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The pressure–volume–temperature (PVT) relationships for trimethoxymethylsilane (MTMS, CH3(CH3O)3Si) and tetramethyl orthosilicate (TMOS, (CH3O)4Si) were measured at temperatures ranging from 303.2 to 363.2 K and pressures up to 160 MPa. Density measurements were carried out with an experimental apparatus based on the variable volume method. The standard uncertainties u(T) = 0.17 K and u(P) = 0.14 MPa, and the relative combined expanded uncertainty Ur (0.95 level of confidence) were Ur(ρ) = (0.0016 and 0.0022) for MTMS and TMOS, respectively. The obtained PVT relationships were correlated using the Tait equation and the Sanchez–Lacombe equation of state to determine the characteristic parameters.

The solubility of sulfur dioxide (SO2) was measured in polyethelene glycol dimethyl ether (PEGDME) by use of a static type apparatus in the pressure range from 15.2 to 231.2 kPa at 308.18 K. The stated average molecular weight of PEGDME was Mw = 240 g·mol−1 and the molecular structure of the repeating unit is similar to that of dimethyl ether (DME). The bubble point pressure showed a negative deviation from Raoult law. The behavior was expected from consideration of the vapor–liquid equilibrium data of DME + SO2, reported by Noles and Zollweg (Fluid Phase Equilib 66:275–289, 1991). The ‘bridge-like structure’ will be microscopically formed between the DME unit and SO2, because the two unshared electron pairs of the oxygen atom in DME unit act as an electron donner for some molecules. The Peng–Robinson equation of state was used to correlate the experimental data. Two types of mixing rules were employed. One was a conventional model, and the other was of the excess Gibbs energy type. The latter, Wong–Sandler model combined with Flory–Huggins equation, showed a good reproducibility for the experimental data.

Supercritical drying is widely considered as the gold standard to produce aerogels that preserve the microstructure of the gels, but we have found this is not always the case. Chitosan aerogel, one of the emerging biopolymer aerogels, was prepared by chemical cross-linking gelation, followed by solvent exchange with methanol and supercritical drying using CO2. Small-angle X-ray scattering analysis shows that the structure of the wet gel, which consists of Gaussian chains of individual molecular strands, converts into a nanofibrous network during CO2 processing. In situ observation reveals a drastic shrinkage of the gel in CO2, demonstrating that physical coagulation caused by the low affinity between chitosan and CO2 is the main structure-forming step. These results challenge the common perception of supercritical drying: it is no longer an inactive drying method, but rather an active nanostructure forming a tool to produce porous biopolymer materials with tailored structure and properties.

Equations of state (EoS) can be used to estimate a wide variety of physical properties. However, there has been limited verification of the applicability of parameter sets derived from specific physical properties to correlate and estimate various other physical properties. The densities of homogeneous phase fluid mixtures of the carbon dioxide (CO2)/toluene (Tol) binary system were measured and correlated to three equations of state. The density measurements were performed using a high-pressure vibration-type density meter equipped with a circulation pump and variable-volume viewing cell, which guaranteed the homogeneity of the mixtures. The densities were measured at temperatures ranging from 313 to 353 K, pressures up to 20 MPa, and CO2 concentrations from 0 to 80 mol%. The experimental data obtained were correlated to the Tait density equation and three EoS, namely Peng–Robinson (PR), Sanchez–Lacombe (SL), and Perturbed Chain statistical associating fluid theory (PC-SAFT) EoS. Among them, SL and PC-SAFT EoS agree better with the experimental data compared to the PR EoS, presumably due to differences in the pure component parameters used in each EoS. Using parameter sets determined from the density measurements, the vapor liquid equilibrium (VLE) of the CO2/Tol mixtures was estimated. While we were unsuccessful in estimating VLE using the PR EoS, SL and PC-SAFT EoS were successfully used for the estimations. We also attempted to determine the densities from VLE correlations. It was found that SL and PC-SAFT EoS could be used to estimate the density well, whereas the PR was not predictive. From the results of the study, it is clear that for estimating density using EoS, the basic data used for determining the pure component parameters are important.

The phase behaviors of carbon dioxide (CO2)/tetramethyl orthosilicate (TMOS)/poly(methyl methacrylate) (PMMA) and CO2/TMOS/poly(styrene) (PS) ternary systems were measured. The measurements were performed using a synthetic method involving observations of the bubble point and cloud point. The phase boundaries were measured at temperatures ranging from 313.2 K to 393.2 K and CO2 weight fractions ranging from 0.01 to 0.40. At a constant TMOS:polymer weight ratio of 9:1, both systems showed similar CO2 mass fraction dependence of their phase behaviors. When the vapor-liquid (VL) and vapor-liquid-liquid (VLL) phase boundaries of the ternary systems were compared with those of the binary CO2/TMOS system using polymer-free bases, they were found to be nearly identical. On the other hand, the two systems showed completely opposite polymer mass fraction dependence of their phase behaviors at a constant CO2 ratio.

