Thermodynamic Properties and Phase Equilibria in the Si-B System

Vapor composition and thermodynamic properties of silicon-boron alloys in the range of composition 1.5-100 at.% boron at 1522-1880 K were studied using Knudsen mass spectrometry. About 400 values of activities of both components at various compositions and/or temperatures were obtained. Liquid Si-B alloys were described as ideal associated solutions with the only associate B3Si. The phase diagram of the Si-B system was calculated on the basis of the obtained concentration and temperature dependences of thermodynamic functions for the formation of melts and intermetallic phases SiB₆ and SiB_n. The data obtained are in good agreement with previously published experimental data.     

An assessment study in the determination of chemical elements in sediments and fish in the Zarka River and King Talal Dam,Jordan

Instrumental and radiochemical techniques have been developed for the analysis of samples of quartz-adularia veins from the epithermal gold-silver deposit Milogradovka. The optimal separation conditions of the Pt, Au, Ir, Re, Ag from non-noble metals have been determined in A400 MB in the Cl^? form—0.2 M HCl chromatographic system. The concentrations of the Pt, Au, Ir, Re and 36 other trace elements have been measured with combination of the instrumental and radiochemical neutron activation analysis techniques. The concentration range of the determined elements is from 2 × 10^?2 to 7.5 × 10³ mg kg^?1. The study has been confirmed the presence of platinum mineralization of the epithermal deposit Milogradovka.     

A Review of: “Aquatic Chemistry (An Introduction Emphasizing Chemical Equilibria in Natural Waters)”

Abstract

2nd Edition, by Prof. Dr. Werner Stumm, Swiss Federal Institute of Technology, Zurich, and Prof. Dr. James J. Morgan, California Institute of Technology, Pasadena, 780 pages (including 97 tables, 167 figures, an appendix of 8 pages “Thermodynamic Properties of Common Chemical Species in Aquatic Systems”, an author index of 10 pages, and a subject index of 14 pages), stiff paper cover, format 234 ± 161 mm, ISBN 0-471-04831-3, John Wiley & Sons, New York (1981)     

土壤和水体中铝的化学平衡

详细综述了土壤环境中铝的形态及三大化学平衡：沉淀溶解平衡、水解平衡、络合平衡。     

Thermochemistry of Binding of Lead(II) and Cadmium(II) by Saccharides in Aqueous Solution

Solution calorimetry was used to determine enthalpies and stability constants for binding of lead(II) or cadmium(II) by galacturonic acid and several monosaccharides in aqueous solution. New values for enthalpies of solution in water are reported for galacturonic acid and maltose monohydrate. The interaction of water solvent with the reactants is the largest factor in the binding process.     

Copper (II), Lead (II) and Cadmium (II) Complexes with the Antiinflammatory Drugs Piroxicam and Tenoxicam

Abstract

The chelating tendency of the antiinflammatory drugs piroxicam and tenoxicam towards copper (II), lead (II) and cadmium (II) ions has been investigated using both differential pulse polarography and cyclic voltammetry and the stability constants of the formed complexes have been compared. The effect of the nature of the supporting electrolyte, the pH and other parameters have also been considered.

Tenoxicam exhibits relatively stronger chelating properties than piroxicam towards each ion despite of their structural similarity.     

新显色剂四(邻氯对磺酸基苯基)卟啉导数分光光度法同时测定镉和铅的研究

在pH 10.7,有溴化十六烷基二甲基乙酸铵存在,咪唑催化新显色剂四(邻氯对磺酸基苯基)卟啉与镉和铅反应生成三元胶束络合物,最大吸收波长分别为437和470nm,其表观摩尔吸光系数相应为5.6×10~5和2.0×10~5。用二阶导数分光光度法同时测定镉和铅,结果满意。     

电感耦合等离子体原子发射光谱法测定面粉中铅和镉

:采用电感耦合等离子体原子发射光谱法测定面粉中痕量铅和镉。面粉用乙醇和硝酸溶解后,加入分散剂Triton X-80溶液得到样品的悬浊液。然后经均质器分散10 min后,在磁力搅拌下搅拌8 min动态进样分析。铅和镉的检出限(3S/N)分别为0.05,0.006 mg·L~(-1),加标平均回收率分别为98.8%,96.7%。     

儿童常用蜡笔中可溶性铅、镉的测定

采用火焰原子吸收光谱法测定了儿童常用蜡笔中可溶性铅、镉的含量。铅在0.05～10.00μg·mL~(-1)之间,镉在0.02～4.00μg·mL~(-1)之间具有良好的线性关系。方法的RSD≤4.13％。回收率在93.7％～104.5％之间,测定快速简便,结果准确。可用于蜡笔中可溶性铅、镉含量的监测。     

石墨炉原子吸收光谱法测定土壤中铅、镉含量

土壤样品经硝酸、氢氟酸和过氧化氢加热消解,采用石墨炉原子吸收光谱法测定其中铅和镉的含量。以磷酸铵作为基体改进剂,铅和镉的灰化温度分别为400℃,250℃,原子化温度分别为2 100℃,1 800℃。铅和镉的质量浓度分别在0.50～50.0,0.10～2.5μg.L-1范围内与其吸光度呈线性关系,检出限依次为6.5,0.4pg。应用此法分析了4个土壤标准样品,测定值与标准值相符,相对标准偏差(n=6)分别在1.5%～6.3%和2.3%～5.1%之间。铅、镉的加标回收率分别在85.4%～103.2%,91.5%～102.3%之间。     

