Superconductivity studies on Tl-Th-Sr-Ca-Cu-O system

Superconductivity with a maximumT _{c, zero} of 58 K forx > 0·75 has been observed in a nominal starting composition, Th _x Tl₂Sr₂Ca₂Cu₃O _y . X-ray data show that the 1212 phase gets stabilized due to part substitution of Th at the Tl-site forx⩾0·25; however,T _c is low forx<0·75.     

Atmospheric inputs of Ag and Tl to the Arctic: comparison of a high resolution snow pit (AD 1994-2004) with a firn (AD 1860-1996) and an ice core (previous 16,000 yr)

Applying strict clean room techniques and sector field ICP-MS, a total of 567 ice and snow samples from Devon Ice Cap, Arctic Canada, have been analysed for silver (Ag) and thallium (Tl), providing a continuous record of atmospheric deposition of both elements for the past approximately 16,000 yr. Concentrations of Ag and Tl ranged from 0.02 to 5.84 pg/g and from 0.03 to 3.40 pg/g, respectively. The natural Tl/Sc background ratio established with ice samples dating between 10,590 and 15,010 yr BP, amounted to 0.11+/-0.03 which is in good agreement with the corresponding value of 0.107 reported for the Upper Continental Crust (UCC). The Ag/Sc background ratio in ice (0.09+/-0.06), in turn, is much more variable and approximately 10-times higher than UCC values. The high temporal resolution provided by 45 samples from the 5 m snow pit representing the period AD 1994 to 2004, revealed the greatest elemental concentrations as well as accumulation rates during the winter months when air masses reach the Arctic predominantly from Eurasia. The greatest Sc concentrations, however, are also found during winter months which clearly reflect strong seasonal variations in atmospheric dust inputs. Enrichment factors calculated for both elements (Ag, Tl) using Sc show contrasting behaviours, with the maximum EF for Tl (up to 48) during summer when air masses arriving to the Arctic are predominantly from North America, probably reflecting coal burning, base metal mining and smelting. The greatest enrichments of Ag (up to 17), on the other hand, tend generally to be found in winter, although some enrichment maxima corresponding to summer months are also seen. While modern Ag EF are comparable to those corresponding to ancient (back to ca. 3 k yr) anthropogenic activities, modern Tl EF clearly exceed the impact of Medieval, Roman and Greek/Phoenician civilization. Accumulation rates during the past decade have been variable (mean 36 and 130 ng/m(2)/yr for Ag and Tl, respectively), but the trend is clearly in decline. Based on the best estimate of natural inputs, more than 80% of the Ag and 90% of the Tl supplied to the Arctic today (AD 1994-2004) are derived from anthropogenic sources.     

非真空坩埚下降法生长CsI(Tl)晶体的闪烁性能

研究了用非真空铂坩埚下降法生长的CsI(Tl)晶体的在紫外和γ射线激发下的光致发光和光衰减特征,探索了CsI(Tl)晶体的发光强度和发光不均匀性与Tl离子含量和分布之间的关系以及改善晶体发光均匀性的措施.并对CsI(Tl)晶体在γ射线辐照下光输出随积分时间和辐照剂量的变化做了分析和讨论.实验表明,用这种方法所生长的CsI(Tl)晶体的发射波长、衰减时间和辐照硬度与其他方法生长的同类晶体相同.     

液膜分离富集与测定工业废水中痕量铊

研究了ＴＢＰ,聚丁二烯,磺化煤油,ＴＵ和Ｎａ２ＳＯ３溶液乳状液膜体系中,Ｔｌ＾３＋的迁移行为,在选择条件下Ｔｌ＾３＋的迁移率达９９．４％以上。该条件下许多金属离子如Ｃｕ＾２＋,Ｐｂ＾２＋,Ｚｎ＾２＋,Ｃｏ＾２＋,Ｎｉ＾２＋,Ｃｄ＾２＋,Ｃａ＾２＋,Ｍｇ＾２＋,Ｆｅ＾３＋,Ａｌ＾３＋,Ｍｎ＾２＋Ａｕ＾３＋等都不被迁移,只有Ｔｌ＾３＋能与这些金属离子得到彻底的分离富集,用于富集测定工业废水中痕量铊,结     

