Sulfonic Acid Ion Research Articles

A cucurbit[6]uril-based fluorescence supramolecular assembly for information encryption and visualization detection of nitro compounds and antibiotics

A novel CB[6]-based supramolecular assembly [K(ANS)(CB[6])2(DMF)2(H2O)0.5] (1) (CB[6] = cucurbit[6]uril, ANS- = 8-amino-1-naphthalene sulfonic acid ion) was successfully synthesized under solvothermal condition. Performance studies have shown that 1 exhibited excellent chemical stability and recycling performance. Meanwhile, 1 exhibited remarkable potential as a fluorescence sensor for the detection of 2,4,6-trinitrophenol (TNP), 4-nitrophenol (4-NP), and rifampicin (RFP) in both aqueous environments and practical samples. This sensing capability is achieved through fluorescence quenching, which offers fast response times and exceptional sensitivity, with detection limits of 0.19 μM for both TNP and 4-NP, and 0.21 μM for RFP. Even more remarkably, an anti-counterfeiting ink based on 1 and a portable test hydrogel were devised for encrypting information and visually detecting using a smartphone application. This work has the potential to expand the utilization of CB[6]-based materials in optical applications.

The concept of gel diffusion in the kinetics of swelling and shrinking of a polystyrene sulfonic acid ion exchanger in the K+ form

The kinetics of swelling and shrinking of polystyrene resins of the sulfonic acid type was investigated. The ion-exchange bead in the K+ form, equilibrated with a 0.1 M, 0.5 M, 1.0 M or 2 M KCl solution was placed into water and its diameter was measured continuously. In the reverse experiments, the bead, which came into equilibrium with water, was transferred into KCl solutions and the kinetics of grain shrinking was studied analogously. The experimental data were processed by using the theory of "gel diffusion", the parameter of which is the so-called gel diffusion coefficient, similar to the molecular diffusion coefficient. In contrast to previously published works, in which only the first term of the series in the corresponding equation was taken into account, in our work the first ten members of the series were taken into account. It turned out that it is necessary to take into account not only the first member of the series (as was done in previously published works), but also the second member of the series. It also turned out that the values of the obtained gel diffusion coefficient, obtained by this method, quite logically increased somewhat during the process of swelling (for example, in experiments with 1 M KCl from 2.1×10−6 to 3.0×10−6 cm2/s) and decreased somewhat during the process of shrinking. It was shown that the average values of the diffusion coefficients of the gel make it possible to adequately describe the main part of the kinetic curve. The concept of gel diffusion allows comparing the swelling kinetics of various polyelectrolyte gels in terms of diffusion coefficients, regardless of the particle shape, systematize data for various materials, and comparing their properties with the molecular diffusion of other substances.
 It also turned out that in the very final parts (5-10%) of the kinetic curves a sharp decrease in the diffusion coefficient value was observed both in experiments with the swelling and shrinking of grains. It indicates that during the final stages there was a sharp deceleration of the process due to a change in its mechanism.

Optimal method for preparing sulfonated polyaryletherketones with high ion exchange capacity by acid‐catalyzed crosslinking for proton exchange membrane fuel cells

AbstractSulfonated polyaryletherketones (SPAEK) bearing four sulfonic acid groups on the phenyl side groups were synthesized. The benzophenone moiety of polymer backbone was further reduced to benzydrol group with sodium borohydride. The membranes were crosslinked by acid‐catalyzed Friedel‐Crafts reaction without sacrifice of sulfonic acid groups and ion exchange capacity (IEC) values. Crosslinked membranes with the same IEC value but different water uptake could be prepared. The optimal crosslinking condition was investigated to achieve lower water uptake, better chemical stability (Fenton's test), and higher proton conductivity. In addition, the hydrophilic ionic channels from originally course and disordered could be modified to be narrow and continuous by this crosslinking method. The crosslinked membranes, CS4PH‐40‐PEKOH (IEC = 2.4 meq./g), reduced water uptake from 200 to 88% and the weight loss was reduced from 11 to 5% during the Fenton test compared to uncrosslinked one (S4PH‐40‐PEK). The membrane showed comparable proton conductivity (0.01–0.19 S/cm) to Nafion 212 at 80°C from low to high relative humidity (RH). Single H2/O2 fuel cell based on the crosslinked SPAEK with catalyst loading of 0.25 mg/cm2 (Pd/C) exhibited a peak power density of 220.3 mW/cm2, which was close to that of Nafion 212 (214.0 mW/cm2) at 80°C under 53% RH. These membranes provide a good option as proton exchange membrane with high ion exchange capacity for fuel cells.

