scholarly journals Adsorption and Desorption Mechanisms of Rare Earth Elements (REEs) by Layered Double Hydroxide (LDH) Modified with Chelating Agents

2019 ◽  
Vol 9 (22) ◽  
pp. 4805 ◽  
Author(s):  
Shuang Zhang ◽  
Naoki Kano ◽  
Kenji Mishima ◽  
Hirokazu Okawa
Keyword(s):  
Rare Earth ◽  
Quantum Chemistry ◽  
Rare Earth Elements ◽  
Adsorption Capacity ◽  
Density Functional ◽  
Stable State ◽  
Experimental Result ◽  
Adsorption And Desorption ◽  
Adsorption Affinity ◽  
Quantum Chemistry Calculations

In order to obtain the adsorption mechanism and adsorption structures of Rare Earth Elements (REEs) ions adsorbed onto layered double hydroxides (LDH), the adsorption performance of LDH and ethylenediaminetetraacetic acid (EDTA) intercalated LDH for REEs was investigated by batch experiments and regeneration studies. In addition to adsorption capacity, the partition coefficient (PC) was also evaluated to assess their true performance metrics. The adsorption capacity of LDH increases from 24.9 μg·g−1 to 145 μg·g−1 for Eu, and from 20.8 μg·g−1 to 124 μg·g−1 for La by intercalating EDTA in this work; and PC increases from 45.5 μg·g−1·uM−1 to 834 μg·g−1·uM−1 for Eu, and from 33.6 μg·g−1·μM−1 to 405 μg·g−1·μM−1 for La. Comparison of the data indicates that the adsorption affinity of EDTA-intercalated LDH is better than that of precursor LDH no matter whether the concept of adsorption capacity or that of the PC was used. The prepared adsorbent was characterized by XRD, SEM-EDS and FT-IR techniques. Moreover, quantum chemistry calculations were also performed using the GAUSSIAN09 program package. In this calculation, the molecular locally stable state structures were optimized by density functional theory (DFT). Both the quantum chemistry calculations and the experimental data showed that REEs ions adsorbed by EDTA-intercalated LDH are more stable than those adsorbed by precursor LDH. Furthermore, the calculation results of adsorption and desorption rates show that adsorption rates are larger for Eu(III) than for La(III), which agrees with the experimental result that Eu(III) has a higher adsorption ability under the same conditions. The LDHs synthesized in this work have a high affinity for removing REEs ions.

Removal of Fission Products in the Spent Electrolyte Using Iron Phosphate Glass as a Sorbent

2010 ◽  
Author(s):  
Ippei Amamoto ◽  
Naoki Mitamura ◽  
Tatsuya Tsuzuki ◽  
Yasushi Takasaki ◽  
Atsushi Shibayama ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Phosphate Glass ◽  
Alkali Metals ◽  
Fission Products ◽  
Iron Phosphate ◽  
Experimental Result ◽  
Filtration Method ◽  
High Level ◽  
Filtration Experiment

This study is carried out to make the pyroprocessing hold a competitive advantage from the viewpoint of environmental load reduction and economical improvement. As one of the measures to reduce the volume of the high-level radioactive waste (HLW), the phosphate conversion method is applied for removal of fission products (FP) from the melt, referring to the spent electrolyte in this paper. Among the removing target chlorides in the spent electrolyte i.e., alkali metals, alkaline earth metals and rare earth elements, only the rare earth elements and lithium form the precipitates as insoluble phosphates by reaction with Li3PO4. The sand filtration method was applied to separate FP precipitates from the spent electrolyte. The iron phosphate glass (IPG) powder, which is a compatible material for the immobilization of FP, was used as a filter medium. After filtration experiment, it was proven that insoluble FP could almost be completely removed from the spent electrolyte. Subsequently, we attempted to separate the dissolved FP from the spent electrolyte. The IPG was being used once again but this time as a sorbent instead. This is possible because the IPG has some unique characteristics, e.g., changing the valence of iron, which is one of its network modifiers due to its manufacturing temperature. Therefore, it would be likely to sorb some FP when the chemical condition of IPG is unstable. We produced three kinds of IPG under different manufacturing temperature and confirmed that those glasses could sorb FP as anticipated. According to the experimental result, its sorption efficiency of metal cations was attained at around 20–40%.

