用于稀土元素发射光谱分析的偶氮砷—Ⅲ螯含树脂

为了用发射光谱法测定岩石中的稀土元素,前人已制定了一些预富集方法。最常用的阳离子树脂离子交换分离法流程很长,费时很多。我们制备了一种新的螯合形成树脂,负载偶氮砷-Ⅲ作为功能团,对于富集岩石中的稀土元素非常有效。偶氮砷-Ⅲ是一种普通试剂,容易得到。制备这种树脂的方法很简单,只需把偶氮砷-Ⅲ溶液和普通大孔型阴离子树脂(预先处理成砷酸根型)混合并搅动,即可制得。在某些络合剂存在下,偶氮砷-Ⅲ树脂富集稀土元素的选择性高,上柱后不需淋洗分离,稀土被吸附,其它阳离子流出。再用浓硝酸收集稀土。     

毛细管电泳电感耦合等离子体原子发射光谱法分析铁的形态

用毛细管电泳电感耦合等离子体原子发射光谱法研究了Fe2+-Fe3+在络合剂o-phen中,混合络合试剂o-phen和EDTA中的形态分离,以及游离态Fe2+-Fe3+的分离。考察了电压、缓冲液的pH值和络合剂浓度等对游离态铁形态分离的影响,获得了满意的分离条件。在分析过程中,阳离子、阴离子、以及络合试剂均不产生干扰,该方法优于毛细管电泳紫外-可见光谱法。     

流动注射-在线富集测定镍电解液中痕量的锌

本文报道用流动注射－在线富集技术原子吸收法测定镍电解液中痕量锌。将Ｚｎ从电介液中的大量镍和其他成分中分离出来,锌以络阴离子形式被吸附到阴离子交换树脂上。电介液含有氯化钠,其氯离子的浓度足以形成锌络阴离子,测定时不必再加任何试剂。本方法每小时可测定３０个样品。     

聚酰胺富集双波长光度法同时测定金和银

本文研究了聚酰胺树脂的吸附性能，发现Ａｕ和Ａｇ蝗形成稳定的硫氰酸络阴离子。在稀硝酸介质中吸附于聚酰胺树脂进行富集并与大部分贱金属元素分离。采用Ｎａ２ＳＯ３作为解脱剂，可以定量解脱树脂上的Ａｕ和Ａｇ而树脂不被破坏可以反复使用。     

离子交换-间接原子吸收法测定邻苯二酚

研究了在pH=9-10的碱性介质中邻苯二酚和铁（Ⅲ）反应生成的暗红色阴离子络合物,此络合物与强碱性阴离子树脂发生离子交换,并与过量的铁离子分离,利用原子吸收法测定过量的铁离子,从而达到测定邻苯二酚的目的。本方法线性范围为0－100mg/L,检出限为0.1mg/L,回收率为94．5％－102％,结果令人满意。     

含磺酸基的有机络合剂对铬(Ⅲ)增感作用的研究应用

本文对１３种含磺酸基的有机络合剂在铬的火焰原子吸收光谱分析中的作用进行了实验。发现含磺酸基的有机络合剂普遍能提高铬（Ⅲ）的吸光度。初步探讨了磺酸基的增感、消除干扰作用，选择了含磺酸基的有机络合剂存在时酸度、浓度、干扰离子量和线性范围等条件，并用茜素红、铬天青Ｓ直接测定水系沉积物中的微量铬，结果令人满意。     

含磺酸基的有机络合剂结铬（Ⅲ）增感作用的研究应用

本文对13种含磺酸基的有机络合剂在铬的火焰原子吸收光谱分析中的作用进行了实验，发现含磺酸基的有机络合剂普遍能提高铬（Ⅲ）的吸光度。初步探讨了磺酸黄的增感、消除干扰作用，选择了含磺酸基的有机络合剂存在时酸度、浓度、干扰离子量和线性范围等条件，并用茜素红、铬天青S直接测定水系沉积物中的微量铬，结果令人满意。     

D371树脂-火焰原子吸收光谱测定湿法冶金工艺中的金

离子交换富集分离金，具有较好的动力学性能和较高的吸附容量。使金的吸附与离子交换过程在金的湿法冶金中日趋重要［１，２］。本文研究用新型Ｄ３７１树脂在静态动态条件下吸附和解吸金的性能。拟定了一个离子交换树脂分离富集火焰原子吸收光谱测定湿法冶金工艺中微量金的方法。     

