Heating of radiation-chemical systems by γ-irradiation

1968 ◽  
Vol 25 (3) ◽  
pp. 980-984
Author(s):  
F. A. Makhlis
Keyword(s):  
Γ Irradiation ◽  
Radiation Chemical ◽  
Chemical Systems

Radiation Chemical Conversions in Fluorine Containing Elastomers under Different γ-Irradiation Conditions

1974 ◽  
Vol 47 (2) ◽  
pp. 282-284 ◽  
Author(s):  
A. B. Kryukova ◽  
A. S. Kuz'minskii ◽  
N. S. Gilinskaya ◽  
F. A. Galil-Ogly ◽  
G. A. Sankina
Keyword(s):  
Stressed State ◽  
Vinyl Ether ◽  
High Temperatures ◽  
Vinylidene Fluoride ◽  
Chemical Crosslinking ◽  
Γ Irradiation ◽  
Radiation Chemical ◽  
Γ Radiation ◽  
Copolymer 1

Abstract Rates of radiation chemical crosslinking and scission of fluorine containing elastomers based on copolymers of vinylidene fluoride with trifluorochloroethylene (Copolymer 1), with hexafluoropropylene (Copolymer 2), and with a perfluoroalkyl vinyl ether (Copolymer 3) and also the behavior of their radiation vulcanizates in the stressed state at high temperatures are determined both by the type of polymer and by the irradiation conditions. Crosslinking rates of Copolymers 2 and 3 are higher than those of Copolymer 1; oxygen of the air inhibits crosslinking by γ-radiation; by irradiation in the presence of oxygen of the air, the sol fraction is 8–10 times higher than in its absence, Copolymer 3 vulcanizates obtained by irradiation in the absence of air appear to be optimal.

Effect of Irradiation on the Molecular Weight, Structure and Apparent Viscosity of Xanthan Gum in Aqueous Solution

2011 ◽  
Vol 239-242 ◽  
pp. 2632-2637 ◽  
Author(s):  
Yan Jie Li ◽  
Yi Ming Ha ◽  
Feng Wang ◽  
Yong Fu Li
Keyword(s):  
Aqueous Solution ◽  
Molecular Weight ◽  
Apparent Viscosity ◽  
Irradiation Dose ◽  
Xanthan Gum ◽  
Gel Permeation Chromatography ◽  
Uv Spectra ◽  
X Ray Diffraction ◽  
Γ Irradiation ◽  
Radiation Chemical

Xanthan gum samples were irradiated in aqueous solution at different doses (0-120 kGy) of 60Co γ-rays. The changes of molecular weight and structures of irradiated xanthan gum samples were investigated and characterized by using gel permeation chromatography(GPC), X-ray diffraction (XRD), fourier-transform infrared spectra (FTIR), ultraviolet–visible spectral (UV–vis) analysis and rheometer. Results showed the molecular weight decreased gradually with increasing irradiation dose. The radiation chemical yields G(d) of xanthan gum was 26.55. FTIR spectra and XRD indicated that γ-irradiation introduced no significant changes into the structure and crystal texture, but UV spectra showed a distinct absorption peak at about 265 nm, increasing with irradiation dose, which was attributed to the formation of carbonyl groups or double bond. Apparent viscosity of xanthan gum solution decreased with increasing irradiation dose and remain basically constant with the prolonging of shear time after irradiation.

scholarly journals Electron beam irradiation of r-SANEX and i-SANEX solvent extraction systems: analysis of gaseous products

Nukleonika ◽  
2015 ◽  
Vol 60 (4) ◽  
pp. 899-905 ◽  
Author(s):  
Tomasz Szreder ◽  
Rafał Kocia
Keyword(s):  
Electron Beam ◽  
Organic Phase ◽  
Electron Beam Irradiation ◽  
Safety Issue ◽  
Extraction Process ◽  
Beam Irradiation ◽  
Γ Irradiation ◽  
Radiation Chemical ◽  
Safety Issues ◽  
Gaseous Products

Abstract 1-Octanol/kerosene mixtures and water contacted with organic solvents were used as model solutions for r-SANEX and i-SANEX extractions systems. Investigations aimed on a quantitative evaluation of gaseous products generated in these systems under exposure to an electron beam irradiation. Influence of O2, HNO3 and the presence of model ligands and complexes on the radiation chemical yields was studied. Relatively high G(H2) values (up to 420 nmol·J-1) for the organic phase compromise the safety issues of the extraction process and should be considered on the stage of extraction apparatus design. Based on the obtained results gaseous hydrocarbons seem to have negligible impact on safety issue. The upper limit of G(H2) values in water contacted with organic phase was established to be 85 nmol·J-1. This value is relatively low, however, the literature data indicate that G(H2) values measured in aqueous solutions are over twice higher for α-particles irradiation than for electron beam or γ-irradiation. Thus, further investigations of these systems are necessary.

