Sorption properties of chemically treated clinoptilolites with respect to Cs and Co

The sorption ability of clinoptilolite treated by NaOH solution has been studied. The distribution coefficients of¹³⁷Cs and⁶⁰Co were studied by the radiochemical method. The variation of distribution coefficients with pH was studied. Also the influence of competitive ions on distribution coefficients were investigated. The total cation exchange capacity and XRD analysis were also measured.     

Direct measurement of diffusion coefficients of Sr and Co in silica gel layers under various conditions

The diffusion coefficients of Sr in gelled silica gel layers have been measured at various porosities. They decreased with the second power of porosity. At constant porosity, the diffusion coefficients of Sr and Co were measured at various pHs. They were dependent on the distribution coefficients (K) of the species between silica gel and pore water as a function of 1/(1+K). Gelation of the porous layer enables a stable measurement of diffusion coefficients under various conditions and facilitates the analysis of the distribution of ions after the diffusion experiments.     

On the distribution coefficient of nickel dimethylglyoximate between an aqueous solution and organic solvents

The distribution coefficients of nickel dimethylglyoximate between an aqueous solution and 6 inert solvents were determined at 20°. The distribution coefficients of the nickel chelate were quantitatively interpreted in terms of solubility parameters. The solubility parameter for the nickel chelate was evaluated to be 12.9, that for the aqueous solution to be 18.6, and the molar volume of the chelate to be 182 ml/mol.     

5709萃淋树脂色层分离稀土元素的研究

研究了在盐酸体系中十四个钢系元素和钇被５７０９萃淋树脂吸附的分配系数和相邻两元素的分离系数．测量了Ｌａ、Ｅｕ、Ｙｂ在树脂上吸附平衡时间．结果表明，随着原子库数的增加，稀土元素达到平衡吸附所需时间愈短．     

Evaluation of distribution coefficients in micellar liquid chromatography

The possibilities of micellar liquid chromatography for evaluating distribution coefficients are discussed. Determination of solute-micelle association constants and distribution coefficients of solutes between stationary-aqueous, stationary-micellar and aqueous-micellar phases is described. Application of the calculation of distribution coefficients to the study of the retention mechanism of solutes in the chromatographic system and prediction of separation selectivity is also presented.     

Equilibration studies of an inorganic ion exchange material with liquid nuclear waste simulant using radiotracer techniques

Ion exchange distribution coefficients of zirconium, ruthenium, europium, and strontium, elements found in high level nuclear waste, were determined for a new titanium hydrous oxide-type inorganic ion exchange compound. Coefficients were determined at ambient temperatures and at 85°C. The equilibrations were done in solutions simulating the composition of nuclear waste expected from the Allied-General Nuclear services, Barnwell. South Carolina plant. The progress of each reaction was monitored by adding a radiotracer of the element investigated to the simulated waste solution. Ambient temperature distribution coefficients ranging from a high of 1.2·10⁶ for Zr to a low of 58 for Eu were obtained when equal weights of ion exchange material were used. Significantly higher distribution coefficients were found at 85°C than at ambient temperatures. This work was supported by the U. S. Energy Research Development Administration.     

Pressure effect on cation exchange distribution of some fission products on a strongly acidic cation exchanger of sulfonic acid type in nitric acid

Distribution coefficients of fission products on a cation exchanger in 1M nitirc acid were measured as a function of the pressure by means of the column method. The distribution coefficients were found to decrease with the pressure, and this became more pronounced with increasing charge of the ions. The distribution coefficients of yttrium and RuNO³⁺ decreased with the pressure to a relatively greter extent than lighter lanthanides, and RuNO³⁺ appeared at a separate peak from europium in the elution chromatogram as the pressure was increased up to 900 kg/cm².     

Specific Features of Reversed-Phase High-Performance Liquid Chromatography as Applied to Determining the Distribution Coefficients of Pesticides in the Hexane-Acetonitrile System

The suitability of reversed-phase high-performance liquid chromatography for determining the distribution coefficients of organic compounds in the hexane-acetonitrile system was considered. A version of the necessary additional step in the sample preparation procedure was proposed, namely, changing from nonpolar hexane to a solvent unlimitedly miscible with the eluent. The distribution coefficients were determined for 20 pesticides by the proposed method and compared with those determined by gas chromatography.     

A multitracer study on the adsorption of 47 elements on a calcareous soil and its solid components

The distribution coefficients of 47 elements from Na to Bi on untreated calcareous soil, treated soil to remove CaCO₃ and treated soil to remove both CaCO₃ and organic matter, respectively, were determined by using a multitracer technique. The variation of the distribution coefficients of 47 elements was explained in terms of chemical bond formation and hydration. The effect of different solid components of the calcareous soil on the adsorption was investigated.     