Ultrasound is used in various chemical reaction processes, and these reactions are influenced by ultrasonic frequency. A threshold power is required for the ultrasonic degradation reaction and oxidation reaction caused by hydroxyl radicals, and the cavitation threshold power is also influenced by frequency generally. In this study, the effects of frequency on the threshold power of methylene blue degradation and KI oxidation were investigated in the range between 22.8 kHz and 1640 kHz. The threshold power of KI oxidation reaction increased with increasing frequency. This phenomenon well agrees with previous study, and it is revealed that the generation of I- 3 ion is caused by oxidation reaction of Iˉ ions with hydroxyl radicals. On the other hand, the threshold power of methylene blue degradation reaction was not affected by frequency. The ultrasonic degradation of methylene blue is considered to be caused by hydroxyl radicals, and there is a linear relationship between degradation rate constant and sonochemical efficiency value. However, it is guessed that the degradation of methylene blue is occurred inside cavitation bubble by pyrolysis at high frequency regions.

The phase behaviors of carbon dioxide (CO2)/trimethoxy(methyl)silane (MTMS) and CO2/Methylsilicate 51 (MS-51: methylsilicate tetramer) binary systems were determined. The experiments were performed using a synthetic method by observing the bubble point. The phase boundaries were determined at temperatures of 313.2 K–393.2 K and CO2 molar fractions of 0.2–0.9. The experimentally obtained bubble points of the CO2/MTMS binary system were correlated using the Peng-Robinson equation of state (PR EoS), and the molecular interaction parameters kij and lij were determined. The results of the CO2/MS-51 binary system were correlated using the PR EoS and the Sanchez-Lacombe equation of state (SL EoS). In the SL EoS, two types of mixing rules, originally proposed by Sanchez et al. which uses kij as a fitting parameter and modified by McHugh et al. which uses two fitting parameters kij and lij, were used. For this system, the experimental results were correlated better using the SL EoS than using the PR EoS, and the latter mixing rule was more suitable than the former.

The pressure-volume-temperature (PVT) relationships of pure diisononyl phthalate (DINP) were measured at temperatures of 303.15–363.15 K and pressures up to 160 MPa by a variable-volume method. Using a synthetic method that involved observing the bubble point, the phase behavior of the CO2/DINP binary system was also measured. The phase boundaries were determined at temperatures of 313.15–393.15 K and CO2 molar fractions of 0.3–0.9. The characteristic parameters of DINP were obtained by correlating the measured PVT data using the Sanchez-Lacombe equation of state (SL EoS), and the bubble points of the system were correlated using the SL EoS with the determined characteristic parameters. The interaction parameter exhibited temperature dependence, and the introduction of the temperature dependence improved the correlation.

In this study, we introduced an artificial neural network (ANN), which can represent objects that are difficult to formulate, rather than the integrated model of the group contribution method (GCM), because the integrated model in the existing GCM is no longer able to manage enormous diversification of substances. Hence, a model to estimate the pure component parameters m, σ, and e of the perturbed chain statistical associating fluid theory (PC-SAFT) equation of state (EoS) was developed. We optimized the structure of the ANN by changing the number of neurons and layers in the hidden layer. In this study, the optimized ANN structure was two hidden layers and 40 neurons. The results confirm that the model can determine the pure component parameters of PC-SAFT EoS, which can estimate the liquid density, saturated vapor pressure, and critical properties. In terms of the critical properties, the estimated results were almost as good or better than those obtained using the GCMs, which are specified for the critical properties. We were able to calculate properties for substances whose parameters were not reported in the literature by using this ANN. The results would be useful for chemical process design, for example, to be incorporated into process simulators.

Alkyl groups of tetraalkoxysilane have different chain lengths, which results in different reactivity of the sol–gel reaction. Hence, it is essential to understand the phase behavior for designing chemical processes using the sol–gel reaction. The phase behavior of CO2/tetrapropyl orthosilicate (TPOS) and CO2/tetrabutyl orthosilicate (TBOS) binary systems was measured. The experiments were performed using a synthetic method combined with a laser displacement measurement wherein the movement of the piston inside the high-pressure vessel was measured. The phase boundaries were determined at 313–373 K and CO2 molar fractions of 0.1–0.9. No significant difference was observed in the phase behavior of tetraalkoxysilanes, which have alkyl groups of different chain lengths. The experimentally obtained vapor–liquid equilibria of the two binary systems were correlated by the Sanchez–Lacombe equation of state using the original mixing rule reported by Sanchez et al. The results showed that molecular interaction parameter kij exhibits a clear temperature dependence.

