A Numerical Strategy for Nernst–Planck Systems with Solvation Effect

A thermodynamically consistent model of an isothermal, incompressible ionic mixture in mechanical equilibrium is presented. It accounts for differing ion sizes and differing solvation numbers of the ionic species. For this model, a numerical solution procedure based on a two point flux finite volume ansatz on unstructured triangular meshes is developed. Based on a reformulation of the continuous problem in terms of absolute activities, the Scharfetter‐Gummel upwind scheme for semiconductor simulation is generalized to take into account finite ion size and solvation effects.     

Explaining Ionic Liquid Water Solubility in Terms of Cation and Anion Hydrophobicity

The water solubility of salts is ordinarily dictated by lattice energy and ion solvation. However, in the case of low melting salts also known as ionic liquids, lattice energy is immaterial and differences in hydrophobicity largely account for differences in their water solubility. In this contribution, the activity coefficients of ionic liquids in water are split into cation and anion contributions by regression against cation hydrophobicity parameters that are experimentally determined by reversed phase liquid chromatography. In this way, anion hydrophobicity parameters are derived, as well as an equation to estimate water solubilities for cation-anion combinations for which the water solubility has not been measured. Thus, a new pathway to the quantification of aqueous ion solvation is shown, making use of the relative weakness of interactions between ionic liquid ions as compared to their hydrophobicities.     

Prediction of Equilibrium Partitioning of Nonpolar Organic Solutes in Water‐ Surfactant Systems by UNIFAC and COSMO‐RS Models

In the present study the potential of two thermodynamic‐based models (the group‐contribution UNIFAC model and the a priori predictive COSMO‐RS model) to predict solute partitioning in aqueous surfactant solutions is evaluated. In order to take into account the small size of micelles, the UNIFAC model was extended by the interfacial contribution based on the Gibbs‐Thompson equation. The applicability of the approach was successfully proved for the partitioning of nonpolar solutes (toluene, p‐xylene) in aqueous solutions of nonionic surfactants. The original COSMO‐RS model underestimates the concentration of the solute in the aqueous phase in the case of micellar systems since it does not account for the small size of micelles. At the same time, this model gives quantitative results for the octanol/water partition coefficients of both solutes under study leading to the conclusion that the affinity of both solutes to a certain solvent is well described. Thus, extending the COSMO‐RS by the interfacial term seems to be promising.     

LSER modeling of extraction of succinic acid by tridodecylamine dissolved in 2-octanone and 1-octanol

Reactive extraction can be used for the recovery of carboxylic acids from fermentation broth. Through the formation of complex with extractants at the two-phase interface, the carboxylic acids are partitioned into organic solvents. But, the recovery of carboxylic acids is interrupted by the conditions of fermentation broth. In this work, kinetic studies for the extraction of succinic acid from aqueous solution with tridodecylamine diluted in 2-octanone and 1-octanol have been carried out. Equilibrium and kinetic studies for the extraction of succinic acid from aqueous solution with tridodecylamine diluted in two functional groups (alcohol and ketone) such as 2-octanone and 1-octanol are reported. All measurements have been carried out at 298.15 K. The results of the liquid–liquid equilibrium measurements have been correlated by a linear solvation energy relationship – LSER model which takes into account physical interactions.     

Spinning of a chemisorptive sulfonic acid fibre

Conclusions Special features of spinning a fibre by the wet method from a copolymer based on acrylonitrile and sodium methallylsulfonate which are connected with dissociation and solvation of the sulfonate groups have been examined.It has been found that, to obtain a fibre with satisfactory physico-mechanical properties which assure processing into textile articles from a sulfonate-containing copolymer, it is necessary to carry out the spinning either into nonaqueous baths or into aqueous baths which contain lyophilic salts.Translated from Khimicheskie Volokna, No. 3, pp. 10–12, May–June, 1988.     

