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The application of intense ultrasound to a liquid-gas interface results in the formation of an ultrasonic fountain and generates both mist and vapor from the liquid. Here, the composition of the vapor and aerosol above an ultrasonic fountain is determined as a function of irradiation time and compared with the results of sparging for five different solutions. The experimental apparatus for determining the efficiency of separation consists of a glass vessel containing a piezoelectric transducer driven at either 1.65 or 2.40 MHz. Dry nitrogen is passed over the ultrasonic fountain to remove the vapor and aerosol. The composition of the liquid solutions are recorded as a function of irradiation time using gas chromatography, refractive index measurement, nuclear magnetic resonance, or spectrophotometry. Data are presented for ethanol-water and ethyl acetate-ethanol solutions, cobalt chloride in water, colloidal silica, and colloidal gold. The experiments show that ultrasonic distillation produces separations that are somewhat less complete than what is obtained using sparging. 10.1021/ac102057g

A new approach to solid sample preparation for the simultaneous isolation of polar and nonpolar compounds using a microemulsion as leaching medium is proposed. Methanol/water (dispersed-phase)-hexane (continuousphase) emulsions formed in the presence of ultrasound and a solid sample allow polar and nonpolar compounds to be transferred to the dispersed and continuous phase, respectively. The efficiency of this dual sample preparation approach was assessed in the characterization of natural products of variable hardness including acorns, grape seeds, and alperujo (a residue of olive oil production). The time needed for quantitative extraction of the target fractions (phenol compounds and fatty acids) is 9 min for acorns and alperujo and 20 rain for grape seeds; the longer time needed for grape seeds can be attributed to higher matrix hardness. Such good performance can be ascribed to the ultrasound-enhanced formation of methanol/water microdroplets 1-15 [micro]m in size, which act as solid-liquid microextractors spanning a large surface area. The presence of the sample was found to greatly improve emulsion stability, which can be ascribed to the amphiphilic nature of the fatty acids in the samples. Following leaching and separation of the two phases by centrifugation, the polar and nonpolar fractions were analyzed by HPLC-diode array detection and GC/MS, respectively. The proposed approach provides extraction efficiency similar to the Folch method (reference method for fat extraction, 4.5 h) in a shorter time and extraction efficiency equal to or higher than the stirring-based method (reference method for phenol compounds extraction, 24 h).

A novel method, free flow acoustophoresis (FFA), capable of continuous separation of mixed particle suspensions into multiple outlet fractions is presented. Acoustic forces are utilized to separate particles based on their size and density. The method is shown to be suitable for both biological and nonbiological suspended particles. The microfluidic separation chips were fabricated using conventional microfabrication methods. Particle separation was accomplished by combining laminar flow with the axial acoustic primary radiation force in an ultrasonic standing wave field. Dissimilar suspended particles flowing through the 350[micro]M-wide channel were thereby laterally translated to different regions of the laminar flow profile, which was split into multiple outlets for continuous fraction collection. Using four outlets, a mixture of 2-, 5-, 8-, and 10-[micro]M polystyrene particles was separated with between 62 and 94% of each particle size ending up in separate fractions. Using three outlets and three particle sizes (3, 7, and 10 [micro]m) the corresponding results ranged between 76 and 96%. It was also proven possible to separate normally acoustically inseparable particle types by manipulating the density of the suspending medium with cesium chloride. The medium manipulation, in combination with FFA, was further used to enable the fractionation of red cells, platelets, and leukocytes. The results show that free flow acoustophoresis can be used to perform complex separation tasks, thereby offering an alternative to expensive and time-consuming methods currently in use.

Research describing the preparation of hydrodesulfurization catalysts under high ultrasonic irradiation is presented. Particular attention is given to the characteristics of the elemental composition of the catalysts obtained from sonochemical preparation.

Ultrasound irradiation is able to modify the course of a number of photochemical reactions. The study of benzophenone photopinacolization in ethanol illustrates the effect of ultrasound irradiation

Aqueous solutions of the chlorinated C1 and C2 volatile organic compounds (VOCs) were irradiated with ultrasonic waves in a sonochemical reactor to examine the use of sonochemical destruction for removing certain VOCs from water. Solutions of carbon tetrachloride, methylene chloride, chloroform, trichloroethylene, 1, 2-dichloroethane, 1,1,1-trichloroethane and perchloroethylene were used. Results showed that the concentrations of all the solutes decreased after irradiation, and no chorinated by-products were produced. There was a concomitant decrease in pH, indicating that liberated chlorine was converted to HCl or other acid species.

The ultrasound-induced switching of sheetlike coordination polymer microparticles to nanofibers capable of gelating a variety of organic solvents is described. The experimental results provide insight into the gelation that possibly originates from the change of coordination chemistry of metal ions driven by sonication.

The formation of fiberlike micelles in hexane with a very narrow weight-average distribution of lengths and the nature of their fragmentation following exposure to ultrasound are described. The results have shown that these fibers also rupture according to Gaussian fragmentation model and display a fracture rate that is very sensitive to fiber length.

The application of high-frequency ultrasound irradiation for the synthesis of different microemulsion polymerizations is analyzed. The process is also shown to use ionic surfactants as the stabilizers for the formation of transparent latex particles.

Ultrasound is used for reshaping sheet-like dipeptide particles into elongated molecular assemblies that are at the origin of solvent gelation. Sonication time, temperature and solvents have played a major role in determining the morphology of the particles, features that are appealing for templating materials.

A study is conducted to establish a systematic and accurate method for evaluating the sound velocity of polymer gels containing magnetic particles using 2.25- and 10-MHz ultrasoni c waves at 295.5 K. the observed anisotropy in the modulus at these frequencies would be ascribed to the magnetic interaction between magnetic particles in the range of ~100 (mu)m.