谷氨酸钠从其水溶液中的周期结晶现象

早在本世纪初物理化学家们就已观察到，某些物质从其熔融态或溶液中结晶出来时，在某些条件下可形成周期性的宏观结晶条纹［1，2］，这就是周期结晶现象，由于这种现象和晶体生长、材料物性以及成矿过程等重要问题紧密相关，很早就引起了人们的重视．近年来有关非平衡非线性系统中自发产生各种时空有序现象（自组织现象）的各种理论（如耗散结构理论）［3］的兴起，重新引起了人们对这类现象的兴趣．八十年代，Iwamoto等先后报道了甲基苄基氨基甲酸酯（MethylMesitylcarbamate）从氯仿溶液［4］和抗坏血酸（AscorbicAcid）从甲醇溶液［5］…     

Competitive Sorption of Copper and Nickel Ions from Aqueous Solution Using Peat

Bicomponent aqueous solutions of copper and nickel ions have been used to investigate the sorption of metal ions onto peat. Peat, a low cost sorbent, has shown a high capacity for the sorption of single component metal ions attributed to extensive carboxylic acids within its structure. Copper and nickel ions were selected as typical metals in the effluents of electroplating industries. The effects of competitive sorption in batch systems were studied at various metal ion concentrations. In this study the Butler and Ockrent model was modified using a coefficient, . Two models were developed based on the interaction coefficient . The first model incorporates a constant fixed factor for each metal ion into the Butler-Ockrent equation. The second model incorporates a variable factor into the Butler-Ockrent equation; this interaction factor varies as a function of sorbent surface coverage. Predicted equilibrium data are found to be in excellent agreement with experimental values using both modified models for various mole ratios of copper and nickel ions in competitive sorption.     

Aqueous Sulfate Separation by Crystallization of Sulfate–Water Clusters

An effective approach to sulfate separation from aqueous solutions is based on the crystallization of extended [SO₄(H₂O)₅²⁻]_n sulfate–water clusters with a bis(guanidinium) ligand. The ligand was generated in situ by hydrazone condensation in water, thereby bypassing the need for elaborate syntheses, tedious purifications, and organic solvents. Crystallization of sulfate–water clusters represents an alternative approach to the now established sulfate separation strategies that involve encapsulation of the “naked” anion.     

功能性离子液体萃取水溶液中Cu2+:实验与理论

本工作针对含硫脲基咪唑憎水功能离子液体在溶液中Cu²⁺萃取方面的应用及其机理进行研究. 考察了萃取两相体积比、金属离子浓度、时间、无机盐NaCl、溶液pH及离子液体烷基链长等因素的影响. 结果表明: 室温条件下, 0.1 mL离子液体[C_nMPSM][PF₆] (n=4、6、8)与5 mL 21.94 mg/L的氯化铜溶液室温条件下超声混合30 min, 溶液中Cu²⁺的去除率即超过95%; 且此类离子液体对金属离子的萃取效果顺序为: n=4≈n=6>n=8. 以[HMPSM][PF₆]为研究对象, 发现溶液中无机盐NaCl的含量以及溶液pH 对金属离子的萃取效果影响不明显. 与传统离子液体[C_nbim][PF₆] (n=6、8)相比, 硫脲基的引入使其萃取率由20%左右提高到99%, 且有效避免因阳离子交换而引起水中咪唑阳离子含量增加问题. 通过理论计算发现, 功能离子液体对金属离子的萃取依赖于官能团中的S元素与Cu²⁺之间较强的静电及路易斯酸碱作用, 与萃取实验中离子液体未和Cu²⁺发生阳离子交换作用相吻合.     

Polynuclear Copper(I) Clusters Supported by Carboxylate Ligands with Coordinatively Active Ester Group

Two new copper(I) complexes with polynuclear cores bridged by 4-(ethoxycarbonyl)benzoate ligands, [Cu₆(O₂CC₆H₄CO₂C₂H₅)₄(O₂CCF₃)₂] (1) and [Cu₄(O₂CC₆H₄CO₂C₂H₅)₄] (2), have been prepared by ligand exchange method in high yield and fully characterized by X-ray diffraction and spectroscopic techniques. The important role of intermolecular interactions between the polynuclear copper(I) clusters imposed through the coordinatively active dangling ester groups of bridging carboxylate ligands on the solid-state packing and photoluminescent behavior of 1 and 2 has been revealed.     

水相CdS幻数团簇的室温合成及形成路径探究

<正>水相合成半导体纳米材料具有环境友好、成本低、操作简便等优点,较有机相合成更接近绿色化学的标准^1–4。然而,水溶液中离子环境复杂,反应温度受水沸点的限制。如何提高水相合成半导体量子点(quantum dots,QDs)的可控性,明确水相QDs的形成机理,一直是胶态半导体纳米材料合成领域的一个巨大挑战和难题。     

锰氧化物/石英砂(MOCS)对铜和铅离子的动态吸附

锰氧化物/石英砂(MOCS)对铜和铅离子的动态吸附;锰氧化物/石英砂(MOCS);铜离子;铅离子;动态吸附     

Novel Phenomena of Crystallization and Emulsification of Hydrophobic Solute in Aqueous Solution

Emulsification of lauric acid in an aqueous ethanol solution including lauric acid solute has been observed during cooling before crystallization of lauric acid occurs. The nature of two different solubility curves was explained for the system of lauric acid and aqueous ethanol solution. The mutual solubility of the two liquid phases controls emulsification; the solid solubility of lauric acid controls crystallization. The mutual solubility curve appears at relatively high temperature, and the solid solubility curve at relatively low temperature. Crystallization essentially generates a solid metastable zone under the solid solubility curve. A supersaturated solution can be obtained in the metastable zone. However, no nucleation occurs in the metastable zone. The metastable zone, therefore, still caused emulsification at low temperature before crystallization of lauric acid occurred. The hypothetical mutual solubility curve for the aqueous solution including hydrophobic solutes appeared invariably even at low temperature in the metastable zone under the solid solubility. Copyright 2001 Academic Press.     

