Synergistic effects in the solvent extraction of zinc with salicylaldoxime

The extraction of zinc with salicylaldoxime was studied. The adduct-forming tendency of zinc salicylaldoximate with pyridine, alpha-picoline, beta-picoline, quinohne and isoquinoline was also investigated. This tendency decreases in the order beta-picoline > pyridine > alpha-picoline > isoquinoline > quinoline.     

The application of substoichiometric radioisotopic dilution principles to controlled-potential coulometry and solvent extraction

Radioisotope dilution principles are applied to controlled-potential electrolysis and solvent extraction with dithizone for the determination of trace amounts of cadmium. A method was developed to verify whether or not the substoichiometric principle was obeyed. If the substoichiometric principle was not obeyed, analysis was still possible by means of calibration curves. In order to obtain independent verification of the series controlled-potential method and to establish a means of comparison with the radioisotope dilution technique a current integration procedure was also employed. A microtechnique was used to extend the sensitivity of the solvent extraction system for cadmium. Standard zinc spelter and high-purity zinc were analyzed for cadmium after separation by a method of standard addition.     

The solvent extraction of zinc with dithizone

The extraction of 10^-5M zinc ion from aqueous solution into an organic solvent 1.8 . 10–3m in dithizone has been investigated. The effects of pH, other ions in the aqueous phase including ions which complex with zinc, and various organic solvents have been investigated. Ions which complex with zinc (citrate, oxalate, nitrilotriacetate, ethylenediaminetetracetate) change the position and/or shape of the extraction curve. Changes in the organic solvent alter the position of the curve, this alteration being qualitatively related to the solubility of dithizone in the organic solvent. Spectra for dithizone and for zinc dithixonate in several organic solvents have also been determined.     

Predominance zone diagrams and their application to solvent extraction techniques

Predominance zone diagrams have been useful tools in solving problems in analytical chemistry. They can be used to establish the best conditions for separation of mixtures or to optimize recovery procedures for a given species. The few reports on predominance zone diagrams for the participant species in liquid-liquid extraction systems, describe their construction as diagrams of the Pourbaix type (epsilon/pH). With the generalized species and equilibria method (GSEM) it is possible to elaborate Predominance zone diagrams for extraction (PZDE) in proper spaces and with parameters strictly related to these processes such as pH and the volume ratio, r. Therefore, using the GSEM, PZDE that allow us to determine the best conditions for the extraction of a given substance have been elaborated. The stoichiometry of the species been extracted can also be determined from the experimental conditions. It has been demonstrated that with the GSEM, PZDE can be constructed for systems of one and two components. In this work, we intend to demonstrate that the algorithm is valid for the elaboration of PZDE in systems of three and four components. Examples of analytical interest are presented such as lead (II) extraction with diphenyltiocarbazone (dithizone) and that for cadmium (II) with 8-hydroxyquinolein (oxine) in chloroform. The influence of a masking agent, the etilendiaminotetraacetic acid (EDTA) over the extraction of both metals was also assessed.     

Catalytic effects in solvent extraction

Catalytic phenomena in solvent extraction of metals with hydrophobic chelating extractants are reviewed. Interface modification by adsorption of additives, phase transfer catalysis, formation of micelles, reversed micelles and microemuslions are discussed and examples are given.     

The solvent extraction of iridium with 2-mercapto-benzothiazole

Quantitative solvent extraction of iridium is possible by formation of the yellow iridium—2-mercaptobenzothiazole complex in acetic acid medium after boiling, and extraction into chloroform. Iridium is then easily determined. The applicability of the method is shown by determining iridium in noble-metal mixtures and in a copper—nickel platiniferous sample, with satisfactory recoveries.     

Synergistic effect of neutral donors on the extraction of zirconium(IV) by salicylaldoxime in dichloromethane

Liquid-liquid extraction of zirconium(IV) was investigated from dilute hydrochloric acid medium by salicyaldoxime (HA) in dichloromethane. The metal was spiked with ⁹⁵Zr and analyzed by its radioactivity. The effects of different donors, like trioctyl phosphine oxide (TOPO), triphenyl phosphine oxide (TPPO), tributyl phosphine oxide (TBPO), tributyl phosphate (TBP), trioctyl amine (TOA) and Amberlite LA-2 were studied. The adduct formation constants for both binary species (metal-ligand) and ternary species (metal-ligand-donor) were also calculated form the distribution data.One of the authors (S.B.) thanks The University of Burdwan for providing senior research fellowship to her. She also wishes to thank Dr. D. Mukherjee and Dr. S. Bhattacharya, B.U. for their valuable suggestions.     