The thermal decomposition of copper (II) acetylacetonate (Cu(II)(acac)2) in supercritical carbon dioxide (scCO2) was investigated via in situ UV–vis spectroscopy. Release of acetylacetone ligands from the central metal atom was observed as the initial step in the decomposition. The kinetics of the decomposition at 423–453 K and 15–25 MPa in scCO2 were studied. The decomposition reaction generally followed the first-order kinetics. The reaction rate was slightly increased with an increase in the pressure, due to changes in the scCO2 density. The activation energy of the decomposition was calculated as 60.3 kJmol−1 at 15 MPa, 56.3 kJmol−1 at 20 MPa and 52.4 kJmol−1 at 25 MPa, which are lower values than those observed in air and in vacuum. The pressure dependence of the activation energy of the decomposition reaction was clarified quantitatively for the first time, and revealed the energy conservation benefit of using scCO2 as a process solvent for a variety of metal/metal oxide deposition process of nanomaterials.

Supercritical drying is widely considered as the gold standard to produce aerogels that preserve the microstructure of the gels, but we have found this is not always the case. Chitosan aerogel, one of the emerging biopolymer aerogels, was prepared by chemical cross-linking gelation, followed by solvent exchange with methanol and supercritical drying using CO

For the design of spray propellants, bubble point pressures were measured for binary mixtures of ethanol with propane, dimethyl ether (DME) or trans-1,3,3,3-tetrafluoropropene (R1234ze(E)), with a static type apparatus at (293.15–313.15) K. Experimental data were correlated with the Peng-Robinson (PR) and Stryjek-Vera (PRSV) equations of state using the Wong-Sandler (WS) mixing rules. The NRTL activity coefficient model in the WS mixing rules was effective for correlation of systems that exhibited large non-idealities (ethanol - propane, ethanol - R1234ze(E)). Correlation of the bubble point pressures with the PRSV equation of state and WS mixing rules was to within an average of 2.391% absolute deviation in pressure for all systems, which is considered to be sufficient for design of spray devices with propellants that have low global warming potential.

The phase behavior of a carbon dioxide (CO2)/toluene (Tol)/polystyrene (PS) ternary system was measured. The measurements were performed using a synthetic method combined with a reflected light intensity measurement. The bubble points were determined by visual observation, and the cloud points were determined from the change in the reflected light intensity. The phase boundaries were measured at temperatures ranging from 313.2 K to 373.2 K and CO2 weight fractions ranging from 0.10 to 0.41. The homogeneous phase area decreased when the molecular weight of PS and/or the ratio of PS to Tol increased. It was found that the phase behavior of ternary systems, especially the liquid-liquid phase separation behavior, was altered by a change in the mutual solubility between the three components.

The density of homogeneous phase fluid mixtures for various carbon dioxide (CO2)/organic solvent systems was measured in homogeneous phase. Solvents included cyclohexane (C6H12), methylcyclohexane (C6H11CH3), and ethylbenzene (C6H5C2H5). Density measurements were performed using a high-pressure vibration type density meter equipped with a circulation pump and variable volume viewing cell which guarantee the homogeneity of mixtures. The density was measured at temperatures ranging from 313 K to 353 K and pressures up to 20 MPa, and the CO2 composition varied from (0 to 80) mol%. The obtained experimental data were correlated according to a density equation. The resulting correlation agrees well with the experimental data.

It is well known that high-pressure carbon dioxide (CO2) lowers the glass transition temperature (Tg) of polymers. We therefore investigated whether Tg depression of high-pressure CO2 results in interparticle bridging of a polymer and the tablet characteristics that makes the manufacture of an orally disintegrating tablet (ODT) possible. Copolyvidone (Kollidon®) and polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft copolymer (Soluplus®) were examined and found to exhibit a large Tg depression. Placebo ODTs were prepared and hardness, disintegration rate, porosity, and change in thickness and appearance were evaluated before and after the high-pressure CO2 treatment. This enabled the establishment of the optimal conditions for pressure, temperature, and treatment time under pressure. Experimental results showed that it was possible to manufacture ODTs comprising Kollidon® as a water-soluble polymer with CO2 treatment under the suitable conditions such as temperature at 45°C, pressure lower than 8 MPa, and a treatment time shorter than 30 min, which is a new ODT manufacturing process called "Carbon Dioxide Assisted Tablet Formation Scheme" (CATS). In comparison to the conventional processes, which require high temperatures or humidity, CATS is expected to be applicable to drugs that are unstable at high temperature and humidity, and to functional drug particles used for bitter taste masking, sustained release, and other uses.

The ultrasonic degradation of methylene blue at a frequency of 490 kHz was carried out in the absence and presence of TiO2 or Al2O3 particle, and the effects of amounts of particle on the enhancement of degradation rate constant estimated by assuming first-order-kinetics were investigated. The degradation reaction was enhanced by particle addition, and the apparent degradation rate constant is proportional to the increase in amount of particle. In addition, the constant of proportionality is not influenced by degraded material and ultrasonic frequency. However, particle type influences the constant of proportionality, and the value of TiO2 particle is about 6 times as large as that of Al2O3 particle.

