共查询到20条相似文献,搜索用时 15 毫秒
1.
Teodora Retegan Laurence Berthon Christian Ekberg Anna Fermvik Gunnar Skarnemark Nicole Zorz 《溶剂提取与离子交换》2013,31(5-6):663-682
In the framework of nuclear waste reprocessing, the separation processes of minor actinides from fission products are developed using liquid‐liquid extraction. To gain an understanding of the mechanism involved in the extraction process, a complex formation of actinides and lanthanides with BTBPs (6,6′‐bis(5,6‐dialkyl‐1,2,4‐triazin‐3‐yl)‐2,2′‐bipyridines) was characterized using the Electrospray Ionization Mass Spectrometry (ESI‐MS) technique. This study was carried out to compare the influence of diluents and side groups of the extractants on complex formation. Three different diluents, nitrobenzene, octanol and cyclohexanone, and two extractants, C5‐BTBP and CyMe4‐BTBP, were selected for this experiment. It was found that the change of the diluent and of the substituent on the BTBP moiety does not modify the stoichiometry of the complexes which is L2M(NO3)3. It is proposed that one nitrate is directly coordinated to the metal ion, the two other anions probably remaining in the outer coordination sphere. The difference observed in extracting properties is probably due to the solvation of the complexes by the diluent. The noncovalent force that holds complexes together are likely to be largely governed by electrostatic interactions even if the hydrophobic exterior of the complexes plays an important role in the complexation/extraction mechanism. The study of the stability of the ions in the gas phase shows that the C5‐BTBP ligand has a labile hydrogen atom, which is a fragility point of C5‐BTBP. 相似文献
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《分离科学与技术》2012,47(10):1587-1592
The coagulation–filtration process using Fe(III) salts is the most frequently practiced technology for As(V) removal in full scale water treatment plants. The co-existing As(III) is usually oxidized to As(V) prior to removal. Nonetheless, research studies applying high As(III) initial concentrations showed significant As(III) removal capacities, however, the efficiency of the process for initial As(III) concentrations commonly encountered in drinking water, i.e., 10-100 μg/L is not sufficiently investigated. The experimental results of this study indicated that the coagulation–filtration process using Fe(III) can safely meet the drinking water regulation limit of 10 μg/L, only when the initial As(III) concentration is < 25 μg/L and the Fe(III) dose ≥ 5 mg/L, for experiments performed with NSF challenge water. The limitations for efficient As(III) removal are attributed to the fact that As(III), under circumneutral pH values is mostly present with the uncharged H3AsO3 form, which is not efficiently adsorbed onto iron oxy hydroxides (FeOOH), the product of Fe(III) hydrolysis. Adsorption isotherms data were best fitted to BET model, indicating multi-layer adsorption and low affinity of As(III) for Fe(III) hydroxides. 相似文献
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Abstract Eu(III) was selectively reduced to Eu(II) at three‐dimensional glassy carbon cathode in 0.01 mol · dm?3 hydrochloric acid medium. Eu(III) reduction took place after all the dissolved oxygen was reduced and then proceeded steadily. Separation of Eu(II) from trivalent rare earths (La, Ce, Sm, Gd, Er, Yb) was carried out using a novel impregnated resin based on bis(2‐ethylhexy1)phosphoric acid. Eu(II) showed much lower affinity towards the resin than the trivalent rare earths and broke through the column readily. Eu of purity higher than 99.8% was yielded. The back‐oxidation of Eu(II) was observed during the sorption and Eu(III) was absorbed onto the resin. Adsorbed light and middle rare earths could be stripped from the loaded resin by 3M hydrochloric acid. Stripping of heavy rare earths (Er, Yb) was problematic. 相似文献
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《Inorganic chemistry communications》2003,6(5):593-597
The mononuclear [YbracL]Cl3·2H2O and dinuclear [Yb2(OH)2Cl2(racL)2]Cl2·4CH3OH·2H2O complexes of the macrocyclic ligand L derived from trans-1,2-diaminocyclohexane and 2,6-diformylpyridine have been obtained. The formation of the dinuclear species upon addition of hydroxide to the [YbracL]Cl3·2H2O or the enantiopure [YbrrrrL(NO3)2](NO3) has been followed using 1H NMR spectroscopy. The X-ray crystal structure of [Yb2(OH)2Cl2(racL)2]Cl2·4CH3OH·2H2O complex has been determined. The complex is a dimer consisting of two macrocyclic units. The Yb(III) ion is coordinated by six nitrogen atoms of the macrocyclic ligand, two bridging OH groups and chloride anions. The chiral macrocycle L in this complex exhibits twist-bent conformation of approximate C2 symmetry. 相似文献