Degradation of Acetaminophen in Aqueous Media by H2O2 Assisted Gamma Irradiation Process

2018 ◽  
Vol 0 (0) ◽  
Author(s):  
Murtaza Sayed ◽  
Fazal Hadi ◽  
Javed Ali Khan ◽  
Noor S. Shah ◽  
Luqman Ali Shah ◽  
...  
Keyword(s):  
Aqueous Media ◽  
Absorbed Dose ◽  
Degradation Process ◽  
Chemical Yield ◽  
Spectrophotometric Analysis ◽  
Γ Irradiation ◽  
Solution Ph ◽  
Radiation Chemical ◽  
G Value

Abstract In the present study, degradation of acetaminophen (ACT) aqueous solution was investigated up to an absorbed γ-irradiation dose of 1000 Gy. The effects of various additives on the degradation efficiency of ACT were also studied. The results showed that ACT degradation was increased with the increase of an absorbed dose. Based on spectrophotometric analysis, 82.5% degradation of the initial ACT concentration (9.98×10−5 M) was easily achieved at an absorbed dose of 1000 Gy. The decay of ACT followed pseudo-first order reaction kinetics at different initial concentrations. The radiation chemical yield (G-value) decreased with the increase of an absorbed dose, however at a specific absorbed dose G-values increased with the increase of ACT initial concentration. The addition of H2O2 in the range of 0.1–0.7% was effective for degradation of ACT. The degradation of ACT was inhibited in both acidic and basic solutions while maximium degradation effiency was acheived at nearly neautral solution pH, 7.6. The degradation process was markedly enhanced under oxidative conditions while strongly restrained under reductive conditions, which suggests the key role of oxidative radicals (˙OH) in the degradation of ACT.

γ-Irradiation of N-vinylpyrrolidin-2-one and its homopolymer

1981 ◽  
Vol 34 (7) ◽  
pp. 1413 ◽  
Author(s):  
JE Davis ◽  
E Senogles
Keyword(s):  
Molecular Weight ◽  
Hydrogen Bonding ◽  
Main Chain ◽  
Theoretical Data ◽  
Radical Mechanism ◽  
Promoting Effect ◽  
Γ Irradiation ◽  
Radiation Chemical ◽  
Γ Radiation ◽  
Molecular Weights

The effect of γ-radiation on N-vinylpyrrolidin-2-one and its homopolymer, poly(N-vinylpyrrolidin-2-one), has been investigated. With N-vinylpyrrolidin-2-one, polymerization occurs by a radical mechanism and the presence of water has been shown to have a promoting effect on the reaction, giving both increased polymerization rates and molecular weights. This has been primarily attributed to an enhancement of N- vinylpyrrolidin-2-one reactivity through hydrogen bonding. In contrast, irradiation of N-vinylpyrrolidin-2-one in the presence of organic solvents leads to lower polymerization rates and lower molecular weights than with the undiluted monomer. ��� Poly(N-vinylpyrrolidin-2-one) primarily crosslinks on being irradiated. Gel fractions have been determined as a function of radiation dose and the results shown to be consistent with the theoretical data derived by Inokuti for a polymer with an initial molecular weight distribution of the Schulz-Zimm type. This leads to values for the radiation chemical yields of crosslinks and main chain scissions, G(X) and G(S), of 0.13�0.03 and 0.02�0.01, respectively, at 0°C.