Biobased nanofiber aerogels are ones of the attractive emerging materials in the fields of biochemistry and materials chemistry, but their poor humidity stability due to high hydrophilicity has limited their practical uses. In this paper, a new series of hydrophobic nanofibrous aerogels made from regenerated chitosan and alkyl aldehydes were prepared via a simple one-pot reaction followed by supercritical drying. Hexanal-modified chitosan aerogel shows excellent hydrophobicity with a water contact angle of ∼136°, a low density of 0.04–0.07 g cm–3, and structurally homogeneous three-dimensional nanofiber network at the nanoscale. Systematic investigations using various alkyl aldehydes revealed that pentanal-modified aerogel has similar high hydrophobicity and low density compared to the hexanal-modified material, while heptanal- and octanal-modified aerogels show drastic shrinkage during gelation. The aldehyde modification also suppresses permeation of water droplets into aerogel monoliths as well as reduc...

Ultrasound has been used as an advanced oxidation method for wastewater treatment. Sonochemical degradation of organic compounds in aqueous solution occurs by pyrolysis and/or reaction with hydroxyl radicals. Moreover, kinetics of sonochemical degradation has been proposed. However, the effect of ultrasonic frequency on degradation rate has not been investigated. In our previous study, a simple model for estimating the apparent degradation rate of methylene blue was proposed. In this study, sonochemical degradation of methylene blue was performed at various frequencies. Apparent degradation rate constant was evaluated assuming that sonochemical degradation of methylene blue was a first-order reaction. Specifically, we focused on effects of ultrasonic frequency and power on rate constant, and the applicability of our proposed model was demonstrated. Using this approach, maximum sonochemical degradation rate was observed at 490 kHz, which agrees with a previous investigation into the effect of frequency on the sonochemical efficiency value evaluated by KI oxidation dosimetry. Degradation rate increased with ultrasonic power at every frequency. It was also observed that threshold power must be reached for the degradation reaction to progress. The initial methylene blue concentration and the apparent degradation rate constant have a relation of an inverse proportion. Our proposed model for estimating the apparent degradation rate constant using ultrasonic power and sonochemical efficiency value can apply to this study which extended the frequency and initial concentration range.

In this study, we propose a novel chemical reaction process using Pluronic micelles as reactant carriers in order to reduce complicated piping. A Pluronic micelle containing the hydrophobic dye NKX-1595 was prepared by a dialysis method, and the release of the internal dye from the micelle by external stimulation was investigated. In particular, we investigated the effects of the combination of ultrasonic frequency and type of Pluronic on degree of dye release ( DDR ). A low ultrasonic frequency is effective for the release of the internal dye from the micelle and ultrasonic physical effects are an important factor. Furthermore, under a weak ultrasonic physical effect at 490 kHz, the inhibition effect when the internal substance moves to the corona from the micelle core is also important for estimating the retention of the internal substance by the micelle. In addition, we investigated the effects of thermal stimulation on DDR at several environmental temperatures. The internal dye was gradually released from the micelle when the environmental temperature was greater than 303 K. Thus, appropriate design of external stimulation enables controlling not only the amount of effluence but also the release rate of the internal dye from the micelle.

The direct methanol fuel cell (DMFC) is the battery of the system, which directly supplies methanol to the cell containing a polyelectrolyte membrane. As for DMFC, a miniaturization and weight saving in the whole system are possible, because device does not have to constitute reformer. Therefore, DMFC is expected as a power source of a mobile device. Polyelectrolyte membranes for DMFC need a characteristic of the proton conductivity and the reduction of methanol crossover (MCO). In this research, hybrid membrane comprising a polystyrene sulfonate (PSS) and a glycol chitosan (G-Ch) was investigated. PSS/G-Ch hybrid membranes were prepared by cast method and were cross-linked with glutaraldehyde (GA) to reduce the water content. From the Attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) measurement, the amino group of the G-Ch origin and the sulfonate group of the PSS origin in hybrid membranes generated ionic bond. On the other hand, the proton conductivity of the hybr...

