Sulfuric Acid Groups Research Articles

Development of a Novel Sulfated Poly (ether sulfone) with Aliphatic Chain for High Temperature Fuel Cell

Polymer electrolyte membrane fuel cells (PEFCs) as one of fuel cell systems, offer a board range of benefits, including: (1) high efficiency, (2) clean process (no CO2 emission), (3) compact design1, and (4) quiet operation. As one of solutions to current technical problems, PEFC operation at high temperature (low humidity) has been considered as a promising system to reduce cost of PEFCs. High temperature PEFCs have some additional merits such as fast reaction kinetic, low activation energy for power generation and high CO catalyst poisoning tolerance2. These advantages make high temperature PEFCs very attractive. However, there are also some technical barriers to develop this attractive system. Especially, harsh environment such as high temperature and low humid condition are very severe for polymer electrolyte membranes (PEMs) as components of PEFCs. Sulfonated poly(ether sulfone)s (SPESs) have been commonly developed as hydrocarbon-type PEMs3,4for high temperature PEFCs, because of the high durability at high temperature condition. Several kinds of SPESs with different structures were investigated previously. However, most of them used only aromatic chain as backbone, which lead the membranes to be tough. In this research, we have investigated a series of copolymerized sulfated poly (ether sulfone) (SPES) with aliphatic chain for high temperature PEFCs. Sulfuric acid was attached to the hydroxyl group connected to the aliphatic main chain. The attached sulfuric acid would be able to move easily and work as a proton conductor because aliphatic unit is more flexible than aromatic unit. We evaluated the basic property of the aliphatic SPES as high temperature PEMs although chemical stability of the aliphatic unit is not higher than that of the aromatic unit. SPES shown in Figure 1 was prepared by sulfation of the hydroxyl group of aliphatic PES. Purification and protonation of the obtained SPES were carried out thoroughly by dialysis from SPES HCl aq. The structure of SPES was confirmed by 1H NMR. SPES films were prepared by cast method. SPES DMSO solution was cast on a petri dish and dried at 60 ˚C in vacuo overnight. The membrane showed hydrophobicity. This property indicated that it showed strong durability against water, which is necessary in fuel cell system. Thermal stability of PEMs is significantly required for high temperature PEFC operation. The obtained SPES was investigated by TGA/DSC experiment as shown in Figure 2. From the result of TGA, SPES had three stages of weight loss. The weight loss was assigned to the removing of water from 66 ˚C to 100 ˚C, thermal decomposition of sulfuric acid2from 176 ˚C to 343 ˚C and the thermal decomposition of the main chain from 343 ˚C to 600 ˚C. And DSC result indicated that no glass transition temperature was observed from SPES at operation temperature region for high temperature PEFC (<120 ˚C). In addition, the proton conductivity of SPES film was observed. The obtained proton conductivity was 0.3 mS/cm at 120 ˚C, 100%RH, which may be caused the high hydrophobic and long distance between sulfonic acid group. We introduce more sulfuric acid group in SPES, and the effect of the sulfuric acid amount and introduction position of sulfonic acid on the proton conductivity is discussed and an optimum condition for preparing MEA for high temperature PEFC is investigated. Reference T. Husaboe, J. A. Rittenhouse, M. D. Polanka, P. J. Litke, J. Hoke, AIAA Paper. DOI, 10, (2013).S. Bose, T. Kuila, T.X. Nguyen, N. H. Kim, K. T. Lau, J. H. Lee, Prog. Polym. Sci., 36, 813 (2011).Y. S. Ye, J. Rick, B. J. Hwang, Polymers, 4, 913 (2012).M. Ulbricht, Polymer, 47, 2217 (2006). Figure 1

Structure and Characterization of Strong Acid Cationic Exchange Fiber

A novel polypropylene strong acid cationic exchange fiber (SACEF) was prepared by sulphonation reaction of polypropylene graft styrene (PP-g-St) fiber. The structure of SACEF was characterized through IR, TG, DTG, EA and SEM testing. The physicochemical properties of PSACEF, including adsorption capacity, adsorption dynamics, water content, and regeneration stability were evaluated. The results showed that the adsorption capacity of SACEF was 4.42 mmol·g-1. Infrared spectra indicated that hydrogen on the benzene ring was substituted by sulfuric acid group. TG and DTG confirmed that SACEF was more stable under the 250 °C. The adsorption dynamics suggested that the adsorption on SACEF was fast and it nearly reached equilibrium within 1 min. The water content of SACEF was 55%~60%. SACEF showed good regeneration performance. The adsorption capacity was constant after being used many times.