示波极谱法测定饮料中铅和镉

铅和镉是人类重点研究的有害元素,目前测定方法有原子吸收光谱法、双硫腙比色法、微分电位溶出法、示波极谱法等。本文在文献[2,3]的基础上研究了饮料中铅和镉的示波极谱法,对底液条件、准确度、精密度、干扰因素等进行试验,结果满意。     

Solid-Solute Phase Equilibria in Aqueous Solutions XVII [I]. Solubility and Thermodynamic Data of Nickel(II) Hydroxide

Summary.  The solubility of nickel(II) hydroxide (theophrastite) in water was determined as a function of temperature and ionic strength by the pH variation method. In each experiment the inert electrolyte medium was made up with sodium perchlorate. The experimental data were thermodynamically analyzed, and the standard solubility constant was extrapolated to zero ionic strength with the specific ion-interaction equation. Furthermore, the standard molar Gibbs energy and the enthalpy of formation for theophrastite, β-Ni(OH)₂, were evaluated. For all calculations, ChemSage and its optimizer routine were used. Received October 25, 2001. Accepted October 29, 2001     

Antimony Film Microelectrode for Anodic Stripping Measurement of Cadmium(II), Lead(II) and Copper(II)

The antimony film microelectrode (SbFME) is presented for measuring trace heavy metal ions in combination with anodic stripping voltammetry. The SbFME was tested in model solutions of 0.01 M HCl containing Cd(II) and Pb(II) in the presence of dissolved oxygen. The microsensor exhibited good linear behavior in the examined concentration range 20 μg L⁻¹ to 100 μg L⁻¹ and LoD of 1.9 and 3.1 μg L⁻¹ for Cd(II) and Pb(II), respectively. The suitability of SbFME for measuring trace levels of Cu(II) was demonstrated using the standard reference material of natural water exploiting the sensor's specific characteristic of low re‐oxidation signal for antimony.     

Peculiarities of Chemical Binding in Anhydrous Lead(II) and Tin(II) Hexacyanoferrates(II,III)

The electronic structure and chemical binding of anhydrous lead and tin hexacyanoferrates(II,III) Pb₂Fe(CN)₆, Pb_1.5Fe(CN)₆, and Sn₂Fe(CN)₆ were studied by the linear muffm-tin orbital (tight binding approximation) and extended Hückel theory methods. The general tendencies of variation for the stability of the Pb–N, Sn–N, Fe–C, and C–N bonds were determined for Pb₂Fe(CN)₆, Pb_1.5Fe(CN)₆, and Sn₂Fe(CN)₆ crystals. Peculiarities of Pb(Sn)–N chemical interactions in the structure of the phases have been found.     

Acid-Base Equilibria in Solutions of Polybasic Acids (Model and Experiment): I. Thermodynamic Dissociation Constants of Dibasic Acids

A procedure was developed for determining the thermodynamic dissociation constants of dibasic acids when the functional groups are neutralized jointly. The procedure is based on the electroneutrality and material balance laws. The equilibrium concentrations of all the ions and dibasic acid molecules are taken into account in calculation of the activity coefficients of the species formed in the course of neutralization and of the solution ionic strength.     

上海市区大气颗粒物(PM2.5)中铅、镉的分析测定和污染特征研究

以石英超细纤维滤膜采集上海市长宁区的大气颗粒物(PM2.5)样品,采用球磨机将滤膜研磨成细微颗粒,并以0.7％ Triton X-100作为分散剂,制备了稳定均一悬浮液,建立了一种简便、绿色、快速的悬浮液进样-石墨炉原子吸收法测定PM2.5中铅和镉的方法.铅在0.1～75 μg/L范围内,镉在0.2～3 μg/L范围内,校正曲线的线性相关性大于0.998;铅和镉的检出限分别为0.36和0.06 μg/L,相对标准偏差小于5％.采用HF-HN03体系酸消解样品,并与电感耦合等离子体质谱法和石墨炉原子吸收光谱法测试结果对比,验证了方法的准确性.采用本方法对2014年11月～ 2015年5月期间上海市区大气中PM2.5及铅和镉的污染特性进行分析,结果表明,铅和镉的质量浓度随时间变化趋势与PM2.5的质量浓度随时间的变化趋势呈现良好的一致性.     

Identification of Chemical Forms of Lead, Cadmium and Nickel in Sewage Sludge of Waste Water Treatment Facilities

 Lead, cadmium and nickel levels in sewage sludge of a waste water treatment facility were determined by slotted tube atom trap (STAT)-flame atomic absorption spectrometry after using different extraction reagents. In addition, a sequential extraction procedure was applied to the same samples and the results were compared. It was found that Pb and Cd were relatively mobile as organically bound, carbonate or adsorbed on the Fe–Mn oxides and the concentrations in the extracts were higher than 50%. However, the percentage of Ni bound to these phases was found to be very low. Received October 23, 2001; accepted August 2, 2002