Sulfonate Ions Research Articles

Influence of the Temperature on the Proton Transport in Poly(styrene-co-divinylbenzene) Membranes from Molecular Dynamics Simulations

The effect of the temperature on the properties of sulfonated poly(styrene-co-divinylbenzene), P(S-DVB), cation exchange membranes has been examined in the absence and presence of an external electric field of 0.7 V·nm–1. Results indicate that the temperature provokes local structural deformations around the sulfonate groups, which are manifested by the distortions at the C–S bonds (random and preferential in the absence and presence of the electric field, respectively). These distortions affect both the density and porosity of the membranes, even though the effects of the electric field decrease with increasing temperature. The electric field dominates over the thermal energy in the motion of the hydronium ions, while the external field does not affect the motion of water molecules, which follow a Brownian behavior similar to that observed for the two species in the absence of an electric field. The calculated electro-osmotic drag coefficient indicates that the hydronium flow is several times higher than the water flow in the presence of the electric field, and this effect increases the temperature. The diffusion of hydronium ions in the absence of the external field increases slowly and isotropically with the temperature, this behavior being preserved in the presence of the external electric field once the component associated with the drift velocity is discounted. Finally, the structure and dynamics of hydration shells at hydronium and sulfonate ions have been examined. Interestingly, the shells associated with two such ions as well as their response toward the temperature and electric field are significantly different, which has been attributed to the fact that sulfonate–water interactions are stronger than hydronium–water interactions.

Effect of Nafion on the preparation and capacitance performance of polyaniline

With manganese dioxide (MnO2) as the oxidant, perfluorinated sulfonic acid ion exchange resin (Nafion) as the doping agent and emulsifier, Nafion doped polyaniline (PANI-Nafion) was prepared by emulsion polymerization method. Scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) were carried out to characterize the structure and morphology of PANI-Nafion. Symmetric redox supercapacitor was assembled with PANI-Nafion as active electrode material and 1.0 mol L−1 H2SO4 aqueous solution as electrolyte. The electrochemical characteristics of these supercapacitors were investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) and galvanostatic charge/discharge tests. These results show that the diameter of PANI-Nafion nanofiber is about 30 ∼ 40 nm and the pores between PANI-Nafion composite materials are distributed uniformly. The specific capacitance of PANI-Nafion electrode is about 385.3 F g−1, which is higher than that of undoped PANI (235.8 F g−1). After 1000 charge/discharge cycles the specific capacitance of PANI-Nafion electrode is 272.4 F g−1, its capacity retention is 70.7%, which is significantly better than that of PANI electrode materials.

Activity coefficients of alkyl sulfate and alkylsulfonate ions in aqueous and water-salt premicellar solutions

Potentiometry has been employed to determine the activity coefficients of n-decyl sulfate and n-alkyl(C5–C10)sulfonate ions in aqueous solutions of their sodium salts containing NaCl or Na2SO4 as a background electrolyte. The selectivity factors have been estimated for ion-selective electrodes exhibiting responses to surfactant ions in the presence of inorganic salts. The pattern of the dependences of the activity coefficients of the surfactant anions on the length of their hydrocarbon radicals and the nature of functional groups has been revealed. The results obtained have been compared with the data on long-chain carboxylates.

Catalytic, Enantioselective, Intramolecular Carbosulfenylation of Olefins. Mechanistic Aspects: A Remarkable Case of Negative Catalysis

In the course of developing an enantioselective, Lewis base/Brønsted acid co-catalyzed carbosulfenylation of alkenes, a seemingly impossible conundrum arose: How could a catalyst inhibit a stoichiometric reaction? Despite the observation of very good enantioselectivities, the rate of the uncatalyzed reaction (i.e., no Lewis base) was found to be comparable to or slightly faster than that of the catalyzed process. A combination of detailed kinetic and spectroscopic studies revealed that the answer is not the direct involvement of the Lewis base catalyst, but rather the secondary consequences of its conversion to the catalytically active sulfenylating agent. Generation of the chiral sulfenylating species is accompanied by the formation of equimolar amounts of sulfonate ion and phthalimide which serve to buffer the remaining Brønsted acid and thus inhibit the racemic background reaction. Thus, the actual background reaction operative under catalytic conditions is not well mimicked by simply removing the catalyst.

Synthesis and oxygen reduction properties of three-dimensional sulfur-doped graphene networks.