CO2 Gas Transport Property of Sulfonated Poly(Arylenen Ether Sulfone) Copolymer Membrane.

The effect of functional groups such as sulfuric acid group and metal ions on the CO2 gas transport property of membranes was investigated. Sulfonated poly(arylene ether sulfone) (SPAES) was prepared by direct copolymerization with a non-sulfonated monomer and sulfonated monomer. The sulfonation degree of SPAES was controlled from 0 to 50%. Metal ions such as lithium and sodium were substituted for the protons of the -SO3H group. The thermal properties, microstructure of polymer chains, and the permeability and selectivity of membranes were evaluated. The solubility coefficient of CO2 gas increased with an increase in sulfonation degree. But the diffusivity was largely decreased and the CO2/N2 selectivity of the membrane substituted for metal ions was increased.

Studies of sulfonated polyphenylene containing fluorine moiety via nickel catalyzed C–C coupling polymerization

The synthesis of polyphenylenes containing fluorine moiety (PPTF), their functionalization with sulfonic acid groups, and the measurement of apposite parameters for PEMs are described. The polymers were prepared by Ni-catalyzed carbon–carbon coupling reaction of -(2,2,2-trifluoro-1-phenylethylidene)-bis(4-chlorobenzene) (TFPECB) and 2,5-dichlorobenzophenone, followed by sulfonation reaction with chlorosulfuric acid. These polymers have all carbon–carbon linkages without any ether linkage on the polymer backbone, which was not attacked by nucleophiles (H2O, hydrogen peroxide, hydroxide anion and radical), and sulfuric acid groups were selectively attached to the side phenyl rings of the TFPECB unit. A series of membranes was studied by 1H NMR spectroscopy, ion exchange capacity (IEC), water uptake, and proton conductivity. The membranes' degradation was tested with Fenton reagent and compared with normal sulfonated poly(ether sulfone)s and Nafion.

Preparation and performance of different amino acids functionalized titania-embedded sulfonated poly (ether ether ketone) hybrid membranes for direct methanol fuel cells

A series of amino acid functionalized titania submicrospheres were synthesized and incorporated into sulfonated poly (ether ether ketone) (SPEEK) to fabricate organic–inorganic hybrid proton exchange membranes. Pristine TiO2 with a uniform particle size of ~200nm were synthesized and functionalized with four kinds of amino acids including oxidized l-cysteine, O-phospho-l-serine, aspartic acid and histidine, designated as TiO2–Scys, TiO2–Pser, TiO2–Asp and TiO2–His, respectively. The effects of amino acid attribute on the membrane properties were investigated. At the filler content of 15wt%, the TiO2–Scys embedded membrane exhibited the highest proton conductivity of about 5.98×10−3Scm−1 (20°C, 100% RH), while the TiO2–His embedded membrane exhibited the lowest conductivity due to the strong acid-base interaction between the basic imidazole groups of histidine and the sulfuric acid groups of SPEEK. The TiO2–Pser embedded membrane exhibited the highest selectivity of 17.10×103Sscm−1. In addition, the methanol crossover of the hybrid membranes was reduced by two folds, and the anti-swelling property and thermal stability of the hybrid membranes were also enhanced.

Sulfuric acid를 도입한 열가소성 폴리우레탄 탄성체의 슬립특성 및 기계적 물성에 관한 연구

We synthesized thermoplastic polyurethane elastomer (TPU) with different contents of sulfuric acid group, and characterized their physical properties such as mechanical, thermal and grip properties. And the results were compared with carboxylic acid-introduced TPU. Wet slip, tensile strength and abrasion properties were increased by the introduction of acid group. Mechanical properties increased with increasing the acid content up to 0.3 wt%. However, wet slip was continually increased as the acid content increased due to increase of hydrophilicity of TPU.

MCM-41-SO3H: a novel reusable nanocatalyst for synthesis of amidoalkyl naphthols under solvent-free conditions

Nanosized MCM-41-SO3H based on an ordered mesoporous material with covalently anchored sulfuric acid groups inside the mesochannels was used as an acid catalyst for synthesis of amidoalkyl naphthols in the multicomponent reaction of 2-naphthol, aromatic aldehydes, and an amide. The products were characterized by Fourier-transform infrared (FT–IR), nuclear magnetic resonance (NMR), and mass spectroscopy. The surface area and pore size of MCM-41-SO3H were also determined by the Brunauer–Emmett–Teller (BET) calculation model. This novel approach for preparation of amidoalkyl naphthols offers several advantages: short reaction times, simple purification and simple isolation of products, high reusability of the catalyst, to name but a few. .

