Radiation induced decomposition of halogenated organic compounds in water

Decomposition by ionizing radiations of p-chlorophenol and tetrachloroethylene in synthetic water samples at about 2 mg Cl L⁻¹, has been studied on laboratory-scale experiments. Bicarbonate/carbonate and nitrate ions, at two concentration levels (20 and 200 mg HCO₃⁻¹ and 1 and 50 mg NO₃⁻L⁻) were added to synthetic samples in order to evaluate their influence on decomposition yield. At 5 kGy γ dose level, a quantitative degradation of p-chlorophenol is obtained whereas only qualitative consideration can be drawn on tetracholoroethylene. Comparative study with respect to degradation of p-cholophenol solutions (about 2 mg Cl L⁻¹) by γ-rays and electron beam irradiation treatment at 0.5 kGy dose level, are in progress; preliminary results indicate that irradiation with γ-rays seems to be more efficient in terms of removal efficiency respect to electron beams source.     

Thermal investigations on γ-radiation processed natural medicinal products (Ashwagandha,Amla and Hartiki)

DSC and TG studies were carried out on -radiation processed Indian natural products of medicinal importance, namely Ashwagandha (Withania Somnifera), Amla (Emblica Officinalis) and Hartiki (Terminalia chebula). DSC thermoanalytical curves were recorded from 35 to 400°C in air and nitrogen atmosphere. Similarly, TG thermoanalytical curves were taken from 35 to 700°C in air and nitrogen atmosphere. Irradiated products gave significantly different thermoanalytical profiles in comparison to non-irradiated samples. The differences were observed above decomposition temperature of 200°C and were non-linear with respect to radiation dose. Partial oxidation of the products during irradiation in air could be responsible for the observed differences.     

Irradiation of detonation nanodiamonds with γ-rays does not produce long living spin radicals

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γ-Radiation Effects on the Thermal Stability of Bovine γ-Globulin

Low-dose γ-radiation produces subtle effects on bovine γ-globulin, as revealed by calorimetric investigations carried out on concentrated aqueous solutions. The irradiation rate used seems below the threshold that allows complete protein denaturation; the denaturation temperature, T_d, remained unaffected; nonetheless, modifications of the shape of the calorimetric signal reveal that other changes, such as the dissociation of protein oligomers, could take place. This revised version was published online in July 2006 with corrections to the Cover Date.     

Calculation of the scatteredγ-radiation spectrum of radionuclides for problems of aerial gamma-ray photography

We obtained analytical expressions for the intensities of γ-quanta fluxes that were emitted by radioactive isotopes distributed in soil and that experiented n-tuple scattering. We present these expressions in the form of a sum of multiple integrals of simple form. The results of numerical integration performed for test examples are given. Scientific-Research Institute of Nuclear Problems at the Belarusian State University, 11, Bobruiskaya St., 220050, Minsk, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 3, pp. 405–411, May–June, 1997.     

γ-Radiation Induced Functional Modification of Silica and Radiation Vulcanization of SBR-Silica Composites

Summary: The γ-ray induced “grafting” of polybutadiene olygomers onto precipitated silica and the radiation induced crosslinking of the blends prepared with the modified silica in SBR matrices have been investigated in the dose range up to 290 kGy. Enhanced mechanical properties have been detected for the SBR blends containing the modified silica after γ-ray induced crosslinking. The comparison with the analogue mixtures containing pristine silica, supported by EPR measurements, suggests that the PB coating is effective in enhancing the mechanism of formation of filler-rubber chemical links.     

Effect of γ-radiation on the birefringence of stretched polyethylene films

The spectral dependences of the birefringence and of the retardance of polyethylene films of thickness 67 μm exposed to γ-radiation doses up to 500 kGy are studied in the spectral range 400–700 nm. It is shown that the characteristics of polymeric polarization elements could be controlled by irradiation processes.     

