Effects of Tl-filling into the voids and Rh substitution for Co on the thermoelectric properties of CoSb3

In order to enhance the thermoelectric (TE) properties of CoSb₃, we tried to reduce the lattice thermal conductivity (κ_lat) by filling Tl into the voids and substitution of Rh for Co. We prepared polycrystalline samples of Tl_x(Co_1−yRh_y)₄Sb₁₂ (x = 0, 0.05, 0.10, 0.15, 0.20 and y = 0.1, 0.2) and examined their TE properties from room temperature to 750 K. All the samples indicated negative values of the Seebeck coefficient (S). Both the electrical resistivity and the absolute values of the S decreased with increasing the Tl-filling ratio. The Tl-filling and Rh substitution reduced the κ_lat, due to the rattling and the alloy scattering effects. The minimum value of the κ_lat was 1.54 W m⁻¹ K⁻¹ at 550 K obtained for Tl_0.20(Co_0.8Rh_0.2)₄Sb₁₂. Tl_0.20(Co_0.8Rh_0.2)₄Sb₁₂ exhibited the best TE performance; the maximum value for the dimensionless figure of merit ZT was 0.58 at around 600 K.     

铅锌尾矿库铊迁移转化及污染控制

通过对取自云南氧化铅锌尾矿、硫化铅锌尾矿和库周土壤样品中的铊进行含量、形态和有效态分析，结合产酸试验和静态浸出试验研究铊在铅锌尾矿中的迁移转化过程和影响因素。结果表明：pH值和尾矿组成是影响铊释放的主要因素；而尾矿中有效态铊与铊总量比值是表征其释放风险的重要指标；酸性条件下铊更易溶解释放，碱性条件下尾矿中铊的活性会被抑制；pH=2时，受试硫化铅锌尾矿中铊的浸出率达32.25%；尾矿中铊由水体进入到土壤中应是造成库周土壤铊污染的主要途径，针对调查的受铊污染铅锌尾矿库周土壤，提出了“工程措施+化学沉淀+植物修复”的综合铊污染控制治理方案。     

Adsorption of thallium cations on RuO<Subscript>2</Subscript>–TiO<Subscript>2</Subscript> electrodes

The electrochemical ion-exchange properties of RuO₂–TiO₂ film electrodes with different composition have been studied in acidic and alkaline media. Thallium-cation uptake has been observed only from the latter and its extent was found to be a function of electrode potential and composition. At potentials near 0.0 V (RHE), the amount of adsorbed Tl⁺ exhibited a maximum, and decreased with increasing potential, reaching a broad minimum in the range 0.4–0.8 V. A further increase in the electrode potential, above about 1.0 V, led to an increase of adsorbed thallium species, essentially due to deposition of a few layers of Tl(III) hydroxide. In fact, the release of the latter species was found to be much slower than that of thallium ions adsorbed at 0.0 V. For the latter, in turn, the double injection/ejection mechanism, currently accepted to explain the charge-storage in oxide electrodes, seems to be confirmed. The high Γ values attained at 0.0 V indicate that the large ionic radius of Tl⁺ does not prevent its diffusion through the thinner pore texture of the oxide coatings, possibly because of its poor hydration, related with lower charge density at the ion surfaces.     

精铟中铊的氯化脱除

探索了采用NH4Cl的甘油溶液熔炼除铊来代替传统除铊的方法。研究表明 :NH4Cl的甘油溶液浓度为15 % (质量分数 ) ,熔炼时间为 2 0min ,熔炼温度为 2 2 0℃时 ,可除去精铟中 6 0 %～ 70 %的铊 ,铊含量降低 4 0 μg/g左右。该方法具有纯化效果好、操作简单、能缩短工艺流程、避免了有毒物质的使用的优点。     

Sawdust: A green and economical sorbent for thallium removal

Removal/preconcentration of thallium(I) ions from aqueous solution by sawdust; a waste material derived from the commercial processing of Cedrus Deodar wood for furniture production was investigated. A simple and low-cost modification results in increasing the sorption capacity of raw sawdust from 2.71 to 13.18 mg g⁻¹. Sorption was found to be rapid (98% within 8 min). The binding of metal ions was found to be pH dependent, optimal sorption accruing at around pH 6–9. Potentiometeric titrations of sawdust revealed two distinct pK_a values, the first having the value similar to carboxylic groups (3.3–4.8) and second comparable with that of amines (8.53–10.2) with the surface site densities of 1.99 × 10⁻⁴ and 7.94 × 10⁻⁵ mol g⁻¹, respectively. Retained Tl(I) ions were eluted with 5 ml 0.1 mol l⁻¹ HCl. Detection limit of 0.0125 μg ml⁻¹ was achieved with an enrichment factor of 160. Recovery was quantitative using sample volume of 800 ml. The Langmuir, Freundlich and D–R isotherm equations were used to describe partitioning behavior for the system at different temperatures. Kinetic and thermodynamic behavior of sawdust for Tl(I) ions removal was also studied.     

