活性炭自溶液吸附锌(II)离子及其配合物

近年来，有人提出通过表面处理提高活性炭表面电荷，加强对无机离子吸附力等观点，但活性炭对无机离子的吸附活性点，表面含氧基团及配体对吸附的影响等重要问题仍众说纷经[1－4]为此，本文提出用氧化一负离子化法处理活性炭，以表面酸度表征表面含氧基团的量，探讨活性炭对Zn（Ⅱ）及其配合物的吸附特性．1试验（1）试验材料活性发由北京光华木材厂出品，分析纯．过20－30目，BET法测得比表面为1316m2·g-1．在2．5×10－2mlo·dm－3的NaNO3中，测得等电点pHIEP为7．75[5]，元素含量（质量分数）为C（83．9％），N（0．07％），H（1…     

Speciation of Phytate Ion in Aqueous Solution. Thermodynamic Parameters for Zinc(II) Sequestration at Different Ionic Strengths and Temperatures

Results of an investigation on phytate interactions with zinc(II) cation in NaNO_3aq at different ionic strengths (0.1≤I/mol⋅L⁻¹≤1.0) are reported. Stability constants of various Zn _i H _j Phy^{(12−2i−j)−} species were determined by potentiometry (ISE-H⁺ glass electrode) and the corresponding formation enthalpies by direct calorimetric titrations. Data obtained were used to provide an exhaustive speciation scheme of zinc(II) in the presence of phytate, as well as a comprehensive representation of the binding ability of phytate toward zinc(II) in different conditions. Different pL₅₀ values [an empirical parameter already proposed, expressed as the −log ₁₀ C _Phy, where C _Phy is the total phytate concentration necessary to bind 50% zinc(II)] were calculated in several conditions, and equations were formulated to model its dependence on different variables, such as ionic strength, temperature and pH. Other empirical predictive relationships are also proposed. Previous contributions to this series reviewed in ref. [1].     

Formation of Zinc(II) and Cadmium(II) Complexes with Pyridine Oxime Ligands in Aqueous Solution

Complex formation equilibria involving pyridine-2-carboxaldehyde oxime (1), 1-(2-pyridinyl)ethanone oxime (2) and 6-methylpyridine-2-carboxaldehyde oxime (3), HL, with zinc(II) and cadmium(II) ions were studied in aqueous 0.1 M NaCl solution at 25° C by potentiometric titrations with a glass electrode. Experimental data were analysed with the least-squares computer program SUPERQUAD to determine the complexes formed and their stability constants. With Ligands 1 and 2 the sets of complexes for Zn(II) and Cd(II) are essentially the same, mono- and dinuclear oxime complexes and their deprotonated/hydrolysed products H_pM_q(HL)^2q+p _r. Owing to the steric requirements of the 6-methyl group, sets of complexes formed with 3 are distinctly different. For zinc(II), only dinuclear oximato species H_pZn₂(HL)^4q+p ₂ ( p = ? 2, ? 3, ? 4) are found, while for the larger cadmium(II) ion mononuclear oximato species CdL⁺ and CdL₂ are detected in addition to the dinuclear complex H_pCd₂(HL)^4q+p ₂ ( p = ? 3).     

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.     

Solubility of Zinc Silicate and Zinc Ferrite in Aqueous Solution to High Temperatures

Crystalline zinc silicate, Zn₂SiO₄, and zinc ferrite, ZnFe₂O₄, were prepared and characterized. The solubilities of these phases were measured using flow-through apparatus from 50 to 350 °C in 100 °C intervals over a wide range of pH. Both solid phases dissolve incongruently, presumably to form ZnO(s) and Fe₂O₃(s) (or the corresponding hydroxide phases at low temperature), respectively. The respective concentrations of zinc(II) and iron(III) matched those of ZnO(cr) and Fe₂O₃(s) (≥150 °C) reported in the literature, whereas the corresponding Si(IV) and Zn(II) concentrations were at least an order of magnitude below the solubility limits for their pure oxide phases. Therefore, the solubility constants for zinc silicate and ferrite were determined with respect to the known solubility constants for ZnO(cr) and Fe₂O₃(s) (≥150 °C), respectively, and the corresponding concentrations of Si(IV) and Zn(II) measured in this study. The results of independent experiments, as well as those reported in the literature provide insights into the mechanism(s) of formation of zinc silicate and ferrite in the primary circuits of nuclear reactors. D.A. Palmer is retired.     

