Complexing tendencies of UO 22+ and Th4+ in their mixed ligand complexes with aminopolycarboxylates and resorcinol or its derivatives

Formation contants (log K _MAL ^MA ) of mixed ligand complexes MAL, where M = UO ₂ ²⁺ or Th⁴⁺, A = IMDA, NTA, HEDTA, EDTA, CDTA or DTPA, and L = resorcinol (res), 2-methyl resorcinol (2-Me-res), 5-methyl resorcinol (5-Me-res) or 4-chloro resorcinol (4-Cl-res), have been determined pH-metrically by the Irving-Rossotti approach at 25°C and at an ionic strength,I = 0.2(moldm⁻³KNO₃). The observed stability sequences are IMDA > NTA > HEDTA > EDTA > CDTA > DTPA, and 4-Cl-res > 5-Me-res > 2-Me-res > res with respect to primary and secondary ligands, respectively. Th⁴⁺ forms more stable mixed complexes than UO ₂ ²⁺ . The A ΔlogK values are negative due mainly to the charge repulsion involved in the complexation MA + L⇋MAL.     

Metal Chelates of Cerium (III), Thorium(IV) and Dioxouranium(VI) with Some Heterocyclic AZO Dyes; Potentiometric and Spectrophotometric Studies

ABSTRACT

The stepwise formation constants of Ce³⁺, Th⁴⁺ and UO₂ ²⁺ complexes with four azo compounds based on I-phenyl-2, 3-dimethylpyrazoline-5-one nucleus namely; 4-phenylazo- (2-hydroxy, 5-x) 1-pheny1-2, 3-dimethy1-pyrazoline-5-one, where x= H (1), OH (II), COOH (III) and NH₂ (IV) have been determined potentiometrically at different temperatures and ionic strengths in 30% (v/v) ethanol-water solutions, then the thermodynamic parameters are calculated.

Negatives values of both ∠H and ∠G are obtained indicating the exothermic and spontaneous nature of complexation reactions, whereas positive values of ∠S show that entropy consideration favour complex formation. The study at different ionic strengths shows that an increase in the latter causes a decrese in the pK values. The azo compounds are also tested as new reagents for the spectrophotometric determination of Ce³⁺, Th4⁺ and UO₂ ²⁺ ions in synthetic and natural solutions by extensive investigation of the optimum conditions favoring the formation of colored complexes.     

Uranyl-catalyzed chemiluminescent reaction of U4+ oxidation by dioxygen in aqueous HClO4 solution

Chemiluminescence (CL) accompanying the reaction of U⁴⁺ with O₂ in 0.0004–0.1M HClO₄ was studied. It was found that the electron-excited uranyl ion (UO₂ ²⁺)^* is the CL emitter. The fact that the reaction rate and the CL yield increase as the solution acidity decreases was explained by different reactivities of the U _aq ⁴⁺ aquation and the products of its stepwise hydrolysis, UOH³⁺ and U(OH)₂ ²⁺, toward O₂. Based on the results of analysis of the chain-radical mechanism of the reaction between U⁴⁺ and O₂, it was concluded that transfer of an electron from the UO₂ ⁺ ion to the oxidizing agent (a ·OH radical) is the most plausible elementary step of the reaction of (UO₂ ²⁺)^* formation. It was found that the reaction rate, as well as the CL yield, increase substantially in the presence of uranyl ion. Catalytic action of UO₂ ²⁺ was explained by the formation of a UO₂ ²⁺·UO₂ ⁺ complex, which reduces the rate of the UO₂ ⁺ disproportionation reaction (UO₂ ⁺ is an intermediate of the reaction and is involved in chain propagation), and by regeneration of the active center, UO₂ ⁺, in the reaction of UO₂ ²⁺ with U⁴⁺. Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1522–1528, September, 2000.     