Additive concentration effects on dicalcium phosphate dihydrate cements prepared using monocalcium phosphate monohydrate and hydroxyapatite

In our previous study, we investigated the setting time, mechanical properties and microstructure of dicalcium phosphate dihydrate cements prepared using monocalcium phosphate monohydrate (MCPM) and hydroxyapatite (HA). Despite the use of sodium citrate as a setting regulator, setting occurs rapidly in the MCPM/HA system and further studies on other retardants are needed. In the present study, sodium pyrophosphate and sulfuric acid were tested to evaluate their effectiveness in maintaining workability of the cement paste. MCPM/HA cements at a powder to liquid ratio of 1.0 with sodium pyrophosphate and sulfuric acid at 10, 25, 50, 75 and 100 mM were manufactured and studied based on their setting time, mechanical and porosity properties, phase composition, and microstructure. These measurements were compared to our previous data using sodium citrate. The results showed that the additives have a dose-dependent effect on the setting time. Their order of efficiency is sodium pyrophosphate > sodium citrate > sulfuric acid. However, the sulfuric acid group exhibited the highest compressive strength (CS) compared to the other groups. A lack of correlation between the CS and the porosity of the cements suggested that a mechanism other than porosity reduction was responsible for the CS increase. Since x-ray diffraction analysis did not indicate an effect on composition, explanations based on calcium sulfate dihydrate formation and changes in microstructure were proposed based on scanning electron micrograph observations.

Polymer electrolyte membrane with nanomatrix channel prepared by sulfonation of natural rubber grafted with polystyrene

AbstractHigh‐proton‐conductive polymer electrolyte with a nanomatrix channel was prepared by graft copolymerization of styrene onto deproteinized natural rubber followed by sulfonation with chlorosulfonic acid. First, natural rubber latex was purified with urea in the presence of surfactant to remove almost all proteins present in the rubber. Second, graft copolymerization of styrene onto deproteinized natural rubber was carried out with tert‐butyl hydroperoxide/tetraethylenepentamine as an initiator at 30°C in latex stage. The graft‐copolymerized natural rubber (DPNR‐graft‐PS) was sulfonated with chlorosulfonic acid in chloroform solution at an ambient temperature. The resulting sulfonated DPNR‐graft‐PS was characterized by FTIR spectroscopy, solid state 13C CP/MAS NMR spectroscopy, elemental analysis, and transmission electron microscopy. High proton conductivity of about 0.1 S/cm, less water uptake of 24 wt % and comparatively good stress at break of 9 MPa were accomplished at suitable contents of styrene units and sulfur, i.e., 32 wt % and 75 mol %, respectively. The high proton conductivity, excellent stability, and good mechanical properties were associated with not only the formation of the nanomatrix channel but also a specific concentration of sulfuric acid group. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.

Deordorization Performance of Oxidized and Succinylated Wool Fibers -Removal of Ammonia and Alkylamines-

This report describes the addition of deodorizing functionality to wool fibers by chemical modification for recycling used wool into a functional fiber material. Wool fibers were oxidized and succinylated and the effects of these treatments on ammonia sorption were evaluated. Oxidation significantly improved the ammonia sorption of wool fibers. The oxidized wool fibers also considerably sorbed methyl amine and dimethyl amine, though butyl amine and trimethyl amine were poorly sorbed. Ammonia sorbed rapidly with sulfuric acid groups but sorbed more slowly with carboxylic groups in oxidized and succinylated wool fibers. The sorbability of oxidized wool fibers after repeated sorption could be completely restored by washing with 0.5mM sulfuric acid.

Characterization of Sulfonated Poly(ether ether ketone)/Silane Nanocomposite Membrane for High Temperature Polymer Electrolyte Membrane Fuel Cells

The perfluorosulfonic acid polymer membrane is most widely used in PEMFCs. However, its some major drawbacks like high cost and performance limitation at high temperature are obstacles of its commercialization. The goal of this study was to develop low cost membranes which have good conductivity in the range of PEMFCs operating temperature. We fabricated new sPEEK/3-APTES nanocomposite membrane where inorganic particles were chemically bonded to sulfuric acid group of sPEEK. PEEK is a thermally stable, mechanically tough and very cheap polymer. And the addition of 3-APTES and phosphorous acid increased the proton conductivity of composite membranes at high temperatures. This nanocomposite membranes maintained good conductivity at 110 degrees C.