Measuring experimental cyclohexane-water distribution coefficients for the SAMPL5 challenge

Small molecule distribution coefficients between immiscible nonaqueuous and aqueous phases—such as cyclohexane and water—measure the degree to which small molecules prefer one phase over another at a given pH. As distribution coefficients capture both thermodynamic effects (the free energy of transfer between phases) and chemical effects (protonation state and tautomer effects in aqueous solution), they provide an exacting test of the thermodynamic and chemical accuracy of physical models without the long correlation times inherent to the prediction of more complex properties of relevance to drug discovery, such as protein-ligand binding affinities. For the SAMPL5 challenge, we carried out a blind prediction exercise in which participants were tasked with the prediction of distribution coefficients to assess its potential as a new route for the evaluation and systematic improvement of predictive physical models. These measurements are typically performed for octanol-water, but we opted to utilize cyclohexane for the nonpolar phase. Cyclohexane was suggested to avoid issues with the high water content and persistent heterogeneous structure of water-saturated octanol phases, since it has greatly reduced water content and a homogeneous liquid structure. Using a modified shake-flask LC-MS/MS protocol, we collected cyclohexane/water distribution coefficients for a set of 53 druglike compounds at pH 7.4. These measurements were used as the basis for the SAMPL5 Distribution Coefficient Challenge, where 18 research groups predicted these measurements before the experimental values reported here were released. In this work, we describe the experimental protocol we utilized for measurement of cyclohexane-water distribution coefficients, report the measured data, propose a new bootstrap-based data analysis procedure to incorporate multiple sources of experimental error, and provide insights to help guide future iterations of this valuable exercise in predictive modeling.     

甲醇对1-丁基-3-甲基咪唑四氟硼酸离子液体结构与性质影响的模拟研究

采用分子动力学模拟方法研究了298.15 K、0.1 MPa下摩尔分数为0.1-0.9 的甲醇对1-丁基-3-甲基咪唑四氟硼酸盐([BMIM][BF₄])结构与性质的影响. 获得了体系的密度、径向分布函数、配位数、自扩散系数、粘度和电导率, 模拟得到的密度值与实验值符合较好. 结果显示: 体系各组分之间的径向分布函数随甲醇摩尔分数的增加呈规律性变化; 体系内阴阳离子的自扩散系数随着甲醇摩尔分数的增加不断增大; 甲醇的加入削弱了阴阳离子之间的相互作用, 体系粘度随着甲醇摩尔分数的增加逐渐减小, 电导率不断增大. 分析空间分布函数得到体系中各组分的三维空间分布情况.     

Über die trennung anorganischer stoffgemische durch verteilung: Mitteilung1. die verteilung von polyjodiden zwischen wässrigen lösungen und organischen lösungsmitteln

Polyiodides of alkalimotal halidos can be extracted from aqueous solutions by various organic solvents. The distribution coefficients increase from lithium to cesium halides, and from chlorides to iodides. The fluorides were found to fall between chlorides and bromides in all cases tested. Furthermore the distribution coefficients increase with increasing concentration of free iodine. The Nemst law docs not hold in the system KI-I₂-H_2O-nitromethane, The separation factors are small with nitromethane, nitrobonzene and diethyl ether, but can be improved by using mixtures of organic solvents.     

Synergism in the extraction of ascorbic and nicotinic acids by binary solvent mixtures

The distribution coefficients of ascorbic and nicotinic acids in systems aqueous salt solution-binary mixture of hydrophilic solvents were determined. Butanol, ethyl acetate, and butyl acetate were used as hydrophilic solvents and sodium chloride and sulfate as salting out agents. The synergistic effect was interpreted and the synergistic coefficients, complex formation constants, and solvation numbers calculated.     

Distribution coefficients of purine alkaloids in water-ammonium sulfate-alkyl acetate-dialkyl phthalate systems

The distribution of purine alkaloids (caffeine, theobromine, theophylline) was studied in the systems: alkyl acetates-dialkyl phtalate-salting-out agent (ammonium sulfate). The quantitative characteristics of the extraction-distribution coefficients (D) and the degree of extraction (R, %) are calculated. The relationships between the distribution coefficients of alkaloids and the length of the hydrocarbon radical in the molecule of alkyl acetate (dialkyl phtalate) are determined. The possibility of predicting the distribution coefficients is demonstrated.     

