Fuming Sulphuric Acid Research Articles

PROTON EXCHANGE MEMBRANE FUEL CELL; EMPIRICAL REVIEW ON THE DEGREE OF SULPHONATION

Empirical review on the degree of sulphonation of polymeric materials for proton exchange membrane fuel cell (PEMFC) was carried out. Fuel cell generally applies the principle of electrochemistry in which chemical energy is converted directly into electrical energy. Amongst the league of fuel cells, the proton exchange membrane fuel cell is the most promising. However, the central component of PEMFC is the ionic polymer membrane that must be rendered conductive. This study showed that the measure of sulphonation is pivotal in achieving conductivity of the polymer for fuel cell application. The study revealed that for an optimum conductivity to be achieved, optimum degree of sulphonation (DS) is needed. The recognized factors that affect the optimum degree of sulphonation were the type of sulphonating agent (as chlorosulponic acid achieved 39.04% and 50.21% differential increment over both sulphuric acid and fuming sulphuric acid, respectively), sulphur content (while the lowest Sc of 1.76% achieved 9.13% DS, the highest Sc achieved 20.04% DS), optimum acid concentration (as DS of 20.04 % was achieved with 1.6 mmol/g as against 2.0 mmol/g of 16.76 %), nature of the polymer base material (as more –SO3H groups attached to aliphatic polymers than aromatic), optimum time and stirring speed, optimum temperature, and optimum weight of the base polymer. The study was able to unravel that the degree of sulphonation can be determined via elemental sulphur analysis either by analytical or titrimetric method. The study also showed that the degree of sulphonation can be predicted correctly using a predictive model.

Synthesis and characterization study of solid carbon biocatalyst produced from novel biomass char in a microwave pyrolysis

Biochar is considered to be one of the most significant by-products obtained from biomass pyrolysis. Biochar is of significant importance in soil amendment, catalyst preparation, and activated carbon formation. Microwave pyrolysis is one of the emerging trends in biochar production. Since the residence time in a typical microwave pyrolysis reactor is quite high, biochar is often the major by-product of biomass microwave pyrolysis. Microwave pyrolysis additionally is an extremely energy-efficient method. This present study involves the preparation and characterization of biochar produced from senna pendula seedcake. The biochar produced from the pyrolysis (up to 600 ˚C) is then subjected to sulphonation using fuming sulphuric acid. TG analysis shows that pyrolysis occurred between 200 and 450 ˚C. FTIR analysis results show that upon sulphonation, the biochar has been strongly carbonized. Both FTIR and XRD analyses showed that biochar had been impregnated with carbonyl and sulphonyl groups post sulphonation. SEM micrography results showed that sulphonation had caused a breakdown of existing organic compounds along with an increase in pore diameter.

The synthesis of a new chitosan based superplasticizer and investigation of its effects on concrete properties

Chitosan-g-POEGMA (Chitosan-g-poly[oligo(ethyleneglycol) methyl ether methacrylate]) graft copolymers are prepared by grafting of oligo (ethylene glycol methyl ether) methacrylate (OEGMA) on chitosan via redox free radical polymerization method using ceric ammonium nitrate (CAN) as the initiator at 40 °C. Then the resulting copolymers are sulphated by sulphuric acid, chlorosulfonic acid and fuming sulphuric acid (Oleum). The compounds are characterized by FT-IR, NMR, and Elemental analysis. The chitosan homopolymer is also sulphated to compare the results. Taking all characterization results and water solubility ratios into account, it is decided to conduct tests on concrete specimens containing graft copolymers sulphated with oleum sulfuric.Water-reducing properties in the fresh concrete have been examined. Compared to the reference concrete; it is observed that water-reducing of sulphonated graft is %6 and sulphonated chitosan is %5. The unit weights of the reference concrete is as 2380 kg/m3, sulphonated graft is as 2395 kg/m3 and sulphonated chitosan is as 2388 kg/m3. The air content of the reference concrete is measured as 2%, sulphonated graft as 1.5% and sulphonated chitosan as 1.6%. 28-day concrete durability results are determined as 30.1 MPa for the reference concrete, 34.7 MPa for sulphonated graft and 33.8 MPa for sulphonated chitosan.

