两相滴定法对HEH/EHP萃取锶(Ⅱ)的机理研究

由于2一乙基己基磷酸单（2一乙基已基）酯（HEH／EHP）的PK。比二（2一乙基已基）磷酸（HDEHP）的高，从而用HEH／EHP革取金属离子时所需的水相酸度低，反革容易，国内外对HEH／EHP革取金属离子的机理研究较多［’－‘j，且用于工业生产．但用两相滴定法研究较少“，’‘．在确定机理和革合物组成时，两相滴定法比传统的斜率法快速简便，试剂消耗少．适于弱酸性革取剂的革取体系研究，目前对银的革取未见报道．本文采用两相滴定法研究了HEH／EHP的正辛烷溶液在HNO。介质中幸取Sr（I）的机理，测定了军合物组成以及计算了相应…     

辛基膦酸单丁酯萃取钴(Ⅱ)、镍(Ⅱ)的结构-性能关系

在钴、镍的湿法冶炼工艺中,溶剂萃取技术己获得了广泛的应用.自1968年Ritcey等首次提出采用二(2-乙基己基)磷酸(DEHPA)作为硫酸盐介质中分离钻、镍的萃取剂以来,又先后出现了2-乙基己基麟酸单2-乙基己基醋(EHEHPA)和二（2,4,4-三甲基戊基）磷酸(Cyanex 272、二(1-甲基庚基)磷酸等高效钻一镍分离萃取剂.     

酸性膦酸酯碱皂微乳体系的红外光谱研究

近年来对溶剂革取过程中有机相形成微乳状液的研究正引起人们的重视同，我们曾用付里叶变换红外光谱法研究过钢皂及钾皂2一乙基已基股酸单·2一乙基已基酯（简写为NaA及KA下同）加水形成微乳状液的过程，观察到P二0，P－0－C，P－0－HH－0－H和0－H等基团吸收谱带频率或强度的变化［‘剑．本文进一步对＃、销和钾三种碱金属皂化2一乙基已基胁酸单一2一乙基已基酯有机相微乳状液的形成及其红外光谱作深入研究．1实验部分五．1样品的制备问将金属捏、销和钾各置于2一乙基巴基磷酸单一2一乙基已基酯（以HA表示，下同）一正庚烷中加热回流…     

微分简易示波伏安法测定分子筛中微量钴的研究

微分简易示波伏安法是一种新的示波分析方法．与经典示波计时电位法相比，具有灵敏度高、去极剂峰高易于测定等优点．本文研究了CO－4（2一毗院偶氮）间苯二酚钠（PAR）体系的示波特性并探讨了应用微分简易示波伏安法测定微量钻的可能性．试验发现，在O．2mol／LHAc－0·2mol／LNaAc－2·5X10－’mol／LPAR底液中，钻离子在iFE曲线的阴极支上电位为一1．68V处产生一尖锐峰，其峰高与钻离子浓度在1．5X10’～1·2X10－‘mol／L范围内呈线性关系，检测灵敏度为5．OXIO－’mol／L‘以此拟定了测定微量钻的新方法．与光度法相比，该…     

用八羰基合二钴在相转移催化条件下合成1—萘乙酸

1一荣乙酸是一种植物生长调节剂，也是合成茶乙酸甲酯（另一种优良的植物生长调节剂）的原料．其合成方法有多种“’“．本文研究了在常压下，利用CO。（CO）s在相转移催化条件下，使1一氯甲基素和一氧化碳直接反应，转化为帮乙酸的合成方法，气相色谱分析法研究了反应温度、催化剂用量等反应条件对转化率的影响．SP－3410型气相色谱仪（北京分析仪器厂），岛津IR－44O红外光谱仪（日本），EM－36060MHZ核磁共振仪（上海），HP5890－5971色谱一质谱联用仪（美国）．l一氯甲基素（按文献［3」制备，纯度95％），八谈基合二钻（AR），…     

天然产物(±)-Litsenolide C_2的立体选择性合成

含3一烷叉基一4，5一二氢一4一羟基一5一甲基一2－（3H）一吠哺酮（简称AHF）结构的天然产物广泛存在于律科植物中［‘j，该类化合物往往具有高细胞毒性和抗肿瘤等生物活性［’－’1．Litseno－lideC是1972年Ishii等［‘j首次从樟科植物中分离得到的一种AHF，其结构为3一十四烷叉基一4，5一二氢一个羟基一5一甲基一2－（3H）一块哺酮，根据其烷又基构型不同又可分为：（3Z，4a，sp）－LitsenolideC；和（3E，4a，sg）－LitsenolideC。（1）．目前大多数合成LitsenolideC的方法立体选择性较差［’－’j，反应产物多为两种异构体的混…     