Simultaneous Determination of Isothiazolinones and Parabens in Cosmetic Products Using Solid-Phase Extraction and Ultra-High Performance Liquid Chromatography/Diode Array Detector.

Isothiazolinones methylisothiazolinone (MI) and methylchloroisothiazolinone (MCI), and parabens methylparaben (MP), ethylparaben (EP), propylparaben (PP) and butylparaben (BP) are the most common synthetic preservatives. They are all known to be potential skin allergens that lead to contact dermatitis. Thus, the identification of these unsafe chemicals in cosmetic products is of high importance. In the present study, solid-phase extraction (SPE) based on HyperSep reversed-phase C8/benzene sulfonic acid ion exchanger (HyperSep C8/BSAIE) and Sep-Pak C18 sorbents, and ultra-high performance liquid chromatography/diode array detector (UHPLC/DAD) were optimized for the simultaneous determination of MI, MCI, MP, EP, PP and BP in cosmetic products. HyperSep C8/BSAIE and UHPLC/DAD with the eluting solvent mixture (acetonitrile/methanol, 2:1, v/v) and detection wavelength (255 nm) were found to be the optimal conditions, respectively. The method illustrates the excellent linearity range (0.008–20 μg/mL) with coefficient of determination (R2, 0.997–0.999), limits of detection (LOD, 0.001–0.002 μg/mL), precision in terms of relative standard deviation (RSD < 3%, intra-day and <6%, inter-day) when examining a standard mixture at low (0.07 µg/mL), medium (3 µg/mL) and high (15 µg/mL) concentrations. A total of 31 cosmetic samples were studied, achieving concentrations (MI, not detected (nd)-0.89 µg/g), (MCI, nd-0.62 µg/g), (MP, nd-6.53 µg/g), (EP, nd-0.90 µg/g), (PP, nd-9.69 µg/g) and (BP, nd-17.80 µg/g). Recovery values ranged from 92.33 to 101.43% depending on the types of sample. To our knowledge, this is the first specific method which covers the theme and describes background amounts of such preservatives in cosmetics.

Fenton reaction mechanism generating no OH radicals in Nafion membrane decomposition

Mechanism of Fenton reaction, which is a most widely-used degradation test for organic materials using hydrogen peroxide (H_2O_2) and iron (Fe) cations, is revealed for the decomposition of hydrated Nafion membrane. This reaction mechanism has been assumed to generate OH radicals. For a doubly-hydrated Nafion membrane model, Fenton reaction with divalent and monovalent Fe (Fe^{2+} and Fe^+) cation hydration complexes is explored for experimentally-supported hydration numbers using long-range correction for density functional theory. As a result, it is found that H_2O_2 coordinating to the Fe^{2+} hydration complexes first approaches Nafion side chains in high humidity, then leads to the C–S bond dissociation of the side chain to produce carbonic acid group and sulfonic acid ion. On the other hand, once electron transfer proceeds between iron ions, the O–O bond of the coordinating H_2O_2 is extended, then the C–S bond is dissociated to produce trihydroxymethyl group and sulfur trioxide, which are rapidly transformed to carboxyl group and sulfonic acid ion in aquo. This mechanism is confirmed by the vibrational spectrum analysis of the decomposed product. Collective Nafion decomposition mechanisms also suggest that the decomposition reaction uses the recycle of generated Fe cation hydration complexes under acidic condition near membrane surface.

Layer-by-layer self-assembled multilayer films of sulfonated-β-cyclodextrin and its reversible adsorption of methyl orange

Multilayer film based on photosensitive p-diphenyl diazonium salt (biPh-N2+) and sulfonated-β-cyclodextrin (S-β-CD) were fabricated by layer-by-layer self-assembly. The ionic bonds formed between diazonium salt and sulfonic acid ion in the multilayer film converted to covalent bonds and formed stable ultra-thin film when the diazonium groups decomposed under UV light irradiation. Meanwhile, the concentration of S-β-CD aqueous solution can influence the self-assembled multilayer films, while the pH value (pH=3~9) had little effect on the self-assembled process except the strong alkaline solution (pH=11). Moreover, based on the electrostatic interactions of S-β-CD and MO to form a host-guest complexation, the multilayer film of (biPh-N2+/S-β-CD)12 can absorb methyl orange (MO), and which can release reversibly in ethanol.