Partition Performance of Biological Sulfonate Synthesized from Waste Cooking Oil by Sulfonation in Oil and Water

Biological sulfonate was synthesized from waste cooking oil by sulfonation. Fourier transformation infrared spectrometer was employed to characterize biological sulfonate. The influences of the surfactant concentration, alkali concentration and emulsification on the partition coefficient of biological sulfonate in oil and water were investigated. The experimental results show the waste cooking oil can react with the fuming sulphuric acid to successfully produce biological sulfonate. The partition coefficients of biological sulfonate have a small decrease when biological sulfonate concentration is more than 0.2%. Adding alkali to biological sulfonate solution or emulsifying biological sulfonate solution and crude oil can both improve the partition coefficients of biological sulfonate in oil and water, and the variation law of the partition coefficients with the concentration of biological sulfonate remain unchanged. By contraries, after adding alkali to solution and emulsifying it with crude oil, the partition coefficients of biological sulfonate will increase with the increase of surfactant concentration.

Synthesis of tert -amyl methyl ether (TAME) over modified activated carbon catalysts

Abstract Industrial production of ether antiknock substances (e.g. ETBE or TAME) involves the use of catalysts based mainly on acidic ion-exchange resins. However, the use of such resins causes certain drawbacks leading to technological difficulties and for this reason the search for other catalysts suitable for the purpose is continued. Our studies were focused on the synthesis of tert-amyl methyl ether (TAME) in which different modified activated carbons were tested as catalysts. The modifications were undertaken to introduce sulphonic groups on the surface of activated carbon, as a result of reactions with such reagents as concentrated or fuming sulphuric acid, in situ generated diazonium salt of 4-aminobenzenesulphonic acid or sodium sulphide and hydrogen peroxide. For the sake of comparison, the activated carbon with P-containing and/or O-containing groups on the surface and the commercial catalyst Amberlyst-15 were used. The most effective method of SO3H groups introduction has been proved to be the reaction of activated carbon with in situ generated diazonium salt. The majority of catalysts obtained were active in tert-amyl methyl ether synthesis, however, significant differences in yields of TAME were observed, depending on the method of activated carbon modification.

Synthesis of sulphonated mesoporous phenolic resins and their application in esterification and asymmetric aldol reactions

Mesoporous phenolic resins were functionalized with sulphonic acid groups by four different types of sulphonation procedures: (i) direct sulphonation on the aromatic ring, (ii) alkyl sulphonation of the aromatic ring, and functionalizations of the phenolic hydroxyl surface by using an aryl silane, 2-(4-chlorosulphonylphenyl)ethyl trichlorosilane (iii) or a propyl silane, 3-mercaptopropyltrimethoxysilane (iv). The highest acidity loadings were obtained through direct sulphonation with fuming sulphuric acid (1.90 mmol H+ g−1) or chlorosulphonic acid (1.31 mmol H+ g−1) and these materials showed the highest conversion (97+ %) in Fischer esterification of acetic acid with propanol. However, the alkyl sulphonic groups, obtained through sulphonation procedure (ii) showed the highest stability in terms of maintenance of their acidity after use in consecutive catalytic runs or leaching treatments. This was demonstrated both through evaluation of the regenerated catalysts in a consecutive esterification run and during a leaching resistance test in aqueous medium. Moreover, the developed sulphonated mesoporous phenolic resins are presented as novel support for the non-covalent immobilization of an l-phenylalanine derived chiral diamine organocatalyst for asymmetric aldol reactions. The immobilization is established by an acid–base interaction between the sulphonic acid group and the amine function. The acidity and in particular the electronic withdrawing environment of the sulphonic acid groups influence enormously the catalytic performance of the non-covalent immobilized chiral diamine catalyst (aromatic > aliphatic).

