Product selectivity control based on a liquid-liquid parallel laminar flow has been successfully demonstrated by using a microreactor. Our electrochemical microreactor system enables regioselective cross-coupling reaction of aldehyde with allylic chloride via chemoselective cathodic reduction of substrate by the combined use of suitable flow mode and corresponding cathode material. The formation of liquid-liquid parallel laminar flow in the microreactor was supported by the estimation of benzaldehyde diffusion coefficient and computational fluid dynamics simulation. The diffusion coefficient for benzaldehyde in Bu(4)NClO(4)-HMPA medium was determined to be 1.32 × 10(-7) cm(2) s(-1) by electrochemical measurements, and the flow simulation using this value revealed the formation of clear concentration gradient of benzaldehyde in the microreactor channel over a specific channel length. In addition, the necessity of the liquid-liquid parallel laminar flow was confirmed by flow mode experiments.

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.

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.

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 (SE KI). 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.

We synthesized iron nanoparticles, 15–20 nm in size, having saturation magnetization, Ms, of 170emu∕g. They were embedded in copolymer beads of styrene (St) and glycidyl methacrylate (GMA), which were coated with poly-GMA by seed polymerization. The resultant Fe∕St-GMA/GMA beads had diameters of 100–200 nm and Ms of 60emu∕g. By coating with poly-GMA, the zeta potential of the beads changed from −93.7 to −54.8mV, as measured by an electrophoresis method. This facilitated (as revealed by gel electrophoresis method) nonspecific protein adsorption suppression, a requisite for nanoparticles to be applied to carriers for bioscreening.