Synthesis,Crystal Structure and Fluorescence of A 1-D Polymeric Zinc(Ii) Complex with Pyrazine-2-Carboxylate as a Bridging Ligand

A one-dimensional chain complex {[Zn(pyz)(SCN)(H₂O)₂]·H₂O}_∞ (pyz = pyrazine-2-carboxylic anion) has been synthesized and its crystal structure determined by X-ray crystallography. The complex crystallizes in an orthorhombic system and the space group is P2 ₁2₁2₁ with a = 6.873(3), b = 9.847(4), c = 16.466(7) Å. The Zn(II) ion is located in a distorted octahedral environment with two oxygen atoms O(3) and O(4) from terminal ligands of two water molecules, another oxygen atom O(1) from the carboxylate group of pyz, and three nitrogen atoms, N(1), and N(2A) from two different pyz and N(3) from a terminal thiocyanate anion, in which a chelated five-membered ring is formed by coordination of O(1) and N(1) to the Zn(1) atom. Therefore, an infinite zigzag chain consisting of Zn(II) ions and pyz anions is constructed and the chains are linked together with hydrogen bonding from coordinated and uncoordinated water molecules. The fluorescence spectra for the bridging ligand Na(pyz) and the complex were measured at room temperature in aqueous solution and in the solid state.     

基于T-T碱基错配的荧光传感器特异性检测汞离子

在本文中,我们研制了一种基于T-T碱基错配特异性键合汞离子的荧光传感器用于汞离子的检测。该传感器由两条分别标记了荧光基团（F）和淬灭基团（Q）的DNA探针组成,并且含有两对用于结合汞离子的T-T错配碱基。当汞离子存在时,两条探针之间形成T-Hg2+-T结构,作用力增强,从而拉近了荧光基团与淬灭基团之间的距离,发生能量转移,使荧光信号在一定程度上被淬灭。在优化的条件下,我们使用该传感器对汞离子进行检测,动力学响应范围为50nM到1000nM,线性相关方程为y= 5281.13 - 1650.56 lg[Hg2+] ( R2 = 0.985),检测下限为79nM。此外,我们还考察了该传感器的选择性,当用其它干扰离子（浓度都为1.0µM）代替待测离子进行实验时,没有发生明显的荧光淬灭,说明该传感器具有较高的选择性。该传感器的构建为汞离子的检测提供了一条快速、简便的新途径。     

汞离子的高灵敏度裸眼识别和荧光传感探针

设计合成了一种以耐尔蓝为母体的Hg2+光学探针分子1-苯甲酰-3-{2-[9-(乙氨基)-10-甲基-9H-苯并[α]苯酚-5-胺基]乙基}硫脲盐酸盐(NBET).在pH=7.4的Tris-HCl缓冲液中,探针分子最大吸收波长为640 nm,此时溶液为淡蓝色;加入汞离子可以诱导探针分子在640 nm处的吸收降低,并在556 nm处产生新的吸收峰,溶液变为浅紫色,而其它金属离子的加入未引起显著变化,基于此可对水溶液中的痕量Hg2+进行裸眼识别.荧光光谱显示,汞离子可以特异性地猝灭探针分子在660 nm处的荧光发射.该探针分子的灵敏度、选择性及荧光量子产率高,激发/发射波长长,可以实现水溶液中0.005 μmol/L Hg2+的荧光检测.     

