화학공학소재연구정보센터
Journal of Colloid and Interface Science, Vol.315, No.2, 482-492, 2007
Ultrasonic attenuation spectroscopy of emulsions with droplet sizes greater than 10 mu m
Ultrasonic attenuation measurement is a frequently used tool for non-destructive determination of dispersion characteristics. Useful information like particle or droplet size and their concentration can be obtained, if the relation between size and attenuation of the dispersion is known. In this work, the theoretical model by Faran for the intermediate sound wave regime (IWR) is presented in combination with experimental data. In the lWR, the acoustic behavior is governed by elastic scattering rather than by dissipative effects. Experiments with emulsion of droplet sizes greater than 10 mu m were carried out. Silicone oil, sunflower oil and olive oil were selected for the disperse phase of the oil-in-water emulsions. First, emulsions having droplets in the micrometer range were created. Afterwords, attenuation measurements of different concentrated emulsion were carried out. Some adjustments reflecting concentration influence were performed to outline the agreement between calculations and measurements. The validity of the model can be confirmed, if the volume fraction of the disperse phase is considered as a variable. Finally, droplet size distributions from theoretical attenuation spectra could be calculated based on a log-normal distribution. (c) 2007 Elsevier Inc. All rights reserved.