Measurement of 129 I Radioactivity in Groundwater of Radioactive Waste Disposal Site

The investigation of the environmental radioactivity around the radioactive waste disposal site in Gyeongju is being carried out. The radioactivity of 129 I in groundwater and seaweed are to be measured. The analytical method to measure the radioactivity of 129 I in aqueous media was established. This method contains oxidation-reduction reaction, anion-exchange separation and palladium precipitation. The 129 I radioactivity in the PdI 2 precipitates was measured by using low-energy gamma spectrometer. The counts of peak at 39.6 keV of gamma energy were used for determination of 129 I radioactivity. The chemical recovery was determined by the weights of PdI 2 precipitates. The deionized water and groundwater spiked with 129 I tracer were tested. In the case of deionized water, the relative deviations of measured concentration from spiked one are from 1.1 to 10.7%. The relative deviations of measured radioactivity from spiked one in the groundwater experiments are 2.9 and 3.7%. The measured concentration is in good agreement with spiked one. The groundwater sampled from radioactive waste disposal site was tested. The concentrations of 129 I in the groundwater are below minimum detectable activities of 36.7 and 36.6 mBq/L

Photocatalytic enhancement of cesium removal by Prussian blue-deposited TiO2

After the Fukushima nuclear accident, tremendous efforts were made to treat radiocesium, radiostrontium, and other radioactive materials. For the first time, we demonstrate that a TiO2 photocatalyst can significantly enhance Cs adsorption by Prussian blue-deposited TiO2 (PB/TiO2) under UV irradiation. In this study, we synthesized PB/TiO2 using the photodeposition method. After the Cs ions were adsorbed on the PB/TiO2 in darkness, we then exposed the PB/TiO2 to UV light irradiation. This resulted in a further increase in Cs ion adsorption of more than 10 times the amount adsorbed in darkness. This photocatalytic-enhanced adsorption of Cs ions was not observed on PB mixed with SiO2, nor under visible light irradiation. We investigated the effects of PB concentration, PB/TiO2 concentration, and gas purging on both dark and photocatalytic-enhanced adsorption of Cs ions by PB/TiO2. Based on the results, we suggest that the photocatalytic-enhanced adsorption of Cs ions on PB/TiO2 is due to photocatalytic reduction of PB, which leads to additional adsorption of Cs ions. The change in solution color before and after the reaction, and the change in solution pH in the dark and during UV irradiation strongly support this suggestion. The photocatalytic-enhanced adsorption of Cs ions was equivalent during radioactive 137Cs removal, indicating important applications for pollutant removal from contaminated water. © 2018 Elsevier B.V.1

Binding of phenolic model compounds with noble metal doped graphene sheets

Presence of large number of oxygenates in raw bio-oil restrict its application as transportation fuel. Therefore, there is a strong necessity of finding a viable catalyst for upgrading raw bio-oil to transportation fuel level. In this study, palladium- and platinum- doped graphene sheets are examined theoretically for possible interactions of oxygenates such as guaiacol, phenol, anisole, vanillin, and salicylaldehyde on to metal doped graphene catalyst surfaces to understand preliminary adsorption mechanisms. For this purpose, B3PW91 functional of density functional theory (DFT) has been utilized. Adsorption kinetics, for instance, adsorption free energy, adsorption enthalpy, and equilibrium rate constant at a fixed pressure of 1 atm but over a wide range of temperature (400–800 K) are reported. Briefly results indicate that binding of both metals at vacant site of graphene sheet is found to be high energy releasing process and excellently agree with their contemporary literature results. The interaction of hydroxyl group of salicylaldehyde with Pd-doped graphene (PdGr) surface is most favourable configuration, whereas, Pt-doped graphene (PtGr) surface exhibited superior adsorption stability through phenyl ring. Binding of guaiacol, phenol, and anisole are energetically most favourable by phenyl ring interaction over each surface. Vanillin interacts strongly by oxygen atom of formyl group over PtGr surface. Further the values of adsorption kinetic parameters are very high for all model species; however, temperature increment deteriorates them. Finally, for each adsorption configuration of all model species over both catalyst surfaces, ln(Keq) vs. 1/T relation is proposed

Evolution of the morphological and rheological properties along the extruder length for compatibilized blends of a commercial liquid-crystalline polymer and polypropylene

In a previous article, we reported on the evolution of the morphological and rheological properties along the length extruder for blends of a liquid-crystalline polymer (LCP), Rodrun LC3000, and polypropylene (PP). In this work, we extended this study to compatibilized PP/ Rodrun LC3000 blends, containing 10 wt % LCP and different compatibilizers, to determine the influence of the addition of a compatibilizer during the processing and, consequently, on the final properties of such systems. The results revealed that the addition of compatibilizers led to a decrease in the mean diameters of the LCP structures, in comparison with those presented by the noncompatibilized blend containing the same LCP content. This phenomenon occurred more quickly for those blends in which compatibilization was carried out in an efficient way. Linear oscillatory shear was mainly sensitive to the type of morphology present in the blends, whereas nonlinear oscillatory shear was more sensitive to the evolution in the droplet/fibril size and along the extruder length