Techniques for the degradation of hazardous organic compounds have been investigated such as solvent extraction, incineration, chemical dehalogenation and biodegradation, etc. Ultrasound has been found to be an attractive advanced technology for the degradation of hazardous organic compounds in water. In addition, the sonochemical reaction is enhanced by particle addition. However, the enhancement mechanism of particle addition has not been investigated well, because ultrasound enhances not only chemical reaction but also mass transfer. In this study, the degradation process of methylene blue as the model hazardous organic compound by ultrasonic irradiation was investigated. The effects of ultrasonic irradiation condition on degradation rate were investigated. The effect of ultrasonic frequency on improvement of degradation reaction by particle addition was also investigated. In addition, the effects of ultrasonic frequency on ultrasonic power and chemical efficiency were investigated by calorimetry and SE value. The degradation rate constants were estimated from the results of temporal change of the concentration of methylene blue assuming first order kinetics for the decomposition. There was a linear relation in the degradation rate and the ultrasonic power. In addition, the degradation rates at 127 kHz and 490 kHz were much larger than that at 22.8 kHz. The effect of ultrasonic frequency on sonochemical efficiency has been investigated, and the sonochemical effects in the range of frequency of 200 - 500 kHz are 10 times larger than those in the lower or higher frequency regions. Therefore, the degradation rate of methylene blue was considered to estimate using sonochemical efficiency. The degradation process of methylene blue was intensified by particle addition, and the degradation rate increased with increasing amount of particle. On the other hand, the enhancement of degradation rate by particle addition was influenced by both ultrasonic frequency and species of particle. The relationship between particle size and resonance diameter of ultrasound is considered to influence the enhancement of ultrasonic degradation process.

Phase diagrams of carbon dioxide (CO2)/tetramethoxysilane (TMOS) and CO2/tetraethoxysilane (TEOS) binary systems were measured. Liquid phase measurements were performed by observing the bubble point pressure with a synthetic method. Vapor phase measurements were conducted with a flow type apparatus. For the CO2/TMOS system, liquid phase lines were measured at temperatures from 313.2 to 393.2 K, and CO2 molar fractions from 0.15 to 0.85, and vapor phase lines were obtained at temperatures 313.2, 353.2 and 393.2 K and pressures up to 12 MPa. For the CO2/TEOS system, measurements were conducted only for liquid phase lines at temperatures from 313.2 to 373.2 K and CO2 molar fractions from 0.25 to 0.75. Phase behavior of these two systems was almost the same with each other. Experimental data were correlated with the Peng–Robinson equation of state (PR EoS), and the molecular interaction parameter kij and lij for both systems were determined. For large difference in the molecular size of CO2 and tetraalkoxysilanes, it was found that the lij could be negligible.

In this study, we developed a well-of-the-well (WOW) system-based embryo culture plate with an oxygen sensing photoluminescent probe (OSPP). This system can incubate single embryos in an array of microwells and continuously and non-invasively monitor their morphology by microscopy and respiration metabolic activity based on the quenching of photoexcited platinum octaethylporphyrin by oxygen. Although the development rate to the blastocyst stage obtained in the WOW embryo culture plate with the OSPP was about 11% lower than that obtained with the conventional drop culture method because of the absence of paracrine effects due to the size of the microwells, the average cell number in the embryo at the blastocyst stage was not significantly different between the two culture systems. However, the present embryo culture plate enabled the selection and harvest of high quality blastocysts by monitoring both their morphology and their oxygen consumption rate, making it suitable for the high throughput evaluation of embryos.

Electrostatic emulsification of an acidic chitosan solution into an organic solvent was examined for chitosan sphere production of controlled size ranging from nano to submicron scale. Droplets formation by the electrostatic emulsification was observed with a charge-coupled device camera. The diameters of generated water in oil emulsion droplets were measured by dynamic light scattering. At voltages greater than critical voltage, over which the electrostatic emulsification occurs, the droplet diameter “D” depended on the applied voltage “U”, the electrode distance “L”, and the flow rate of aqueous phase “F”. An empirical formula for the relationship between the “D” and “U”, “L” and “F” was obtained as D∝U−0.65 L0.43 F0.14. Further, the chitosan spheres were obtained by cross-linking the emulsion droplets with glutaraldehyde, and were observed by using a scanning electron microscope. The chitosan nano-spheres of the size equal to the emulsion droplet were successfully obtained by the cross-linking of the chitosan and controlling a specific gravity difference of dispersed phase and continuous phase. These results show that the electrostatic emulsification is an excellent technique for the preparation of functional particles of controlled size ranging from nano to submicron scale. © 2011 Curtin University of Technology and John Wiley & Sons, Ltd.

A new process for the demulsification of oil-in-water (O/W) emulsion with high-pressure carbon dioxide (CO2) was proposed. For the confirmation of the concept, demulsification of O/W emulsion formed with a nonionic surfactant, Tween 20, was conducted. The behavior of O/W emulsion under high-pressure CO2 was examined with a visual observation and an electrical conductivity measurement of the emulsions. Efficiency of the demulsification was evaluated by the oil content of water-rich phases and the amount of water-rich phases separated from the emulsion by the creaming of the oil phases. Experimental results revealed that the high-pressure CO2 acts as a swelling reagent that lowers the density of the dispersed oil phase to induce the floatation of the oil droplet that leads to an efficient demulsification.