Mechanistic insights into aqueous phase propanol dehydration in H‐ZSM‐5 zeolite

Aqueous phase dehydration of 1‐propanol over H‐ZSM‐5 zeolite was investigated using density functional theory (DFT) calculations. The water molecules in the zeolite pores prefer to aggregate via the hydrogen bonding network and be protonated at the Brønsted acidic sites (BAS). Two typical configurations, i.e., dispersed and clustered, of water molecules were identified by ab initio molecular dynamics simulations of the mimicking aqueous phase H‐ZSM‐5 unit cell with 20 water molecules per unit cell. DFT calculated Gibbs free energies suggest that the dimeric propanol–propanol, the propanol–water, and the trimeric propanol–propanol–water complexes are formed at high propanol concentrations in aqueous phase, which provide a kinetically feasible dehydration reaction channel of 1‐propanol to propene. The calculation results indicate that the propanol dehydration via the unimolecular mechanism becomes kinetically discouraged due to the enhanced stability of the protonated dimeric propanol and the protonated water cluster acting as the BAS site for alcohol dehydration. © 2016 American Institute of Chemical Engineers AIChE J, 63: 172–184, 2017     

Analysis of solvation in ionic liquids using a new linear solvation energy relationship

A new linear solvation energy relationship (LSER) equation, where the solute internal energy term has been incorporated into the traditional LSER equation, is used for the analysis of solvation in ionic liquids. Modeling results obtained using the new LSER equation indicate that all solute parameters (dispersion, polarity, hydrogen bonding, cavity formation, and solute internal energy) have approximately equal importance in the solvation of organic solutes in ionic liquids. The magnitude of dispersion interaction is stronger in ionic liquids than in aqueous solution, whereas hydrogen‐bonding interactions are stronger in water than in ionic liquids. This indicates that the solubility of polar compounds that contain bulky and aromatic groups can be enhanced in ionic liquids due to higher dispersion interactions in ionic liquids than in aqueous solution. On the other hand, the LSER equation without the solute internal energy term does not yield the meaningful solute–solvent interaction terms, indicating that the inclusion of a solute internal energy term is necessary to properly describe the solvation of organic solutes in liquid solvents. Copyright © 2004 Society of Chemical Industry     

A Hydration Shell‐Based Thermodynamic Model for Aqueous Two‐Phase Systems

In this work a Flory‐Huggins model modified to account for some unique features of Aqueous Two‐Phase Systems is presented. The model takes into account observed solvation between water and polymer molecules through the incorporation of a hydration shell to express the number of water molecules bonded to each polymer molecule. The parameters of the modified equation were determined using experimental data of ATPS containing poly (ethylene glycol) and dextran. The results revealed remarkable improvement in the correlation ability of the model. A general expression that defines the number of water molecules in the hydration shell was also obtained.     

On the concentration dependence of the UNIQUAC/UNIFAC models

The UNIQUAC/UNIFAC models can not in general represent vapor-liquid and liquid-liquid equilibria simultaneously with satisfactory results. Recent modifications of the models take into account association and solvation effects by means of chemical theory. However, this approach leads to complicated expressions for the activity coefficients and the improvements are only moderate. A modification of the UNIQUAC/UNIFAC models is presented which takes into account solvation and association by allowing the interaction energies to vary with composition. This approach leads to explicit expressions for the activity coefficients. It is shown that the modified models in simultaneous correlations lead to quantitative representation of vapor-liquid equilibrium data and semi-quantitative representation of binary and ternary liquid-liquid equilibrium data.     

On the Implication of Water on Fragment‐to‐Ligand Growth in Kinase Binding Thermodynamics

A ligand‐binding study is presented focusing on thermodynamics of fragment expansion. The binding of four compounds with increasing molecular weight to protein kinase A (PKA) was analyzed. The ligands display affinities between low‐micromolar to nanomolar potency despite their low molecular weight. Binding free energies were measured by isothermal titration calorimetry, revealing a trend toward more entropic and less enthalpic binding with increase in molecular weight. All protein–ligand complexes were analyzed by crystallography and solution NMR spectroscopy. Crystal structures and solution NMR data are highly consistent, and no major differences in complex dynamics across the series are observed that would explain the differences in the thermodynamic profiles. Instead, the thermodynamic trends result either from differences in the solvation patterns of the conformationally more flexible ligand in aqueous solution prior to protein binding as molecular dynamics simulations suggest, or from local shifts of the water structure in the ligand‐bound state. Our data thus provide evidence that changes in the solvation pattern constitute an important parameter for the understanding of thermodynamic data in protein–ligand complex formation.     

