Extraction and Spectrophotometric Determination of Zirconium(IV)

Abstract

A sensitive and selective method for the extraction and spectrophotometric determination of Zr(IV) with N-p-chlorophenyl-3,4-,5-trimethoxycinnamohydroxamic acid (PTCHA) has been developed. The binary complex of Zr(IV)-PTCHA is extracted from 2–6 M HCl into chloroform, having a maximum absorbance at 385 nm; molar absorptivity 2.1 × 10⁴ 1 mol^?1 cm^?1. A ternary complex with xylenol orange (Zr-PTCHA-XO) have been studied in chloroform-ethanol media, which absorbs at 540 nm; molar absorptivity 4.3 × 10⁴ 1 mol^?1 cm^?1. The present method is applied for the analysis of zirconium in standard samples.     

Effect of solvent upon competitive liquid-liquid extraction of alkali metal cations by isomeric dibenzo-16-crown-5-oxyacetic acids

The selectivity and efficiency of competitive liquid-liquid extraction of alkali metal cations into organic solvents containingsym-(octyl)dibenzo-16-crown-5-oxyacetic acid (2) andsym-bis[4(5)-tert-butylbenzo]-16-crown-5-oxyacetic acid (3) have been determined. Solvents examined include: dichloromethane, chloroform, carbon tetrachloride, 1,2-dichloroethane, 1,1,1-trichloroethane, benzene, toluene,p-xylene, chlorobenzene, 1,2-dichlorobenzene, and 1,2,3,4-tetrahydronaphthalene. The Na⁺/K⁺ and Na⁺/Li⁺ extraction ratios are highest in chloroform. The extraction selectivity is found to correlate with the diluent parameter (DP) of the organic solvent.This paper is dedicated to the memory of the late Dr C. J. Pedersen.     

Ions in Aqueous Acetic Acid Mixtures: Solvent Reorganization around Protons and Gibbs Energies of Transfer from Water

The photo-absorbing, basic sensor, 4-nitroaniline, has been used to determine theequilibrium constant for solvent reorganization around the proton in mixtures ofvarying composition of water with acetic acid. In all the mixtures used, theself-ionization of the acetic acid was suppressed. In contrast to mixtures of waterwith the related ethanol or acetone, this equilibrium is shifted more toward thewater-solvated species as the mole fraction x ₂ of the cosolvent increases. TheGibbs energy of transfer of protons from water into the mixture G ^o _t (H⁺) can bederived with the aid of this equilibrium constant for the solvent reorganization.Using G ^o _t (H⁺), G ^o _t (i) for i denoting anions and other cations can be evaluated.In comparison the G ^o _t (i) for cations have lower negative values than when eitherethanol or acetone is added to water. Correspondingly, for halide anions, thepositive G ^o _t (i) with added acetic acid are rather less than is found with eitherethanol or acetone added. The influence on the ion-solvent interaction of bothelectron withdrawing hydroxy and carbonyl groups in acetic acid may beresponsible for this. Although G ^o _t (i) for C10^– ₄ and Re0^– ₄ are also positive, both picrateions and OH^– give negative values with acetic acid added to water. With picrateions, the hydrophobic effect of the carbon ring produces stabilization in themixture relative to water. With OH^–, complete conversion to acetate anionsoccurs. As is found with other cosolvents, the contribution of the charge onacetate anion to G ^o _t (CH₃COO^–) is found to increase as x ₂ rises. The aciddissociation constant K _a for acetic acid is found to decrease slowly as x ₂ rises to0.5, followed by a rapid decrease for x ₂ greater than 0.7 where dimerization ofacetic acid occurs.     

