Sonoluminescence intensity and ultrasonic cavitation temperature in organic solvents: Effects of generated radicals.

Ultrasonic cavitation in organic solvents remains poorly understood in contrast with aqueous systems, largely because of complexities related to solvent decomposition. In this study, we sonicated different types of organic solvents (i.e.

Periodic Expansion and Contraction Phenomena in a Pendant Droplet Associated with Marangoni Effect.

A spontaneous oscillation between the expansion and contraction of a nitrobenzene pendant droplet containing di-(2-ethylhexyl)phosphoric acid (DEHPA) was observed in an aqueous phase under alkaline conditions. We described this phenomenon as the spontaneous oscillation of the oil-water interfacial tension. The oscillation characteristics such as the induction period and the interfacial-tension oscillation frequency were investigated under different temperatures and aqueous phase polarities.

Sonochemical degradation of surfactants with different charge types: Effect of the critical micelle concentration in the interfacial region of the cavity.

Ionic surfactants tend to accumulate in the interfacial region of ultrasonic cavitation bubbles (cavities) because of their surface active properties and because they are difficult to evaporate in cavitation bubbles owing to their extremely low volatilities. Hence, sonolysis of ionic surfactants is expected to occur in the interfacial region of the cavity. In this study, we performed sonochemical degradation of surfactants with different charge types: anionic, cationic, zwitterionic, and nonionic.

Mechanism for sonochemical reduction of Au(III) in aqueous butanol solution under Ar based on the analysis of gaseous and water-soluble products.

When an aqueous Au(III) solution containing 1-butanol was sonicated under Ar, Au(III) was reduced to Au(0) to form Au particles. This is because various reducing species are formed during sonication, but the reactivity of these species has not yet been evaluated in detail. Therefore, in this study, we analyzed the effects of Au(III) on the rates of the formation of gaseous and water-soluble compounds (CH, CH, CH, CH, CO, CO, H, HO, and aldehydes), and the rate of Au(III) reduction as a function of 1-butanol concentration.

Quantitative Analytical Method for Single Rain Droplets via Crystal Formation in Photocrosslinking Polymer Gel.

Ion composition contained in individual rain droplets provides important information to investigate the chemistry in rain and clouds, but general rain sampling equipment temporally and spatially averages the information. Determination of the SO concentration in an individual rain droplet was achieved by precipitate production in synthesized acrylamide polymer gel. Concentration of the target ion was calculated from the droplet print diameter and precipitation area measured from digital microscope images.

Sonochemistry of aqueous NaAuCl solutions with C3-C6 alcohols under a noble gas atmosphere.

The effect of the type of C3-C6 alcohol, solution temperature, and dissolved gas on the rate of Au(III) reduction was investigated in NaAuCl aqueous alcohol solution with a 200-kHz ultrasound irradiation system. It was confirmed in the presence of C3-C6 alcohol that more highly hydrophobic alcohols more effectively accumulated at the argon bubble interface region, and the reducing radicals formed here. To avoid changes in the bubble temperature during collapsing bubble, the effects of the solution temperature on the rate of Au(III) reduction and on the rate of formation of the gaseous compounds (CO, CO, CH, CH, CH, CH) were investigated in the presence of low concentration (1.

Effects of Na2SO4 or NaCl on sonochemical degradation of phenolic compounds in an aqueous solution under Ar: Positive and negative effects induced by the presence of salts.

Sonochemical degradation of 4-chlorophenol, phenol, catechol and resorcinol was studied under Ar at 200 kHz in the absence and presence of Na2SO4 or NaCl. The rates of sonochemical degradation in the absence of salts decreased in the order 4-chlorophenol>phenol>catechol>resorcinol and this order was in good agreement with the order of log P (partition coefficient) value of each phenolic compound. The effects of salts on the rates of sonochemical degradation consisted of no effect or slight negative or positive effects.

Preliminary study of quantitative analysis of ammonium ions in a raindrop following Liesegang ring formation.

