Ultrasound vibration potential

Use of Ultrasonic Vibration Potential To Monitor Coalescence. The complex chemical nature of crude oils makes it difficult to relate the dispersion behavior to the physicochemical properties at the crude-oil-water interface. In addition, the nonpolar and nontransparent nature of the oleic phase provides significant obstacles for studies of the interactions of the suspended water droplets in real systems. Recent development (28, 29) of electroacoustical techniques has shown considerable promise for electrokinetic measurements of colloidal systems and the direct monitoring of the rate and extent of coagulation (flocculation and coalescence) of water droplets in nontransparent water-in-oil media. The electroacoustic measurement for colloidal systems in nonpolar media is based on the ultrasound vibration potential (UVP) mode, which involves the applica-... 

Figure 1 Schematic diagram showing the principles of Ultrasound Vibration Potential (UVP). 

Electroacoustics — Ultrasound passing through a colloidal dispersion forces the colloidal particles to move back and forth, which leads to a displacement of the double layer around the particles with respect to their centers, and thus induces small electric dipoles. The sum of these dipoles creates a macroscopic AC voltage with the frequency of the sound waves. The latter is called the Colloid Vibration Potential (CVP) [i]. The reverse effect is called Electrokinetic Sonic Amplitude (ESA) effect [ii]. See also Debye effect. 

These are fundamental considerations and are of interest not just to electrochemists and sonochemists, but care must be taken in correctly attributing an apparent shift in an experimentally observed potential under ultrasound. As already mentioned, system parameters and other factors may influence an observation beyond the effect under investigation. Thus there have been reports on the use of the titanium tip of the sonic horn itself, suitably electrically insulated, as the electrode material [50]. Dubbed the sonotrode , this is a clever idea to combine the two active components of a sonoelectrochemical system the authors noted the expected enhancements in limiting currents and an alteration in the morphology of copper electrodeposited from aqueous solution on to the titanium tip, which was the reaction under test. However, although titanium is widely used in sonochemistry because of its low-loss characteristics under vibration, it is not a common electrode material for electroanalysis because of its inferior electron transfer characteristics... 

To harness the full potential of amorphous systems for all types of chemical compounds, alternate technologies are constantly being added to the toolbox. Ultrasonic-assisted compaction is a modified tabletting process that can provide heat, pressure, and shear due to ultrasonic energy to the powder mixture during compaction. The application of ultrasound to solubility enhancement is based on the fusion method and in some ways mimics the extrusion process (Fini et al. 1997 Sancin et al. 1999). The ultrasonic frequency vibration is applied at the same time as compaction force. The key features of the technology include ... 

In 1880, Pierre Curie and his brother Jacques made the first observation of the piezo-dectric effeU. What they found was that some crystals, e.g. quartz, are deformed mechanically when an electrical voltage is applied to them. An AC electric potential might thus cause vibration. This made possible the generation and reception of ultrasound (a sound with such a high frequency, more than 15 000 Hz = 15 kHz, so that the human ear cannot hear it). For technical and medical uses of ultrasound, still... 

The use of ultrasound with the dye bath can also be of potential benefit regarding dye diffusion and uptake. Uitrasonic frequencies typically range from 20 kHz to 500 MHz, although most applications for textiles are below 50 kHz. In principle, the ultrasonic generator controls tube resonators, which emit ultrasonic waves in these frequency ranges. The vibration created by the generator is sent to an ultrasound head by a shielded wire and converted into mechanical vibrations. A sono-trode is placed in close proximity so the vibrations can be transmitted to the material and the dye bath (see Figure 8.12)... 

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