Novel three-dimensional sulfur-doped graphene networks were synthesized using an ion-exchange/activation combination method using a 732-type sulfonic acid ion exchange resin as the carbon precursor, which showed high electrocatalytic activity, good stability and excellent methanol tolerance for four-electron oxygen reduction in alkaline solution.

Rational design of a zinc phthalocyanine binding protein.

Phthalocyanines have long been used as primary donor molecules in synthetic light-powered devices due to their superior properties when compared to natural light activated molecules such as chlorophylls. Their use in biological contexts, however, has been severely restricted due to their high degree of self-association, and its attendant photoquenching, in aqueous environments. To this end we report the rational redesign of a de novo four helix bundle di-heme binding protein into a heme and Zinc(II) phthalocyanine (ZnPc) dyad in which the ZnPc is electronically and photonically isolated. The redesign required transformation of the homodimeric protein into a single chain four helix bundle and the addition of a negatively charge sulfonate ion to the ZnPc macrocycle. To explore the role of topology on ZnPc binding two constructs were made and the resulting differences in affinity can be explained by steric interference of the newly added connecting loop. Singular binding of ZnPc was verified by absorption, fluorescence, and magnetic circular dichroism spectroscopy. The engineering guidelines determined here, which enable the simple insertion of a monomeric ZnPc binding site into an artificial helical bundle, are a robust starting point for the creation of functional photoactive nanodevices.

Morphological changes of gel-type functional polymers after intermatrix synthesis of polymer stabilized silver nanoparticles

This paper reports the results of intermatrix synthesis (IMS) of silver metal nanoparticles (Ag-MNPs) in Purolite C100E sulfonic ion exchange polymer of the gel-type structure. It has been shown that the surface morphology of the initial MNP-free polymer is absolutely smooth, but it dramatically changes after the kinetic loading of Ag on the polymer and then IMS of Ag-MNPs. These morphological changes can be explained by the interaction of Ag-NPs with the polymer chains, leading to a sort of additional cross-linking of the polymer. As a result, the modification of the gel-type matrix with Ag-MNPs leads to the increase of the matrix cross-linking, which results in the increase of its surface area and the appearance of nanoporosity in the polymer gel. Ag-MNPs are located near the polymer surface and do not form any visible agglomerations. All these features of the nanocomposites obtained are important for their practical applications in catalysis, sensor applications, and bactericide water treatment.

Effect of sulfonated 3-pentadecyl phenyl acrylate as surfmer in the emulsion polymerization of styrene: synthesis and polymer properties

In this work, the evaluation of a newly developed anionic polymerizable surfactant (surfmer), viz., sulfonated 3-pentadecyl phenyl acrylate, in the emulsion polymerization of styrene and its effect on the polymer properties is reported. The results were compared with the commercially available non-reactive anionic surfactant sodium lauryl sulfate. The surfmer has a low critical micellar concentration value of 40.11 mg/L (8.7 × 10−5 mol/L) in comparison to 2,400 mg/L (8.28 × 10−3 mol/L) for sodium dodecyl sulfate. Nanosized polystyrene dispersions with varying concentration of this surfmer were prepared and characterized for conversion, particle size, and size distribution at a fixed monomer/water ratio of 0.1. The particle radii decreased from 560 nm for the surfactant-free dispersions to 45 nm for the dispersion with 2.3 mol% surfmer. Increasing surfmer content above this concentration did not further affect the particle size but increased the width of the particle size distribution. Transmission electron microscopy results along with particle size data show that with increasing surfmer content the particle size distribution broadens, and film formation is facilitated. The microstructure analysis of the copolymers using infrared and 1H-NMR spectroscopy confirms that the surfmer is chemically attached to the polymer chains. The effect of the ionic sulfonate groups and the alkyl chains of the surfmer moieties on the polymer properties have been studied through measurement of dilute solution viscosity and thermal and viscoelastic properties. These results indicate that the behavior of surfmer-containing polymers resembles that of plasticized ionomers.

Chemoembolization and Radioembolization for Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) continues to represent a major worldwide problem. Although treatments such as resection, transplantation, and ablation may provide a chance for a cure, these options are often precluded because of advanced disease presentation. Palliative treatments include transarterial embolization and systemic therapies. This review will summarize the state of the science for embolic therapies in HCC (conventional and drug-eluting chemoembolization, radioembolization) as well as discuss related topics including HCC staging, assessment of response, and ongoing clinical trials.