One-Step Synthesis of Bifunctional TiO2Catalysts and Their Photocatalytic Activity

In this paper, we have investigated in detail the preparation of anatase TiO2 catalysts by the controlled thermal decomposition of ammonium titanyl sulfate ((NH4)2TiO(SO4)2) and their catalytic activity. The structures of anatase TiO2 catalysts have been characterized by powder X-ray diffraction, N2 adsorption−desorption isotherms, diffuse reflectance UV−vis spectroscopy, infrared spectroscopy, X-ray photoemission spectroscopy, NH3 temperature-programmed desorption, and solid-state MAS NMR spectrometer. We report for the first time that the anatase TiO2 catalyst prepared by calcination of (NH4)2TiO(SO4)2 at 600 °C (TiO2-600) is a very active bifunctional catalyst. TiO2-600 is doped with N and S and thus very active in the photodegradation of methyl orange under visible light illumination (λ > 420 nm); meanwhile, it also has a large number of Bronsted acid sites arising from the covalently bonded sulfuric acid groups and thus is active in the esterification of ethanol and acetic acid to ethyl acetate. The ...

One-step synthesis of novel sulfuric acid groups' functionalized carbon via hydrothermal carbonization

The novel sulfuric acid groups' functionalized carbon has been synthesized via one-step hydrothermal carbonization of polyvinyl alcohol and hydroxyethylsulfuric acid. The novel carbon exhibited high acidity and comparable activities to sulfonic acid for the traditional acid-catalyzed reactions, which indicated that it has great potential for the environmental-friendly processes. The copolymerization method provides an efficient procedure for the synthesis of various functioned carbons by one-step hydrothermal carbonization.

Preparation and properties of chitosan/carbon nanotube nanocomposites using poly(styrene sulfonic acid)-modified CNTs

Poly(styrene sulfonic acid)-functionalized carbon nanotubes (CNT-PSSA), which was obtained with atom transfer radical polymerization (ATRP), was utilized in preparation of chitosan/CNT nanocomposites (CH/CNT-PSSA). Chemical linkages between chitosan and CNTs form in the nanocomposites through the reaction between the sulfuric acid groups of CNT-PSSA and the amino groups of chitosan, to warrant the homogenous dispersion of CNTs. The CH/CNT-PSSA nanocomposites were superior to the neat chitosan polymer in thermal and mechanical properties, water and solvent uptakes, bond water ratios, and electrical conductivity. The attractive property of the CH/CNT-PSSA nanocomposites also implied their application potentials for separation membranes and sensor electrodes.

Preparation of Nafion® nanocomposite membrane modified by phosphoric acid-functionalized 3-APTES

We have fabricated a fuel cell nanocomposite membrane based on Nafion®/conductive inorganic materials. To introduce inorganic materials into Nafion® membrane, 3-aminopropyl triethoxysilane (3-APTES) was reacted with sulfuric acid groups of Nafion® and the obtained membrane was subject to reacting with phosphoric acid to bestow proton conductivity. Methanol permeability for the modified membranes was found to be at least 50% lower than for Nafion®. The proton conductivity of the membrane showed maximum conductivity of 0.07S/cm at 3wt% of APTES, which was comparable with the conductivity of Nafion®.

Interference with Chemical Crosslinking of Sulfated Polysaccharides by Sulfuric Acid Groups of Polysaccharide Chain

The chemical crosslinking of funoran, a sulfated galactan, was attempted by using polyethylene glycol diglycidyl ethers in order to prepare a gel for using as a water-absorbing network polymer contained in disposable napkins. The funoran gel was not obtained under a series of crosslinking conditions. Other sulfated polysaccharides, such as Kappa-and Lambda-carrageenan, were not also crosslinked by the diglycidyl ethers, while agarose was chemically crosslinked to give its gel. Agarose has the same chemical main chain as funoran but has no sulfuric acid groups. The bulky sulfuric acid groups may intercept sterically the reaction between the hydroxyl groups and the glycidyl groups of the crosslinker.

