This report shows the novel method for the synthesis of gold nanoparticles. We have applied the electrospray nebulization to the reduction of hydrogen tetrachloroaurate (HAuCl4) with ascorbic acid (AA) as a reducing agent. Face-to-face double electrospray nozzles have been used as an anode and a cathode spray nozzle. The solutions of HAuCl4 and AA were nebulized as positively and negatively charged liquid droplets, and they were collided to be merged along their electrostatic attractive force in the electric field between the two electrospray nozzles. The Au3+ was reduced by the AA in the merged liquid droplets, and the resulting gold nanoparticles showed a size distribution around 5 nm.

Ultrasonic atomization, a process of generating fine droplets through irradiation of high-frequency ultrasound to a gas-liquid interface from the liquid underneath, is applied to separating ethanol from its aqueous solution. Towards its practical use, the process of collecting in two cooling stages the ethanol-enriched mist-generated via an ultrasonic atomizer (ultrasonic transducer operated at 2.4 MHz) with continuous feed of ethanol-water solution-using two cooling units in a series has been developed. The effects of operating conditions, especially cooling temperatures and gas flowrate, on ethanolenrichment and condensation characteristics are examined. It is found that the highly-enriched ethanol recovery could be attained in the 2nd stage by optimizing the 1st- and 2nd-stage cooling temperatures (as moderate as 5°C and up to-10°C, respectively). Regarding the carrier-gas flowrate, ethanol-rich mist consisting of small-size droplets tends to be carried selectively in favor of lower gas flowrate. Nevertheless, the desired recovery of enriched ethanol-i.e., a highest possible value of the recovered quantity of ethanol as well as the recovery concentration itself-is expected to be obtained in the 2nd stage by raising the carrier-gas flowrate under the present operating conditions. While the proposed two-stage cooling process tends to collect rather an appreciable quantity of less-enriched ethanol solution in the 1st stage, it is the 2nd stage that assures the desired quality of enriched-ethanol recovery.

An aqueous solution of ethanol was ultrasonically atomized, and the mist was recovered to obtain concentrated ethanol solution. The atomization vessel was vacuumed, and the recovery vessel was pressurized for enhancing mist generation and recovery. Batch operation was carried out with and without pressure control, and the results obtained were compared. The amounts of produced and recovered mist increased dramatically upon pressure control. The ethanol concentration in the collected liquid was higher in the presence of ultrasound irradiation than in its absence. It was suggested that production of very fine ethanol-rich droplets was facilitated at reduced pressures, and the recovery was enhanced at elevated pressures.The effect of pressure in the atomization vessel on the amount of mist production and the ethanol concentration in the collected liquid was examined in the presence and absence of ultrasound irradiation. Without ultrasound irradiation, only evaporation would occur. Comparison of the results obtained with and without ultrasound irradiation indicated that the formation of fine droplets affected ethanol separation. The amount of mist collected was 1.4 times the amount of vapor. The ethanol concentration in the collected mist exceeded that in the collected vapor by 5 mol%. The results also suggested that the formation of fine droplets affected the ethanol separation degree by ultrasonic atomization.

High-frequency (2.4 MHz) ultrasonic irradiation to an ethanol-water mixture can induce the generation of ethanol-rich mist droplets at lower temperatures. Two groups of droplets in micrometer- and nanometer-sized were observed in the mist generated by the ultrasonic atomization. Nanosized droplets were considered to be ethanol-rich droplets which cause ethanol condensation.

Being relatively volatile components of a commercial gasoline, hydrocarbons whose carbon number ranges from four to six, C4 to C6, were effectively removed by ultrasonic atomization. The ultrasonic frequency was 2.4 MHz, and the voltage applied to the oscillating unit was 24 V. More than 60% of C4 and C5 hydrocarbons were removed during 900 s of operation. In regard to the energy requirement for the separation, ultrasonic atomization needs only about half the energy required for evaporation. This finding is interpreted as a result of the phase change of liquids; the input energy was effectively utilized for the removal of light hydrocarbons. Operation at ambient temperature is advantageous for making use of a difference in vapor pressure among hydrocarbons.