Calculation of surface tension and surface phase transition line in binary Ga–Tl system

The surface phase transition (SPT) line has been calculated at the Ga-rich side of the binary Ga–Tl system. The liquid alloys at a given temperature can be divided into the following four different regions as a function of Tl-content of the alloy: (i) at very low Tl-content one bulk Ga-rich alloy is obtained not covered by any nano-layer, (ii) at a somewhat higher Tl-content one bulk Ga-rich liquid phase is obtained, covered by a Tl-rich nano-layer, (iii) at medium Tl-content two bulk liquids are obtained, (iv) at high Tl-content one Tl-rich liquid is obtained with no nano-layer on it. An improved version of the Ga–Tl phase diagram is offered, showing the equilibrium SPT line and the region of the Ga-rich bulk liquid, covered by a Tl-rich nano-layer. The presence of the latter changes some physical properties of the system. Particularly, the temperature coefficient of the surface tension changes from a low negative value to a high positive value when increasing the Tl-composition of the alloy and the SPT line is crossed. The position of the SPT line is essential to control Marangoni convection in liquid monotectic alloys.     

PDB-18C6对TI(Ⅰ),An(Ⅲ),Cu(Ⅱ)的吸附及从α轰击的金靶中分离~(199)TI

本文研究了用冠醚树脂二苯并-18-冠-6甲醛聚合物(简称PDB-18C6)对T1(Ⅰ),Au(Ⅲ),Cu(Ⅱ)的吸附行为。实验表明,在盐酸溶液中冠醚树脂的吸附效率顺序为Au(Ⅲ)>T1(Ⅰ)>Cu(Ⅱ)。用高氯酸和乙二醇乙醚淋洗T1(Ⅰ),Au(Ⅲ),它们的回收率一般在82-98.9％和98-100％。还在1.2m回旋加速器的外靶装置上,用25-27MeV的α粒子轰击金靶,累计束流强度为27μA·h,经处理分离后得到仅含0.50％~(200)T1的较高纯度的~(199)T1。     

铊原子激光共振电离研究

用 N d:YAG激光及其泵浦的染料激光进行铊原子三步共振电离。求解了非饱和共振过程速率方程 ,计算出基态和激发态吸收截面 ,给出电离效率分别与激发电离速率以及作用时间的变化关系 ,得到饱和激发电离的流量条件和通量条件。     

ICP-MS法测定生活饮用水和地表水中的铊元素

用电感耦合等离子体质谱法测定生活饮用水和地表水中的铊元素,该方法不需要进行繁琐的分离富集等预处理,也避免了光谱干扰,十分简便、快速。结果表明,该元素的检出限为7.0×10-4μg/L,加标回收率在95-102%,对质控样品平行测定6次,相对标准偏差为0.6%,完全满足对生活饮用水和地表水进行铊元素分析的要求。     

Transfer of thallium from rape seed to rape oil is negligible and oil is fit for human consumption

Rape and other Brassicaceae family plants can accumulate appreciable amounts of thallium from the soil. Because some species of this family are common crops utilised as food for direct consumption or raw materials for food production, thallium can enter the food chain. A useful method for thallium determination is inductively coupled plasma mass spectrometry. The limit of detection (0.2 pg ml^–1 Tl or 0.02 ng g^–1 Tl, taking in the account dilution during sample decomposition) found in the current study was very low, and the method can be used for ultra-trace analysis. Possible transfer of thallium from rape seed to the rape oil was investigated in two ways. The balance of thallium in rape seed meal (content 140–200 ng g^–1 Tl) and defatted rape seed meal indicated that thallium did not pass into the oil (p < 0.05). Moreover, the analyses of thallium in six kinds of edible rape seed oil and three kinds of margarines showed that the amount of thallium in rape seed oil is negligible.