Investigation on removal of SU-8 electroplating mould using fuming sulphuric acid

In some microelectromechanical system device fabrication, using fuming sulphuric acid to remove crosslinked SU-8 mould from integrated thick metal structures is an inexpensive and effective wet etching technique. The fabrication of stator for a suspended rotational microgyroscope, which has surface-micromachined structures integrated, was investigated to study the removal process of 250-µm thick SU-8 plating mould. Immersion time in the acid was a critical factor for complete removal of SU-8 mould without detectable damage to the nickel structures. Variation of etch rate was investigated every 0.5 h in the range from 0.5 to 6 h; 5 h was found to be a suitable time setting to remove 250-µm thick SU-8 mould. During the process, etch rate was measured slowing down from 110 µm/h in the first 0.5 h to 18 µm/h in the last 0.5 h. It was better to finish the whole removal process in a consistent manner because although taking sample out of the acid, cleaning, and immersing it back into the acid again was able to accelerate subsequent etch rate, metal structures were likely to be etched black. The etch rate which slowed down with the increase of etch time based on continuous etching provided useful reference for time control during SU-8 application for ultra-thick integrated microstructure fabrication.

Preparation of SiO2–Al2O3 and Its Supported Co3O4 Catalysts for Nitrosation of Cyclohexane

Amorphous SiO2–Al2O3 was prepared by sol–gel method and cobalt oxide supported on SiO2–Al2O3 was prepared by impregnation method. These materials were characterized by BET, XRD, TPD and FT-IR. The activity of SiO2–Al2O3 and Co3O4/SiO2–Al2O3 catalysts for nitrosation of cyclohexane with nitrosyl sulfuric acid in the presence of fuming sulphuric acid was evaluated. The results indicate that SiO2–Al2O3 and Co3O4/SiO2–Al2O3 can catalyze efficiently this nitrosation reaction. And Co3O4/SiO2–Al2O3 gave better results with 11.93% of conversion and 54.68% of selectivity to e-caprolactam. This discovery establishes a potential method for one-pot synthesis of e-caprolactam from cyclohexane. It may be of potential application prospect and of prominent theoretical significance. Amorphous SiO2–Al2O3 and its supported Co3O4 catalysts were prepared and characterized. These catalysts were employed to catalyze the reaction of cyclohexane with nitrosyl sulfuric acid in the presence of fuming sulphuric acid. It indicates that Co3O4/SiO2–Al2O3 gave better results with 11.93% of conversion and 54.68% of selectivity to e-caprolactam. This discovery establishes a potential method for one-pot synthesis of e-caprolactam from cyclohexane.

Metal foundation construction to consolidate electroplated structures for successful removal of SU-8 mould

For integrating thick microstructures with microfabricated circuitry on the same chip, a metal foundation method to consolidate adhesion of the electroplated microstructures to the substrate for successful removal of SU-8 mould is proposed. Along with multilevel interconnections microfabrication or other required metal deposition, the metal foundations are constructed and then tamped by interlevel dielectric. With metal foundations formed along with fabrication of interconnections and thin film electrodes, the electroplated Ni structures of an electrostatically levitated rotational microgyro, with thickness of 200 µm after lapping the whole wafer, are successfully released by removing the SU-8 mould using the fuming sulphuric acid oxidising method.

Oxidative coupling of coumarin compounds with fuming sulphuric acid : 4-,4' -bicoumarinyls as axially chiral compounds

Oxidative coupling of coumarin compounds with fuming sulphuric acid : 4-,4' -bicoumarinyls as axially chiral compounds

Voltammetric determination of alkaline phosphatase and horseradish peroxidase activity using 3-indoxyl phosphate as substrate: Application to enzyme immunoassay

The use of 3-indoxyl phosphate (3-IP) as an electrochemical substrate for ELISAs with voltammetric detection was investigated. Indirect measurements of alkaline phosphatase (AP) and horseradish peroxidase (HRP) activity in solution were carried out. Picomolar levels of both enzymes can be detected, which enables the design of electrochemical immunoassays using this substrate. The enzymatic turnover of the substrate gives indigo blue, insoluble in aqueous solutions. This product is easily converted into its soluble parent compound, indigo carmine (IC), by addition of fuming sulphuric acid to the reaction media. IC shows a reversible voltammetric peak at the formal potential of −0.15 V (versus Ag pseudo-reference electrode) when a screen-printed carbon electrode (SPCE) is used. The peak current of this process constitutes the analytical signal. Using this approach an ELISA assay to quantify pneumolysin (PLY, a toxin related to respiratory infections) was carried out using AP or HRP as enzymatic label. Calibration plots obtained are reported. 3-IP is demonstrated to be the first suitable substrate for the two most common enzyme labels used in immunoassays.

