Ein α-Spektrometcr für Untersuchungen mit Umweltnukliden

Es wird ein einfaches α-Spektrometer mit einem Halbleiterdelektor beschrieben, das für die Messung von Umweltnykliden entwickelt wurde. Zur Anpassung an unterschiedliche Meßaufgaben kann die Meßgeometrie durch Variation des Präparat-Detektor-Abslandes und durch Einbau von Blenden verändert werden. Dabei ist eine gewählte Meßgeometrie mit hoher Genauigkeit reproduzierbar. Die Nachweisgrenze des α-Spektrometers beträgt bei einer Meßzeit von 4 · 10⁵ s etwa 2,3 mβq, das entspricht 0,18 μg U bzw, 0,55 μg Th.     

Simultaneous extraction and preconcentration of uranium and thorium in aqueous samples by new modified mesoporous silica prior to inductively coupled plasma optical emission spectrometry determination

A new synthesized modified mesoporous silica (MCM-41) using 5-nitro-2-furaldehyde (fural) was applied as an effective sorbent for the solid phase extraction of uranium(VI) and thorium(IV) ions from aqueous solution for the measurement by inductively coupled plasma optical emission spectrometry (ICP OES). The influences of some analytical parameters on the quantitative recoveries of the analyte ions were investigated in batch method. Under optimal conditions, the analyte ions were sorbed by the sorbent at pH 5.5 and then eluted with 1.0 mL of 1.0 mol L⁻¹ HNO₃. The preconcentration factor was 100 for a 100 mL sample volume. The limits of detection (LOD) obtained for uranium(VI) and thorium(IV) were 0.3 μg L⁻¹. The maximum sorption capacity of the modified MCM-41 was found to be 47 and 49 mg g⁻¹ for uranium(VI) and thorium(IV), respectively. The sorbent exhibited good stability, reusability, high adsorption capacity and fast rate of equilibrium for sorption/desorption of uranium and thorium ions. The applicability of the synthesized sorbent was examined using CRM and real water samples.     

Pectin based cerium (IV) and thorium (IV) phosphates as novel hybrid fibrous ion exchangers synthesis,characterization and thermal behaviour

Summary Pectin based cerium (IV) and thorium (IV) phosphates have been synthesized as new phases of hybrid fibrous ion exchangers. Both materials were characterized using X-ray diffraction, infrared (IR) spectra, thermogravimetric analysis (TG), differntial thermogravimetry (DTG), differntial thermal analysis (DTA) and scanning electron microscopy (SEM), as well as the determination of their ion exchange capacity, elution and pH titration. The X-ray study reveals the amorphous nature of the materials, while SEM studies confirm the fibrous nature of the materials. The thermal studies of these materials indicate that both of them are highly stable on heating as they retain about 97% of their ion-exchange capacity (i.e.c.) on heating up to 100°C and about 81% on heating up to 200°C.     

Determination of thorium by adsorptive type chemically modified electrode with a polycomplex system

A preconcentration and determination method for thorium in aqueous solution with a tri-n-octylphosphine oxide modified glassy carbon electrode is proposed. In the presence of 2-thenoyltrifluoroacetone, thorium in NaAc-HAc supporting electrolyte is preconcentrated on a modified rotating disk electrode, and a highly sensitive reduction peak is obtained by cathodic stripping voltammetry at –1.10 V versus Ag/AgCl. A linear response of reduction peak height and concentration is observed for 1.15×10^–9–1.44×10^–8 mol·1^–1 of thorium and the detection limit is 1.0×10^–9mol·1^–1. It is very selective and sensitive, with a standard deviation of 3.4% and a recovery of 90–110%.     

Measurement and Modeling of Th Sorption onto TiO(2)

The sorption and desorption of Th onto TiO₂ (10 g/L) was studied as a function of pH (1–11), ionic strength (0.005–0.1 M NaCl, NaClO₄), thorium concentration (from 1 × 10⁻⁹ to 3 × 10⁻² M), and carbonate concentration (up to 10⁻² M) using ²³⁴Th tracer. The results indicate the reversible formation of an inner sphere complex with a strong pH dependence. No effect of the carbonate on sorption could be measured in the pH range investigated (5–10.5). The data were fitted with five different conceptual models (constant capacitance, diffuse layer, Stern, triple layer, and a nonelectrostatic model) using FITEQL. Different hydroxy complex surface reactions were tried, one at a time, varying the site density (1–12 sites/nm²). The reaction that provided the best fit depended strongly on the surface site density and the model used. To be able to fit a reaction to the pH-dependent data with the compact layer models, the effect of the electrostatic term had to be decreased by decreasing the site density below 5 sites/nm². None of the electrostatic models could be used to fit all of the isotherm data. The nonelectrostatic model could be used to reasonably fit both the pH-dependent and isotherm data.     

Syntheses and crystal structures of SmIII and ThIV complexes with macrocyclic cavitand cucurbituril

Slow evaporation of solutions of samarium nitrate and thorium chloride in hydrochloric acid containing the macrocyclic cavitand cucurbituril (C₃₆H₃₆N₂₄O₁₂) afforded crystals of the [{Sm(H₂O)₅(NO₃)}₂(C₃₆H₃₆N₂₄O₁₂)](NO₃)₄·6.5H₂O and [{Th(H₂O)₅Cl}₂(C₃₆H₃₆N₂₄O₁₂)]Cl₆·13H₂O complexes, respectively. The [Sm(C₃₆H₃₆N₂₄O₁₂)(H₂O)₅(SO₄)][Sm(H₂O)₅(SO₄)₂]·17H₂O complex was generated upon heating (130 °C) of a mixture of samarium sulfate, cucurbituril, and water in a sealed tube. X-ray diffraction analysis demonstrated that the metal atoms in these complexes are bound to the portal oxygen atoms of the cucurbituril molecules. In addition, the portal oxygen atoms of cucurbituril are linked to the coordinated H₂O molecules via hydrogen bonds.     

异丙基磷酸单(1-已基-4-乙基)辛酯萃取分离锆、钍、钛、铁、镥及其机理

本文通过异丙基膦酸单(1-己基-4-乙基)辛酯在硫酸介质中对Zr~(4+)、Th~(4+)、Ti~(4+)、Fe~(3+)、Lu~(3-)的萃取平衡研究,探讨了Zr~(4-)与其它离子分离的可能性,提出了萃取Zr~(4-)的三种反应机理,并计算了萃取反应平衡常数和热力学函数.     

New Twists and Turns for Actinide Chemistry: Organometallic Infinite Coordination Polymers of Thorium Diazide

Two organometallic 1D infinite coordination polymers and two organometallic monometallic complexes of thorium diazide have been synthesized and characterized. Steric control of these self‐assembled arrays, which are dense in thorium and nitrogen, has also been demonstrated: infinite chains can be circumvented by using steric bulk either at the metallocene or with a donor ligand in the wedge.     

电感耦合等离子体质谱法测定水中铀钍元素的含量

建立了电感耦合等离子体质谱测定水中铀钍元素含量的方法。水样以硝酸酸化处理后直接用电感耦合等离子体质谱法测定,为了消除铀记忆效应对测定结果的干扰,测试溶液的质量浓度以不超过10μg/L为宜,样品测定间隙设置清洗时间为2 min。铀钍元素标准曲线线性相关系数分别为0.999 4,0.999 5;铀、钍的检出限分别为0.000 9,0.002 1μg/L;加标回收率分别为95.70%~112.33%,96.94%~109.98%;测定结果的相对标准偏差分别为0.61%~5.33%,1.16%~1.33%。