Comparison of NaOH- N-acetyl cysteine and sulfuric acid decontamination methods for recovery of mycobacteria from clinical specimens

We compared the NaOH- N-acetyl cysteine (NaOH-NALC) and the sulfuric acid decontamination procedure in the detection of mycobacteria using the Mycobacteria Growth Indicator Tube (MGIT). In total 219 sputum specimens were collected from 142 Zambian patients and subjected to mycobacterial culture. One half of the specimen was decontaminated with NaOH-NALC and the other half was decontaminated with sulfuric acid. From the 438 samples a total of 261 (60%) cultures yielded growth of mycobacteria, consisting of 22 different species. The sulfuric acid method was more successful than the NaOH-NALC method in recovering mycobacteria in MGITs (146 versus 115 respectively, p=0.001). Of the 146 positive mycobacterial cultures recovered after sulfuric acid decontamination 28 were Mycobacterium tuberculosis, 84 nontuberculous mycobacteria (NTM) and 34 acid fast bacterial isolates which could not be identified to the species level. The 115 mycobacteria recovered by the NaOH-NALC method consisted of 34 M. tuberculosis strains, 55 NTM and 26 acid fast bacteria that could not be identified. The most frequently isolated NTM were Mycobacterium lentiflavum and Mycobacterium intracellulare. Comparing the two decontamination methods the recovery of NTM in the sulfuric acid group was significant higher than in the NaOH-NALC group ( p=0.001). In contrast, no significant difference was found for the recovery of M. tuberculosis. These results show that the decontamination method used affects the recovery of nontuberculous mycobacteria in particular.

Characteristics of Sulfonated Poly(arylene ether sulfones) Cation-Exchange Membrane by Variation of Sulforic Acid Group Concentration

Sulfonated Polysulfone (SPSF) cation-exchange membranes were synthesized by introducing various ratio of chlorosulfuric acid (CSA) onto the main chain of polysulfone (PSF). Properties such as ion exchange capacity, water content, liked ion concentration, and partition coefficient were measured, respectively. Through the analysis of DSC and TGA, it has been shown that glass transition temperature increased and weight loss decreased as sulfuric acid group concentration increased. Structure of membrane measured by AFM and SEM was seen to be asymmetric. Apparent diffusion coefficient of sodium ions through SPSF membrane by AC impedance was increased as sulfuric acid group concentration increased.

Usefulness of Derivatization in High-Performance Liquid Chromatography/Tandem Mass Spectrometry of Conjugated Vitamin D Metabolites

The usefulness of derivatization in high-performance liquid chromatography/ion trap tandem mass spectrometry (electro-spray ionization) of conjugated vitamin D metabolites was examined. 24,25-Dihydroxyvitamin D3 [24,25(OH)2D3]-3-and -24-glucuronides (G) were converted to the adducts with 4-phenyl-1,2,4-triazoline-3,5-dione (PTAD), the methyl esters and the acetates. The combination of the derivatization with PTAD and methylation improved the detection limit in both the positive- and negative-ion modes. The PTAD adducts of 24,25(OH)2D3-3G and -24G also gave a characteris-tic product ion indicating the conjugation position by the positive-MS/MS/MS, which was not observed in the intact forms. 25-Hydroxyvitamin D3 3-sulfate gave the deprotonated ion in the negative-ion mode, but no characteristic ion was observed in the positive-ion mode. On the contrary, its PTAD adduct gave a molecular-related ion in the positive-ion mode, the MS/MS/MS of which provided structural information, that is, the conjugation position and the existence of a sulfuric acid group.

Ready chemical conversion of acid hydrolysis lignin into water-soluble lignosulfonate III: Successive treatment of acid hydrolysis lignin and a lignin model compound by phenolation and arylsulfonation*

The chemical conversion of red pine sulfuric acid lignin (Klason lignin) (SAL) as an acid hydrolysis lignin sample to water-soluble arylsulfonates of lignin derivation (i.e., phenolized SAL) was investigated. Treatment of phenolized SAL with chlorosulfonic acid followed by alkali hydrolysis gave water-soluble sulfonated products with a sulfonic acid group on their aromatic nuclei quantitatively. The products possess 2.0 SO3Na/C9 C6. In contrast, the content of sulfuric acid group in sulfonated SAL was only 0.33C9. Chlorosulfonation of 1-guaiacyl-l-p-hydroxyphenylethane as a phenolized guaiacyl lignin model compound revealed that the sulfonyl chloride group was introduced at thepara position of an aromatic methoxyl group, theortho position of a phenolic hydroxyl group, or both.