Simultaneous mixture analysis by using non-linear spectrophotometric data and linear iterative target transformation factor analysis

Non-linear absorption spectral data obtained from ternary mixtures of analytes are analyzed by using a linear model, iterative target transformation factor analysis (ITTFA). The use of transformed original variables is used to correct non-linearities in the original data. Absorbance below a certain limit (k) is described as linear and above this limit as non-linear. The extension of the regressor variables is the squared absorbances above the linear range. The variation of the prediction error as a function of the number of the factors and the k-values were considered and the minimum prediction error was evaluated for reaching to optimum. Except the natural non-negativity constraint the correlation constraint also is used on concentration vector in each iteration of ITTFA algorithm. The reliability of the method is evaluated using model data for ternary mixtures by spectral overlapping and different degrees of non-linearity. Simultaneous spectrophotometric determination of Eu³⁺, UO₂²⁺ and Th⁴⁺ with arsenazo III as chromogenic reagent is used as experimental model systems with non-linearity behavior of Eu³⁺and UO₂²⁺ components. The application to both synthetic and real data sets with different degrees of non-linearity demonstrate the ability of the proposed methodology to obtain better results than original data and ITTFA. The relative standard errors of prediction for proposed method in comparison with using the PLS calibration on original and extended data are nearly smaller.     

CMPO/[Cnmim][NTf2]体系对Eu3+和UO22+的萃取行为

讨论了辛基(苯基)-N,N-二异丁基胺甲酰基甲基氧化膦(CMPO)/1-烷基-3-甲基咪唑双(三氟甲烷磺酰)亚胺盐([C_nmim][NTf₂],n=2,8,12)萃取体系分别对硝酸溶液中的铕离子(Eu³⁺)和铀酰根离子(UO₂²⁺)的萃取行为。主要研究了硝酸浓度、接触时间、温度、CMPO浓度对CMPO/[C_nmim][NTf₂]体系萃取性能的影响,并选取CMPO/[C2mim][NTf₂]体系对模拟高放废液中的镧锕元素进行了萃取分离。结果表明:随着离子液体侧链长度增长,萃取平衡时间逐渐延长;CMPO/[C2mim][NTf₂]体系对Eu³⁺的萃取是放热反应,萃取率随酸度增加而逐渐降低,对UO₂²⁺则是吸热反应,萃取率随酸度增加而逐渐升高;通过机理研究,推测出对Eu³⁺的萃取反应是离子交换,而对UO₂²⁺的萃取反应则是中性配位;CMPO/[C2mim][NTf₂]体系能有效的萃取模拟高放废液中的镧系、锕系元素,且在高酸下有一定的镧锕分离效果。     

不同浓度Sn4+离子掺杂TiO2的结构、性质和光催化活性

采用溶胶-凝胶法制备出纯TiO₂和不同浓度Sn⁴⁺离子掺杂的TiO₂光催化剂(TiO₂-Snx%, x%代表Sn⁴⁺离子掺杂的TiO₂样品中Sn⁴⁺离子摩尔分数). 利用X 射线衍射(XRD)、X 射线光电子能谱(XPS)和表面光电压谱(SPS)确定了TiO₂-Snx%催化剂的晶相结构和能带结构, 结果表明: 当Sn⁴⁺离子浓度较低时, Sn⁴⁺离子进入TiO₂晶格, 取代并占据Ti⁴⁺离子的位置, 形成取代式掺杂结构(Ti_1-xSn_xO₂), 其掺杂能级在导带下0.38 eV处; 当Sn⁴⁺离子浓度较高时, 掺入的Sn⁴⁺离子在TiO₂表面生成金红石SnO₂, 形成TiO₂和SnO₂复合结构(TiO₂/SnO₂), SnO₂的导带位于TiO₂导带下0.33 eV处. 利用瞬态光电压谱和荧光光谱研究了TiO₂-Snx%催化剂光生载流子的分离和复合的动力学过程, 结果表明, Sn⁴⁺离子掺杂能级和表面SnO₂能带存在促进光生载流子的分离, 有效地抑制了光生电子与空穴的复合; 然而, Sn⁴⁺离子掺杂能级能更有效地增加光生电子的分离寿命, 提高了光生载流子的分离效率, 从而揭示了TiO₂-Snx%催化剂的光催化机理.     