Crosslinking of alkylpolysiloxane filsm on various types of glass surfaces including fused silica using γ-radiation of a60cobalt-source. Comparison to crosslinking by thermal peroxid treatment

Summary Crosslinking of alkylpolysiloxane stationary phases, especially in thick film capillary columns, is useful for the homogenous coating of fused silica and pretreated alkaliglass surfaces. The films of the stationary liquid are immobilized against solvent rinsing using CH₂Cl₂, pentane, and acetone, and maintain homogenity even at high temperature. Various doses of -radiation from a⁶⁰Co. source were used for the crosslinking instead of the thermal peroxid treatment recently described by other authors. The effect of the -radiation crosslinking-procedure was investigated in comparison to the peroxid method in regard of: decrease of stationary phase content by solvent rinsing, separation efficiency, tailing behaviour, and bleeding of the columns obtained. Similar results as with the cumylperoxid-treatment were achieved using the -radiation-method. By -radiation no polar functional groups or moleculs are introduced into the stationary phase, however, as with the peroxid method. Less than 20% of the various stationary liquids are usually removed from the columns by solvent rising after crosslinking using both methods depending on the doses of radiation and the cumylperoxid concentration applied respectively.Dedicated to Dr. L. S. Ettre on the occasion of his 60th birthday.     

Tailored functionalized polymer nanoparticles using gamma radiation for selected adsorption of barium and strontium in oilfield wastewater

To improve oil recovery from oilfield wells mineral scales derived by insoluble BaSO₄ and SrSO₄ salts during oil extraction should be diminished. In this work, adsorption selectivity of Barium (Ba²⁺) and Strontium (Sr²⁺) ions associated with saline formation waters was examined for the first time using nano-sized bi-functional polymer blend synthesized by Cobalt-60 (⁶⁰Co) γ-rays, as green technology. A bifunctional polymer formed from poly(acrylonitrile)/(styrene-butadiene rubber) homogenous blend is functionalized by -SO₃H and -COOH terminal groups (termed as SASB). Those functional groups were selected based on systematic calcium (Ca²⁺) ions adsorption studies of carboxylate containing molecules. Main and binary interactive effects of solution pH (3–9), adsorbents dose (1-3 g/L), total dissolved salts (TDS, up to 30 g/L), initial Ba²⁺ and Sr²⁺ concentrations (10-500 mg/L) and temperature (20–50 ^oC) on the adsorption selectivity were examined and optimized using Plackett-Burman factorial design (PBD) combined with multiple regression analysis. The regression statistics revealed the significance of quadratic polynomial model to optimize interactive sorption conditions from salty waters with high accuracy level ($R^2$≈ 0.99) rather than linear and two-way interactive models at 95% confidence level. Interestingly finding, the regression and experimental data proved that the presence of up to 10 g/L TDS from alkali metal ions had a significant effect on the enhancement sorption capacity of Ba²⁺ and Sr²⁺ when using the prepared sorbent. The SASB adsorbent showed higher sorption selectivity with maximum equilibrium capacity ($q_{\mathit{mg}/g}$) of 175.3 mg Ba⁺² and 210.5 mg Sr⁺² per each gram sorbent used in kinetic study. Adsorption kinetics of Ba²⁺ and Sr²⁺ sorption by both adsorbents obey pseudo-first and pseudo-second order kinetics, respectively. In sum, the adsorptive power of SASB sorbent is found to be in reverse order of the electronegativity and the hydration radii of the metal ions.     

Effect of Ionizing Radiation on the Characteristics of EPDM/UHMW-PE Composites

Ultra high molecular weight polyethylene (UHMW-PE) fibers were used in a chopped form and at different concentrations as a reinforcing material in ethylene–propylene–diene terpolymers (EPDM). The effect of radiation dose and fiber concentration on the mechanical properties of the vulcanized rubber composites obtained was measured. It was found that γ-irradiation improves the interfacial adhesion between UHMW-PE fiber (Spectra 1000) and EPDM matrix which was detected by scanning electron microscopy (SEM). In addition, the Young modulus of the composites increases as the irradiation dose increases. Increasing the concentration of the fibers up to 40 phr leads to an enhancement in mechanical properties and swelling resistance of obtained composites, especially in the absence of carbon black. The absolute value of the modulus increased by a factor of at least two with the addition of carbon black. Moreover the tear strength of reinforced and filled EPDM was improved with respect to reinforced rubber. © 1997 John Wiley & Sons, Ltd.