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《分离科学与技术》2012,47(9):1913-1930
Abstract The solid‐liquid extraction of lanthanum(III), europium(III), and lutetium(III) by mesostructured silicas doped with 1‐phenyl‐3‐methyl‐4‐stearoyl‐5‐pyrazolone (HPMSP, bearing one chelating site) or with 1,12‐bis(1′‐phenyl‐3′‐methyl‐5′‐hydroxy‐4′‐pyrazolyl)‐dodecane‐1,12‐dione (HL‐10‐LH, bearing two chelating sites) has been studied and compared to the analogous solvent and micellar extractions in terms of the stoichiometry of the extracted complex and of the extraction efficiency. The solid‐liquid extraction order in the lanthanoid series is La<Eu<Lu; it is the usual liquid‐liquid extraction order obtained with acidic extractants. A theoretical model is used to determine the stoichiometries of the extracted complexes and the extraction yield is measured as a function of the pH, of the extractant/metal ratio (S/M) and of the volume ratio of the two phases (φ). For HPMSP, the extracted complexes involve three ligand molecules for one metal. For HL‐10‐LH, the complex stoichiometries are found to be either Ln(L‐10‐L)(L‐10‐LH) (Ln=La, Eu) or Lu2(L‐10‐L)3 for S/M=25, or Eu2(L‐10‐L)3 for S/M=5. For the first time, the synergistic solid‐liquid extraction is studied after a successful attempt at simultaneously immobilizing both extractants HL‐10‐LH and 2,4,6‐tri(2‐pyridyl)‐1,3,5‐triazine, “TPTZ”, into silica; the complex extracted in this case differs from the one obtained in solvent extraction. 相似文献
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Ken‐Ichiro Ishimori Tsuyoshi Yaita Takaumi Kimura Takashi Yamada Satoshi Shinoda 《溶剂提取与离子交换》2013,31(4):489-500
The extraction equilibria of Am(III) and Eu(III) by using a tripodal ligand, tris(2‐pyridylmethyl)amine (tpa), with various lipophilic anions have been investigated. The extractability of both Am(III) and Eu(III) was increased by the combination of tpa and counteranions due to a synergistic effect. The separation factors between Am(III) and Eu(III) were also increased from 7.6 to 49 by the combination of counteranions and organic solvents. The extraction equilibria of Am(III) and Eu(III) with tpa in 1,2‐dichloroethane were determined by slope analysis. It was found that three anions and one molecule of the ligand coordinated to Am(III) and Eu(III) was extracted regardless of the anions. 相似文献
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《Inorganic chemistry communications》2001,4(1):12-15
The addition of lanthanide(III) nitrates (Sm–Lu) to the actinide(III) extracting agent – 2,6-bis(5,6-dipropyl-1,2,4-triazin-3-yl)pyridine (L1) in a 1:1 ratio results in the crystallisation of complexes containing [Ln(L1)3]3+ moieties and a variety of anions. 相似文献
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SOHAIL ASLAM SHAPOUR VOSSOUGHI G. PAUL WILLHITE 《Chemical Engineering Communications》2013,200(4-6):287-301
Gelled polymers are being used increasingly to modify the movement of injected fluids in secondary and enhaced oil recovery processes. A common gelation process involves the reduction of Cr(VI) to Cr(III) in the presence of polyacrylamide. The Cr(III) reacts or interacts with the polymer to form a gel network. Although correlations of gelation time with principal process variables have been obtained, viscometric data have not been reported during or after gelation. These data are needed for fluid flow calculations in surface equipment and estimation of flow behaviour in reservoir rocks. A Weissenberg Rheogoniometer, with cone and plate geometry, was used to obtain viscometric data for the gelation of polyacrylamide and chromium (III). Solutions consisting of polyacrylamide polymer, sodium dichromate-dihydrate and sodium bisulfite were gelled under a steady shear field at constant temperature. The shear stress versus time profile for the galation process was interpreted to define a gelation time and to determine the apparent viscosity of the gelled fluid. The gelation time decreased as the applied shear rate increased up to about 14.25 sec?1 and was affected by shear rate history. Viscometric properties of the gelled solutions were determined. Apparent viscosity of the gelled solutions decreased as the shear rate under which they were formed increased. Post gelation studies indicated that gels exhibited a residual stress at zero shear rate and behaved as Bingham plastics under steady shear. Gels formed at low shear rates were more viscous than gels formed at high shear rates. However, the structure of these gels was susceptible to shear degradation. 相似文献