离子交换树脂均匀沉淀法制备Nd2O3纳米粒子的研究

以Nd(NO)3·6H2O和(NH4):C2O4·2H2O为原料,分别采用阴离子交换树脂均匀沉淀法和阳离子交换树脂均匀沉淀法制备Nd2O3前驱体,经700℃焙烧后制得Nd2O3纳米晶体a和b.分别用热分析、X射线粉末衍射、透射电子显微镜、高分辨电子显微镜、选用电子衍射和BET等对前驱体和样品进行表征,并对均匀沉淀形成机理进行了探讨.结果表明,制备的Nd2O3纳米晶体属六方晶系,样品分散性较好,平均粒径约为26～32 nm;Nd2O3纳米晶体清晰、有序的电子衍射点阵,表明晶体的结晶度较好;样品a和样品b的比表面积分别是42.57和29.43 m2·g-1.离子交换树脂均匀沉淀法具有操作简单易行,对设备要求不高,成本低,同时避免使用有机溶剂和表面活性剂,污染小,后处理容易,离子交换树脂可再生重复使用等优点.     

硫酸锌(镉)盐的动态吸附提纯方法研究

硫酸锌和硫酸镉是制备荧光材料的重宴原料之一.实践证明,这些盐类中的重金属杂质Cu、Fe、Co、Ni、Pb、Cr和Mn等的含量,如超过0.1~0.3ppm,将会对荧光材料的发光性能产生严重影响.因此,一般市售的试剂级硫酸锌(镉)只有经过仔细提纯后方可使用.     

Synthesis of lactic acid–Zr(IV) phosphate nanocomposite ion exchanger for green remediation

Lactic acid–Zr(IV) phosphate nanocomposite (LA/ZPNC) ion exchanger was synthesised by sol-gel method. The nanocomposite ion exchanger was characterized by different techniques such as Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy X-ray diffraction (XRD) and thermogravimetric analysis (TGA/DTA/DSC). LA/ZPNC was employed for different physicochemical properties such as ion exchange capacity, elution behaviour, effect of eluent concentration, pH titration and thermal stability. The ion exchange capacity of LA/ZPNC was higher as compared to their inorganic counterpart. pH results indicate the bifunctional nature of nanocomposite. A degradation efficiency of 89.47 % was attained in 4 h of illumination. The distribution coefficient (K _d) studies of LA/ZPNC ion exchanger were investigated for eight different metal ions and found more selective for Al³⁺ with higher K _d value. It was explored for photocatalytic study of methylene blue under solar illumination.     

Optical Flow-Through Sensor for the Determination of Norfloxacin Based on Emission of KMnO<Subscript>4</Subscript>–Na<Subscript>2</Subscript>SO<Subscript>3</Subscript>–Tb<Superscript>3+</Superscript> System

A simple and selective method to determine norfloxacin using an optical flow-through sensor has been developed. The present sensor was prepared by packing anionic ion exchange resin in a glass tube, followed by introducing KMnO₄ solution to the glass tube for immobilization on resin. The optical sensor is based on the emission intensity from the Tb(III) solution sensitized by norfloxacin. The excitation of norfloxacin occurred by the chemiluminescence from the reaction of KMnO₄ and Na₂SO₄ solutions. The effects of pH, concentration of Tb(III) ion, KMnO₄ and Na₂SO₄ solutions and flow rate of the norfloxacin solution on the chemiluminescence intensity were studied to find the optimum experimental conditions. The emission intensity increased linearly with increasing norfloxacin concentration from 1.0 × 10⁻³ to 1.0 × 10⁻⁸ M and the detection limit (3σ) was 8.7 × 10⁻⁹. The applicability of the present method was demonstrated by determination of norfloxacin in various pharmaceutical preparations and serum sample.     

Modelling of mutual diffusion for associated electrolytes solution: ZnSO4 and MgSO4 aqueous solutions

We study mutual diffusion of associated electrolyte in water. A theory based on the Smoluchowski equation and on the mean spherical approximation is proposed. It is found to be valid up to molar concentrations. The values of the association constant obtained for ZnSO₄ and MgSO₄ aqueous solutions are consistent with further methods of measurements. Thanks to the elimination of fast variables method, the theory can be generalised to any association in solution. Comparison with molecular dynamics and Brownian dynamics simulations in the case of MgSO₄ indicates that the pair is a global association phenomenon since it corresponds to several association phenomena (contact ion pair and solvent separated ion pair).     