Separation of water–isopropyl alcohol mixtures with novel hybrid composite membranes

New‐fangled hybrid composite membranes were prepared by the incorporation of 5, 10, and 15 mass % NaY–zeolite particles into blend membranes of carboxymethyl cellulose (CMC)‐g‐acrylamide/sodium alginate (NaAlg) and crosslinked with glutaraldehyde. The pervaporation (PV) separation performance of the hybrid composite membranes was explored for the dehydration of isopropyl alcohol from their aqueous solutions at 30°C. The effect of NaY–zeolite in these blend membranes was investigated in PV dehydration. From the experimental results, we found that NaY particles could be intercalated in the aqueous polymer solution. The obtained results show that both the flux and selectivity increased simultaneously with increasing zeolite content in the membrane. This was explained on the basis of an enhancement of the hydrophilicity, selective adsorption, and molecular sieving action by the creation of pores in the membrane matrix. The membranes were characterized by differential scanning calorimetry, scanning electron microscopy, and Fourier transform infrared spectroscopy. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2012     

A Continuum Solvation Model for the AM1 Semi-Empirical Method

We outline a continuum solvation model for aqueous solution similar to the recent SMx models of Cramer and Truhlar.^1–3 As in those models, the solvation energy is given as a sum of polarization and cavity-dispersion contributions. The numerical integration required for calculation of the polarization energy in the SMx models has been replaced by a scaled two-center Coulomb integral. The cavity-dispersion energy is based on molecular volume and includes a term involving the molecular dipole moment. The present method is more accurate than the SMx models and is considerably less time-consuming.     

SOLVENT EXTRACTION OP COPPER (II), NICKEL (II) AND COBALT(II) PROM HALIDE AND THIOCYANATE SOLUTIONS BY ALDOXIMES

The extraction of divalent copper, nickel and cobalt from acidic chloride solutions with solutions of heptaloxime, nonaloxime and 2-methyldekaloxime in toluene has been studied at 18*C.

These metals were found to be extracted according to the following solvation reaction:

The influence of syn-anti isomerization of aldoximes on the extraction has been discussed. Taking into account association and syn - anti isomerization constants of aldoximes in organic phase,hydration of extracted oomplexes and activities of salts in aqueous phase, effective extraction oonstants have been calculated for chloride solutions.

Separation of nickel and cobalt from aoidic chloride, bromide and thiooyanate solutions by extraction with heptaloxime has been studied.     

Towards an integrated description of hydrogen bonding and dehydration: decreasing false positives in virtual screening with the HYDE scoring function

We developed a new empirical scoring function, HYDE, for the evaluation of protein-ligand complexes. HYDE estimates binding free energy based on two terms for dehydration and hydrogen bonding only. The essential feature of this scoring function is the integrated use of log P-derived atomic increments for the prediction of free dehydration energy and hydrogen bonding energy. Taking the dehydration of atoms within the interface into account shows that some atoms contribute favorably to the overall score, while others contribute unfavorably. For instance, hydrogen bond functions are penalized if they are dehydrated unless they can overcompensate this loss by forming a hydrogen bond with excellent geometry. The main stabilizing contribution represents the removal of apolar groups from the water: the hydrophobic effect. Initial studies using the DUD dataset show that with HYDE, there is a significant decrease in false positives, a reasonable categorization of compounds as either non-binders, weak, medium or strong binders, and in particular, there is a generally applicable and thermodynamically sensible cutoff score below which there is a high likelihood that the compound is indeed a binder.     

Zur Kinetik der stabilisierten Fällungs-polymerisation eines Kationischen Monomeren in wäßrigen Natriumchlorid-Lösungen

The stabilized free-radical precipitation polymerization of the cationic monomer N-(2-methacryloyloxyethyl)-N,N-dimethylbenzylammonium chloride (MADAMBQ) in aqueous solutions of sodium chloride was studied by reaction calorimetry. Poly(ethylene oxide) was used as stabilizer. The rate of polymerization reaches its maximum immediately after initiation and remains nearly constant up to 50 % conversion followed by a decrease that could be described by a first order kinetics. The particles formed are approximately 1 to 30 μm in diameter and are stable over a period of several months. A model based on the theory of homogeneous particle nucleation is suggested to describe the kinetic course of polymerization, taking into account the rate of polymerization in both phases. With the assumption that the concentration of monomer in the phases is determined by a Nernst distribution law, the kinetics of the early stage of polymerization can be modelled reasonably well. The solution polymerization and the unstabilized precipitation polymerization of MADAMBQ was also studied.     