Catalytic performance of strong acid catalyst: Methyl modified SBA-15 loaded perfluorinated sulfonic acid obtained by the waste perfluorinated sulfonic acid ion exchange membrane

Mesoporous molecular sieve (SBA-15) was modified using the trimethylchlorosilane as functional agent and the silylation SBA-15 mesoporous material was prepared in this work. The alcohol solution of perfluorinated sulfonic acid dissolved from the waste perfluorinated sulfonic acid ion exchange membrane (PFSIEM) was loaded onto the resulting mesoporous material by the impregnation method and their physicochemical properties were characterized by FT-IR, N2-physisorption, XRD, TG-DSC and TEM. The catalytic activities of these synthesized solid acid catalysts were evaluated by alkylation of phenol with tert-butyl alcohol. The influence of reaction temperature, weight hour space velocity (WHSV) and reaction time on the phenol conversion and product selectivity were assessed by means of a series of experiments. The results showed that with the increase of the active component of the catalyst, these catalysts still remained good mesoporous structure, but the mesoporous ordering decreased to some extent. These catalysts exhibited good catalytic performance for the alkylation of phenol with tert-butanol. The maximum phenol conversion of 89.3% with 70.9% selectivity to 4-t-butyl phenol (4-TBP) was achieved at 120°C and the WHSV is 4h−1. The methyl group was loaded on the surface of the catalyst by trimethylchlorosilane. This is beneficial to retard the deactivation of the catalyst.

PVDF based ion exchange membrane prepared by radiation grafting of ethyl styrenesulfonate and sequent hydrolysis

A new synthesis route for poly(vinylidene fluoride)-g-polystyrene sulfonic acid ion exchange membrane (PVDF-g-PSSA IEM) has been developed via preradiation-induced grafting of ethyl styrenesulfonate and sequent hydrolysis. A high grafting yield (GY) 120% for PETSS grafted onto PVDF could be obtained at a reaction time of 3h and dose of 50kGy. The structure of PVDF-g-PSSA IEM was testified by FTIR, XPS, TGA and SEM analysis. At the GY above 80%, the ion exchange capacity, water uptake and proton conductivity of the resultant PVDF-g-PSSA IEM exceeds Nafion 117 membrane. This work provides an environmental method for the preparation of the IEM used in fuel cell or water treatment.

Heterogeneous reactive extraction for isopropyl alcohol liquid phase synthesis: Microkinetics and equilibria

The reaction kinetics for the liquid phase synthesis of isopropyl alcohol (IPA) from propene (P) and water (W) using a macroporous sulfonic acid ion exchange resin as catalyst were determined experimentally in a multiphase CSTR in the temperature range 398K to 433K at 8MPa. This high pressure is necessary to dissolve propene in the aqueous phase and to ensure a liquid or supercritical state of all components. At typical reaction conditions, the reactants form two immiscible phases; the reaction takes place in the water swollen gel phase of the catalysts microspheres. Due to the large excess of water in the gel phase the compositions in the gel phase, in the macropore fluid, and in the catalyst surrounding aqueous phase are assumed to be identical. For temperatures up to 413K the reaction kinetics for the used catalyst size are not influenced by mass transfer resistances within the catalyst matrix. Two reactions, the formation of IPA and the condensation reaction of two IPA molecules forming the by-product diisopropyl ether (DIPE), are investigated. The experimental results can be described sufficiently by pseudo-homogeneous rate expressions in aqueous phase activities. For the formation of IPA, the forward reaction is first-order in propene and water while the reverse reaction is first-order in IPA. The activation energy of the forward reaction was determined to 115.3kJ/mol. The formation of DIPE is second order with respect to the activity of IPA. The reverse reaction is first order with respect to the activities of DIPE and water. The activation energy was determined to 85.6kJ/mol. Simultaneous chemical and phase equilibria were investigated theoretically using the volume translated Peng-Robinson equation of state (VTPR-EoS) in combination with a gE-mixing rule. Parameters of the used gE-model were adjusted to experimental liquid-liquid equilibrium (LLE) data.

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.

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.

Ion exchange membranes as electrolyte for high performance Li-ion batteries

High ionic conductivity exceeding 10−3 S cm−1 at room temperature is achieved with lithiated perfluorinated sulfonic acid (PFSA-Li) ion exchange membranes by swelling in nonaqueous organic solvents. The dependence of ionic conductivity on the membrane equivalent weight, solvent uptake, solvent properties including viscosity and dielectric constant and temperature is investigated for PFSA-Li membranes. The high performance of Li-ion battery using the PFSA-Li membranes as both electrolyte and separator is demonstrated. This new battery shows very good thermal stability and cyclic performance as compared to conventional Li-ion battery using organic liquid electrolytes. At 55 °C, this battery shows less than 3% discharge capacity loss over 120 cycles, however battery with liquid electrolyte decreased to 76% of the initial capacity after 80 cycles.