Defect structure of Cu2+ center in K2SO4‒Na2SO4‒ZnSO4 glasses

The spin Hamiltonian parameters (g factors g _//, g _⊥ and hyperfine structure constants A _//, A _⊥) of Cu²⁺ in K₂SO₄?Na₂SO₄?ZnSO₄ glasses are calculated from the high-order perturbation formulas of 3d⁹ ion in tetragonal octahedral sites. The calculated results are in agreement with the observed values. Since the EPR parameters are sensitive to the local structure of a paramagnetic impurity center, the defect structure of Cu²⁺ center in K₂SO₄?Na₂SO₄?ZnSO₄ glasses is estimated. The validity of results is discussed.     

Photocatalytic reduction of potassium chromate by Zn-doped TiO2/Ti film catalyst

The aim of this work was to investigate the photocatalytic (PC) reduction of potassium chromate by Zn-doped TiO₂/Ti film catalysts. The film catalyst was prepared by plasma electrolytic oxidation method in H₂SO₄ solution with different dosages of ZnSO₄. The composition and structure of the film catalysts was studied by XRD, SEM and EPMA. The removal rate of potassium chromate was investigated under the conditions of the different dosages of ZnSO₄ and the initial concentration of chromate potassium, and the reductive product during the PC reduction process was analyzed. The results showed that the film catalyst was composed of anatase TiO₂ and rutile TiO₂ with the porous structure. When the dosage of ZnSO₄ was 0.2 g/L, the film catalyst presented the highest catalytic activity, which related to the amount and the crystal grain size of anatase TiO₂ in the film. The PC reduction of potassium chromate by the film catalyst obeyed the pseudo-first-order kinetic equation. The UV-vis spectrum and XPS analyses proved that chromate Cr(VI) was reduced to Cr(III), which existed in the form of insoluble Cr(OH)₃.     

Structural and phase transformations of sulfide mineral surfaces irradiated by nanosecond electromagnetic pulses

The effect of high-voltage nanosecond electromagnetic pulses on the phase composition of chalcopyrite and sphalerite surfaces is investigated by IR-Fourier spectroscopy, XPS, and UVS. Electromagnetic pulse treatment results in the formation and accumulation of copper and/or iron sulphates Me _x (SO₄) _y in superficial chalcopyrite layers, zinc sulphate ZnSO₃, and carbonate ZnCO₃ on sphalerite surfaces, changing their electrochemical and physicochemical properties; i.e., a rise in electrode potentials creates favorable conditions for anionic collector sorption and promotes sulfide flotation activity.     

Ion-isotopic exchange reaction kinetics using Duolite ARA-9366B and Indion-AGR resins

Radiotracer isotopic technique as an effective analytical tool was used to study the kinetics of ion-isotopic exchange reactions in the nuclear- and nonnuclear-grade anion exchange resins Duolite ARA-9366B and Indion-AGR. On the basis of kinetic data, specific reaction rate (per minute), amount of ion exchanged (millimoles), initial rate of iodide ion exchange (millimoles per minute), and log K _d values were calculated for the two resins. It was observed that under identical experimental conditions of 35.0 °C, 1.000 g of ion exchange resins, and 0.002 mol/L of labeled iodide ion solution, the values calculated were 0.200 min^?1, 0.278 mmol, 0.056 mmol/min, and 9.6, respectively, for Duolite ARA-9366B resin, which were higher than 0.102 min^?1, 0.216 mmol, 0.022 mmol/min, and 5.7, respectively, for Indion-AGR resins. An identical trend was observed for the two resins during bromide ion-isotopic exchange reaction. The overall results indicate that under identical experimental conditions, Duolite ARA-9366B resins show superior performance than Indion-AGR resins. The results of the present experimental work have demonstrated that the radioanalytical technique used here can be successfully applied for the characterization of different ion exchange resins so as to evaluate their performance under various process parameters.     

