Comparative studies on co-extraction of uranium(VI) and different mineral acid from aqueous feed solutions using TBP,TOPO and TOA

Equilibrium and kinetics of co-extraction of hexavalent uranium and mineral acids from aqueous solutions into a hydrocarbon phase (paraffin) using tri n-butyl phosphate (TBP), tri-n-octyl phosphine oxide (TOPO) and tri-n-octyl amine (TOA) has been studied. Relative rates of extraction of uranium(VI) and mineral acid by different complexing ligands were measured simultaneously using bulk-liquid membrane system. Acid extraction by complexing ligands was found to be significant. Wherever there was a possibility of the formation of the third phase, isodecanol was used as an organic phase modifier. Study revealed that isodecanol promotes acid extraction and substantially reduces distribution coefficient of U(VI) into the hydrocarbon phase. The rate of acid extraction by different ligand was in the order of TOPO > TOA > TBP–isodecanol > TBP, whereas the rate of extraction of uranium(VI) was in the order TOPO > TOA > TBP > TBP–isodecanol. A kinetic model was developed to predict concentration of acid and U(VI) in the feed, organic and the strip phase during extraction. The mass transfer coefficients for acid and metal were determined by fitting the model to the observed concentration–time data.     

Influence of preferential adsorption of mobile phase on retention behavior of amino acids on the teicoplanin chiral selector

The adsorption behavior of two amino acids, i.e., l,d-threonine and l,d-methionine has been investigated on the chiral stationary phase (CSP)column packed with teicoplanin bonded to a silica support. The study has been performed under non-linear conditions of adsorption isotherm for various types of organic modifiers (methanol, ethanol, propan-2-ol and acetonitrile) in the reversed-phase mode. A heterogeneous adsorption mechanism of amino acids has been identified that was strongly affected by the nature of organic modifier. Generally, isotherm non-linearity and retention decreased with decrease of the modifier content in the mobile phase exhibiting a minimum at water-rich mobile phases. These trends were suggested to result from a combined effect of the mobile as well as the adsorbed phase composition. To determine the composition of the adsorbed phase the excess adsorption of modifiers in aqueous solutions has been measured and their binary adsorption equilibria have been quantified and compared. Strongly non-ideal behavior of solvents in the mobile phase and the adsorbed phase has been accounted for by activity coefficients. The fraction of the modifiers in the adsorbed phase decreased in the sequence: methanol, ethanol, propan-2-ol and acetonitrile.     

Ultrathin organic semiconductor films — Soft matter effect

The growth of organic semiconductor thin films has been a crucial issue in organic electronics, especially the growth at the early stages. The thin-film phase has been found to be a common phenomenon in many organic semiconductor thin films, which is closely related with the weak van der Waals interaction between organic molecules, the long-range interaction between organic molecules and the substrate, as well as the soft matter characteristics of ultrathin films. The growth behavior and soft matter characteristics of the thin-film phase have great effects on thin film morphology and structure, for example, the formation and coalescence of grain boundaries, which further influences the performance of organic electronic devices. The understanding of thin-film phase and its intrinsic quality is necessary for fabricating large-size, highly ordered, continuous and defect-free ultrathin films. This review will focus on the growth behavior of organic ultrathin films, i.e., the level of the first several molecular layers, and provide an overview of the soft matter characteristics.     

甲氧苄氨嘧啶纯度的反相高效液相色谱分析

本工作建立了抗菌药物甲氧苄氨嘧啶中少量杂质的反相高效液相色谱分析方法。方法操作简便，分析快。同时考察了有机改进剂对该药物分离的影响。     

The investigation of the solvent extraction of molybdenum from concentrated solution of sulphuric acid

The solvent extraction of molybdenum(VI) from sulphuric acid solutions with di-(2-ethylhexyl)-phosphoric acid (HDEHP) and monododecylphosphoric acid (HDDP) in n-heptane has been studied (a) as a function of the concentration of sulphuric acid, molybdenum and the extractant; (b) in the presence of copper and zinc in the aqueous phase and (c) in the presence of tri-n-butylphosphate (TBP) in the organic phase. The distribution of the sulphuric acid between aqueous and organic phase has also been studied.     

Novel imidazolium stationary phase for high-performance liquid chromatography

A new imidazolium anion-exchange phase immobilized on silica is synthesized. HPLC separations of common inorganic anions (IO3-, Cl-, NO2-, Br-, NO3-, I-, SCN-) have been performed using a HPLC column (200 mm x 4.6 mm I.D.) packed with this stationary phase, with a phosphate buffer solution as the mobile phase and UV detection at 200 nm. The effects of pH and concentration of eluent on the separation of anions have been studied. Chromatographic parameters are calculated and the results show that the new stationary phase is of significant potential for the analysis of these anions. Successful separations of some ordinary organic anions have also been achieved with the said stationary phase. Meaningfully, organic and inorganic anions can be determined simultaneously and satisfactorily with several neutral compounds using the column. The separation of some organic compounds including hydroxybenzenes, bases and amines by this stationary phase with only water as the eluent has been investigated.     