Kinetics of hydrogen isotope exchange reactions - XXIX. Radiation-induced tritiation of 1, 4-dioxan in aqueous solutions

1975 ◽  
Vol 346 (1647) ◽  
pp. 443-467 ◽  
Keyword(s):  
Hydrogen Exchange ◽  
High Reactivity ◽  
Exchange Reactions ◽  
High Concentration ◽  
Γ Irradiation ◽  
Solvated Electrons ◽  
Radiation Chemical ◽  
Molecular Product ◽  
Chemical Studies ◽  
Radiation Induced

Under the influence of tritium β-radiation, 1, 4-dioxan undergoes hydrogen exchange with the solvent water. The inhibition of the reaction by known electron scavengers (Ag + , Cu 2+ , Ni 2+ , Co 2+ , Zn 2+ , H + 3 O and also by species with high reactivity towards hydroxyl radicals but negligible reactivity towards solvated electrons (N - 3 , Br - , SCN - ) has been examined in detail. γ-Irradiation similarly induces hydrogen exchange. The action of scavengers is interpreted as requiring the involvement of two separately scavengeable primary radiolysis products in the sequence of reactions leading to exchange. Evidence is presented that the reactions of these species occur in spur regions, and the scheme RH + OH˙→ R˙ + H 2 O e - aq → R - HTO → RT is considered to explain the main features of the mechanism. The presence of electron scavengers, even at high concentration, does not totally inhibit the exchange, and a secondary exchange route, involving a lower valency state of inhibitor cations, is considered responsible for the ‘unscavengeable’ portion of the reaction, by providing an alternative exchange route, e. g. R˙ + Ni + → R - + Ni 2+ HTO → RT Analogies are drawn between the exchange reaction and other radiation-induced reactions that are thought to involve spur processes (such as the formation of H 2 O 2 as a molecular product in the radiolysis of water). Some implications of the present results for the interpretation of radiation-chemical studies in water-alcohol mixtures are indicated.

Radiation chemical data in water using nitrous oxide

1967 ◽  
Vol 45 (18) ◽  
pp. 2051-2058 ◽  
Author(s):  
D. A. Head ◽  
D. C. Walker
Keyword(s):  
Nitrous Oxide ◽  
Hydrogen Atom ◽  
Acid Solution ◽  
Low Dose ◽  
Chemical Data ◽  
Γ Irradiation ◽  
Radiation Chemical ◽  
Dose Rates ◽  
Small Doses

By using small doses and very low dose rates, it is shown that in the γ-irradiation of water ~ 8 × 10−5M nitrous oxide completely scavenges eaq− in the absence of other additives and gives a yield G(eaq−) = 2.45 ± 0.1. When used at concentrations of ~ 15 mM, N2O scavenges a second species having a yield G = 0.65 ± 0.1, which can probably be attributed to a hydrated hydrogen atom species resulting from the reaction of eaq– with H3O+ within the spur. Previous studies on the competition between N2O and Haq+ for eaq− have been conducted at concentrations of N2O much too high for simple competition to be valid, which probably accounts for the erratic results obtained. This paper reports on the competition studied at ~ 10−4 M. The results cannot be interpreted either in terms of a simple competition or by one, or both, of the immediate products reacting with either of the additives. The data can only be rationalized by assuming that in acid solution N2O is converted to a species, tentatively suggested to be H2N2O2, which reacts with eaq− 5 times more slowly than does N2Oaq at pH 7.

Role of the exosporial membrane in attachment and germination of C. sporogenes

1993 ◽  
Vol 51 ◽  
pp. 38-39
Author(s):  
B.J. Panessa-Warren ◽  
G.T. Tortora ◽  
J.B. Warren
Keyword(s):  
Enzymatic Degradation ◽  
Light Transmission ◽  
Extended Period ◽  
Growth Conditions ◽  
Clostridium Sporogenes ◽  
Radiation Chemical ◽  
Physical Trauma ◽  
Extended Contact ◽  
Cold Pressure

Some bacteria are capable of forming highly resistant spores when environmental conditions are not adequate for growth. Depending on the genus and species of the bacterium, these endospores are resistant in varying degrees to heat, cold, pressure, enzymatic degradation, ionizing radiation, chemical sterilants,physical trauma and organic solvents. The genus Clostridium, responsible for botulism poisoning, tetanus, gas gangrene and diarrhea in man, produces endospores which are highly resistant. Although some sporocides can kill Clostridial spores, the spores require extended contact with a sporocidal agent to achieve spore death. In most clinical situations, this extended period of treatment is not possible nor practical. This investigation examines Clostridium sporogenes endospores by light, transmission and scanning electron microscopy under various dormant and growth conditions, cataloging each stage in the germination and outgrowth process, and analyzing the role played by the exosporial membrane in the attachment and germination of the spore.

Thermodynamics of Chemical Systems

1990 ◽  
Author(s):  
Scott Emerson Wood ◽  
Rubin Battino
Keyword(s):  
Chemical Systems
Sign in / Sign up

Export Citation Format

Share Document