Further insights into the role of carbon surface functionalities in the mechanism of phenol adsorption

The presented study describes the temperature as well as pH dependence of phenol adsorption (and adsorption kinetics) on four carbons with different chemical compositions of the surface layer but almost identical porosity. In the first part, it is shown, applying the most sophisticated method of carbon porosity characterization (i.e., the method of Do and co-workers—ND method), that the porosity does not change much after the chemical modification of carbons. Then it is shown that the ND method leads to the same results as the DFT (density functional theory) does. Next, the TPD results for D43/1 carbons (initial, modified with HNO 3, fuming H 2SO 4, and with NH 3) are described. The TPD results for carbon modified with fuming sulphuric acid has not been reported yet by others. The deconvolution of peaks is performed. The obtained results, together with those already published, lead to the chemical structures of surface functionalities for all studied carbons. The thermogravimetric analysis of phenol adsorption shows that the amount of chemically bonded molecules is small. Then it is shown that the adsorption at the acidic pH (1.5) level is lower for all studied carbons than that at the neutral one. The description of the isotherms applying adsorbability, quasi-Freundlich and DA models, together with enthalpy measurements, lead to the mechanism of phenol adsorption at both pH values. The mechanism is, furthermore, confirmed by some empirical correlations. The analysis of the average hysteresis on adsorption–desorption isotherms as well as the comparison of phenol adsorption in oxic and anoxic conditions leads to the mechanism of irreversible phenol adsorption. It is suggested that the irreversibility is caused by two effects: the creation of strong complexes between phenol and surface carbonyl and lactones as well as by the polymerization. The last effect is due to the ability of carbon to adsorb the oxygen from solution and form superoxo ions. Finally, the kinetics is considered. The analytical solution of Fick's law of diffusion for adsorption in cylindrical particles is applied, the diffusion coefficients are calculated. It is shown that phenol diffusion is mixed between a surface process and a pore one. The obtained energy of diffusion is correlated with the values of the physicochemical parameters of studied carbons. As a final point, it is concluded that the mechanism of phenol adsorption is not only determined by so called “ π– π interactions” and “donor–acceptor complex formation” but also by (strongly depending on temperature) the “solvent effect” balancing the influence of the two mentioned factors on this mechanism.

Analysis of silica fume produced by zircon desilication

Novel chemical methods have been developed to allow for the determination of the components of silica fume produced by zircon desilication. Hitherto, no methods have been described for the analysis of this material. The amorphous silica is first removed by treatment with sodium hydroxide. The residue from the hydroxide treatment may then be subjected to a suite of reagents to determine the zircon, the total zirconia, the monoclinic zirconia and the tetragonal zirconia content of the fume. The zircon content of the fume is determined by treatment of the hydroxide residue with concentrated hydrofluoric acid (HF). The total zirconia content of the fume is determined by digestion of the hydroxide residue with fuming sulphuric acid (oleum), while the relative amounts of monoclinic and tetragonal zirconia may be found by treatment of the hydroxide residue with 10%w/v HF, which attacks the less stable tetragonal phase. Both X-ray diffraction and particle size analysis were used to validate the steps in the analytical procedure. An explanation of the presence of tetragonal zirconia in the fume is proposed. A greater understanding of the composition of the fume led to the installation of a separator in the company's production line to remove the zircon. Australian Fused Materials (AFM) now produces a vastly superior grade of fume marketed under the code SF-98.

