Atsushi Shono

FT-IR analysis of BSA fouled on ultrafiltration and microfiltration membranes

Abstract Protein fouling is a critical problem for ultrafiltration (UF) and microfiltration (MF). In the latest decade, a Fourier-transform infrared (FT-IR) spectroscopic method has been developed to quantify protein secondary structure by employing the amide I spectral region. The most attractive feature of FT-IR analysis is its ability to analyze proteins in various conditions. In this study, we employed FT-IR to quantify the conformational change of protein fouled on polysulfone (PS) UF membrane and polytetrafluoroethylene (PTFE) MF membrane. Bovine serum albumin (BSA) was adopted as a model protein. BSA adsorption onto the membranes was performed at 4°C and gel-like BSA deposits on the membranes were prepared by filtration at room temperature. FT-IR analysis revealed that the BSA adsorbed onto PS UF membrane had little change in the secondary structure, whereas the BSA adsorbed onto PTFE MF membrane had remarkable changes in the secondary structure, which were a decrease in α-helix content from 66 to 50% and an increase in β-sheet content from 21 to 36%. In addition, gel-like BSA deposits on both of the membranes had marked changes in secondary structure, which were similar to the changes in the BSA adsorbed onto the PTFE MF membrane. And the BSA concentration did not significantly affect the changes in the secondary structure of BSA fouled on both the UF and MF membranes.

Hydrogen recovery from cyclohexane as a chemical hydrogen carrier using a palladium membrane reactor

A palladium membrane reactor was applied to recover the hydrogen from cyclohexane as one of the promising chemical hydrogen carriers. The operation conditions of the palladium membrane reactor to obtain a higher hydrogen recovery were predicted by computer simulation. As a result, it was shown that the hydrogen recovery rate becomes higher as the pressure on the hydrogen permeation side is lowered below atmospheric pressure or as the reaction pressure increases. This was confirmed experimentally. As the perm-side pressure was lowered, the conversion as well as the hydrogen recovery rate at 573 K was found to increase. About 80% of the hydrogen contained in cyclohexane, depending on the operation condition was successfully recovered.

Microscopic observation of emulsion droplet formation from a polycarbonate membrane

Real-time microscopic observations of the membrane emulsification process were performed using a novel membrane module and a microscope video system. The droplet growth and detachment processes from the membrane pores were analyzed from visual images taken during the experimental runs. A hydrophilic polycarbonate membrane with a mean pore size of 10 μm was employed. Microscopic observations of the oil droplet formation process from the membrane verified the continuous phase flow-driven droplet formation. This paper also describes the influences of the continuous phase flow velocity and the surfactant type on membrane emulsification. The use of anionic and nonionic surfactants resulted in successful membrane emulsification with no droplet coalescence at flow velocities greater than 0.1 m s−1. The droplet size of the resulting oil-in-water (O/W) emulsions decreased with an increase in the flow velocity, remaining almost constant at flow velocities greater than 0.4 m s−1. The emulsions prepared under these conditions had the average droplet sizes of about 20 μm and the coefficients of variation of 20–50%. In contrast, a cationic surfactant-containing system resulted in no droplet formation due to complete wetting of the membrane surface with the dispersed phase. An analysis of the surfactant–polycarbonate membrane interaction and contact angle measurements explained well the results that the membrane emulsification behavior critically depended on the type of surfactant used.

Comparison of ultrasonic degradation rates constants of methylene blue at 22.8 kHz, 127 kHz, and 490 kHz

Techniques such as solvent extraction, incineration, chemical dehalogenation, and biodegradation have been investigated for the degradation of hazardous organic compounds. We found ultrasound to be an attractive technology for the degradation of hazardous organic compounds in water. However, the effects of ultrasonic frequency on degradation rate constants were not investigated quantitatively. In this study, the degradation process of a model for hazardous organic compound methylene blue was investigated using ultrasonic irradiation. The study focused on the effects of ultrasonic frequency and ultrasonic power on the degradation rate constant. The apparent degradation rate constants were estimated based on time dependence of methylene blue concentration assuming pseudo-first-order kinetics for the decomposition. A linear relationship between the apparent degradation rate constant and ultrasonic power was identified. In addition, the apparent degradation rate constants at frequencies of 127 and 490 kHz were much larger than those at 22.8 kHz. A relationship between the apparent degradation rate constant and the sonochemical efficiency value (SE value) was also found. Based on these results, a simple model for estimating the apparent degradation rate constant of methylene blue based on the ultrasonic power and the SE value is proposed in this study.

Kinetics analysis for development of a rate constant estimation model for ultrasonic degradation reaction of methylene blue

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.

Effects of ultrasonic frequency and initial concentration on degradation of methylene blue

The ultrasonic degradation of hazardous organic compounds in an aqueous solution is an attractive technology for wastewater treatment. The kinetics of ultrasonic degradation has been investigated. However, there have been only a few quantitative studies of the effect of ultrasonic frequency on degradation rate. In this study, the ultrasonic degradation of methylene blue was performed at various frequencies, especially in the high frequency region, and various initial concentrations. From the results of the time dependence of the methylene blue concentration in this study, ultrasonic degradation was considered to be a pseudo-first-order reaction. The apparent degradation rate constant and sonochemical efficiency have a linear relationship, and the apparent rate constant and initial concentration have an inversely proportional relationship. These phenomena well agree with our proposed formula for estimating the apparent degradation rate constant. In addition, our proposed model is also applicable to the ultrasonic degradation of nonvolatile and hydrophilic compounds.

Catalytic hydrogen supply from a decalin-based chemical hydride under superheated liquid-film conditions

Efficient hydrogen supply from decalin was only accomplished by the superheated liquid-film-type catalysis under reactive distillation conditions at moderate heating temperatures of 210-240°C. Carbon-supported nano-size platinum-based catalysts in the superheated liquid-film states accelerated product desorption from the catalyst surface due to its temperature gradient under boiling conditions, so that both high reaction rates and conversions were obtained simultaneously.

Development of polystyrene sulfonate/glycol chitosan hybrid membrane for direct methanol fuel cell

ABSTRACT 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...

Effluence of Internal Substances from Pluronic Micelle Using Ultrasound

The application of micelles as a drug carrier for chemical reaction processes was investigated from the viewpoint of process intensification. The effects of ultrasonic stimulation and thermal stimulation on the effluence of internal hydrophobic dye from Pluronic micelles were investigated by measuring the absorbance of sample solutions. Internal substances could be released from the micelle rapidly by ultrasonic irradiation, and the ultrasonic physical effect is important for the effluence of internal substances. The possibility of new chemical reaction process using Pluronic micelles as a reactant carrier is revealed.

Effect of Particle Addition on Degradation Rate of Methylene Blue in an Ultrasonic Field

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 reactions but also mass transfer. In this study, the ultrasonic degradation of methylene blue was carried out, and the effects of the ultrasonic irradiation condition on the degradation rate were investigated. The effect of ultrasonic frequency on the improvement of degradation by particle addition was also investigated. The order of degradation rate with frequency was the same as the tendency of sonochemical efficiency value obtained using KI oxidation dosimetry method (SEKI). The degradation process of methylene blue was intensified by particle addition, and the degradation rate increased with increasing amount of particle addition. The enhancement of degradation rate by particle addition was influenced by both ultrasonic frequency and type or diameter of particles.