How the Influence of Different Salts on Interfacial Properties of Surfactant–Oil–Water Systems at Optimum Formulation Matches the Hofmeister Series Ranking

In this work, we present the effects of salts on sodium dodecyl benzene sulfonate micellization and on the interfacial performance of a sodium dodecyl benzene sulfonate–heptane–brine system at optimum formulation, i.e., hydrophilic–lipophilic deviation (HLD) = 0. In order to do that, interfacial tension and dilational interfacial rheology properties of surfactant–heptane–water systems at optimum formulation are measured using an interfacial spinning drop tensiometer with an oscillating velocity, which can accurately measure interfacial rheology properties at both low and ultralow interfacial tensions. The brines used contain one of the following salts: MgCl₂, CaCl₂, NaCl, NH₄Cl, NaNO₃, CH₃COONa, or Na₂SO₄. We performed a one-dimensional salinity scan with each of these salts to achieve an optimum formulation. In relation to the Hofmeister series, we found that, at optimum formulation, systems with chaotropic ions (NH₄⁺, NO₃⁻) present interfaces with ultralow interfacial tensions, very low dilational modulus, and a low phase angle, whereas kosmotropic ions (Mg²⁺, Ca²⁺, SO₄⁻²) generate high interfacial tension and high rigidity monolayers. Intermediate ions in the Hofmeister series (Na⁺, CH₃COO⁻, Cl⁻) present interfaces with intermediate properties. Furthermore, according to the Hofmeister series, interfaces can be respectively ordered from higher to lower rigidity for surfactant counterions Mg²⁺ > Ca²⁺ > Na⁺ > NH₄⁺ and coions SO₄²⁻ > CH₃COO^– > Cl⁻ > NO₃⁻, which correspond to a salting-out (highest rigidity) and salting-in (lowest rigidity) effect. We observed that counterions have a more significant effect on surfactant–oil–water system properties than those that act as coions.     

Solvent Extraction or Copper(II) and Lead(II) with N-p-Aikyloxybenzoyl-N-phenylhydroxylamine

The extraction of copper(II) and lead(II) with a series of alkyloxy derivatives of N-benzoyl-N-phenylhydroxylamine(BPHA) in benzene has been studied. The extraction constants of these metal chelates did not change with increasing the carbon number of the substituted alkyloxy groups. Extraction behavior of these metal ions from strongly alkaline media with these extractants has also be investigated.     

The salting-out effect and phase separation in aqueous solutions of electrolytes and poly(ethylene glycol)

The compositions of coexisting phases have been determined for aqueous two-phase systems containing poly(ethylene glycol) (PEG) of nominal molecular weight 8000 and a series of eight electrolytes: NaOH, Na₂CO₃, Na₂SO₄, Na₂HPO₄, Na₃PO₄, (NH₄)₂SO₄, MgSO₄, ZnSO₄. The salting-out effects of the electrolytes on the polymer were obtained by fitting a Setschenow-type equation to the tie line data to derive a salting-out coefficient for each electrolyte. For the sodium salts the relative effectiveness of the anions in forming biphasic mixtures follows the Hofmeister series. The relative salting-out effectiveness of the sulphate salts, however, is probably influenced by complexation of the cations by PEG. The values of the salting-out coefficients reflect the extent of preferential hydration of the ethylene oxide units in the polymer chains.     

Partition Coefficients of Alkaloids in Biphasic Ionic-Liquid-Aqueous Systems and their Dependence on the Hofmeister Series

The aim of this work is to test the potential of hydrophobic phosphonium-based ionic liquids for the extraction of caffeine and nicotine from aqueous phases through the determination of the alkaloids' partition coefficients. It was found that the caffeine partitioning for the ionic-liquid-rich phase increases with the ionic liquid hydrogen-bonding accepting capability (or water content), while for nicotine a nearly opposite behavior was observed. In addition, both the influence of the ionic concentration of the aqueous solution (ranging from 0.0 mol · kg^?1 to 3.0 mol · kg^?1), and the salt nature (with K- and Na-based salts), in the partitioning of caffeine for the ionic-liquid-rich phase were investigated. The influence of the inorganic salt nature in the alkaloid partitioning for the ionic-liquid-rich phase closely follows the Hofmeister series.     

DMSO Chemically Alters Cell Membranes to Slow Exocytosis and Increase the Fraction of Partial Transmitter Released

Dimethyl sulfoxide (DMSO) is frequently used as a solvent in biological studies and as a vehicle for drug therapy; but the side effects of DMSO, especially on the cell environment, are not well understood, and controls with DMSO are not neutral at higher concentrations. Herein, electrochemical measurement techniques are applied to show that DMSO increases exocytotic neurotransmitter release, while leaving vesicular contents unchanged. In addition, the kinetics of release from DMSO‐treated cells are faster than that of untreated ones. The results suggest that DMSO has a significant influence on the chemistry of the cell membrane, leading to alteration of exocytosis. A speculative chemical mechanism of the effect on the fusion pore during exocytosis is presented.     