Ca2+-Mg2+-Zn2+体系在水溶性聚磷酸铵溶液中螯合规律的研究

近年来,水溶性聚磷酸铵在液体肥料和复合肥料的领域受到了广泛的关注,并在发达国家中得到了大面积的推广及应用。在pH值为5.5~8.0、温度为278.15 K~323.15 K的条件下,本文采用滴定法研究Ca_²⁺-Mg_²⁺-Zn_²⁺体系在聚磷酸铵溶液中的螯合规律。实验结果表明：相同质量分数的聚磷酸铵溶液对金属离子的螯合量会随着体系中Ca_²⁺、Mg_²⁺、Zn_²⁺的摩尔浓度的变化而变化;随着温度的升高而逐渐降低;随着pH的增加而逐渐增加;随着聚合度的升高而逐渐增加。采用傅里叶红外光谱对聚磷酸铵和A₁B₃C₃体系的螯合物进行表征。     

The crystal structure of ZnFe 2 3+ (SeO3)4

Summary The new synthetic compound ZnFe ₂ ³⁺ (SeO₃)₄ forms at low-hydrothermal conditions at 220 °C. It belongs to the monoclinic system; the structure was determined by single-crystal X-ray diffraction in the space group Pc. The unit cell data are:a=8.196(4) Å,b=7.997(4) Å,c=8.033(4) Å, =92.27(3)°,V=526.1 ų;Z=2. The structure of ZnFe ₂ ³⁺ (SeO₃)₄ contains two types of FeO₆ octahedra, one distorted ZnO₅ trigonal bipyramid, and four selenite groups. Formal clusters consisting of the ZnO₅ group, edge-linked with both FeO₆ groups and one SeO₃ pyramid, are connected by common corners, involving three further selenite groups to a framework structure.

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Die Kristallstruktur von ZnFe ₂ ³⁺ (SeO₃)₄

Zusammenfassung Die neue synthetische Verbindung ZnFe ₂ ³⁺ (SeO₃)₄ bildet sich bei niedrighydrothermalen Bedingungen (220°C). Die Kristallstruktur wurde mit Einkristallröntgenmethoden in der monoklinen Raumgruppe Pc gelöst. Die Zellparameter sind:a=8.196(4) Å,b=7.997(4) Å,c=8.033(4) Å, =92.27(3)°,V=526.1 ų;Z=2. Die Kristallstruktur von ZnFe ₂ ³⁺ (SeO₃)₄ weist zwei Arten von FeO₆-Oktaedern, eine verzerrte trigonale ZnO₅-Dipyramide sowie vier Selenitgruppen auf. Formal können Cluster, bestehend aus dem ZnO₅-Polyeder, kantenverknüpft mit den beiden FeO₆-Gruppen sowie einer SeO₃-Pyramide, beschrieben werden. Die Verknüpfung über Ecken zu einer Gerüststruktur erfolgt unter Beteiligung von drei weiteren Selenitgruppen.

     

Studies of C. I. Acid Red 186 and Metal Complexes with Uo++2, Ce3+ and Th6+ Ions

The electronic absorption spectra of C. I. Acid Red 186 are studied in solution of different pH. The pK values of the acid-base equilibria set are determined and commented upon. The complexes of UO⁺⁺₂, Ce³⁺ and Th⁴⁺ ions are investigated by some spectroscopic techniques and potentiometric titration. The formation of 1:1, 1:2 and 1:2 complexes (M:L) with UO₂⁺⁺, Ce³⁺ and Th⁴⁺ respectively is confirmed and their conditional stability constants are determined. The solid complexes are prepared and analysed for their metal content, their ir spectra are disussed in comparison to that of the ligand to establish the bonding between the ligand and metal ions.     

Ge4+、Sn4+掺杂尖晶石LiMn2O4的合成与电化学表征

使用Ge⁴⁺、Sn⁴⁺作为掺杂离子, 通过高温固相法制备四价阳离子掺杂改性的尖晶石LiMn₂O₄材料. X射线衍射(XRD)和扫描电子显微镜(SEM)分析表明, Ge⁴⁺离子取代尖晶石中Mn⁴⁺离子形成了LiMn_2-xGe_xO₄ (x=0.02,0.04, 0.06)固溶体; 而Sn⁴⁺离子则以SnO₂的形式存在于尖晶石LiMn₂O₄的颗粒表面. Ge⁴⁺离子掺入到尖晶石LiMn₂O₄材料中, 抑制了锂离子在尖晶石中的有序化排列, 提高了尖晶石LiMn₂O₄的结构稳定性; 而在尖晶石颗粒表面的SnO₂可以减少电解液中酸的含量, 抑制酸对LiMn₂O₄活性材料的侵蚀. 恒电流充放电测试表明, 两种离子改性后材料的容量保持率均有较大幅度的提升, 有利于促进尖晶石型LiMn₂O₄锂离子电池正极材料的商业化生产.     