Determination of Sodium Dodecyl Sulfate in Toothpastes by a PVC Matrix Membrane Sensor

AbstractThe construction and characteristic performance of a new potentiometric PVC membrane sensor responsive for sodium dodecyl sulfate (SDS) are described. The sensor is based on the use of cetyltrimethylammonium‐tetraphenylborate (CTA‐TPB) ion‐pair complex as electroactive material in PVC matrix in presence of dioctyl phthalate as a solvent mediator. The sensor exhibits a rapid, stable and near‐Nernstian response for SDS over the concentration range of 5 × 10−3–5 × 10−6 mol dm−3 at 25 ± 2 °C and the pH range 4–8.5 with slope of 59.6 mV/decade change in SDS concentration. The lower detection limit is 5 × 10−6 mol dm−3 and the response time is 45 s. The determination of selectivity coefficients for different anions shows there is no interference except that of dodecyl benzene sulfonate (DBS−) ion which has a strong interference. The results obtained in the determination of SDS in toothpastes, using this sensor as an indicator electrode, were compared with those obtained from the spectrophotometric method using methylene blue as the reagent.

Coordination ability of alkali metal or alkaline earth metal ions with aromatic dicarboxylate, sulfonate, or disulfonate ions in acetonitrile

In a poor solvating solvent, acetonitrile, the coordination ability of alkali metal (Li+, Na+) and alkaline earth metal (Mg2+, Ca2+, Ba2+) ions with carboxylate and sulfonate ions has been thoroughly examined, based on the precipitation of non-charged species and the successive re-dissolution of charged species. At first, the formation of [C6H5CO2Ca]+ (the calcium benzoate cation) in acetonitrile was evidenced by ESI-MS. Tetraethylammonium 3-nitrophthalate (3-nitro-1,2-benzenedicarboxylate, L2−) of 2.0×10−3moldm−3 was precipitated completely by the addition of 2.0×10−3moldm−3 Ca(ClO4)2, although the absorption spectrum of L2− was only slightly changed by 1.0×10−3moldm−3 Ca(ClO4)2. In the presence of 5.0×10−3moldm−3 Ca(ClO4)2, however, the precipitates re-dissolved drastically. The successively formed species between Ca2+ and L2− were proposed to be CaL22−, CaL0, and Ca2L2+. The lithium ion also caused the precipitation of non-charged species (Li2L0) as well as the re-dissolution of charged species (tentatively assigned to be Li3L+ or Li4L2+), however, the re-dissolution with Na+ took place just hardly. We were able to observe the re-dissolution of precipitates for 4-nitrophthalate through the formation of positively charged species in the presence of excess amounts of the alkaline earth metal ions, but not of the alkali metal ions. Tetraethylammonium p-toluenesulfonate, and 1,5-, 2,6-, and 2,7-naphtalenesulfonates were also examined. The “reverse” coordination constants have been successfully evaluated for some of all the systems, e.g., K2=3×107 (2 Mg2++L2− ⇆ Mg2L2+) and K3=2×108 (3 Li++L2− ⇆ M3L+), where L2−=2,7-naphthalenedisulfonate.

Ultrasound-assisted adsorption of 4-dodecylbenzene sulfonate from aqueous solutions by corn cob activated carbon

This study was aimed at removal of 4-dodecylbenzene sulfonate (DBS) ions from aqueous solutions by ultrasound-assisted adsorption onto the carbonized corn cob (AC). The main attention was focused on modeling the equilibrium and kinetics of adsorption of DBS onto the AC. The AC was prepared from ground dried corn cob by carbonization and activation by carbon dioxide at 880°C for 2h in a rotary furnace. The adsorption isotherm data were fitted by the Langmuir model in both the absence and the presence of ultrasound (US). The maximum adsorption capacities of the adsorbent for DBS, calculated from the Langmuir isotherms, were 29.41mg/g and 27.78mg/g in the presence of US and its absence, respectively. The adsorption process in the absence and the presence of US obeyed the pseudo second-order kinetics. The intraparticular diffusion model indicated that the adsorption of DBS ions on the AC was diffusion controlled as well as that US promoted intraparticular diffusion. The ΔG° values, −24.03kJ/mol, −25.78kJ/mol and −27.78kJ/mol, were negative at all operating temperatures, verifying that the adsorption of DBS ions was spontaneous and thermodynamically favorable. The positive value of ΔS°=187J/molK indicated the increased randomness at the adsorbent–adsorbate interface during the adsorption of DBS ions by the AC.