二(2,6-二叔丁基-4-个甲基苯氧基)钐催化丙交酯开环聚合

聚丙交酯（PLA）可以生物降解，产物无毒，可用于外科手术的缝合线、人造器官以及药物缓释等方面，因此引起了人们的广泛注意．丙交酯的开环聚合是合成聚丙交酯的一种方便方法，所用的催化剂主要是主族及副族金属的配合物，如双金属氧桥配合物［‘j，烷基金属有机化合物［‘j，异丙氧基铝［’‘以及叶琳铝「“等．最近，关于三价烷氧基稀土化合物作为单组份催化剂催化丙交酯开环聚会已有报道［’·’‘．我们发现两价芳氧基稀土化合物（ArO）。Sin（THF）。（ArO一2，已二叔丁基一个甲基苯氧基）也可以有效地催化丙文酯的开环聚合．本…     

辛基膦酸单丁酯萃取钴(Ⅱ)、镍(Ⅰ)的结构-性能关系

在钴、在钻、镍的湿法冶炼工艺中,溶剂萃取技术己获得了广泛的应用.自1968年Ritcey等首次提出采用二(2一乙基己基)磷酸(DEHPA)作为硫酸盐介质中分离钻、镍的萃取剂以来,又先后出现了2一乙基己基麟酸单2一乙基己基醋(EHEHPA)     

双核Cu(Ⅰ)配合物的热分解非等温动力学

由于钢作为活性配位中心离子，存在干具有生物功能的蛋白质大分子中，近年来钢的配位化学受到广泛关注．普遍认为，咪唤基在铜蛋白的配位化学中起重要作用＊，开展钢与具咪陵基配体所形成配合物的研究，有助于揭示钢在蛋白质中的生物化学功能及其与咪哩基等其它基团相互键合作用的本质．我们曾报导了四种新型具苯并咪吐基双核CIJ（）配合物：［CllZ’（OCTB）flC104h·1．SHZO川，［Cll。’（NMOCTB）］·（CIO。）。·H。O（2），［Cll。’（NBUOCTB）］（CIO。）z切，［Cll。’（NBOCTB）］·（CIO4h·H。O（4）的合…     

漆原钴法制备四羰基钴钠及羰基化反应

谈基钻的传统制备方法“提在高温高压下，由合成气与钻盐反应制备出CO。（CO）s，再经某些化学处理方法制备Na［CO（CO）。I，但其反应条件苛刻，操作手续繁杂，成本高，不利于大量推广应用．制备四谈基钻盐方法，还有KCN转化法［”，NaBH。还原法‘’‘等，但各种方法均有一定缺点．我们报道了Ranev－Ni催化剂催化合成Na［Co（CO）。」的新方法＊”‘．此方法收率高，反应条件温和，具有较好的应用前景，但仍存在Ni、CO分离的问题．进一步改进催化剂、降低成本、高效地合成N迁C。（CO）。」仍是解决问题的关键．为此，我们探讨…     

Separation and concentration of cobalt from ammoniacal solutions containing cobalt and nickel by emulsion liquid membranes using 5,7-dibromo-8-hydroxyquinoline (DBHQ)

The separation and concentration of cobalt from ammoniacal solutions containing nickel and cobalt by an emulsion liquid membranes (ELMs) using 5,7-dibromo-8-hydroxyquinoline as extractant has been presented. Membrane solution consists of a diluent (kerosene), a surfactant (Span 80), a modifier (tributylphosphate), and an extractant (DBHQ). Very dilute sulphuric solution containing EDTA as complexing agent, buffered at pH 5.0, has been used as a stripping solution. pH of ammoniacal feed solution containing cobalt and nickel was adjusted to 9.0 with hydrochloric acid. The important variables governing the permeation of cobalt have been studied. These variables are membrane composition, pH of the feed solution, cobalt and nickel concentrations of the feed solution, mixing speed, surfactant concentration, extractant concentration, EDTA concentration and pH of the stripping solution, and phase ratio. After the optimum conditions had been determined, it was possible to selectively extract 99.0% of cobalt from ammoniacal feed solution containing Co²⁺ and Ni²⁺ ions. The separation factors of cobalt with respect to nickel, based on initial feed concentration, have experimentally found to be of as high as 247.5 for about equimolar Co–Ni feed solutions.     