The influence of activated carbon surface chemical composition on the adsorption of acetaminophen (paracetamol) in vitro: The temperature dependence of adsorption at the neutral pH

The in vitro adsorption and desorption of acetaminophen from water solution on four activated carbons at three temperatures (300, 310 and 320 K) and at the neutral pH (7) were investigated. The carbons were characterized using the low temperature nitrogen adsorption, the mercury porosimetry, Bachmann’s method, Boehm’s method as well as the water immersion calorimetry. As an initial adsorbent, the de-ashed-commercial, ‘non-modified’ carbon D43/1 (Carbo-Tech, Essen, Germany) was applied. To change the chemical composition of its surface, concentrated nitric and sulfuric acids as well as gaseous ammonia were applied as chemical modificators. The acetaminophen adsorption and desorption isotherms on the ‘non-modified’ as well as on the chemically modified carbons were measured, together with the enthalpy of immersion in paracetamol solution. It is shown that, generally, for all the investigated carbons, acetaminophen adsorption increases with temperature. A slightly marked hysteresis on adsorption–desorption isotherms was observed at higher adsorption values. Among the applied procedures of the changing of carbon surface chemical composition, the modification with fuming sulphuric acid leads to the increase in paracetamol adsorption, whilst the opposite effect is observed for the carbon modified with concentrated nitric acid. The modification in the stream of ammonia practically does not change the adsorption properties towards paracetamol. The changes in the adsorption properties of carbons after modification are analysed using isotherms, adsorbability, relative enthalpy of displacement as well as the values of the integral enthalpy of adsorption. To calculate this enthalpy the solubility of acetaminophen in the investigated range of temperatures was determined, and the enthalpy of solution at infinite dilution was calculated using Abraham’s method.

Preparation of medicinal petroleum Jelly using local petroleum Waxes

AbstractPetroleum waxes are mainly derived from paraffinic crudes. These waxes must be removed from lubricant base oils through a dewaxing process to avoid affecting oil performance at low temperatures. The waxes themselves have uses.This paper describes successful attempts to select the optimum conditions for sulphonation and/or hydrogenation of local waxes to obtain medicinal macro‐ and microcrystalline waxes suitable for use in petroleum jelly blends that meet medicinal specifications.Deoiling was carried out to separate the oil from the wax samples. Concentrated and fuming sulphuric acids were used as sulphonating agents. Sulphonation processes were carried out at different temperatures, stirring speeds, and digestion times. The optimum sulphonation conditions, which give 0.007 UV absorbance at 290 nm and the highest yield, were achieved using 28% concentrated sulphuric acid.The optimum hydrogenation conditions were achieved using a Ni/Mo catalyst at 105°C and 60 bar for paraffin wax and 180°C and 100 bar for petrolatum, for 30 min for both types of waxes.Analysis and field trials of the blended petroleum jelly showed that these blends meet British Pharmacopoeia specifications.

Electropolymerization of benzene in a two-phase benzene/acid system: Comparative study in strong proton acid and superacid media

Anodic polymerization of benzene can be carried out under two-phase conditions, if the electrode is immersed in the interfacial layer between benzene and acids of different strengths such as methanesulphonic, sulphuric, 20% fuming sulphuric, fluorosulphonic and trifluoromethanesulphonic acids. In all these cases the oxidation of benzene occurred in the interfacial layer only and began in the rather low potential region in the vicinity of 1 V (SCE). The characteristics of the film growth and their electrochemical properties change drastically upon transfer from the usual strong acid to fuming sulphuric acid and then to superacids. In the usual acidic media, the film growth and its cyclic voltammetry are characterized by wide ill-defined oxidation—reduction peaks with a half-height width ((Δ E p) 1 2 of about 500–600 mV. On the contrary, in the superacids a metastable state of the film with sharp oxidation—reduction peaks ((Δ E p) 1 2 up to 80 mV), with a great difference between the oxidation and reduction peak potential ( ∼ 400 mV), was formed. IR spectra have shown that a linear chain structure is obtained in all acidic media apart from methanesulphonic acid and in the case of 20% fuming sulphuric acid, the degree of polymerization is high.