The Stability of Bisulfite and Sulfonate Ions in Aqueous Solution Characterized by Hydration Structure and Dynamics

The aqueous solutions of bisulfite (SO(3)H(-)) and sulfonate (HSO(3)(-)) were simulated by the ab initio quantum mechanical charge field molecular dynamics (QMCF MD) formalism. All superimposed trajectories for the atomic coordinates of solutes with three-dimensional alignment here illustrated the reactivities of the ions. Power spectra were evaluated on the basis of the velocity autocorrelation functions (VACFs) with the normal-mode analysis, presenting a higher frequency of the symmetric SO(3) deformation (δ(s)(SO(3))) than the asymmetric SO(3) deformation (δ(as)(SO(3))) modes for the sulfonate ion. The different influence of solvent on the frequency of the O-H and S-H stretching suggests a higher stability of hydrated sulfonate ion. The bisulfite shows a slightly stronger molecular hydration shell than the sulfonate ion with the average number of ion-solvent hydrogen bonds (H-bonds) of 5.3 and 5.0, respectively. Extra water molecules within the molecular hydration shell are found for bisulfite (1.2) and for sulfonate (1.6). The mean residence times for the water ligands classify each ion as a structure maker, while the S-H bond within the sulfonate ion displays a hydrophobic behavior. No tautomerization was observed within the simulation period.

PARTITION VERSUS ELECTROSTATIC MODEL APPLIED TO THE ION-PAIRING RETENTION PROCESS OF SOME GUANIDINE BASED COMPOUNDS

Two models (partition and electrostatic) were utilized to explain the retention data of four polar compounds with guanidine or tertiary amine moieties (metformin, phenformin, tolylformin, and ranitidine) in ion-pairing liquid chromatography based on C18 stationary phase (Zorbax Eclipse XDB column). Mobile phase composition, concentration of the ion-pairing (alkylsulphonates with 5 – 8 carbon atoms), and pH of the aqueous component were varied to determine the corresponding dependence of the retention factors and explanation by one model. Good correlations were found for retention factor versus concentration of ion pairing alkyl sulfonates concentration with a slope similar to the predicted values by the electrostatic model and between retention factor and the content of methanol used as organic modifier in mobile phase. Some extrapolations of the linear dependences were used in estimating the hydrophobic character of the pair between analyte and alkyl sulfonate ions in accordance to the partition model.

Designer Ionic Liquid Crystals Based on Congruently Shaped Guanidinium Sulfonates

Ionic liquid crystals are mesogenic compounds that consist of cations and anions, usually rod-like cations and spherical anions. Herein we report a new method for the synthesis of ionic liquid crystals by using cations and anions of the same molecular shape with oppositely charged head groups. Thus, 4-alkoxyphenylpentamethylguanidinium 4-alkoxyphenylsulfonate ion pairs have been synthesised. 4-Alkoxyphenylpentamethylguanidinium iodides were also prepared to determine the influence of congruently shaped anions, in comparison with their spherical counterparts, on mesophase behaviour, which was investigated by differential scanning calorimetry (DSC), polarising optical microscopy (POM) and X-ray diffraction (XRD). All the liquid crystalline salts exhibit smectic A mesophases with strongly interdigitated bilayer structures. The guanidinium sulfonate ion pairs show mesomorphic properties from shorter alkyl chain lengths (≥C(9)) and lower melting points (≈10 K), whereas the corresponding guanidinium iodides are liquid crystalline for longer alkyl chain lengths (≥C(14)). For chains with ≥C(18), however, the mesophase range decreases for the sulfonate ion pairs, but not for the iodide salts.

Influence of ionic charge placement on performance of poly(ethylene glycol)-based sulfonated polyurethanes