Zum Wesen des Trübungspunktes nichtionogener Tenside

Turbidity Point of Nonionic Surfactants The occurrence of turbidity above a definite temperature in aqueous solutions of many nonionic surfactants, especially in those of ethylene oxide adducts, is due to separation of two liquid phases and not due to dehydration of the hydrophilic group, as is often assumed. In discussing the above phenomenon, the thermodynamic laws governing the resolution of liquid two-component systems are taken into consideration.     

CALORIMETRIC STUDIES OF THE SYNERGISTIC EFFECT: THE REACTION OF UO2, Ln(PMBP)3 AND Th(PMBP)4 WITH TOPO IN NITROBENZENE

Titration calorimetry has been used to measure the thermodynamics of reaction in nitrobenzene solution of PMBP complexes of lanthanides, uranyl and thorium with TOPO. The extraction from aqueous solution into chloroform solutions of PMBP and TOPO was also studied. The role of hydration effects in the extraction and synergistic reactions is discussed based on the enthalpy and entropy values of the processes. Synergism is found to result primarily from the large, positive entropies caused by the dehydration resulting from adduct addition to the PMBP complexes.     

采用氟化钾分离叔丁醇水溶液的研究

测定了叔丁醇-水-氟化钾体系在40℃时的液-液相平衡数据,考察了氟化钾水溶液与叔丁醇水溶液质量比对脱水率的影响.结果表明:当质量分数为60.00%的氟化钾水溶液与60%的叔丁醇水溶液的质晕比为1.00时,氟化钾的脱水率为94.10%,将有机相进行精馏可得到质量分数为99.50%的叔丁醇,水相中氟化钾稀溶液经蒸发回收后循...     

Chemical oxidative polymerization of ethacridine

Novel electroactive paramagnetic ethacridine oligomers were synthesized by the oxidation of ethacridine lactate with ammonium peroxydisulfate in acidic aqueous solution. The oxidative coupling of ethacridine was proved by gel permeation chromatography and MALDI-TOF mass spectrometry demonstrating the presence of oligomeric chains. Theoretical study of the mechanism of oxidation of ethacridine has been based on the semi-empirical quantum chemical computations of heat of formation and ionization energy of ethacridine, protonated ethacridine, generated reactive species and reaction intermediates, taking into account influence of pH and solvation effects. It was revealed that the prevalent ethacridine dimers are N_(C6)C5 coupled. The influence of oxidant to monomer mole ratio on the molecular structure and the morphology of ethacridine oligomers has been studied by elemental analysis, FTIR, Raman, EPR and UV-Visible spectroscopies, MALDI-TOF mass spectrometry and scanning electron microscopy. Besides unoxidized monomeric units as prevalent, oligoethacridines contain the iminoquinonoid and newly formed fused phenazine units. The electroactivity of ethacridine oligomers was investigated by cyclic voltammetry.     

电化学双电层电容器动态模拟：离子尺寸及扩散系数的优化

电化学双电层电容器的低能量密度限制了其在储能动力等领域的应用,而有机电解液作为提升器件能量密度的关键因素,研究其导电电解质的特性具有重要的意义。通过构建电化学双电层电容器的动态模型,模拟了电化学双电层电容器的循环伏安曲线,并定量探究和解析了离子溶剂化尺寸和扩散系数对电容性能的影响。模拟结果表明：在低扫描速率情况下,电容性能主要受控于双电层结构特性,比电容随着离子溶剂化尺寸的减小而增大,而离子扩散系数对其电容性能没有影响;在高扫描速率情况下,电容性能会受控于离子传质过程,比电容随着离子溶剂化尺寸和离子扩散系数的增大而增大。并基于模拟计算和分析结果提出了理性设计和优化电化学双电层电容器的策略。