The aim of this work is to investigate the gelation behavior of chitosans which has various degree of acetylation (DA) of amino group to ensure the preparation of the designed membrane structure. The DA was controlled by the amount of acetic anhydride added to the solution of chitosan/acidified water/methanol mixture. The gelation behavior was evaluated by the gelation time and the quantity of syneresis. The mechanical strength of acetylated chitosan gels was also measured. The optimum condition for the formation of the membrane, i.e. chitosan concentration, acetic acid/ chitosan mass ratio, methanol/water mass ratio, and amount of acetic anhydride for acetylation, was determined. This composition gives low contractility, shorter gelation time, and high mechanical strength to the membrane and the gel. Useful information not only for a preparation of a membrane but also for an immobilized carrier or a chemical reaction system was obtained in this work.

Acid-base equilibria between 2,5-dichlorophenol (DCP) and various bases (LiOH, NaOH, and KOH) were studied in ambient to supercritical methanol, by measuring the absorption spectrum of DCP at alkali metal hydroxide molalities ranging up to 10 mmol⋅kg−1, at temperatures up to 250 °C and a pressure of 25.0 MPa. The spectrum was deconvoluted into contributions for the acidic (HA) and basic (A−) forms of DCP, taking into account a blue shift of the phenolate (A−) spectrum due to the effect of ion pairing with an alkali metal cation. Degrees of dissociation of DCP determined from the spectra suggested that the dissociation constant of DCP has a maximum around 150 °C, whereas that of KOH decreases with temperature. The phenolate-alkali metal ion pairing was examined from the peak shift of the phenolate spectrum in the presence of Li+, Na+, and K+. A smaller cation radius and higher temperature (thus a lower dielectric constant for methanol) give rise to stronger electrostatic interaction in the ion pair. The basicities of the alkali metal hydroxides in supercritical methanol were compared using DCP as an indicator, and were shown to follow the order LiOH < NaOH ≤ KOH. This order is the same as that for the catalytic effect of alkali metal hydroxides on the methylation of phenol in supercritical methanol (Takebayashi et al.: Ind. Eng. Chem. Res. 47:704–709, 2008).

超臨界二酸化炭素(scCO2)を溶媒として用いた化学酸化重合法によりピロール(Py)を重合し，導電性高分子であるポリピロール(PPy)を得た．反応開始剤として，scCO2 に可溶なビストリフルオロアセトキシヨードベンゼン(BTI)を用いることで，助溶媒等の有機溶媒を必要としない溶媒フリーな導電性高分子の重合プロセスとした．得られた PPy の形状を走査型電子顕微鏡(SEM)および動的光散乱(DLS)により評価した．得られた形状と実験条件の関係から粒子径分布幅の狭いナノ粒子となる条件を決定し，PPy ナノ粒子の合成を検討した．この結果，Py 0.1 M，BTI 0.005 M，圧力 20 MPa，温度 40℃，反応時間 1 h を最適条件とした．この反応条件において，50～90 nm 程度の粒子径分布幅の狭いナノ粒子が得られることが明らかとなった．さらに，ピロール誘導体の一つである 3-ヘプチルピロール(HPy)についてもナノ粒子の合成に成功した．

Under boiling and refluxing conditions for catalytic dehydrogenation of organic chemical hydrides (decalin, methylcyclohexane and others) in a batch-wise reactor, either suspended states with excess amounts of substrate or sand-bath states with its scarce amounts were found to be inferior generally to the so-called “liquid-film states” with adequate amount ratios of substrate to catalyst, where the catalyst-layer temperatures were superheated or raised higher than the boiling point, and, consequently, reactivities became more favorable at higher heating temperatures in contrast to the boiling suspended states. Equilibrium shifts due to reactive distillation were well demonstrated under boiling and refluxing conditions in naphthene dehydrogenation. Moreover, desorption of hydrogen from the active sites to the bubble space was enhanced in the superheated liquid-film states, with large translational entropy endowed. Provided the extents of equilibrium deviation were large enough (Prigogine's approach), thermodynamic couplings among irreversible processes would be realized between heat transfer and mass transfer as an example of the extended De Donder's equation. Restriction of chemical equilibrium could be removed under temperature gradient conditions, as the consequence that its Gibbs energy change became more negative than that under iso-temperature conditions. Within the framework of irreversible thermodynamics, the decreased retardation constant K in the superheated liquid-film states was interpreted in terms of a vector-level coupling between temperature gradient and desorption. Moreover, vigorous bubble formation would give additional favor to the reaction rates owing to enlarged repeating frequencies of sequential non-microreversible processes in dehydrogenation catalysis. Organic chemical hydrides are attractive from the viewpoints of safe, economical, exergy-saving and large hydrogen contents for hydrogen storage and distribution. Their main defects have been pointed out hitherto that the endothermic reaction temperatures are too high. In this paper, a new concept on superheated liquid-film catalysis is explored for dehydrogenation temperatures to decrease, which would result in not only saving exergy for external heating but also avoiding catalyst deactivation due to carbon deposit.

