Authors:Lei Chen, Bin Gao, Songsheng Lu, and Yunhui Dong
Sorption of radionickel on attapulgite is studied as a function of contact time, ionic strength, pH and temperature. The results
indicate that the sorption of Ni(II) on attapulgite is strongly ionic strength-dependent at pH <8, and independent of ionic
strength at pH >8. Outer-sphere surface complexation or ion exchange contributes to Ni(II) sorption on attapulgite at pH <8,
whereas the sorption of Ni(II) is mainly dominated by inner-sphere surface complexation at pH >8. The sorption of Ni(II) on
attapulgite increases with increasing temperature, and the thermodynamic parameters (ΔH0, ΔG0 and ΔS0) calculated from the temperature dependent sorption isotherms suggest that the sorption of Ni(II) on attapulgite is a spontaneous
and endothermic process. The high sorption capacity of attapulgite suggests that attapulgite is a suitable material for the
preconcentration and solidification of radionickel from large volumes of aqueous solutions.
Authors:Cheng Dao-wen, Lu Jing-bin, Yang Dong, Wang Hui-dong, and Ma Ke-yan
In boron neutron capture therapy (BNCT), the proportion of the fast neutron in the tumor (PFN) must be no more than 3%. If
a D–T neutron generator is used as a thermal neutron source in BNCT, the moderator must be optimized to decrease the PFN.
Based on the analysis of the theory, water, heavy water, polythene, graphite, lead, and tungsten were used to moderate the
fast neutrons. If the three-layer material is composed of a 4 cm thickness layer of tungsten, a 13 cm thickness layer of lead,
and a 23 cm thickness layer of heavy water, its thermalization efficiency (TE) is highest, which is increased by 191.5% than
the maximum TE moderated by single-layer materials and by 19.3% than the maximum TE moderated by double-layer materials.
Authors:Bin Dong, Christian H. Galka, Lutz H. Gade, Lifeng Chi, and René M. Williams
nanocrystals are formed by self assembly of
tetra(carboxamido)perylenes (BPP) in different solvents. The structure and the
dimensions of the nano-rods may be controlled by the choice of the
hydrogen-bond accepting capacity of the solvent (DMSO, DMF, DMAc, HMPA), by the
concentration and by the composition of solvent-mixture (by adding
hydrogen-bond donating solvents), but is independent of the surface used for
their deposition (mica, silicon, gold, glass). The different forms of
aggregation were examined by AFM and SNOM and were correlated to UV-Vis
absorption spectra of the aggregates in solution. The orientation of the
transition dipole moment of the molecules in the nanocrystals has been
determined by polarized fluorescence microscopy and, in combination with the
crystal structure of the
-Bu substituted analogue of BPP, is used to
develop a model for the internal molecular structure of the rod shaped
Authors:Ye Yu-xing, Hu Jin-xin, Huang Zi-lin, Shi Wei-qun, Wu Guang-min, Tang Hong-bin, Zhu Wen-bin, Wang Xiao-rong, Zhao Hu-gen, Dong Yu, Sheng Dong, Luo Fang-xiang, and Zhao Yan-ju
The partitioning of actinides from simulated high level liquid waste (HLLW) originated from the Purex process has been studied using a mixture of dihexyl N,N-diethylcarbamoylmethyl-phosphonate (DHDECMP) and tributylphosphonate (TBP) in kerosene (OK). The distribution ratios of actinides were investigated as a function of a number of parameters such as the concentration of nitric acid, salting-out reagent, Gd(III) in the aqueous phase, extractant in the organic phase, and temperature. The extraction complexes, extraction reaction constant k, and thermodynamic parameters H, G and S were determined. The extraction of actinides from simulated HLLW by DHDECMP-TBP/OK has been carried out using a miniature countercurrent centrifugal contactor. The results show that the removal efficiency of actinides is greater than 99.9%. A conceptual flowsheet for the removal of actinides from HLLW is proposed.
Authors:Gye-Nam Kim, Suk-Chol Lee, Dong-Bin Shon, Hye-Min Park, Wang-Kyu Choi, and Jei-Kwon Moon
For the disposal of the high efficiency particulate air (HEPA) glass filter to environment, the glass fiber should be leached
to lower its radioactive concentration. To derive the optimum method for removal of Co and Cs from HEPA glass fiber, four
methods were applied in this study. Results of electrochemical leaching of glass fiber by 4.0 M HNO3–0.1 M Ce(IV) solution showed that the removal efficiency of 134Cs, 137Cs, and 60Cs from glass fiber after 5 h was 96.4, 93.6, and 93.8%, respectively. Results by 5 wt% NaOH solution showed that the removal
efficiency of 134Cs, 137Cs, and 60Cs after 30 h was 81.7, 82.1, and 10.0%, respectively. Results by repeat 2.0 M HNO3 solution showed that the removal efficiencies of 134Cs, 137Cs, and 60Cs after 2 h of three repetitions were 96.2, 99.4, and 99.1%, respectively. Finally, results by repeat 4.0 M HNO3 solution showed that the removal efficiencies of 134Cs, 137Cs, and 60Cs after 4 h of three repetitions were 100, 99.9, and 99.9%, respectively, and their radioactivities were below 0.1 Bq/g.
Therefore, the chemical leaching method by 4.0 M HNO3 solution was considered as an optimum one for removal of cesium and cobalt from HEPA glass fiber for self disposal. Also
the removal efficiencies of 60Co, 134Cs, and 137Cs from the waste-solution after its precipitation-filtration treatment for reuse of 4.0 M HNO3 waste-solution were 88.0, 95.0, and 99.8%.