Hydrolysis of dioxouranium(VI): a calorimetric study in NaClaq and NaClO4 aq, at 25 °C

We report the results of a calorimetric study on the hydrolysis of UO₂²⁺ in different ionic media (NaClO_4 aq, NaCl_aq) at 25 °C. Experiments in NaCl were performed at different ionic strength, at I≤1 mol l⁻¹. The species considered in both ionic media were UO₂(OH)⁺, (UO₂)₂(OH)₂²⁺ and (UO₂)₃(OH)₅⁺, and in addition (UO₂)₃(OH)₄²⁺ and (UO₂)₃(OH)₇⁻ in NaCl_aq. The dependence on ionic strength of enthalpy changes in NaCl_aq was expressed by the simple linear equation ΔH_pq=ΔH°_pq+aI^1/2 (a, empirical parameter). Comparison with literature findings is given and some recommended values are reported.     

NaBaPOM4:Tb3+绿色荧光粉制备及其发光特性

采用高温固相法合成了NaBaPOM₄:Tb³⁺绿色荧光粉, 并研究了材料的发光性质. NaBaPOM₄:Tb³⁺材料呈多峰发射, 发射峰位于437、490、543、587和624 nm, 分别对应Tb³⁺的⁵D₃→⁷F₄和⁵D₄→⁷F_{J=6, 5, 4, 3}跃迁发射, 主峰为543 nm; 监测543 nm发射峰, 所得激发光谱由4f⁷5d¹宽带吸收(200-330 nm)和4f-4f 电子吸收(330-400 nm)组成, 主峰为380 nm. 研究了Tb³⁺掺杂浓度, 电荷补偿剂Li⁺、Na⁺、K⁺和Cl^-, 及敏化剂Ce³⁺对NaBaPOM₄:Tb³⁺材料发射强度的影响. 结果显示: 调节激活剂浓度、添加电荷补偿剂或敏化剂均可以在很大程度上提高材料的发射强度.     

Anion-exchange separation of thorium and protactinium from uranium matrix

Summary The distribution behaviour of Th⁴⁺, Pa⁵⁺, and UO₂ ²⁺ ions between the anion-exchanger Amberlite IRA-400 and acetic acid-hydrochloric acid mixtures, has been investigated. It was found that the general behaviour of Th⁴⁺ ions is similar to that of UO₂ ²⁺ ions though the latter are much more highly adsorbed by the resin than Th⁴⁺. Protactinium exhibited a different behaviour from both Th⁴⁺ and UO₂ ²⁺ ions. The separation factors were calculated, and a Chromatographic procedure for sequential isolation of each element was developed.

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Zusammenfassung Das Verteilungsverhalten von Th⁴⁺, Pa⁵⁺ und UO₂ ²⁺ zwischen dem Anionenaustauscher Amberlit IRA-400 und Gemischen aus Essigsäure und Salzsäure wurde untersucht. Das allgemeine Verhalten von Th⁴⁺ ist ähnlich dem von Uranylionen, wenngleich letztere von dem Harz viel stärker adsorbiert werden als Th⁴⁺. Protactinium zeigt ein abweichendes Verhalten im Vergleich zu Th⁴⁺ und UO₂ ²⁺. Die Trennfaktoren wurden berechnet und ein chromatographisches Verfahren zur Isolierung der angeführten Ionen entwickelt.

     

Evaluation of 4-amino-2-hydroxybenzoic acid as an eluent for indirect photometric determination of uncommon anions

Summary The efficacity of 4-amino-2-hydroxybenzoic acids as an eluent for the separation and determination of uncommon anions has been evaluated. The intensely absorbing eluent (λ_max 320 nm) offers a convenient indirect photometric approach to quantitate the species of interest in ppm and sub-ppm range. In the singlecolumn ion chromatography mode at 2 mM/2 mL/min and pH=6.0, clean separations of common and uncommon anions can be realized.     