Phase behavior was investigated for water/supercritical CO 2 (W/scCO2) microemulsions stabilized with sodium bis(1H,1H,2H,2H-heptadecafluorodecyl)-2-sulfosuccinate (8FS(EO) 2) mixed with various guest surfactants. Only for the mixtures with fluorocarbon-hydrocarbon hybrid anionic surfactants (FC6-HC n), the maximum water-to-surfactant molar ratio (W0(c)) was larger than that estimated from linear interpolation of the W0(c) values for pure 8FS(EO) 2 and pure guest surfactant. Fourier transform infrared (FT-IR) measurement for the microemulsion revealed that the mixing of 8FS(EO) 2 with FC6-HC n can prevent a phase transition from the microemulsion to the liquid crystal even in the presence of excess water. It was also found from the measurement of water/scCO 2 interfacial tension that the area occupied per surfactant molecule was markedly increased by the mixing with FC6-HC n. The loose molecular packing, probably due to a microsegregation of 8FS(EO) 2 and FC6-HC n, is consistent with the enhanced stability of the microemulsion upon surfactant mixing.

Fourier transform infrared (FT-IR) spectrum of water-in-supercritical CO(2) microemulsion was measured at 60 degrees C and 30.0 MPa over a wide range of water/CO(2) ratio from 0.0 to 1.2 wt % to study the distribution of water into CO(2), interfacial area around surfactant headgroup, and core water pool. The microemulsion was stabilized by sodium bis(1H,1H,2H, 2H-heptadecafluorodecyl)-2-sulfosuccinate [8FS(EO)(2)] equimolarly mixed with sodium 1-oxo-1-[4-(tridecafluorohexyl)phenyl]-2-hexanesulfonate [FC6HC4] or with poly(ethylene glycol) 2,6,8-trimethyl-4-nonyl ether [TMN-6]. The signal area of the O-H stretching band of water suggested that the number of water molecules in the microemulsion increases linearly with the water/CO(2) ratio, except for a slow initial increase below 0.4 wt % due to a part of water dissolved in CO(2). The amount of water in CO(2) was evaluated by decomposing the bending band of water into two components, one at lower frequency ascribed to water in CO(2) and the other at higher frequency to water in the microemulsion. The decomposition confirmed that CO(2) is saturated with water at the water content of 0.4 wt %. It was also revealed, from the symmetric SO stretching frequency of the surfactant, that the sulfonate headgroup is completely hydrated at the water/CO(2) ratio of 0.4-0.5 wt %. The results demonstrated that water is introduced preferentially into CO(2) and the interfacial area at small water content, and then is loaded into the micelle core after the saturation of CO(2) with water and the full hydration of the surfactant headgroup.

A method has been developed for measuring the solubility of noble metal acetylacetonates by the direct injection of the supercritical carbon dioxide (scCO2) solution into a high pressure liquid chromatograph. We found the use of (1) reverse phase high pressure liquid chromatography (RP-HPLC) to separate the sample peak from the noise peak on chromatogram and (2) a scCO2-philic eluent to eliminate the noise peak, to be effective. Using this improved method, we measured the solubilities of noble metal complexes of Pt, Pd, Ru, Rh and Ag acetylacetonates in scCO2 from 10 to 30 MPa at 313 K. Measurements were conducted with smaller amounts of samples (less than 0.1 g) and with shorter experimental times than by the standard dynamic flow method. The molar fraction y2 was of the order 10−5 to 10−4 for Ru and Rh acetylacetonate, 10−5 for Pd and Pt acetylacetonate, and 10−7 for Ag acetylacetonate. The solubility data for Pd, Pt, Ru, and Rh acetylacetonates were successfully correlated using the Chrastil model.

The product selectivity, reaction pathway, and the effects of acid and base on the kinetics were studied for the methylation of phenol in supercritical methanol without catalyst at 380 °C and 0.237 g cm-3. The reaction gave o-cresol as the major product and p-cresol and anisole in much smaller amounts, where the ortho/para ratio was above 12. The high ortho-selectivity suggests that the methylation proceeds locally around the phenolic OH group. Since no rearrangement was observed from anisole to o-cresol, the high ortho-selectivity was never ascribed to the rearrangement mechanism via anisole. Comparative experiments were carried out for other substituted benzenes to show that the phenolic OH group itself plays an essential role in the supercritical methylation. It was also found, in contrast to ordinary acid-catalyzed alkylations, that the supercritical methylation was retarded by acid and accelerated by base. The results were interpreted by a new reaction mechanism that the phenolic OH group acts as an ...