快速溶剂萃取-离子色谱法测定茶叶中的有机酸

建立了快速溶剂萃取-离子色谱法（ASE—IC）测定茶叶中的9种有机酸。优化了ASE苹取条件,以水为萃取溶剂,80℃下萃取5min,循环两次。采用Ionpac AS11HC柱分离,KOH溶液梯度洗脱,流速1,0mL／min,抑制电导检测。9种有机酸的检出限为0．009-0．160μg／mL,线性范围为0．5—10μg／mL,相关系数大于0．999,加标回收率为93．4％-99．2％,相对标准偏差为1．4％-4．1％。     

Some further observations on the systems cellulose/trifluoroacetic acid/CH2Cl2 and cellulose triacetate/TFA/CH2Cl2

There is little or no trifluoroacetylation of cellulose dissolved in TFA-CH₂Cl₂ admixtures. Both cellulose and cellulose triacetate (CTA)are slowly degraded in the solvent. Cellulose forms a mesophase as low as 4%(w/w)concentration, but CTA has a much higher critical concentration, 20% (w/w), in TFA-CH₂Cl₂. The cellulose behaves as a rigid rod in TFA-CH₂Cl₂ (70/30v/v) and its persistence length calculated using the lattice model approximates its chain length, presumably due to extensive interaction with the solvent. As expected, due to low polymer-solvent interactions, the persistence length of CTA in TFA-CH₂Cl₂ is only one-fourth the chain length.     

粗硼砂的氯化铵溶液浸提动力学

研究了反应温度、溶液浓度、固液比、固体粒径大小和搅拌速度对氯化铵溶液浸提粗硼砂(十水四硼酸钠,Na₂B₄O₇·10H₂O)动力学的影响。结果表明反应速率随反应温度、溶液浓度的增加和固体粒径、固液比的减小而增加,但搅拌速度对溶解速率无显著影响。根据均相和多相动反应力学模型研究了粗硼砂的溶解过程。结果表明溶解速率遵从假一级均相反应模型。粗硼砂在氯化铵溶液中溶解的活化能为82.73 kJ·mol^-1。     

硝酸胺溶液浸提硬硼酸钙的动力学研究

对硬硼酸钙在硝酸铵水溶液的溶解在间歇式反应器中就搅拌速度、粒径大小、反应温度、固液比和溶液的浓度等参数的影响进行了研究。结果表明溶解速度随温度、硝酸铵水溶液的浓度以及粒径和固液比的增加而增加,但搅拌速度对溶解速度无重要影响。硬硼酸钙在硝酸铵水溶液中可以高达100%。硬硼酸钙的溶解动力学根据多相和均相反应模型进行了检验。实验数据表明有高的活化能,说明基于多相反应动力学模型的溶解速度可表达为：1-(1-X)^1/3=3.28 ×10⁴·D^{-0.653 7}·C^{1.295 8}·(S/L)^{-0.490 9}·e^-41.40/(RT)·t。反应过程的活化能为41.40 kJ·mol^-1。     

Extraction and separation of lanthanides from aqueous chloride and nitrate media using mixtures of binary extractants based on secondary and tertiary amines

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压水堆核电站一回路冷却剂系统中硼酸基体对锂含量测定影响的研究

为解决压水堆(PWR)核电站一回路冷却剂系统中硼酸溶液对锂含量测定的影响,对原子吸收法进行了改进。当样品的硼含量小于1000 mg/kg时,使用500 mg/kg硼基体标准工作液,并在样品中加入65 mg/kg的硝酸进行测定;如果样品的硼含量大于1000 mg/kg时,须将样品进行稀释,使稀释后的样品中硼含量小于1000 mg/kg,然后按照硼基体含量小于1000 mg/kg的样品进行测定。测定实际样品L1RCP的精密度为0.48%,回收率为100%,结果证明方法可行。     

Obtimization of separation conditions in reversed phase liquid chromatography using complex solvent mixtures

Summary Four different methods of calculation of retention in ternary mobile phases were compared and it was found that the simple calculation based only on two values of the capacity factors (one for each binary system that composes the ternary mobile phase) provides the accuracy of prediction that is, at least, comparable to the other methods of calculation that require a large number of preliminary experiments. The deviations from ideal behaviour in ternary solvent mixtures are discussed; some sources of errors can be avoided, at least partially, using binary systems of adequate compositions for preparation of ternary mobile phases. Several examples show the comparison of calculated and experimental selectivities in ternary solvent systems. A simple calculation can be used for rapid selection of an adequate ternary (or more complex) mobile phase, if it is necessary to achieve the separation of a given sample mixture.Presented at the 14th International Symposium on Chromatography London, September, 1982     