Anion Exchange Separation of Rare Earths in Methanol-Nitric Acid Mixed Solutions I. Study on the Distribution Coefficients and Column Elution Method

Anion exchange method for the mutual separation of rare earth was studied in methanol-nitric acid mixed solutions. For each of rare earth element, the distribution coefficients in different concentrations of nitric acid and also in various compositions of methanol solution were studied with the batch equilibrium method. From these distribution coefficients, elution of rare earth by gradient variation in the compositions of methonal was devised. That is, by keeping constant nitric acid at 2 N acidity and gradiently diluting methanol from its original 80% by volume. Results were satisfactory for the mutual separation of the lighter rare earths, but only fairly for the heavier earths. The secondary metal effect for this anion exchange was also studied in 80% by volume of methanol solution by keeping total concentration of nitrate at 0.8 N. Distribution coefficients were larger than nitric acid with LiNO₃ but smaller in the case of NH₄NO₃ and NaNO₃. Despite of these difference in distribution coefficients, no remarkable differences were observed for the separation factors of adjacent pairs.     

Activities of the components of glycerol-water binary solutions at 298.15 K

Based on the assumption that there exists a distribution of hydrates over the hydration number, expressions for the hydration number, activity coefficients of the components, and excess Gibbs energy were obtained. It was demonstrated that the van Laar formula for the activity coefficients corresponds to the Poisson distribution of hydrates. It was established that, at a constant ratio of the variance to the mathematical expectation of the distribution of hydrate, the model’s equations adequately describe the available experimental data on the vapor pressure and water activity for the glycerol-water system over the entire concentration range.     

The influence of distribution coefficients on the separation factor of lithium isotopes

The influence of distribution coefficients on the separation factor of lithium isotopes was studied with Dowex 50W-X8, 200–400 mesh, ammonium form, strongly acidic cation exchanger by changing the pH and EDTA concentration of the eluent. It was found that the larger the EDTA concentration in the buffer solution, the smaller the distribution coefficients were. The separation factor was increased with decreasing EDTA concentration. The separation factor of lithium isotopes linearly increased up to a distribution coefficient value of 30, and gradually increased above 30. The optimum value of distribution coefficient of lithium to separate litihium isotopes was about 30. The distribution coefficient was increased with increasing pH, but the separation factor of lithium isotopes has no relation with pH.⁶Li concentrated on the resin phase, and⁷Li in the solution phase.     

Solute-solvent interaction parameters by gas chromatography

Gas-liquid distribution coefficients at ideal dilution in non-volatile solvents can be measured by gas chromatography. The numerical value of a coefficient depends on the choice of the concentration unit in the solvent and in the gas phase. The relationships between different coefficients characterizing gas-liquid equilibria are discussed and summarized. Coefficients determined at several temperatures permit calculation of the standard chemical potential difference of the solute with the ideal gas phase as reference as a function of temperature, the g-SPOT. Following the proposal of Kirchhoff the latter can be formulated as an equation with three constants. As in the gas phase the molecules of the solute have no interacting partners, the three constants, deltaH, deltaS and deltaC, characterize the interaction between solvent and solute molecules. They will be called the "solute-solvent interaction parameters". In the same system the values of these parameters depend on the choice of the distribution coefficient. Five different distribution coefficients result five sets of interaction parameters. It is shown that conversion of a parameter set to another implies additive corrections independent of the nature of the solute. If g-SPOT-s are measured in a series of solvents, the data may be used to calculate the corresponding liquid-liquid partition coefficients by electing one of the solvents as reference (l-SPOT). The corresponding "relative interaction parameters" can be calculated by simple substraction. In a second chapter the precautions are summarized, necessary for gas chromatographic determination of distribution coefficients and examples are given for interaction parameters in different systems. It is concluded that there are significant differences between g-SPOT-s related to different distribution coefficients. On the other hand, differences between l-SPOT-s are negligible.     

Distribution coefficients and cation-exchange selectives of elements with AG50W-X8 resins in perchloric acid

Cation-exchange distribution coefficients with AG50W-X8, a sulphonated polystyrene resin, aie presented for 44 cations in perchloric acid solutions of concentrations varying from 0.1 to 4.0M. The cations are arbitrarily arranged in a table according to their distribution coefficients in 1.OM perchloric acid. Some possible separations are discussed and elution curves are presented for the separation of the ion pairs Zn-Pb, Tl(I)-Bi, Mg-Al and Co(II)-Fe(III). Selectivity sequences for uni-, bi-, ter- and quadrivalent cations are given in which the cations are ordered on the basis of the average numerical value of their distribution coefficients over the straight part of the curve obtained by plotting the logarithm of the distribution coefficient against the logarithm of [H(+)].     

The determination of the thermodynamic characteristics of Lennard-Jones fluids under isobaric conditions by the method of molecular functions

Integral equation theory for partial distribution functions was used to suggest an effective method for calculating the derivative of radial distribution function with respect to temperature under isobaric conditions. The thermodynamic expansion, compression, and pressure coefficients and isobaric and isochoric heat capacities were calculated for Lennard-Jones fluids. The calculation results were in close agreement with the known thermodynamic relations.