汎用エンジニアリングプラスチックであるポリ(2,6-ジメチル-1,4-フェニレンオキサイド) (PPO) は，有機溶媒中で 2,6-ジメチルフェノール (2,6-DMP)を酸化重合することで生産されている．超臨界二酸化炭素(scCO2)を溶媒とすることで，無毒・不燃性・臨界条件が穏和といった優れた特性により，プロセスの安全性の向上が期待できる．筆者らは scCO2 を溶媒とし，分子量分布の狭い高分子量 PPO を合成する重合プロセスの開発を試みてきた．scCO2 を溶媒とした重合では，反応系が不均一相となることが，分子量分布が広くなる原因の一つと考えられる．また，平均分子量が小さくなる原因としては，重合の進行とともに生成する水による触媒失活の影響が考えられる．本報ではこれらの点を考慮して，二段階の重合(二段重合)を試みた．二段重合の一段階目では，反応系を均一相にすることで，分子量分布の狭いプレポリマーを合成する．二段階目では一段階目のポリマーを精製し，水を反応系から除去後，再び重合することで高分子量化する．このような考えに基づいた二段重合の実施により，PPO の分子量分布の制御と高分子量化が示された．また，温度・圧力・触媒濃度の最適化によって，高分子量の PPO を得ることが可能となった．

Liposomes were prepared by the supercritical reverse phase evaporation method developed in our laboratory using various phospholipids with different hydrocarbon chains. The effects of the length of alkyl chain and number of unsaturated bonds of phospholipids on the properties of liposomal membranes were examined through trapping efficiency measurements, transmission electron microscopic observations, and osmotic response measurements. The trapping efficiency for water-soluble drugs of liposomes prepared by our method was greatly higher than that of liposomes prepared by the conventional Bangham method. Liposomes prepared using unsaturated phospholipids showed a high trapping efficiency compared with those prepared using saturated phospholipids. In addition, the trapping efficiency of liposomes prepared using 1-palmitoyl-2-oleoyl phosphatidylcholine (POPC), a complex phospholipid with both saturated and unsaturated alkyl groups, had a value intermediate between L-alpha-dipalmitoyl-phosphtidylcholine (DPPC), a saturated phospholipid, and L-alpha-dioleoylphosphatidylcholine (DOPC), an unsaturated phospholipid. That is, the trapping efficiency of liposomes was dependent on the number of unsaturated bonds rather than the alkyl chain length of phospholipid molecule and it increased with increasing bulkiness of the molecule. The osmotic response was higher for liposomes prepared using unsaturated phospholipids than for those formed by saturated phospholipids.

The reduction of sulfur content in gasoline and diesel fuel is a great environmental concern to reduce the motor vehicle emissions. Oxidative desulfurization using acetonitrile biphasic system has received much attention in recent years. The oxidative desulfurization can be oxidized the unreactive sulfur contents in the hydrodesulfurization and removed effectively. For the oxidative desulfurization process design and development, liquid–liquid equilibria (LLE) for acetonitrile biphasic systems are needed as fundamental information. In our previous work, LLE for acetonitrile + n-octane and + n-decane systems have been reported. In this work, therefore, LLE for acetonitrile + n-hexadecane system was measured. Furthermore, NRTL equation was applied to correlate the LLE for these three acetonitrile + n-alkane systems.

In the present study, the gas permeation properties of carbon molecular sieve (CMS) membranes dispersed with palladium nano particles via supercritical CO2 impregnation method were investigated. The palladium nano particles located near the permeation path consisting of slit-like micropore mouth were shown to function mainly as a selective permeation barrier, resulting in the excellent permselectivity for H2/N2 gas pairs.

High-pressure carbon dioxide in contact with water dissolves to form carbonic acid, causing a decrease in pH. By use of these characteristics of a CO2/H2O biphasic system, chitosan-coated cationic liposomes of l-alpha-dipalmitoylphosphatidylcholine were successfully prepared by an improved supercritical reverse-phase evaporation (ISCRPE) method. Liposome-chitosan complexes carrying a positive charge were prepared in a single-step procedure without the use of acid or organic solvent, including ethanol. The maximum trapping efficiency of liposomes prepared by the ISCRPE method was 17%, with or without the addition of chitosan, compared to only 2% for liposomes prepared by the Bangham method. Furthermore, the liposomal dispersion was stable at room temperature in a sealed tube for over 30 days.

Liposomes of various phospholipids were prepared using an improved supercritical reverse phase evaporation (ISCRPE) method that utilizes supercritical carbon dioxide (scCO(2)) as an alternative to organic solvents. Using this method, in the absence of any organic solvent including ethanol, the maximum trapping efficiency of glucose reached 36% for 20 mM l-alpha-dioleoylphosphatidylcholine (DOPC), compared to less than 10% using the Bangham method. Liposomes prepared by the ISCRPE method were highly stable for one month at room temperature. Freeze fractured TEM observations, osmotic shrinkage measurements, and DSC measurements revealed that the liposomes prepared by the ISCRPE method are unilamellar vesicles with loosely packed phospholipids. Comparison of nitrogen with scCO(2) revealed that the presence of CO(2) is necessary for the formation of liposomes.