Poly(ethylene glycol) (PEG)-based sulfonated polyurethanes bearing either sulfonated soft segments (SSSPU) or sulfonated hard segments (SHSPU) were synthesized using sulfonated monomers. Differential scanning calorimetry (DSC) revealed that sulfonate anions either in the soft segments or hard segments both increased the glass transition temperatures (Tg’s) of the soft segments and suppressed their crystallization. Moreover, dynamic mechanical analysis (DMA) and tensile analysis demonstrated that SSSPU possessed a higher modulus and tensile strength relative to SHSPU. Fourier transform infrared (FTIR) spectroscopy revealed that hydrogen bonding interactions in SHSPU were suppressed compared to SSSPU and noncharged PU. This observation suggested a high level of phase-mixing for SHSPU. In addition, atomic force microscopy (AFM) phase images revealed that both SSSPU and noncharged PU formed well-defined microphase-separated morphologies, where the hard segments phase-separated into needle-like hard domains at the nanoscale. However, SHSPU showed a phase-mixed morphology, which was attributed to increased compatibility of polar PEG soft segments with sulfonated ionic hard segments and disruption of hydrogen bonds in the hard segment. The phase-mixed morphology of SHSPU was further demonstrated using small angle X-ray scattering (SAXS), which showed a featureless X-ray scattering profile. In contrast, SAXS profiles of SSSPU and noncharged PU demonstrated microphase-separated morphologies. Moreover, SSSPU also displayed a broad ionomer peak ranging in q = 1–2 nm−1, which resulted from the sodium sulfonate ion pair association in the polar PEG soft phase. Morphologies of sulfonated polyurethanes correlated well with thermal and mechanical properties.

REMOVED: Transport and Equilibrium Properties of Sulfonic Ion–exchange Membranes

REMOVED: Transport and Equilibrium Properties of Sulfonic Ion–exchange Membranes

Acid–base chemistry enables reversible colloid-to-solution transition of asphaltenes in non-polar systems

The conjugated π-bonding in asphaltenes, a naturally occurring member of the polyaromatic hydrocarbon family, provides a unique platform for investigating electrostatics and electronics in non-polar systems, but at the same time causes asphaltenes to be insoluble in all except aromatic liquids. Asphaltenes precipitate from petroleum fluids under a variety of conditions, including depressurization and compositional changes, plaguing both recovery operations and remediation in the case of equipment failure. Aromatic solvents like toluene dissolve asphaltenes, but only at very high concentrations, nearly 50% by weight. Polymeric dispersants can stabilize asphaltene colloids, and in some cases can inhibit asphaltene precipitation entirely. Strong organic acids such as dodecyl benzene sulfonic acid (DBSA) can dissolve precipitated asphaltenes when introduced in concentrations as little as 1 percent by weight. Here we demonstrate for the first time that DBSA enables a reversible transition from unstable to stable colloidal-scale asphaltene suspensions to molecularly stable solutions. A continuum of acid–base reactions explains the apparent dual-action of DBSA. The suspension–solution transition occurs through the protonation of heteroatomic asphaltene components and subsequent strong ion pairing with DBSA sulfonate ions, effectively forming DBSA-doped asphaltene complexes with a solvation shell.

Evaluation of the thermal effect on separation selectivity in anion-exchange processes using superheated water ion-exchange chromatography

The thermal effect on retention and separation selectivity of inorganic anions and aromatic sulfonate ions in anion-exchange chromatography is studied on a quaternized styrene-divinylbenzene copolymer anion-exchange column in the temperature range of 40-120 °C using superheated water chromatography. The selectivity coefficient for a pair of identically charged anions approaches unity as temperature increases provided the ions have the same effective size, such that the retention of an analyte ion decreases with an increase in temperature when the analyte ion has stronger affinity for the ion-exchanger than that of the eluent counterion, whereas it increases when it has weaker affinity. The change in anion-exchange selectivity with temperature observed with superheated water chromatography has been discussed on the basis of the effect of temperature on hydration of the ions. At elevated temperatures, especially in superheated water, the electrostatic interaction or association of the ions with the fixed ion in the resin phase becomes a predominant factor resulting in a different separation selectivity from that obtained at ambient temperature.

Binding Analysis of 1-Alkyl-3-methylimidazolium Ions to Nonionic Surfactant Micelles by Capillary Zone Electrophoresis

The binding constants (KB) of four kinds of 1-alkyl-3-methylimidazolium ions to nonionic surfactant micelles have been determined through changes in the electrophoretic mobility in capillary zone electrophoresis. Larger binding constants were obtained with much bulky 1-alkyl-3-methylimidazolium ions. A linear free-energy relationship was observed with the KB values against the van der Waals volume of the cations. The KB values obtained with 1-alkyl-3-methylimidazolium ions are almost comparable with a series of N-alkylpyridinium ions previously reported. Both the binding constants and the linear free-energy relationship are smaller than the binding of anionic alkylbenzene sulfonate ions. The results have suggested a weak binding of cations to nonionic surfactant micelles.