Theoretical investigation of [Ru(tpy)2]2+, [Ru(tpy)(bpy)(H2O)]2+ and [Ru(tpy)(bpy)(Cl)]+ complexes in acetone revisited: Inclusion of strong spin–orbit couplings to quantum chemistry calculations

2016 ◽  
Vol 15 (01) ◽  
pp. 1650001
Author(s):  
Kenji Mishima ◽  
Takumi Kinoshita ◽  
Michitoshi Hayashi ◽  
Ryota Jono ◽  
Hiroshi Segawa ◽  
...  
Keyword(s):  
Experimental Data ◽  
Quantum Chemistry ◽  
Absorption Spectra ◽  
Density Functional ◽  
Order Perturbation ◽  
Basis Sets ◽  
Spin Orbit ◽  
First Order ◽  
Quantum Chemistry Calculations ◽  
First Order Perturbation

In the present paper, we theoretically reinvestigate structural properties, and photo-physical and chemical characteristics and electronic absorption spectra of three kinds of ruthenium polypyridyl complexes [Ru(tpy)[Formula: see text], [Ru(tpy)(bpy)(H2O)][Formula: see text], and [Ru(tpy)(bpy)(Cl)][Formula: see text] complexes in acetone (tpy[Formula: see text]2,2[Formula: see text],2[Formula: see text]-terpyridine and bpy[Formula: see text]2,2[Formula: see text]-bipyridine). In particular, the experimental absorption spectra of these complexes are revisited theoretically in detail and are simulated using the first-order perturbation theory based on time-dependent density functional theory (TD-DFT) where the first-order perturbation term is the spin–orbit (SO) coupling Hamiltonian, and quantum chemistry calculations based on various functionals and basis sets. It was found that in general the theory including SO coupling can reproduce experimental data better than the simple quantum chemistry calculation neglecting SO coupling, which indicates that SO coupling is very important to understand the optical features of these complexes and that therefore the mixing between singlet and triplet states is strong due to the large SO coupling constant of Ru atom involved in these complexes. This suggests the fact that the disagreement between the experimental and calculated absorption spectra was found in TDB3LYP/(SDD with triple-[Formula: see text] for Ru and 6-31G* for others) [Jakubikova EJ et al., Inorg Chem 48:10720, 2009] can be tracked down to the neglect of SO couplings. It was also found that the choice of the DFT functionals and basis sets is crucial for a good theoretical reproduction of experimental data.

Recovery of Lanthanides from Indonesian Low Grade Bauxite Using Oxalic Acid

2018 ◽  
Vol 929 ◽  
pp. 171-176 ◽  
Author(s):  
Eny Kusrini ◽  
Zakaria Jaka Bahari ◽  
Anwar Usman ◽  
Arif Rahman ◽  
Eko Adi Prasetyanto
Keyword(s):  
Rare Earth ◽  
Optimum Condition ◽  
Oxalic Acid ◽  
Rare Earth Elements ◽  
Acid Leaching ◽  
Experimental Result ◽  
Low Grade ◽  
Icp Oes ◽  
Temperature Dependent ◽  
Economical Method

The present work describes the extraction of lanthanide (rare earth elements, REE) from low grade bauxite using acid leaching method. The aim of this study is to obtain the best condition for extraction of lanthanides from low grade bauxite. The effect of different parameters such as temperatures and concentration of oxalic acid in leaching process were investigated. The content of La, Ce and Y elements were determined using ICP-OES. The experimental result shows that the efficiencies of lanthanide leaching are the temperature-dependent. Increasing leaching temperature from 45°C to 85°C did not improve recoveries of lanthanides. The most optimum condition was found at oxalic acid leaching of 1 mol/L, leaching temperature at 40°C, and time for 2 hours. The obtained results show that the lanthanides can be leached using oxalic axid. This finding may lead to more effective and economical method to separate lanthanides from low grade bauxite.

scholarly journals Temperature-Dependent Generalized Planar Fault Energy and Twinnability of Mg Microalloyed with Er, Ho, Dy, Tb, and Gd: First-Principles Study

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Lili Liu ◽  
Yelu He ◽  
Dingxing Liu ◽  
Xiaozhi Wu ◽  
Rui Wang
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Density Functional ◽  
Atomic Radius ◽  
Temperature Dependent ◽  
Functional Theory ◽  
Planar Fault ◽  
Change Trend ◽  
Underlying Mechanisms ◽  
Increasing Temperature

The generalized planar fault energies, Rice criterion ductility, and twinnability of pure Mg and Mg-RE (RE = Er, Ho, Dy, Tb, and Gd) alloys at different temperature have been investigated using density functional theory. It is shown that all the fault energies and twinnability in the same materials decrease with increasing temperature. However, the ductility has the opposite change trend. On the other hand, alloying rare earth elements will generally decrease the fault energies and increase the ductility and twinnability of Mg at different temperature. It is interesting to note that alloying larger atomic radius will enhance the ductility of Mg more easily and alloying smaller radius will make twinning tendency of Mg more easily. Finally, the electron structure further reveals the underlying mechanisms for the reduction of fault energies with the addition of rare earth elements.

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