Heterogeneous reactive extraction for secondary butyl alcohol liquid phase synthesis: Microkinetics and equilibria

The reaction kinetics for the liquid phase synthesis of a racemic mixture of the secondary butyl alcohols (SBA) from linear butene isomers (1-butene (1B); cis-2-butene ( c2B); trans-2-butene ( t2B)) and water (W) using a macroporous sulfonic acid ion exchange resin as catalyst were determined experimentally in a multiphase CSTR in the temperature range 39–433 K at 6–8 MPa. This range of pressures is necessary to dissolve butenes in the aqueous phase and to ensure a liquid state of all components. For temperatures higher than 423 K the reaction kinetics for the used catalyst size are influenced by mass transfer resistances within the catalyst matrix. The reaction takes place in the water swollen gel phase of the catalysts microspheres. Due to the large excess of water in the gel phase the compositions in the gel phase, in the macropore fluid, and in the catalyst surrounding aqueous phase are assumed to be identical. According to the literature the reaction is rather catalyzed by hydrated acid protons ( specific catalysis) than by polymer-bonded-SO 3H groups ( general catalysis). The experimental results can therefore be described sufficiently by a pseudo-homogeneous 3-parameter rate expression in aqueous phase activities. The forward reaction is first-order in butene. The reverse reaction is first-order in secondary butyl alcohol. The activation energy was determined to be 108 kJ/mol. Practically no pressure dependence could be observed for pressures exceeding 6 MPa. The ever-present isomerization of the linear butenes on acid catalysts was found to be remarkably faster than the hydration of butenes to SBA. Therefore, the isomerization is considered to be always in equilibrium during the olefin hydration. The formation of the possible by-product di- sec-butyl ether (DSBE) was never observed to a measurable extent. Simultaneous chemical and phase equilibria were investigated theoretically using the volume translated Peng–Robinson equation of state (VTPR-EoS) in combination with a g E -mixing rule. Parameters of the used g E -model were adjusted to experimental ternary liquid–liquid equilibrium (LLE) data.

Removal of cationic dye methyl violet 2B from water by cation exchange membranes

The removal of methyl violet 2B, a cationic dye, from water using two kinds of strong-acid cation exchange membranes, ICE 450 supported (with sulfonic acid groups and ion exchange capacity of 9.6–31 μeq/47 mm disc) and P81 (with phosphate groups and ion exchange capacity of 312 μeq/47 mm disc), was investigated in this study. In the batch process, the adsorption isotherm results show that the P81 membrane exhibited a greater maximum adsorption capacity than the ICE 450 supported membrane. However, the latter exhibited stronger and faster dye adsorption behaviors. Different desorption solutions were tested in the batch desorption process and, for both membranes, the best desorption performance (∼100%) was achieved with an aqueous solution containing 1 M NaCl in 60% methanol. In the membrane chromatography process with one piece of 47 mm membrane at a flow rate of 1 or 8 mL/min, complete dye removal and recovery from a 20 mL feed with an initial dye concentration of 0.015 g/L could be achieved for both membranes. The performance of both membranes remained practically unaltered during three successive cycles of dye adsorption and desorption. Lastly, to mimic the effluent produced by a typical dyehouse, a synthetic dye wastewater made up of 0.03 g/L methyl violet 2B and 2 g/L Na 2SO 4 at pH 3 and 100 °C was prepared and treated by both membranes in the membrane chromatography process. The extent of dye removal was decreased to 84–93% for the P81 membrane, which may be attributable to either salt ion competition or pH influence. By contrast, the ICE 450 supported membrane could attain nearly complete dye adsorption and desorption.

Preparation and study of properties of sulfonic acid ion exchangers based on polypropylene fibrous material

The possibility of raising the static exchange capacity of strongly acidic ion-exchange materials produced by grafting of styrene onto polypropylene fibers, with the subsequent sulfonation of the products synthesized, was analyzed. The chemical and osmotic stabilities of the sulfonic cation exchangers obtained and their frost resistance in freeze-thaw cycles were studied.

Determination of dialkyldimethylammonium surfactants in sewage based on the formation of premicellar aggregates.

A method is described for the determination of dialkyldimethylammonium surfactants (DDAS) in sewage, based on the formation of premicellar aggregates with sodium dodecyl sulfate and using the dye Coomassie Brilliant Blue G (CBBG) as a photometric probe. The mixed aggregates are selectively obtained at DDAS concentrations three orders of magnitude below the critical micelle concentration. As a result, DDAS can be determined at the microg l(-1) level without interference from other quaternary ammonium/pyridinium or anionic/non-ionic surfactants. Because of the selectivity of the method, the clean-up of sewage influents and effluents only involves extraction with chloroform, after formation of the DDAS-sodium dodecane sulfonic acid ion pair, evaporation of the extracts to dryness and dissolution of DDAS in 4 M hydrochloric acid. The recovery of DDAS ranged from 82 to 93% and from 100 to 105% in sewage influents and effluents, respectively.