示波极谱法直接测定锌电解液中钴的研究

研究了pH5 0的HAc -NaAc介质中 ,存在大量锌时 ,钴 -丁二酮肟 -柠檬酸钠 -氯化铵体系灵敏的配合物吸附波。峰电位 -0 .93V ,在0 0001～0 .1mg/L范围内钴质量浓度与峰电流呈线性关系 ,检出限达8 5×10-10mol/L。方法无须预处理可直接测定电解锌料液中微量钴。对电活性配合物的组成、极谱波性质和电极过程机理也作了研究     

Highly Effective Fluorescent Sensor for Hg2+ in Aqueous Solution

A new anthracene fluorophore senses Hg²⁺ selectively in aqueous solution. Among the metal ions examined, fluorescent chemosensor 1 shows selective large CHEQ effects with Hg²⁺ and Ag⁺ at pH 7.     

Thermodynamics of Copper(II) Complexes of Diamino Diamides in Aqueous Solution

The equilibria occurring in aqueous solutions of N,N′-bis(β-carbamoylethyl)ethylenediamine, N,N′-bis(β-carbamoylethyl)trimethylenediamine, N,N′-bis(β-carbamoylethyl)-1,2-propylenediamine, and N,N′-bis(β-carbamoylethyl)-2-hydroxytrimethylenediamine with protons and copper(II) ions as well as the deprotonation reactions of the copper (II) complexes of these four ligands have been studied by calorimetry at T=25.0°C and I=0.10 mol dm^?3 (NaClO₄). The enthalpy changes and the entropy changes for these reactions are reported and discussed.     

Rapid and Convenient Method for the Determination of Sodium Nitroprusside in Aqueous Solution

Abstract

We propose a rapid and convenient method for the determination of sodium nitroprusside in aqueous solution. In alkaline medium and in the presence of dimethylsulfoxide, the concentration of the nitrite ions coming from the nitroprusside corresponds with the initial quantity of this compound.     

Zinc azaphthalocyanines with pyridin-3-yloxy peripheral substituents

Phthalocyanines (Pc), which are peripherally substituted with pyridin-3-yloxy groups, have shown promise as sensitizers for photodynamic cancer therapy (PDT). Some aza-analogues (AzaPc) are reported here. Four monomers were synthesized, i.e. 5,6-di(pyridin-3-yloxy)pyrazine-2,3-dicarbonitrile, and three pyrazine-2,3-dicarbonitriles, substituted with pyridin-3-yloxy- in combination with H, Me and Ph groups. Cyclotetramerizations of these monomers with the reagent Zn(quinoline)₂Cl₂ yielded the targeted ZnAzaPcs in 20–40% yields.The cyclotetramerizations were accompanied, and apparently initiated, by complexation between zinc(II) and the pyridin-3-yloxy groups attached to the pyrazine-dicarbonitriles. Two such zinc(II) complexes were isolated and characterized. Identifications of all new substances were primarily based on NMR spectra, where the pulse techniques COSY, NOESY, HSQC and HMBC were applied. Molecular ions of the ZnAzaPcs were determined by mass spectrometry (MALDI-TOF). The UV–Vis spectra of these macrocycles were as expected, with Q-band absorptions at 630–650 nm and molar extinction coefficients, ε, 70 000–100 000. Eight peripheral pyridin-3-yloxy groups induced a small blue shift of the Q-band, from 636 nm for unsubstituted ZnAzaPc, to 630 nm, whereas a red shifted Q-band at 650 nm resulted from the combination of phenyl and pyridin-3-yloxy substituents. Improved solubilities were observed for the unsymmetrical ZnAzaPcs compared to octa(pyridin-3-yloxy)ZnAzaPc.     