Extraction of perchloric acid by the nitrobenzene solution ofp-nonylphenylnonaethylene glycol

Extraction of perchloric acid by the nitrobenzene solution of Slovafol 909 (p-nonylphenylnonaethylene glycol, L) has been investigated and the composition of species in the organic phase has been determined. It has been found, that perchloric acid is full dissociated in both phase, and H⁺ ion in the organic phase is partially solvated by one or two molecules ofp-nonylphenylnonaethylene glycol. Extraction and stability constants of HL⁺ and HL ₂ ⁺ species in the organic phase has been evaluated.     

Competitional hydrophobicity driven separations under RP‐LC mechanism: Application to sulfonylurea congeners

Retention of a model set of sulfonylurea compounds has been studied under RP‐LC conditions, considering competitional effects brought by different alcohols (ethanol, 1‐propanol, 2‐propanol, 1‐butanol, 1‐pentanol, and 1‐octanol) used as additives in the organic component of the mobile phase (methanol). The capacity factors determined for the model compounds decreased with the increase of the hydrophobic character of the organic additive in the mobile phase. The amount of the additive within the organic component of the mobile phase was kept constant (1% as volumetric ratio). Retention was studied at different mobile phase compositions (aqueous to organic component ratios). Different functional fitting models were used to correlate retention to the content of the organic component in the mobile phase. Extrapolation of retention expressed as capacity factor to a mobile phase composition free of organic component is well correlated to the hydrophobic characteristics of the organic additives. The adsorption model was used for tuning the experimental find‐outs. The possibility of controlling retention through the competitive effects induced by hydrophobic additives in the mobile phase is highlighted.     

Electrochemical synthesis of aromatic sulfur compounds in ionic liquids

Electrochemical properties of ionic liquids (pyridinium and imidazolium salts) and the effect of additives of organic solvents on the electrochemical determination of organic compounds in ionic liquids have been studied. Transformations of aromatic and aliphatic sulfur compounds in ionic liquids in the presence of aromatic substrates are discussed. A new method has been proposed for identification of organic sulfur compounds–gas chromatography on columns with ionic liquid as the active phase.     

萃取有机相的微结构和性质的研究

本文用FTIR, 荧光, ICP/AES等方法研究了含稀土的HDEHP[二(2-乙基己基)磷酸, HA]-正庚烷的萃取有机相的结构和聚集态。结果表明: (1)不同稀土离子与萃取剂的配位能力不一样, La相似文献   

Synthesis and application of inorganic/organic composite materials

A new type of inorganic-organic composite has been developed using organic monomeric or polymerizable silanes (with appropriate organic groupings like double bonds or epoxides) as monomers or in situ prepared or separately added nano-scale ceramic or metal particles. Due to the small size of the particulate phase, these composites are still highly transparent but show properties at least partially to be attributed to the inorganic phase. The introduction of special functions into these materials has been used for the fabrication of interesting functions like non-linear optical properties, low surface free energy coatings, controlled release properties or special mechanical properties (scratch resistance).     

Interactions between surfactant capped CdS nanocrystals and organic solvent

The dispersibility of organic capped nanocrystals (NCs) in diverse solvents is one of the key factor of the success of such a class of nanostructured materials. In this work the α-cyclodextrins, mediated phase transfer has been considered as an effective procedure to direct the NC transfer from the organic solvent to water. The effect of the original organic solvent, namely hexane and chloroform, and of the ligand molecule coordinating CdS nanocrystal surface has been investigated by optical (UV-Vis, Photoluminescence, FTIR, Dynamic Light Scattering) and calorimetric techniques. The calorimetric investigation has been carried out by performing dilution experiments and the correlation between thermal effects and dilution ratio has been evaluated using the McMillan approach. The obtained results have provided relevant insight on the parameters driving the phase transfer process and on the NC mutual interaction, thus resulting valuable on the effectiveness of the phase transfer procedure.     

Polarographic behaviour of uranium (VI) in organic solutions

Polarographic determination of uranium (VI) has been studied in the organic extraction phase TBP—diluent along with a selected aprotic solvent (i. e. dimethyl sulfoxide or N,N-dimethylformamide). DMF was found more suitable because it dissolves the organic extraction phase better than DMSO. U (VI) extracted in TBP-kerosene, n-hexane, cyclohexane, n-dodecane, benzene, from nitric acid medium can be determined in an organic solution (e. g. 50% DMF-30% TBP-20% kerosene) where it gives a well defined wave. In the organic solution, nitric acid added and/or extracted from the aqueous phase was found as an excellent supporting electrolyte for uranium determination.     