果蔬植物营养液在甜瓜的使用效果

果蔬植物营养液采用N、P、K和微量元素的营养型经科学配制而成的一种叶面喷施液体肥料。大田实验表明,在甜瓜果菜上的增产效果优于国内常用的复混肥料,增产率分别达10％-20％。     

Liquid-Liquid Extraction of Acids and Water by a Malonamide: I-Anion Specific Effects on the Polar Core Microstructure of the Aggregated Malonamide

In a solvent extraction process, the compositions of the phases in thermodynamic equilibrium (described as a Winsor-II regime) must be determined to obtain the extraction isotherms of ions as well as co-extracted water. By comparing the extractions of a series of acids by the malonamide DMDOHEMA (N,N’-dimethyl-N,N’-dioctyl hexylethoxy malonamide) in n-heptane, the specific anion effects regarding third phase formation and the strength of the acid-extractant interaction were investigated. It is shown that third phase formation is driven by hydration enthalpy of acid, while the polar core microstructure is controlled by the pKa of the acids. Upon acid extraction, the promotion of third phase formation follows the series H₂SO₄ ≈ H₃PO₄ ≈ HClO₄ > HNO₃ > HCl > HCOOH, which correlates to hydration enthalpy of acid in the case of monoacids. The combination of IR spectroscopy and DFT calculations revealed two different modes of acid extraction, either by hydrogen bonding (extraction of non-dissociated acid: HA) or by protonation of the extractant (extraction of dissociated acid: H⁺A^?). The strength of the amide-acid interaction (protonation vs. hydrogen bonding) is correlated to the pKa of the acid and is responsible for the microstructure of the solution.     

Dielectric spectroscopic characterization of a weak-acid polystyrene colloid

A commercially available aqueous polystyrene colloid with surface -COOH groups was purified by exhaustive dialysis. This was then investigated for dielectric frequency response in the low frequency domain (0.01-100 Hz), as a function of pH, ionic strength and the chemical nature of the counterions in the electrical double layer. In previous work on strong-acid (sulfonate) colloids it had been shown that a plot of the imaginary part of the complex impedance as a function of the real part gave semicircles whose radii were a direct function of the surface charge density. In this work, surface charge is a function of pH. The degree of counterion binding was a function of hydrated ion size, as determined from an analysis of titration data and ionic strength of the continuous phase, which in turn was determined from the phase angle and the characteristic relaxation frequency. Dielectric spectroscopy is thus a powerful non-invasive tool for quantitative analysis of the properties of the electrical double layer in these systems.     

Factors affecting the solubility of Bacillus halmapalus α-amylase

A detailed study of the solubility of recombinant Bacillus halmapalus α-amylase has been conducted. A semi-purified preparation from a bulk crystallisation was chosen that contained six isoforms with pI-values of between 5.5 and 6.1. The solubility was strongly affected by pH and could be reduced approximately 200-fold at pH 6 as compared to pH 10, leaving only 0.1 mg/mL in solution. Solubility could also be dramatically manipulated using salts. The choice of anions was found to be more important than of the cations, and the lowest solubility was found using sodium sulphate. For the anions, solubility followed the order expected from the Hofmeister series, however, a more complex behaviour was seen for the cations. With the exception of lithium, their efficiency to influence the solubility was reversed to what was expected. The polydispersity of the solution was reduced by salt addition and zeta potential measurements indicated a shift in pI caused by lithium. Possible explanations for the observations are discussed, extending our present understanding of how salts affect the solubility of proteins, one that to date is primarily based on experiments with lysozyme.     

电导-紫外串联离子色谱法测定海水中的溴、碘离子

建立了电导-紫外串联离子色谱法测定海水中溴、碘离子的分析方法。样品采用滤膜净化处理,选用TSK Super ICA HR保护柱(4 mm×50 mm)和TSK gel Super IC-HR高性能分析柱(4 mm×250 mm),3.2 mmol/L Na2CO3-1.0 mmol/L Na HCO3为淋洗液。抑制电导和紫外检测器同时检测,碘离子使用紫外法检测以消除氯离子干扰。在优化条件下,整个分析过程8 min内完成。溴离子的方法检出限为2.2μg/L,碘离子的方法检出限为3.6μg/L,相对标准偏差(n=8)分别为1.36%~7.38%、1.97%~8.89%。采用加标法测定,回收率分别为94.5%~105.0%、94.9%~106.1%。     

离子选择性电极定量测定双甘膦产品中氯离子含量

用氯离子选择性电极对双甘膦中的氯离子含量进行了定量测定。测定结果表明:氯离子浓度的对数与测得电位值在0.0005~0.1g/L之间线性相关,其相关系数为0.9985。对实际样品进行了回收率测定,其回收率为97.22%~103.26%之间。结果表明该方法测定迅速、准确、简便、经济且高效,有较高的灵敏度和重现性,适用于工业大生产中的中间体和产品测定。     

Novel PVA-based polymers showing an anti-Hofmeister Series property

A series of poly(vinyl alcohol)-trimellitate (PVA-T) polymers with different esterification degrees (ED: 82, 61, and 32 mol%) were prepared through the esterification of PVA and trimellitic anhydride (TA). Solubilities of these polymers and the swelling properties of PVA-T hydrogels, which were prepared by crosslinking with ethylene glycol diglycidyl ether (EGDGE), were investigated in various salt solutions comprising of SO₄²⁻, Cl⁻, SCN⁻ and Li⁺, Na⁺, K⁺, Cs⁺. The PVA-T polymers proved to have larger solubilities in salt solutions (1 M) than in pure water, and the ionic “salting-in” effect was significant in order of SO₄²⁻ > SCN⁻ > Cl⁻ for anions, and Li⁺ > Na⁺ > K⁺ > Cs⁺ for cations, regardless of their ED values. The PVA-T hydrogels also showed corresponding swelling properties; they significantly swelled in sulfate solutions of medium concentration (0.1-1 M), while in other salt solutions no appreciable swelling occurred. The marked salting-in effects exerted by sulfate anion, which is otherwise a typical “salting-out” agent, means that PVA-T polymers have an “anti-Hofmeister Series” (anti-HS) property. This is naturally ascribed to the trimellitic acid group because the degree of swelling in sulfate solutions was more significant for PVA-T with higher ED values; the combination of π-electron system and acidic protons seems to be essential to endow polymers with the anti-HS property.