水杨醛亚胺镍配合物催化的乙烯水相聚合

在含表面活性剂的水相体系中, 用一系列水杨醛亚胺镍配合物催化乙烯聚合, 得到了高分子量低支化度聚乙烯. 研究表明水杨醛亚胺镍配合物中苯环上取代基的电子效应和空间位阻对乙烯聚合活性和聚合物的分子量有所影响. 提高配合物酚氧环上取代基的吸电子性, 聚合活性相应增加, 但聚乙烯的分子量降低; 而增加苯胺环上取代基的空间位阻, 聚合活性和聚乙烯的分子量均增加. 粘度法测得由水相聚合得到的聚乙烯的分子量在10⁴～10⁵范围内. DSC测得该聚乙烯的结晶度在50%～70%之间, 熔点在115～137 ℃范围内. GPC分析表明用环辛二烯合镍[Ni(COD)₂]助催化乙烯, 聚乙烯的分子量分布随酚氧环上取代基电负性增加而从双峰到单峰变化, 动态流变学研究进一步说明了聚乙烯分子量及其分布的变化.     

Simultaneous Detection of Copper,Lead and Zinc on Tin Film/Gold Nanoparticles/Gold Microelectrode by Square Wave Stripping Voltammetry

In this work, three heavy metals (Cu(II), Pb(II) and Zn(II)) in wide potential window were simultaneously detected on tin film/gold nanoparticles/gold microelectrode (Sn/GNPs/gold microelectrode) by the method of square wave stripping voltammetry. The Sn/GNPs/gold microelectrode was fabricated by in situ plating of a Sn film on a gold nanoparticles (GNPs) modified gold microelectrode. The influence of hydrogen overflow on stripping of Zn(II) on the gold microelectrode was reduced by modification of GNPs, which made the stripping potential of target metals shift positively. The interference of sulfhydryl groups was reduced and the selectivity of the microelectrode was improved due to the addition of Sn in the detection solution. After accumulation at ?1.4 V for 300 s in acetate buffer solution (0.1 mol L^?1, pH 4.5), the Sn/GNPs/gold microelectrode revealed a good linear behavior in the examined concentration ranges from 5 to 500 µg L^?1 for Cu(II) and Pb(II), and from 10 to 500 µg L^?1 for Zn(II), with a limit of detection of 2 µg L^?1 for Cu(II), 3 µg L^?1 for Pb(II) and 5 µg L^?1 for Zn(II) (S/N=3). When compared with a Sb/GNPs/gold microelectrode and a Bi/GNPs/gold microelectrode, the Sn/GNPs/gold microelectrode showed the best stripping performance to Cu(II), Pb(II) and Zn(II). As a new type of environment‐friendly electrode, the Sn/GNPs/gold microelectrode has potential applications for detection of heavy metals.     

CdS Quantum Dots as Fluorescence Probes for the Detection of Selenite

Abstract

Water-soluble cadmium sulfide (CdS) quantum dots (QD) capped by mercaptoacetic acid were synthesized by aqueous-phase arrested precipitation and characterized by transmission electron microscopy, a spectrofluorometer, and an ultraviolet visible (UV-Vis) spectrophotometer. Based on the fluorescence quenching of CdS QD by selenite in the presence of glutathione (GSH), a simple, rapid, sensitive, and selective detection method for selenite was proposed. Under the optimum conditions, the calibration graph was linear in the range of 0.05 µmol L^?1 to 11.2 µmol L^?1. The limit of detection is 0.03 µmol L^?1. The usefulness of the proposed method was evaluated for the determination of selenite in sodium selenite tablet and sodium selenite and vitamin E injection, and the results agreed with the labeled values. In addition, the effect of foreign ions (common anions and biologically relevant cations) on the fluorescence of the CdS QD was examined to evaluate the selectivity. The quenching mechanism is also described.     

The Potential Response Of Copper(Ii) Sulfide Ion Selective Electrode To Hg(Ii) Ions In Aqueous Solution

Abstract

The application of a cupric ion-selective electrode with a membrane of mixed Ag₂S-CuS to measure the activity of Hg(II) is presented. The linear electrode response curve which covers near three decades, from 10^?5 to 10^?2 mol dm^?3, of mercuric concentration range was obtained, under background of acetate buffer.