Evaluations of solid electrodes for use in voltammetric monitoring of heavy metals in samples from metallurgical nickel industry

Evaluation of different solid electrode systems for detection of zinc, lead, cobalt, and nickel in process water from metallurgical nickel industry with use of differential pulse stripping voltammetry has been performed. Zinc was detected by differential pulse anodic stripping voltammetry (DPASV) on a dental amalgam electrode as intermetallic Ni–Zn compound after dilution in ammonium buffer solution. The intermetallic compound was observed at –375 mV, and a linear response was found in the range 0.2–1.2 mg L^–1 (r²=0.98) for 60 s deposition time. Simultaneous detection of nickel and cobalt in the low g L^–1 range was successfully performed by use of adsorptive cathodic stripping voltammetry (AdCSV) of dimethylglyoxime complexes on a silver–bismuth alloy electrode, and a good correlation was found with corresponding AAS results (r²=0.999 for nickel and 0.965 for cobalt). Analyses of lead in the g L^–1 range in nickel-plating solution were performed with good sensitivity and stability by DPASV, using a working electrode of silver together with a glassy carbon counter electrode in samples diluted 1:3 with distilled water and acidified with H₂SO₄ to pH 2. A new commercial automatic at-line system was tested, and the results were found to be in agreement with an older mercury drop system. The stability of the solid electrode systems was found to be from one to several days without any maintenance needed.     

Water polarizability in condensed phase: ab initio evaluation by cluster approach

The polarizability of a water molecule in liquid is evaluated via ab initio and density functional calculations for water clusters. This work has considerably improved our previous effort [J Chem Phys 1999, 110, 11987] to attain quantitative accuracy for polarizability. The calculations revealed that the water polarizability in the liquid is reduced from that in the gaseous phase by 7-9%. These results suggest significant implications for polarizable water models.     

催化褪色光度法测定微量锰（Ⅱ）的研究

本文研究在硫酸介质中，锰（Ⅱ）催化ＥＤＴＡ还原重铬酸银，而使之褪色的新指示反应。确定了催化褪色反应动力学条件，锰（Ⅱ）的浓度在０－０．４μｇ／ｍｌ范围内，工作曲线呈良好的线性关系，检测限为０．０１１μｇ／ｍＬ，该方法用于天然水及污水中锰的测定，获得满意结果。     

Density and Sound Velocity Studies of Aqueous Solutions of Tetradecyltrimethylammonium Nitrate at Different Temperatures

The density and ultrasound velocity of aqueous solutions of tetradecyltrimethylammonium nitrate were measured in the temperature range of 15 to 35°C in 5°C intervals. The concentration range covered the premicellar and micellar regimes. By assuming a pseudophase separation model for the micellar system, we applied the densitometric data to estimate the apparent molar volumes and the apparent thermal expansibility coefficients of the surfactant in monomeric and micellar forms. Ultrasound velocity and density data enabled us to estimate the isentropic compressibility of the surfactant in both forms. The results are compared with relevant literature data for alkyltrimethylammonium bromides.     

水中矿物元素的ICP-MS分析

用ICP－MS对地下水、地表水和饮用水中的矿物元素进行了分析测定，实验证明用ICP－MS可以同时测定地下水，地表水和饮用水中矿物元素；该法灵敏度、精密度和准确度都能满足有关标准的要求，具有多元素同时分析，样品前处理简单，干扰少，测定快速，省事省力等优点。     

二氧化铈还原表面上水煤气变换反应机理

采用原位红外，程序升温脱附，脉冲表面反应技术研究了ＣｅＯ２还原表面在中温变换反应条件下表面物种的生成及脱附，并根据研究结果归纳出水煤气变换反应机理。     

Aqueous solutions—A new perspective. Amorphous carbohydrates: Science and application technology

At a recent meeting of the International Symposium on Solution Chemistry I presented a paper dealing with aqueous solutions in which water was present not in excess but as one component of a supersaturated solution with polyhydroxy compounds. In response to a request from the Editor of this Journal I have submitted this article in which I outline my general interest in the subject and its importance as a new direction for solution chemists.     

难降解有机废水的催化氧化法处理

催化氧化法可通过多种途径来加强传统的化学法处理效果，目前已成为难降解有机废水处理的一项重要新技术。本文介绍了光催化氧化法、均相氧化法、多相氧化法(包括电催化氧化法)以及超临界水氧化技术的国内外研究现状及特点，并对其在有机废水中的应用情况和发展前景作了扼要评述。     

Rheological properties of multisticker associative polyelectrolytes in semidilute aqueous solutions

Multisticker associative polyelectrolytes of acrylamide (≈86 mol %) and sodium 2‐acrylamido‐2‐methylpropanesulfonate (≈12 mol %), hydrophobically modified with N,N‐dihexylacrylamide groups (≈2 mol %), were prepared with a micellar radical polymerization technique. This process led to multiblock polymers in which the length of the hydrophobic blocks could be controlled through variations in the surfactant‐to‐hydrophobe molar ratio, that is, the number of hydrophobes per micelle (N_H). The rheological behavior of aqueous solutions of polymers with the same molecular weight and the same composition but with two different hydrophobic block lengths (N_H = 7 or 3 monomer units per block) was investigated as a function of the polymer concentration with steady‐flow, creep, and oscillatory experiments. The critical concentration at the onset of the viscosity enhancement decreased as the length of the hydrophobic segments in the polymers increased. Also, an increase in the N_H value significantly enhanced the thickening ability of the polymers and affected the structure of the transient network. In the semidilute unentangled regime, the behavior of the polymer with long hydrophobic segments (N_H = 7) was studied in detail. The results were well explained by the sticky Rouse theory of associative polymer dynamics. Finally, the viscosity decreased with an increase in the temperature, mainly because of a lowering of the sample relaxation time. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1640–1655, 2004