含铊废渣无害化处置试验研究

针对当前含铊废渣没有成熟、适用处置技术的问题,开展含铊废渣无害化处置技术的试验研究。结果表明,采用水泥固化和热固性包胶固化处置技术,在药剂投加量与含铊废渣质量比分别为60%和20%的条件下,处置后的含铊废渣浸出液中铊的浓度在2μg/L以下,可以满足现有《工业废水铊污染物排放标准》(DB44/1989—2017)中铊污染物排放浓度限值的要求。     

铊在铅锌矿选冶过程中的转移及环境影响风险

对铊在铅锌矿选、冶过程中的转移及环境影响风险进行了研究。结果表明,铅锌矿选矿过程中95.94%的铊转移至尾矿,铅冶炼过程中88.33%的铊转移至烟气中,在锌冶炼过程中90.51%的铊主要转移至铜镉、钴渣中。对各类尾矿及废渣进行合理堆放,提高资源再利用技术水平,是降低铊污染的主要途径。     

Formation of Thallium-1223 Superconductors

The pathway for the formation of the thallium-based TlBa₂Ca₂Cu₃O₉ superconductor has been studied by X-ray Diffraction and a-c Susceptibility for samples prepared either by solid-state reaction in air of elemental or mixed oxides or oxidation in oxygen flowing of the metallic TlBa₂Ca₂Cu₃ alloy at temperatures determined by DTA. It is shown that independent on the used procedure, the reaction path implies the double-layer Tl-O series, Tl₂Ba₂CuO₆ and Tl₂Ba₂CaCu₂O₈ at the temperature of 800°C and Tl₂Ba₂Ca₂Cu₃O₁₀ at 875°C. The Tl-1223 phase is formed for temperatures higher than 905°C. This path-way is understood on the basis of phase equilibrium diagram.     

Synthesis and characterization of nano-pore thallium (III) ion-imprinted polymer as a new sorbent for separation and preconcentration of thallium

Thallium (III) ion-imprinted polymer (IIP) particles were synthesized by preparing the ternary complex of thallium (III) ions with 5,7-dichloroquinoline-8-ol (DCQ) and 4-vinylpyridine (VP). Thermal copolymerization with methyl methacrylate (functional monomer, MMA) and ethyleneglycoldimethacrylate (cross-linking monomer, EGDMA) was then performed in the presence of acetonitrile (porogen) and 2,2- azobisisobutyronitrile(initiator, AIBN). The imprinted ion was removed from polymer by stirring of the above particles with 5M HNO(3) to obtain the leached IIP particles. Moreover, control polymer (CP) particles were similarly prepared without the thallium (III) ions. The unleached and leached IIP particles were characterized by surface area analysis (BET), X-ray diffraction (XRD), Fourier transform infra-red spectroscopy (FT-IR), thermo gravimetric analysis (TGA) and scanning electron microscopy (SEM). The preconcentration of thallium (III) from aqueous solution was studied during rebinding with the leached IIP particles as a function of pH, the weight of the polymer material, the uptake and desorption times, the aqueous phase and the desorption volumes. Electrothermal atomic absorption spectrometry (ETAAS) was employed for determination of thallium in aqueous solution. The limit of detection for the method was 0.02 ng mL(-1), while the relative standard deviation for five replicates was 2.6%.     

溶出峰电位相近元素铅、铊和镉的微分电位溶出分析法测定

在许多支持电解质中,Pb,T1和Cd的溶出电位相近,特别是Cd和T1的溶出电位很接近,在同时存在时,难于用电位溶出分析法测定。本文对Pb、T1和Cd在二十多种支持电解质中的微分电位溶出法进行了比较研究。选定0.06mol·dm~(-3)HAc—0.05mol·dm~(-3)KAc缓冲液作支持电解质,对T1的微分电位溶出法进行了较详细的研究。在T1含量小时,在此介质中测定Cd和Pb,然后加入EDTA掩蔽Cd、Pb而测定微量的T1。测定了人发中的Pb和T1。     

含铊废水处理技术在铅锌冶炼企业的应用实践

金属铊在高尖端领域的应用愈发广泛,但因采矿废水、冶炼废水的不正规排放,铊对环境造成了严重的威胁。本文综述了铊的危害及污染现状,并介绍湖南某大型冶炼企业废水改造项目,采用"JS-1重金属去除协同脱铊剂"工艺对冶炼废水中的铊进行治理,外排水中铊元素的浓度稳定保持在3μg/L以下,成功完成工业化应用,实现了废水中铊持续、稳定和达标排放。