Influence of the nature of organic phase emulsions on sensitivity in atomic-absorption determinations

The influence of the nature of organic phase emulsions on sensitivity in atomic-absorption determinations has been studied for the copper-APDC chelate extracted into various solvents. Oil-in-water emulsions containing 10% of organic phase emulsified with non-ionic and anionic surfactants were introduced into the flame and the atomic-absorption of copper was measured. An attempt was made to relate the effect on sensitivity to the physical properties of the different emulsions but no correlation was found. Rheological properties such as aspiration rate and nebulization efficiency did not differ significantly for different emulsified organic solvents. Enrichment of the waste solution proved the most important parameter for predicting an increase in sensitivity.     

Spectrophotometric determination of uranium(VI) by solvent extraction with trioctylphosphine oxide and a molten mixture of biphenyl and naphthalene

Uranium in ores has been determined spectrophotometrically after extraction with trioctylphosphine oxide (TOPO) into a molten mixture of biphenyl and naphthalene. By addition of salting-out agents such as sodium nitrate to the aqueous phase and cooling, the organic phase can be obtained as a solid lump on the surface of the aqueous phase, making its collection simple. The uranium can then be determined directly in the organic phase with 1-(2-pyridylazo)-2-naphthol or 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol.     

The complex formation-partition and partition-association models of solvent extraction of ions

Two models of the extraction process have been proposed. In the first model it is assumed that the partitioning neutral species is at first formed in the aqueous phase and then transferred into the organic phase. The second model is based on the assumption that equivalent amounts of cations and anions are at first transferred from the aqueous into the organic phase and then associated to form a neutral molecule. The role of the solubility parameter in extraction and the relation between the solubility of liquid organic substances in water and the partition of complexes have been discussed. The extraction of simple complexes and complexes with organic ligands has been discussed using the first model. Partition coefficients have been calculated theoretically and compared with experimental values in some very simple cases. The extraction of ion pairs has been discussed using the partition-association model and the concept of single-ion partition coefficients.     

Some considerations concerning the composition of the mobile phase in capillary electrochromatography

In capillary electrochromatography (CEC) the propulsion of the mobile phase is effected by electroosmosis. The velocity of the electroosmotic flow is dependent on surface properties of the stationary phase and on bulk properties of the mobile phase. Therefore, in CEC the optimization of the mobile phase composition must take more factors into account than in pressure-driven LC. In this paper, the impact of the electrolyte concentration in the mobile phase and of the volume fraction of the organic mobile phase constituent on the velocity of the electroosmotic flow and on the chromatographic efficiency is investigated for CEC with capillaries packed with octadecylsilica gel. Bias of the data by an open section of the capillary has been excluded by employing completely packed capillaries and detection in a packed section. Acetonitrile as organic constituent of the mobile phase is compared to other possible organic modifiers (polar organic solvents) concerning influence on velocity of the electroosmotic flow and retention of solutes.     

共价有机骨架材料在分离科学中的研究进展

共价有机骨架(COFs)材料是一类由有机单体通过共价键连接而成的新型多功能结晶有机聚合物,具有比表面积大、热和化学稳定性好、结构和功能可控等优点,在气体存储、药物传递、传感和催化等方面有着广泛的应用。多样的结构和丰富的官能团也使COFs在分离科学中具有巨大的应用潜力。COFs及其复合材料作为吸附剂已被用于固相萃取、磁固相萃取、固相微萃取,以及气相色谱、高效液相色谱和毛细管电色谱的新型固定相。该文综述了近3年来COFs在分离科学中的最新进展,着重介绍了COFs在水介质、食品基质、生物样本等复杂基质中样品前处理和有机分子(包括手性和异构化合物)分离等方面的研究进展,为进一步研究COFs的应用提供参考。     

Verteilung des Kieselsäure-Brenzcatechin-Komplexes zwischen wäßrigen Lösungen und organischen Lösungsmitteln

The extraction of silicic acid as catechol complex by different organic solvents in presence of various organic bases has been studied. The influence of pH as well as of catechol und diphenylguanidine concentrations was tested. Ca. 100% extraction of silicic acid can be achieved at pH 9.2–9.3 by nitrobenzene, if the concentration of catechol in the aqueous phase is 0.5 M and that of diphenylguanidine in the organic phase > 0.25 M.     

Relation between the structure and extracting power of higher tertiary amines

The effect of the composition and structure of higher tertiary amines on their efficiency in extracting nitric acid has been examined. The ionization constants of the amines in methanol have been determined by potentiometric titration. The extraction constants for nitric acid have been determined at constant ionic strength in the aqueous phase (μ=1). The dependence of these constants upon the concentrations and the degree of association of the amine salts in the organic phase has been examined. For the cases in which the role of steric factors is negligible it has been shown that at low amine salt concentrations in the organic phase there are quantitative regularities between the ionization constants of the amines in methanol, their extraction constants for nitric acid and the inductive effects of the substituents on the nitrogen atom.