Precipitation of Copper(II) with 1,2-Dibenzoylhydrazine from Aqueous Ammonia Solution

The physicochemical characteristics of 1,2-dibenzoylhydrazine relevant to precipitation of copper(II) with this reagent were studied.     

水溶液中金属团簇的脉冲辐解研究进展

介绍了以脉冲辐解技术为手段研究水溶液中单金属团簇的形成机理,并对团簇的性质及其反应进行了简要的概括,对今后团簇的发展趋势进行了展望.     

Surface‐Roughness Evolution During the Cementation of Silver Ions on Solid Copper in Aqueous Sulfuric Acid Solution

The evolution of the surface roughness during cementation of Ag⁺ conducted either in O₂‐free or O₂‐saturated aqueous H₂SO₄/CuSO₄ was investigated at two different initial concentrations of Ag⁺. The kinetics data of the process determined previously in the rotating cylinder were linked directly with scanning‐electron‐microscope (SEM) images and surface‐height‐distribution diagrams calculated for various cementation times. It was found that, at the beginning of the process, the surface roughness decreases due to formation of a flat Ag layer on the top of the surface, independent of the presence or absence of O₂ in the system. With increasing reaction time, an increase in the surface roughness was observed. The rate enhancement of the process is mainly responsible for the increase of the surface roughness in the O₂‐saturated solutions, especially at the higher initial Ag⁺ concentration (100 mg/dm³). The rate enhancement observed at a latter stage of the process, connected with the increase of the effective surface area of the cathodic sites, was separated from the rate enhancement induced by the competitive chemical process occurring in O₂‐free solution. The difference in the mechanisms of the processes conducted under aerobic and anaerobic conditions was reflected in the surface‐heigth distributions calculated from the SEM images.     

Solution Characteristics for Adsorption of Copper Ion with Iron(III) Hydroxide from Aqueous Ammonia Solution

The distribution of copper ion species in aqueous ammonia solution is evaluated as a function of pH by a numerical approach. Adsorption of copper on colloidal iron(III) hydroxide in solutions of total ammonia (0.14-1.2 M) are performed at various values of pH. The maximum efficiency of adsorption occurs when the sum of the fractions of the species Cu(NH₃)²⁺, Cu(NH₃)₂²⁺ and Cu(NH₃)₃²⁺ in the solution reaches its maximum. With varied solution pH, the distribution of copper species is the determining factor for maximum adsorption, whereas the surface properties of the adsorbing particles show smaller effects under the test conditions.     

Electron－rich Polynuclear Transition Metal Clusters：Ⅰ． The Clusters with Chalcogen Bridges and Phosphine Ligands

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Paradoxes and Paradigms: Aqueous Polynuclear Oxyanions of Sulfur and Homologous Series

The enthalpies of formation of several series of aqueous polynuclear oxyanions of sulfur are discussed. In this context we briefly discuss the nature of homologous series.     

Electron－rich Polynuclear Transition Metal Clusters：Ⅱ．Synthetic and Structural Studies of Some Polynuclear Coinage Metal Cluster Compounds

Ｅｌｅｃｔｒｏｎ－ｒｉｃｈＰｏｌｙｎｕｃｌｅａｒＴｒａｎｓｉｔｉｏｎＭｅｔａｌＣｌｕｓｔｅｒｓ：Ⅱ．ＳｙｎｔｈｅｔｉｃａｎｄＳｔｒｕｃｔｕｒａｌＳｔｕｄｉｅｓｏｆＳｏｍｅＰｏｌｙｎｕｃｌｅａｒＣｏｉｎａｇｅＭｅｔａｌＣｌｕｓｔｅｒＣｏｍｐｏｕｎｄｓＨ...     

Thermal Decomposition and Crystallization of Aqueous Sol-Gel Derived Zirconium Acetate Gels: Effects of the Precursor Solution pH

Crystalline zirconia has previously been formed by desiccation and pyrolysis of a pH 3.4 zirconium acetate precursor solution. In this study, amorphous gels were formed by desiccation of zirconium acetate precursor solutions at pH 0.9 to 3.4 obtained by adding hydrochloric acid and at pH 8.0 by adding ammonium hydroxide to the available pH 3.4 precursor solution. The concentrations of the uncomplexed zirconium ion and the 1 : 1 and 1 : 2 zirconium acetate complexes varied with pH. Decomposition of the amorphous gel and its structure evolution to form crystalline zirconia by pyrolysis were studied. Several decomposition and structure transition temperatures occurring in the pyrolysis and the polymorph distribution in the pyrolysis products were dependent on the pH of the precursor solution. These variations of structure evolution with pH were also related to the relative concentrations of specific zirconium complexes in the precursor solutions. Removal of carbon by pyrolysis was improved by adding hydrochloric acid or ammonium hydroxide to the pH 3.4 precursor solution.