Etherification and hydration of isoamylenes with ion exchange resin

The simultaneous etherification and hydration of 2-methyl-2-butene and 2-methyl-1-butene were studied in a continuous stirred tank reactor (CSTR). The heterogeneous liquid-phase formation of tert-amyl ethyl ether (TAEE) and tert-amyl alcohol (TAOH) was catalyzed by a commercial sulfonic acid ion exchange resin. Addition of a small amount of water to the feed, caused a marked drop in the overall olefin (isoamylenes) conversion and in the etherification rate. The measured reaction rates of the etherification and alcohol formation were fitted to kinetic models of Langmuir–Hinshelwood type. These models are based on single site adsorption of every component and the surface reaction being the rate limiting step. The activation energies for the simultaneous etherification and hydration of isoamylenes were 117.7 and 79.9 kJ mol −1, respectively. The activation energy obtained for the etherification corresponds well with the value of 108 kJ mol −1 obtained in the experiments without water for the etherification of β-olefin (2-methyl-2-butene) with ethanol.

Synthesis and Ion-Complexing Properties of a Novel Polymer-Supported Reagent with Diphosphonate Ligands

A new chelating resin with diphosphonate groups has been synthesized from the tetraethyl ester of 1,1-vinylidenediphosphonic acid. Comonomers such as acrylonitrile allow the sterically hindered monomer to be incorporated into the polymer network. A copolymer was prepared by suspension polymerization in high yield with diphosphonate, acrylonitrile, and styrene in the monomer solution at a 4.5:1:3.1 weight ratio and 5 wt % divinylbenzene as the cross-link agent. Bifunctionality enhances metal ion complexation kinetics. The diphosphonate ligands are selective chelators, while sulfonic acid ligands covalently bound to the phenyl groups enhance the accessibility of metal ions in the polymer matrix. The complexing ability of the polymer is studied with Eu(III) as the target ion in 0.04−4.0 N HNO3 solutions in both the presence and absence of 0.40 N NaNO3. A sulfonic acid ion exchange resin complexes 14.3% Eu(III) while the diphosphonate-based polymer complexes 96.5% from a 1 N HNO3/0.4 N NaNO3 solution.

Mass transfer effects on kinetics of nonideal liquid phase ethyl tert‐butyl ether formation

AbstractEthyl tert‐butyl ether (ETBE) is an alternative fuel oxygenate that can be produced in the liquid phase by addition of ethanol to isobutene catalyzed by sulfonic acid ion exchange resins. A generalized Langmuir‐Hinshelwood rate expression is formulated in terms of the liquid phase activities of the reactants that is quasi‐autocatalytic due to ethanol. This microkinetic model is combined with the generalized Maxwell‐Stefan equations for a detailed investigation of the influence of multicomponent mass transfer limitations inside the macropores of the heterogeneous catalyst. The model is used for revision of experimental rate data for ETBE synthesis in the literature. The analysis reveals that reverse diffusion of isobutene can occur by strong interaction with ethanol and the catalyst effectiveness factor can exceed unity.

Synthesis of tertiary amyl methyl ether (TAME): Equilibrium of the multiple reactions

AbstractThe octane enhancer tertiary amyl methyl ether (TAME) is produced by liquid phase synthesis from methanol and a mixture of isoamylenes, namely 2‐methyl‐1‐butene and 2‐methyl‐2‐butene, using a sulfonic acid ion exchange resin as catalyst. Three reactions take place simultaneously in TAME synthesis: etherification of the two methylbutenes and their isomerisation. In order to study the equilibrium of the multiple reactions in TAME synthesis, the thermodynamic properties of the compounds in the liquid phase and equilibrium constants were calculated using a modified UNIFAC method to describe the nonideality of the system. Four parameters influencing the equilibrium conversion were derived and discussed in detail. Supplemental experiments were performed at three temperatures in the range from 303 to 343 K and at different initial molar ratios of educts. Equilibrium conversions of methanol were determined from these experiments and compared with calculated values. At 298 K the predicted activity based equilibrium constant was 22.9 for TAME synthesis from 2‐methyl‐1‐butene and 1.6 for TAME synthesis from 2‐methyl‐2‐butene; for isomerisation of 2‐methyl‐1‐butene to 2‐methyl‐2‐butene a value of 14.3 was obtained.