B. Vicente ◽  
Henrique G. Colaço ◽  
Francesca Malagrinò ◽  
Paulo E. Santo ◽  
André Gutierres ◽  
...  
Keyword(s):  
Hydrogen Sulfide ◽  
Redox Homeostasis ◽  
Crystallographic Structure ◽  
Wild Type ◽  
Gene Encoding ◽  
Cellular Redox ◽  
Transsulfuration Pathway ◽  
Key Enzyme ◽  
A Minor ◽  
Ferrous Heme

The human disease classical homocystinuria results from mutations in the gene encoding the pyridoxal 5′-phosphate- (PLP-) dependent cystathionineβ-synthase (CBS), a key enzyme in the transsulfuration pathway that controls homocysteine levels, and is a major source of the signaling molecule hydrogen sulfide (H2S). CBS activity, contributing to cellular redox homeostasis, is positively regulated byS-adenosyl-L-methionine (AdoMet) but fully inhibited upon CO or NO• binding to a noncatalytic heme moiety. Despite extensive studies, the molecular basis of several pathogenicCBSmutations is not yet fully understood. Here we found that the ferrous heme of the reportedly mild p.P49L CBS variant has altered spectral properties and markedly increased affinity for CO, making the protein much more prone than wild type (WT) CBS to inactivation at physiological CO levels. The higher CO affinity could result from the slightly higher flexibility in the heme surroundings revealed by solving at 2.80-Å resolution the crystallographic structure of a truncated p.P49L. Additionally, we report that p.P49L displays impaired H2S-generating activity, fully rescued by PLP supplementation along the purification, despite a minor responsiveness to AdoMet. Altogether, the results highlight how increased propensity to CO inactivation of an otherwise WT-like variant may represent a novel pathogenic mechanism in classical homocystinuria.

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