Effect of Association of Curcumin with Chitosan in Presence of TX 100 on Its Degradation

The binding of curcumin with chitosan in the presence of nonionic surfactant, iso-octylphenoxy-polyethoxy-ethanol (Triton X-100) and its stability in such systems have been investigated by monitoring the changes in the absorption spectra at physiological pH (7.4). It was observed that curcumin binds to chitosan more than 10 times stronger in presence of TX 100 at the experimental condition. From spectrophotometric analysis of the kinetics of degradation of the dye, it was observed that the yield of suppression of degradation of curcumin by chitosan increases by 33.5% in the presence of TX 100 than alone. The interaction of the dye with chitosan has been found to be exothermic and driven by hydrophobic interactions, hydrogen bond formation, and electrostatic interactions.     

锌矿原料有机物含量监测方法探究

采用测定化学需氧量(COD)法和有机溶剂抽提法分别对企业常用的两种锌矿原料(A,B)有机物进行监测。通过采用测定化学需氧量(COD)法对锌矿原料中含有的有机物进行定性及半定量分析,实验结果表明,矿粉A中COD为84.9mg/L,矿粉B中COD为96.9mg/L,各自进行了3次平行实验,都能得到稳定的结果,同时确定矿粉A和B中分别含有不同量的有机物。采用有机溶剂抽提法来确定锌矿原料中有机物的含量。考察了溶剂种类、溶剂量、抽提时间对矿粉中的有机物提取效果的影响,得到最佳实验条件,对矿粉的测定结果为:矿粉A中有机物含量为7.6‰,矿粉B中有机物含量为10.1‰。在各自的最佳实验条件下,进行了3次平行实验,都能得到稳定的结果,方法准确、可靠。     

叔胺N235-PtCl6^2- -HCI萃取体系第三相中“超浓盐酸”的生成及其微乳结构

采用分子谱学及同步辐射X射线小角散射（SAXS）等表征手段,研究了三烷基叔胺（N235）莘取PtCl6^2-体系中第三相的形成及溶液微观聚集态结构的变化对PtCl6^2-萃取行为的影响．实验结果表明：萃铂有机相中第三相的形成与萃入有机相的酸和水含量的变化导致溶液结构发生变化有关：与含铂高酸度盐酸水溶液平衡后,第三相微乳水团中形成H^＋／H2O摩尔比远大于37wt％常规饱和浓盐酸的“超浓盐酸”;“超浓盐酸”微观介质内H^＋和Cl^-的大量聚集增浓对Pt离子的络合配位状态产生影响,H^＋参与了Pt离子配位状态的转变：第三相“超浓盐酸”形成后,使得微乳水团中大量存在的H^＋有可能参与调控水团中各种HmPtCl6^z＋复合络离子配位状态的相对含量,被H^＋活化的叔胺（R3NH^＋）与Pt离子的各种配位状态的匹配程度最终决定了铂在第三相中的萃取行为．     

快速溶剂萃取-气相色谱/质谱联用测定塑料桌布中的邻苯二甲酸酯

采用快速溶剂萃取-气相色谱/质谱联用法(ASE-GC/MS)和超声波萃取-气相色谱/质谱联用法(USE-GC/MS)测定了塑料桌布中的邻苯二甲酸酯.结果表明:ASE-GC/MS的测量精度优于USE-GC/MS,后者测量值大约为前者的五分之四;ASE-GC/MS的回收率为89.0%～95.5%,相对标准偏差为4.3%～1...     