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活性炭负载Fe(III)吸附剂去除饮用水中的As(V) 总被引:4,自引:0,他引:4
利用活性炭负载水合铁氧化物制备了复合吸附剂,并用于饮用水中As(V)的去除. 研究了活性炭种类、粒度、溶液pH值、Fe(III)盐浓度和干扰离子等对As(V)去除的影响. 结果表明,煤质活性炭作为基质负载水合铁氧化物比椰壳炭和果壳炭具有更好的除砷效果. 随着炭粒度降低,除砷效率显著增加. 在pH 3~9范围内,活性炭负载水合铁氧化物可有效吸附As(V). F-, Cl-, SO42-的加入对As(V)的去除效率基本无影响,而SiO32-和PO43-则明显抑制As(V)的去除. Langmuir模型比Freundlich模型能更好地描述复合吸附剂对As(V)的吸附平衡. 动力学研究表明,As(V)吸附反应可用二级速率方程描述. 相似文献
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Liladhar B. Kumbhare Amey P. Wadawale Vimal K. Jain Monika Sieger Wolfgang Kaim 《Inorganic chemistry communications》2010,13(4):475-478
Monoselenocarboxylate–bridged binuclear complexes of RhIII and IrIII, [(Cp1MCl)2(μ-SeCOAr)2] (1) (M = Rh or Ir; Cp1 = pentamethylcyclopentadienyl; Ar = Ph, C6H4Me–4), have been isolated either by the reaction between [Cp12M2(μ-Cl)2Cl2] with KSeCOAr in acetonitrile or by treatment of [Cp1MCl(solvent)2][PF6] with KSeCOAr in acetone. The novel binuclear complexes, [Cp1IrCl(μ-SeCOAr)(κ2-SeCOC6H3R–)IrCp1] (2) (R = H or Me-4) with ortho-metallation at one of the iridium centres have been isolated following the use of excess AgPF6. The single crystal structure of [Cp1IrCl(μ-SeCOC6H5)(κ2-SeCOC6H4–)IrCp1] (2a) exhibits two phenylcarboselenolate moieties situated in syn fashion with respect to the “Ir2Se2” plane, one of which leans towards the metal centre in order to undergo ortho-metallation after iridium–chlorine bond dissociation. 相似文献
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A tetranuclear cluster and an alternating zigzag chain were synthesized via rational assembly of the same cyanometalate building blocks with different Mn(III) Schiff bases possessing varying proportions of sterically hindered groups causing steric hindrances. The tetranuclear cluster [(Tp*)Fe(CN)3]2[Mn(salen)]2·H2O [1; [(Tp*)Fe(CN)3]− [Tp* = hydrotris(3,5-dimethylpyrazol-1-yl) borate], salen = N,N′-ethylenebis(salicylideneiminato) dianion] was formed with Schiff bases possessing smaller steric hindrances, whereas the one-dimensional alternating zigzag chain {[(Tp*)Fe(CN)3Mn(salcyen)]·2CH3OH·H2O}n [2; salcyen = N,N′-(1,2-cyclohexanediylethylene)bis(salicylideneiminato) dianion] was formed with Schiff bases possessing larger steric hindrances. Magnetic measurements revealed that 1 exhibits single-molecule-magnet behavior with dominant ferromagnetic interactions, whereas 2 exhibits spin-canting behavior with dominant antiferromagnetic interactions. 相似文献
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废水中As(III)的减少速率在开始半小时内较快,半小时后速率较慢,慢反应阶段遵循一级反应动力学方程: ln[As(III)]=-kt+c. MnO2对As(III)的氧化能力随pH的升高而呈上升趋势.温度的升高有利于MnO2对As(III)的氧化.在MnO2氧化As(III)过程中,As(III)扩散到MnO2表面或As(V)从表面扩散到溶液中的反应是整个过程的限速反应. 相似文献
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《Electrochimica acta》1986,31(5):595-598
The electrochemical behaviour of the cobalt(III)—cobalt(II) couple in 96.5% and 85 wt% H3PO4 have been studied at a stationary gold electrode by using chronopotentiometry and triangular voltamperometry. The results have shown that the Co(III)—Co(II) system is reversible and the electrode reaction involves a single electron. The Co(II) ions' diffusion coefficient in the two phosphoric acid solutions was determined as 4.3 × 10−8 cm2.s− in 96.5% wt % H3PO4 and 1.2 × 10−7 cm2.s−1 in 85 wt % H3PO4. The stabillity of the Co(III) ion in 96.5 wt % H3PO4 media was also investigated. 相似文献
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本研究系统地比较了不同金属离子对邻苯二胺(OPD)的氧化能力,基于Fe3+ 能直接氧化邻苯二胺(OPD) 产生黄色发荧光的产物,发展了Fe3+-OPD显色体系。硫化物的加入促使Fe3+-OPD显色液的颜色,吸光度和荧光成比例下降,而其他还原性物质及硫醇对硫化物的检测无干扰,基于此发展了选择性检测硫化物的比色法。实验结果表明,向OPD溶液中加入Fe3+,吸光度和荧光随着Fe3+浓度上升成比例增加,溶液从无色变为黄色,在50-1000 μmol/L范围内具有良好的线性关系,检测限为10μmol/L。向Fe3+-OPD显色液加入硫化物,在硫化物浓度1~300 μmol/L 范围内,吸光度和荧光强度成比例下降,溶液的黄色褪去,检测限为0.1μmol/L。在此基础上,将Fe3+-OPD显色体系结合纸芯片,所构建的纸基比色体系蓝色分析色道值即B值与硫化物的浓度在20~150μmol/L浓度范围内呈现良好的线性关系,检测限为 2 μmol/L,可用于定量加标自来水和血清中硫化物含量。 相似文献
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