NH(4)(+) concentration in an individual droplet was determined by forming a Liesegang ring on a gelatin film containing NaB(C(6)H(5))(4). The NH(4)(+) concentration (mol L(-1) abbreviated to M) was calculated from the NH(4)(+) amount (mol) ascertained in a droplet using pixel count measurements. The droplet volume (L) was calculated by measurement of the diameter of a droplet print on the gelatin film.

Threshold for spontaneous oscillation in a three-phase liquid membrane system involving nonionic surfactant.

This study of self-oscillation was conducted using a new three-phase liquid membrane system of ethanol aqueous solution, benzyl alcohol solution with nonionic surfactant, and pure water. Relations of the initial ethanol concentration to the oscillation amplitude and frequency, and to the induction period before oscillations were investigated. The oscillation amplitude is independent of the initial ethanol concentration, but the frequency and the induction period are related to it.

Sonochemical reduction of permanganate to manganese dioxide: the effects of H2O2 formed in the sonolysis of water on the rates of reduction.

Chemical effects of ultrasound have been actively researched in the field of the synthesis of various metal nanoparticles and nanostructured materials. It is very important to understand the reduction mechanism of metal ions, because the reduction processes can be often applied to the synthesis of various materials. In this study, the sonochemical reduction of MnO4- to MnO2 in water under Ar atmosphere was investigated to discuss the reduction mechanism.

Sonochemical decomposition of organic acids in aqueous solution: understanding of molecular behavior during cavitation by the analysis of a heterogeneous reaction kinetics model.

The sonochemical decomposition of a low concentration of butyric acid was performed in an aqueous solution by use of 200 kHz ultrasound to discuss the reaction kinetics and molecular behavior during cavitation. Taking into account a Langmuir-type adsorption model, we propose a heterogeneous reaction kinetics model, which is based on the local reaction zone at the interface region of the cavitation bubbles, where the adsorption and desorption of butyric acid molecules from the bulk solution occur during bubble oscillation and then the existing molecules inside the local reaction zone are finally decomposed. To confirm our proposed kinetics model, the rates of decomposition were investigated as a function of the initial concentration of butyric acids in the different pH solutions.

Influence of adding salt on ultrasonic atomization in an ethanol-water solution.

Ethanol was enriched by ultrasonic atomization. Enrichment ratios were increased by adding salt to the ethanol solution. Different enrichment ratios were observed for different types of salts in a range of low ethanol concentrations.

Effect of reaction vessel diameter on sonochemical efficiency and cavitation dynamics.

The influence of reaction vessel diameter on the sonochemical yield was investigated by using reaction vessels with five different diameters. It was revealed that the formation of H(2)O(2) and chloride ion, from the sonolysis of pure water and 1,2,4-trichlorobenzene aqueous solution, was affected by the reaction vessel diameter. That is, these yields increased as the reaction vessel diameter increased up to ø 90 mm and then decreased over ø 90 mm.

Effect of carbon tetrachloride on sonochemical decomposition of methyl orange in water.

Two types of sonicators were used for the sonochemical decomposition of methyl orange (MO) in the presence and absence of carbon tetrachloride (CCl4): One is a 45kHz ultrasonic cleaning bath (a low intensity sonicator) and the other is a 200kHz ultrasonic reactor (a high intensity sonicator). It was clearly confirmed that the rates of the sonochemical decomposition of MO increased with increasing the concentration of CCl4 in both sonicators. The enhancement effect of CCl4 was much higher in the high intensity sonicator than in the low intensity one: by the addition of 100ppm of CCl4, the decomposition ratio of MO with the high intensity sonicator became 41 times larger, while that with the low intensity sonicator became 4.

Sonochemical degradation of various monocyclic aromatic compounds: relation between hydrophobicities of organic compounds and the decomposition rates.

Various aromatic compounds, i.e., nitrobenzene, aniline, phenol, benzoic acid, salicylic acid, 2-chlorophenol, 4-chlorophenol, styrene, chlorobenzene, toluene, ethylbenzene and n-propylbenzene were decomposed under identical ultrasonic irradiation conditions.