Isomerization ofn-butane on the SO4/ZrO2 catalyst promoted by IV Period metals

The catalytic activity of superacidic systems based on SO₄/ZrO₂ and modified by IV Period metals in isomerization ofn-butane was studied. At low temperatures of the reaction, the introduction of Fe³⁺, Sc³⁺, Co²⁺, or Zn²⁺ ions (1%) increases the yield of isobutane by 1.5 times due to the activation ofn-butane on the sites created by the promoting ions. The addition of Cr³⁺, V⁴⁺, or Mn²⁺ (1%) decreases the catalytic activity because of a decrease in the catalyst acidity, most likely, due to the reduction of surface sulfur species. The influence of the nature of the support and surface additives of SiO₂, TiO₂, and ZrO₂ on the activity and selectivity of the catalytic system inn-butane isomerization was studied. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7 pp. 1276–1280, July, 1999     

Solubility of (UO2)3(PO4)2?4H2O in H+-Na+-OH?-H2PO?4-HPO2?4-PO3?4-H2O and Its Comparison to the Analogous PuO2 +2 System

The objectives of this study were to address uncertainties in the solubility product of (UO₂)₃(PO₄)₂⋅4H₂O(c) and in the phosphate complexes of U(VI), and more importantly to develop needed thermodynamic data for the Pu(VI)-phosphate system in order to ascertain the extent to which U(VI) and Pu(VI) behave in an analogous fashion. Thus studies were conducted on (UO₂)₃(PO₄)₂⋅4H₂O(c) and (PuO₂)₃(PO₄)₂⋅4H₂O(am) solubilities for long-equilibration periods (up to 870 days) in a wide range of pH values (2.5 to 10.5) at fixed phosphate concentrations of 0.001 and 0.01 M, and in a range of phosphate concentrations (0.0001–1.0 M) at fixed pH values of about 3.5. A combination of techniques (XRD, DTA/TG, XAS, and thermodynamic analyses) was used to characterize the reaction products. The U(VI)-phosphate data for the most part agree closely with thermodynamic data presented in Guillaumont et al.,⁽¹⁾ although we cannot verify the existence of several U(VI) hydrolyses and phosphate species and we find the reported value for formation constant of UO₂PO⁻₄ is in error by more than two orders of magnitude. A comprehensive thermodynamic model for (PuO₂)₃(PO₄)₂⋅4H₂O(am) solubility in the H⁺-Na⁺-OH⁻-Cl⁻-H₂PO⁻₄-HPO²⁻₄-PO³⁻₄-H₂O system, previously unavailable, is presented and the data shows that the U(VI)-phosphate system is an excellent analog for the Pu(VI)-phosphate system.     

Microwave synthesis and photoluminescent properties of Sr2CeO4/Ln3+ (Ln = Er, Ho, Tm)

Sr₂CeO₄/Ln³⁺ (Ln = Er, Ho, Tm) phosphors were synthesized with the microwave radiation method for the first time. The luminescent properties of the samples were investigated and the up-conversion luminescence of Er³⁺, Ho³⁺ and Tm³⁺ doped Sr₂CeO₄ phosphors was observed. The spectra indicate that the energy transfer takes place from the triplet excited state of MLCT (metal-to-ligand charge transfer) state for Sr₂CeO₄ (sensitizer) to the rare earth ions (activator). __________ Translated from Journal of Hebei Normal University (Natural Science Edition), 2007, 31(2): 212–216 [译自: 河北师范大学学报 (自然科学版)]     

Complex compounds of tetracycline with WO 4 2− and MoO 4 2− ions. Investigation by pH-metric and conductometric methods

By using pH-metric and conductometric methods it has been found that tetracycline (H₃TC) forms with WO ₄ ^2– and MoO ₄ ^2– ions the following complex compounds: [WO₃HTC]^2–, [WO₃(H₂TC)₂]^2– and [MoO₃(H₂TC)₂]^2–. Stability constants log/gb ₁ ^k =7.86 and log ₁ ^k =7.80 for [WO₃HTC]^2– and [MoO₃HTC]^2–, respectively, have been calculated from pH-metric measurements.     

Complex formation of Al2(SO4)3 in water-formamide mixtures

The kinetics of formation of AlSO ₄ ⁺ has been investigated in mixtures of water and formamide. In contrast to similar measurements with BeSO₄, the substitution of solvating formamide molecules by the sulfate ion cannot be observed on the aluminum cation. On the other hand, with Al³⁺ cations three well separated water substitution processes are observed, as compared to a single one only with Be²⁺. An explanation for this behavior and for the different pH dependence of the sulfate complex formation for Al³⁺ and Be²⁺ cations is suggested.