AIChE JournalVolume 53, Issue 3 p. 737-740 Separation Efficient separation coupled with ultrasonic atomization using a molecular sieve Kazuo Matsuura, Corresponding Author Kazuo Matsuura [email protected] Ultrasound Brewery Co., Ltd., Naruto, Tokushima 779-0303, JapanUltrasound Brewery Co., Ltd., Naruto, Tokushima 779-0303, JapanSearch for more papers by this authorTetsuo Fukazu, Tetsuo Fukazu Ultrasound Brewery Co., Ltd., Naruto, Tokushima 779-0303, JapanSearch for more papers by this authorFusatsugu Abe, Fusatsugu Abe Ultrasound Brewery Co., Ltd., Naruto, Tokushima 779-0303, JapanSearch for more papers by this authorTaisuke Sekimoto, Taisuke Sekimoto Japan Alcohol Corporation Head Office, Minato-Ku, Tokyo 105-0003, JapanSearch for more papers by this authorToshiro Tomishige, Toshiro Tomishige Japan Alcohol Corporation Head Office, Minato-Ku, Tokyo 105-0003, JapanSearch for more papers by this author Kazuo Matsuura, Corresponding Author Kazuo Matsuura [email protected] Ultrasound Brewery Co., Ltd., Naruto, Tokushima 779-0303, JapanUltrasound Brewery Co., Ltd., Naruto, Tokushima 779-0303, JapanSearch for more papers by this authorTetsuo Fukazu, Tetsuo Fukazu Ultrasound Brewery Co., Ltd., Naruto, Tokushima 779-0303, JapanSearch for more papers by this authorFusatsugu Abe, Fusatsugu Abe Ultrasound Brewery Co., Ltd., Naruto, Tokushima 779-0303, JapanSearch for more papers by this authorTaisuke Sekimoto, Taisuke Sekimoto Japan Alcohol Corporation Head Office, Minato-Ku, Tokyo 105-0003, JapanSearch for more papers by this authorToshiro Tomishige, Toshiro Tomishige Japan Alcohol Corporation Head Office, Minato-Ku, Tokyo 105-0003, JapanSearch for more papers by this author First published: 05 February 2007 https://doi.org/10.1002/aic.11113Citations: 9Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Citing Literature Volume53, Issue3March 2007Pages 737-740 RelatedInformation

Small-angle x-ray scattering measurements using a brilliant x-ray source revealed nanometer sized liquid droplets in a mist formed by ultrasonic atomization. Ultrasonic atomization of ethanol-water mixtures produced a combination of water-rich droplets of micrometer order and ethanol-rich droplets as small as 1 nm, which is 10(-3) times smaller than the predicted size. These sizes were also obtained for mists generated from the pure liquids. These results will help to clarify the mechanism of "ultrasonic ethanol separation," which has the potential to become an alternative to distillation.

Small-angle X-ray scattering measurements of water droplets in a mist were carried out using the BL15XU beamline at SPring-8. The diameter of the water droplets generated by ultrasonic atomization was found to be >= 50 nm and had no distribution in the range under 50 nm, as predicted. The study also showed how difficult it is to measure the small-angle scattering of low-density materials, such as liquid droplets in a mist.

In situ x-ray diffraction measurements were carried out for investigating the liquid structure in the ultrasonic fountain jet to consider the mechanism of the “ultrasonic ethanol separation” reported by Sato et al. [J. Chem. Phys. 114, 2382 (2001)]. For pure liquids (water and ethanol), it was found that the high frequency ultrasound does not affect the liquid structure microscopically. For the 20mol% ethanol-water mixture, the estimated ethanol mole fraction in the ultrasonic fountain jet by using the position of the main maximum in the x-ray diffraction profile coincided with that in the reservoir. This result suggests that the ethanol separation is not caused by any distorted liquid structure under the ultrasound irradiation and occurs when or after the generation of the liquid droplet mist.

The microscopic structures in ethanol-water binary mixtures were examined by analyzing the mass spectra of clusters generated through fragmentation of liquid droplets. From the effects of temperature and mixing ratios on the cluster structures, we have demonstrated that the ethanol-water binary mixtures have microscopic phase separation at the cluster level in wide mixing ratios: 10 vol.% < [EtOH] < 90 vol.%. In this region, ethanol-rich clusters whose molecular composition is independent of the mixing ratio were observed at lower temperatures, and the ethanol-rich clusters interacted with water molecules with increasing temperature. Furthermore, we would like to present the mechanism for the formation of ethanol-rich clusters, induced by the contact with water molecules. (C) 2006 Elsevier B.V. All rights reserved.