Separation of cobalt and nickel by emulsion liquid membrane with the use of EDTA as masking reagent

EDTA was used to complex nickel to allow a separation of trace amounts of nickel and cobalt in an emulsion liquid membrane (ELM), which contains P204, L-113A, liquid paraffin, kerosene and HCl. Separation time is about 20 min. Separated cobalt and nickel can be easily determined by spectrophotometer. The favorable range of pH is 4.4–5.2. The total separation coefficient is over 220 and the recoveries of cobalt and nickel are more than 95% and less than 8%, respectively. Among the coexisting ions investigated, only copper ion affects the separation.     

In-situ separation of the matrix for the direct determination of traces of chromium, cobalt, and nickel in titanium dioxide powder by electrothermal atomic-absorption spectrometry with slurry sampling

A novel method has been developed for the direct determination of traces of chromium, cobalt, and nickel in TiO2 powder; it entails slurry sampling and electrothermal atomic-absorption spectrometry (ETAAS) with a polytetrafluoroethylene (PTFE) slurry (6% m/v) as fluorinating reagent. The factors which could affect the vaporization of the matrix and analytes were studied in detail; the fluorinating vaporization behavior of the analyte both in the slurry and in solution were also investigated. Owing to the in-situ separation of the matrix, the matrix influences were reduced significantly. The proposed method has been applied to the direct determination of traces of chromium, cobalt, and nickel in high-purity TiO2 powder without chemical pretreatment. Under the optimum experimental conditions the detection limits of the analytes (Cr, Co, and Ni) were 1.9 ng g(-1), 2.4 ng g(-1) and 5.4 ng g(-1), respectively, the relative standard deviations (RSD) were 3.4% (n=6, c=7.0 ng mL(-1)), 2.9% (n=6, c=0.70 ng mL(-1)), and 7.6% (n=6, c=4.0 ng mL(-1)), again respectively, and the characteristic masses for Cr, Co, and Ni were 8.4 pg/ 0.0044A, 9.3 pg/0.0044A, and 40.0 pg/0.0044A, respectively.     

Extraction of cobalt (II) and nickel (II) by a solvent impregnated resin containing bis(2,4,4-trimethylpentyl)monothiophosphinic acid

In the present work, studies have been conducted on the equilibrium distribution of cobalt (II) and nickel (II) between aqueous hydrochloric solution and macromolecular resin impregnated with bis(2,4,4-trimethylpentyl)monothiophosphinic acid (Cyanex302, HL). Effects of extraction time, pH values, metal ion concentration, and temperature were investigated. Analysis of the results shows that the extraction of the two metal ions can be explained assuming the formation of metal complexes in the resin phase with a general composition ML ₂. An extraction reaction is proposed and the equilibrium constants of the complexes were determined. The Freundlich isotherm and thermodynamic quantities, i.e., ΔG, ΔH and ΔS were also obtained. Both of the extraction reactions of cobalt (II) and nickel (II) are endothermic ones. The efficiency of the resin in the separation of cobalt (II) and nickel (II) is provided according to the separation factors. Under the experimental conditions employed, pH₅₀ values for cobalt (II) and nickel (II) are 3.76, 5.01, respectively. The logarithmic value of separation factor was calculated as 2.50.     

Cloud point extraction, preconcentration and simultaneous spectrophotometric determination of nickel and cobalt in water samples

Cloud point extraction has been used for the preconcentration and simultaneous spectrophotometric determination of nickel and cobalt after the formation of a complex with 2-amino-cyclopentene-1-dithiocarboxylic acid (ACDA), and latter analysis by spectrophotometer using Triton X-114 as surfactant. The parameters affecting the separation phase and detection process were optimized. Under the optimum experimental conditions (i.e. pH=5, 0.07 mM ACDA, Triton X-114=0.25% (w/v)), calibration graphs were linear in the range of 20-500 and 20-200 microg l(-1) with detection limits of 10 and 7.5 microg l(-1) for Ni and Co, respectively. The method was applied to the determination of Ni and Co in natural and waste water samples with satisfactory results.     

Starch coated titanium dioxide nanoparticles as a challenging sorbent to separate and preconcentrate some heavy metals using graphite furnace atomic absorption spectrometry

In this study, a challenging nanosorbent was described for preconcentration/separation method based on the sorption of cadmium, cobalt, copper, nickel, lead on starch coated titanium dioxide nanoparticles and its analysis by graphite furnace atomic absorption spectrometry. Optimum conditions were investigated for quantitative sorption. By using the proposed technique, the analyte elements were determined in spiked tap-water samples in the range of 95% confidence level. Limit of detection (3δ) was 0.05, 0.28, 1.90, 3.10 and 0.11 µg/L (3σ, N = 10) for cadmium, cobalt, copper, nickel and lead, respectively. The optimised technique is fast, easy handled, simple and environmental friendly.     