Ionic equilibria in aqueous organic solvent mixtures the dissociation constants of acids and salts in tetrahydrofuran/water mixtures

The dissociation constants of several acids (perchloric, hydrochloric, phosphoric, acetic and benzoic acids) and of some sodium salts (chloride, acetate and benzoate) have been conductometrically determined in tetrahydrofuran/water mixtures up to a 90% of tetrahydrofuran in volume. The results demonstrate that conductometry can be successfully applied to determine the dissociation constants of salts and moderately weak and strong acids in the studied mixtures. The dissociation constants of the acids and some bases taken from the literature have been fitted to solvent composition through a previously derived equation, which is based on a preferential solvation model. The fitting parameters obtained allow calculation of the dissociation constant for any solvent composition inside the applicability solvent composition range. From the pK value, the pH of any buffered solution, such as those used in liquid chromatography, can be calculated for the particular tetrahydrofuran/ water composition of interest. Appreciable ion-pairing for sodium salts and strong acids has been observed for tetrahydrofuran contents higher than 60% in volume. Therefore, the accurate calculation of the pH values of buffers in tetrahydrofuran-rich solutions must take into account the pK values of the acid and salt.     

有机溶剂性质及其水含量对酶催化合成含D－氨基酸残基的二肽衍生物的影响

有机溶剂性质及其水含量对酶催化合成保护的寡肽及其衍生物有显著影响。系 统地研究了有机溶剂性质及在不同有机溶剂中水含量对α－胰凝乳蛋白酶催化合成 含D－氨基酸残基的二肽衍生物产率的影响。用α－胰凝乳蛋白酶、枯草杆菌蛋白 酶和嗜热杆菌蛋白酶在有机溶剂中催化合成了一系列保护的二肽及其衍生物，并研 究了水含量对反应产率的影响，得到了十分有意义的结果。     

高效液相色谱-原子荧光光谱法测定海产品中甲基汞

为调查渤海海域海产品中甲基汞的污染情况,建立了高效液相色谱-原子荧光光谱法测定海产品中甲基汞的分析方法。样品中甲基汞经提取剂磁力搅拌提取20min,0.1μm有机系尼龙微孔滤膜过滤,以10%甲醇+0.04mol/L乙酸铵+0.1%L-半胱氨酸为流动相,用HC-C18 0.5um色谱柱分离,原子荧光光谱法进行测定。甲基汞在2-40ng/mL范围内线性关系良好,相关系数r＞0.999,方法检出限为0.02ng/mL,回收率在97.2-99.2%之间,相对标准偏差为3.7%。首次采用0.1%L-半胱氨酸+10%甲醇作为提取剂,该方法操作简单,精密度高,干扰少,可用海产品中甲基汞的测定。     

Spectrophotometric Determination of Antimony (III) By Solvent Extraction with Mandelic Acid and Malachite Green

Abstract

A sensitive and selective method has been developed for the spectrophotometric determination of antimony in the tervalent oxidation state. It was found that antimony (III) reacts with mandelic acid to form a complex anion extractable into chlorobenzene with malachite green in weak acidic media (pH 2.2 to 3.5) at room temperature and is determined indirectly by measuring the absorbance of malachite green in the extract at 628 nm. The calibration graph is linear for antimony (III) over the range 0.088–1.8 mg 1^?1 (7.2 × 10^?7–1.5 × 10^?5 mol 1^?1) with the apparent molar absorptivity ε × 6.9 × 10⁴ 1 mol^?1 cm^?1. Antimony (V) was slightly extracted in the presence of phosphate buffer with ε × 2.7 × 10³ 1 mol^?1 cm^?1.     

显微镜图像分析研究非相容高密度聚乙烯/尼龙1010共混体系熔体动态过程中相结构的形成与发展

讨论了非相容高密度聚乙烯,尼龙1010共混体系在熔融混炼过程中相结构的形成与发展.应用在线连续采样方法,获得共混过程中体系不同时刻的样品,应用扫描电子显微镜观察并得到共混物相结构的显微图像.用图像处理和图估计方法求得了体系分散相平均粒径和粒径分布宽度,讨论了平均粒径和分布宽度随混炼时间的变化.结果表明,共混物相结构的变化主要发生在混炼初期,即混炼两分钟以前,之后平均粒径和分布宽度趋于平稳,保持在一定数值范围内.引入分性概念,应用测度法计算了体系的分形维数,表明体系相结构的变化具有自相似性,分形维数的变化与体系的均匀性有关.同时,研究了混炼温度和混炼设备的转速(剪切速率)与体系分散相平均粒径、分布宽度和分形维数等结构参数的关系.