Theoretical investigation of the ultrafast NeNePo spectroscopy of Au 4 and Ag 4 Clusters

Ultrafast ground state nuclear dynamics of Au₄ and Ag₄ is theoretically explored in the framework of negative ion - to neutral - to positive ion (NeNePo) pump-probe spectroscopy based on the ab initio Wigner distribution approach. This involves the preparation of a nonequilibrium neutral ensemble by pump induced photodetachment of a thermal anionic ground state distribution, gradient corrected DFT classical trajectory simulations “on the fly” on the neutral ground state, and detection of the relaxation process of the ensemble in the cationic ground state by a time-delayed probe pulse. In Au₄, the initially prepared linear structure is close to a local minimum of the neutral state giving rise to characteristic vibrations in the signals for probe wavelength near the initial Franck-Condon transition. A timescale of ∼1 ps for the structural relaxation towards the stable rhombic D_2h neutral isomer was determined by the increase of the signal for probe wavelength in vicinity of the vertical ionization energy of the rhombic structure. In contrast, the relaxation dynamics in Ag₄ is characterized by normal mode vibrations since both the initially prepared anionic ground state and the neutral ground state have rhombic minimum geometries. Thus, time-resolved oscillations of pump-probe signals are fingerprints of structural behaviour which can be used experimentally for the identification of particular isomers in the framework of NeNePo spectroscopy. Received 22 December 2000     

希土离子对铁磁共振的影响

本文利用关联函数的方法(久保理论),讨论了强交换耦合系统的亚铁磁共振,给出了系统总磁化率张量的一般表达式,由此可以定出铁磁支与交换支的共振场H₀(或共振频率)和峯宽2△ω。所得结果表明,所谓快弛豫及慢弛豫机理不过是铁磁共振的两个分支(横分支与纵分支)。横分支相应于J及S的横向磁矩之间的耦合运动J,S分别为希土离子及铁离子的磁矩),而纵分支相应于J的纵向分量与S的横向分量之间的耦合运动。由于晶场及各向异性交换场的作用,J的量子化方向与S的量子化方向偏离一个角度φ。此外由于交换作用的各向异性,在交换作用哈密顿J·λ·S中,张量λ的非对角元可以相当大。结果表明,纵分支对峯宽的贡献近似地正比于φ²及λ_i3(i=1,2)。根据2△ω的一般表达式,在极低温下(4.2°K以下),峯宽主要是由横分支决定的。沿某些晶轴方向?_a,当希土离子最低两个能级接近“交叉”时,共振场及峯宽应该出现反常峯值,这在实验上已经得到了证实。当温度升高时,纵分支将逐渐“压过”横分支。当纵向弛豫频率达到高频场的频率ω时,峯宽将出现极大值,一般实验中观察到的就是这个极大值。当温度继续升高时,横分支又将起主要作用。当横向弛豫频率接近相应于希土离子最低两个能级之间的间距ω₂₁时(?=1),峯宽将出现第二个极大值。实验上只有沿希土离子最低两个能级接近交叉的方向进行测量时,才有可能观测到第二个峯值。当频率足够高,满足|ω₂₁(?_a)-ω|<<ω的条件时,在极低温下,将出现由横分支决定的尖锐的峯宽极大值。根据所得理论结果,除上述现象外,还可以统一地解释在希土石榴石铁氧体中观测到的下列实验事实:有效旋磁比随温度的显著变化;在抵消点附近峯宽的急剧上升;在镱铁氧体中观测到的在峯宽极大值出现的温度共振场显著上升等。指出了经典磁矩运动方程的局限性,在铁氧体中,晶场的作用与交换场其大小可以相比时,利用经典方程求解所得出的结果只能定性地解释某些与希土离子具体能级结构无关的现象。     

Hydrogen isotope exchange in alkylidynes on Pt(111)

The exchange of deuterium and hydrogen in ethylidyne and propylidyne on Pt(111) has been studied using temperature programmed desorption and secondary ion mass spectroscopy. Activation energies of near 7 kcal/mol characterize the initial rate of deuterium incorporation into both species. The exchange in ethylidyne is readily described by a sequential exchange model with equal exchange rates for each of the three deuterium atoms. In propylidyne, the situation is quite different in the following respects: (1) comparable incorporation rates require 100-fold higher D₂ pressures, and (2) incorporation rates are very nonuniform, some D being incorporated very rapidly and some H remaining unreacted even at very long D₂ exposures. Possible active exchange intermediates are discussed.