Comparison of different synthetic routes for sulphonation of polyaniline

Polyanilines containing sulphonic groups covalently bonded to the back bone were synthesized from parent polyaniline via sulphonation of the polymer utilizing differing sulphonation agents and differing means. The sulphonation conditions were studied as a function of several parameters including sulphonation time, starting forms of the precursor polymer, presence of oxidizer [(NH 4) 2S 2O 8] and temperature. The sulphonated polyanilines were characterized by FTi.r., elemental analyses, d.c. conductivity and electrochemical methods. It was found that using fuming sulphuric acid as the sulphonation agent gave both higher conductivity and higher sulphonation level for sulphonated polyaniline than implementation of other sulphonation agents and means.

Synthesis and purification of trisulphoindigo and reversed-phase high performance liquid chromatographic determination of trisulphoindigo in FD & C Blue No.2

The effect of temperature on product formation during the sulphonation of indigo with concentrated sulphuric acid and 30 % fuming sulphuric acid was studied with the aid of high performance liquid chromatographic (HPLC) analysis. Trisulphoindigo was prepared by the sulphonation of indigo with concentrated sulphuric acid at 160°C. The di- and tetra-sulphoindigo side products formed during the reaction were removed by preparative HPLC to yield a product of high chromatographic purity. The trisulphoindigo content of the food dye FD & C Blue No. 2 and the purity of commercially available trisulphoindigo were determined by HPLC analysis.

Aromatic sulphonation. Part 70. The sulphuric acid sulphonation of α,ω-diphenylalkanes, biphenylene, fluorene, 9,10-dihydrophenanthrene, 10,11-dihydro-5H-benzo[a,d]cycloheptene, and triptycene

The sulphonic acid isomer distribution for the sulphonation of α,ω-diphenylalkanes, biphenylene (2a), fluorene (2b), 9,10-dihydrophenanthrene (2c), 10,11-dihydro-5H-benzo[a,d]cycloheptene (2e), and triptycene (3) with concentrated aqueous and with fuming sulphuric acid at 25 °C has been determined by multicomponent 1H-n.m.r. analysis. With Ph[CH2]nPh in 95.4% H2SO4 the degree of ortho-substitution increases with increasing length of the alkylidene chain to reach for n 4 the same limiting value as observed for the 1-phenylalkanes (Ph[CH2]nMe) with n 3. Further sulphonation of the α,ω-bis(sulphophenyl)alkanes yields the o,o′,p,p′-tetrasulphonic acids.Sulphonation of (2a) and biphenylene-1-sulphonic acid in 98.4% H2SO4 yields the 2,6- and 1,6-(or 1,7-)di-sulphonic acid respectively.The sulphonation of (2b), (2c), and (2e) in 95.3–98.3% H2SO4 leads to a mixture of disulphonic acids, that of (3) to a mixture of trisulphonic acids, all containing one sulpho-group per phenylene. The isomer distribution for the monosulphonation of (2b) has been estimated from the disulphonic acid isomer composition. For (2c), (2e), and (3) the substitution ratio per phenylene has been estimated.The isomer distributions of the tri- and of the tetrasulphonic acid mixtures obtained from (2b), and of the tetrasulphonic acid mixture formed from (2e) have also been determined.

Polyfluorocycloalkenes. Part XIV.[1] A novel hydrolysis of decafluorocyclohepta-1,4-diene. Crystal structure of 2H, 4H-hexafluoro-1,5-dimethoxy-8-oxabicyclo(3,2,1)octan-3-one

Decafluorocyclohepta-1,4-diene and fuming sulphuric acid at 100° gave a bright yellow solution which was decolourised on dilution with water to give 2H,4H-hexafluoro-1,5-dihydroxy-8-oxabicyclo(3,2,1)octan-3-one. This was methylated with diazomethane in ether to give 2H,4H-hexafluoro-1,5-dimethoxy-8-oxabicyclo(3,2,1)octan-3-one and 2H-hexafluoro-1,3,5-trimethoxy-8-oxabicyclo(3,2,1)oct-3-ene. The crystal and molecular structure of the former compound was determined by a single crystal X-ray analysis from three-dimensional counter data.