Separation of high purity gadolinium for reactor application by solvent extraction process

A solvent extraction process for the production of nuclear grade Gd₂O₃ for its applications in pressurized heavy water reactor (PHWR) from a crude concentrate of rare earths containing ~70 % Gd₂O₃ has been developed and tested on bench-scale and continuous counter-current operations. The separation of gadolinium from other rare earths with similar chemical properties has been successfully accomplished by adopting a dual cycle solvent extraction employing 2-ethylhexylphosphonic acid, mono-2 ethylhexyl ester (EHEHPA) as an extractant. Taking advantage of the extraction order of rare earths with EHEHPA, in the first cycle, heavy rare earths including Tb, Dy and Y were separated in the product strip solution, while gadolinium was separated in the raffinate solution along with samarium and neodymium. In the second cycle, gadolinium was purified to the extent of >99.5 % with respect to other rare earths. Effects of process variables such as aqueous acidity, phase ratio, metal concentration in the aqueous feed, scrubbing and stripping acidity etc. on separation of terbium and other heavy rare earths in the first cycle and upgrading the purity of Gd₂O₃ in the second cycle have been investigated. The experimental conditions were optimized using computer simulation and validated by bench scale counter-current operations. Under optimized conditions of process parameters, continuous operations of mixer settler yielded kilogram quantity of nuclear pure Gd₂O₃ which was subsequently converted to gadolinium nitrate for PHWR application. The overall recovery was found to be >98 %.     

The solvent extraction of trace antimony(V)

An investigation of the extraction of trace amounts of antimony(V) from aqueous hydrochloric acid solutions into various others and chloroform has been carried out. Before extractions were made, mutual solubility studies of the two-phased systems were conducted. Then extraction experiments were performed using original aqueous acid concentrations from 0 to 12N and non-aqueous phases of ethyl ether, isopropye ether, isoamyl ether, n-hexyl ether, and chloroform. Dielectric constant determinations were made in the equilibrated non-aqueous phases, and spectrophotormetric and salting-out studies were carried out on the ethyl ether system. It was found that the isopropyl ether system presents the most advantageous conditions for the extraction of trace antimony(V)     

The application of salicylaldoxime in solvent extraction : Part II. Spectrophotometric determination of copper with 2-(5-nitro-2-pyridylazo)-1-naphthol after separation with salicylaldoxime

A highly sensitive spectrophotometric method for the determination of traces of copper with 2-(5-nitro-2-pyridylazo)-l-naphthol (5N-α-PAN) has been developed. At a pH of 3–4copper(II) is selectively extracted into chloroform as its salicylaldoxime chelate and then stripped into an aqueous acid solution; the pH is adjusted to 9.3, and 5N-α-PAN is added. The 1:2 chelate between copper(II) and the reagent, which promptly precipitates, is extracted into chloroform and measured at 598 nm. The molar absorptivity is 86,000. The application of the method to the analysis of high-purity magnesium and cobalt is described.     

Some solvent effects on the solvent extraction of 8-quinolinol

The distribution constants of 8-quinolinol between water and a series of substituted aliphatic hydrocarbons, at 25 degrees , are reported. The results are discussed in terms of dielectric constant and solubility parameter of the solvents. For 8-quinolinol, and possibly for its chelates, bromochloromethane, dibromomethane and chloroform seem to be about the best solvents, in that order. Among the solvents studied, chloroform shows significantly higher values than expected; the deviation may be explained as a specific interaction of the hydrogen- bonding type.     

Anomalous solvent extraction behavior of astatine

We studied the solvent extraction behavior of astatine and found the anomalous behavior of this element similar to radioiodine. Astatine was extracted into CS₂ from acidic solution over a wide range of carrier iodine concentration. The distribution ratios of astatine were determined by measuring the -ray from 210 At with a Nal(TI) detector. A drastic change was observed around at 10^–4 mol/l as in the case of 131 I. This tendency is well explained by the kinematics of the chemical reactions concemed.     

The solvent extraction of some thallium(I) chelates

Studies of the extraction of thallium (I) from aqueous solution into an immiscible organic solvent have been made using 71 chelating reagent-solvent pairs involving 16 reagents and 17 solvents. The data have been analyzed to identify the predominant species involved, and association and partition constants have been estimated in many cases, The best extraction systems seem to be those involving 3phenylpropylxanthate and chloroform, chlorobenzene or methylene chloride.     

The solvent extraction of some thallium(I) chelates

Fourteen different chelating reagents have been investigated, as possible extradants for radioiabelled 10^-6M thallium(I) from aqueous solutions into chloroform. The data have beun analyzed theoretically to identify the predominant species involved and to estimate association and distribution constanta.     

加速溶剂萃取法快速提取黄连中的生物碱

探讨了快速溶剂萃取法（ASE）提取黄连中生物碱的可行性,并比较了该方法与回流提取法和超声提取法的优越性。以黄连中盐酸小檗碱的提取率为指标,以高效液相色谱法（HPLC）为检测方法,用正交实验对快速溶剂萃取法从黄连中提取盐酸小檗碱的工作条件进行优化。最佳仪器参数：提取溶剂为80%乙醇＋0.5%HCl,提取温度为130℃,静态提取时间为10 min,提取次数为1次。快速溶剂萃取法可作为黄连中生物碱分析测定的前处理方法。