Extractive separation of Cu<Superscript>2+</Superscript>–Co<Superscript>2+</Superscript> and Ni<Superscript>2+</Superscript>–Co<Superscript>2+</Superscript> mixtures using <Emphasis Type="Italic">N</Emphasis>-salicylideneaniline

A study on the extraction of copper(II), cobalt(II), and nickel(II) from solutions containing ions of both metals with N-salicylideneaniline(SAN) in chloroform has been realized. Distribution of the metal ions in wide range of pH has been studied. Extraction of copper(II) was always favored over that of cobalt(II). Extraction of copper(II) from binary metal solution is selective and it can be quantitatively separated from cobalt(II). The equilibrium constant of the extraction of cobalt and nickel from an aqueous solution containing both metals using SAN were evaluated. The separation factors for cobalt and nickel were expressed as a function of the distribution of nickel and cobalt. From these results, salicylideneaniline is an adequate extractant for extractive separation of such mixtures.     

Separation of large amounts of iron(III) from cobalt,nickel, and aliminum by combined ion exchange-solvent extraction

A method is described for the cation-exchange separation of large amounts of iron(III) from cobalt, nickel, and aluminium. On the strongly acidic Dowex 50-X8, iron(III) is not adsorbed from an 80% tetrahydrofuran-20% 3 M hydrochloric acid mixture, while cobalt, nickel, and aluminium are retained; a quantitative separation is thus possible. Cobalt and nickel or aluminium are then separated by elution with 90% tetrahydrofuran-10% 6 M hydrochloric acid. In these mixtures combined ion exchange-solvent extraction appears to occur; both ion exchange and liquid-liquid extraction are. effective simultaneously.     

Determination of uranium, iron, copper, and nickel from ore samples by MEKC using N,N'-ethylene bis(salicylaldimine) as complexing reagent

An analytical procedure has been developed for the separation of dioxouranium(VI), iron(III), copper(II), nickel(II), cobalt(II), cobalt(III), palladium(II), and thorium(IV) by MEKC using N,N'-ethylene bis(salicylaldimine) (H(2)SA(2)en) as a complexing reagent with total runtime <4.5 min. SDS was used as micellar medium at pH 8 with sodium tetraborate buffer (0.1 M). An uncoated fused-silica capillary with an effective length of 50 cm x 75 microm id was used with an applied voltage of 30 kV with photodiode array detection at 231 nm. Linear calibrations were obtained within 0.111-1000 microg/mL of each element with LODs within 37-325 ng/mL. The developed method was tested for analysis of uranium ore samples indicating its presence within 103-1789 microg/g with RSD within 0.79-1.87%. Likewise copper, nickel, and iron in their combined matrix were also simultaneously determined with RSD 0.4-1.6% (n = 6).     

Dissolution optimization and kinetics of nickel and cobalt from iron-rich laterite ore,using sulfuric acid at atmospheric pressure

More than 70% of the world's nickel reserves are found in laterite ores. In this research, a laterite ore sample, containing Ni, Co, and Fe, was employed to study the recovery of nickel and cobalt. Thus, the effect of calcination, acid concentration, percent solids, and stirring rate on nickel and cobalt recoveries from an iron-rich laterite sample was investigated. Optimization with response surface methodology and kinetic studies were performed. The calcination of the sample prior to leaching at 500°C for 2 h provided condition for better nickel and cobalt dissolutions. At optimal conditions, the concentration of sulfuric acid, solid-to-liquid ratio, stirring speed, temperature, and time test were equal to 5 M, 0.1, 370 rpm, 90°C, and 2 h, respectively. The highest recoveries of nickel and cobalt were 65.9% and 63.1%, respectively. Solids content had a negative effect on Ni and Co recovery, whereas acid concentration was positively affected. Addition of 10% (w/v) NaCl in the presence of 5 M acid concentration, 60°C, 370 rpm, and leaching time of 2 h increased the nickel and cobalt recoveries, 15.3% and 21.4%, respectively. The high dependence of process on temperature indicates chemical control; the activation energies E_a = 59.54 and E_a = 45.74 kJ/mol, respectively, for nickel and cobalt, were also consistent with this conclusion.