Electroacoustic characterization techniques

Hunter, R. J., The electroacoustic characterization of colloidal suspensions, in Handbook on Ultrasonic and Dielectric Characterization Techniques for Suspended Particulates, Hackley, V. A. and Texter, J. (Eds), American Ceramic Society, Westerville, OH, 1998, pp. 25-46. 

Rowell and co-workers [62-64] have developed an electrophoretic fingerprint to uniquely characterize the properties of charged colloidal particles. They present contour diagrams of the electrophoretic mobility as a function of the suspension pH and specific conductance, pX. These fingerprints illustrate anomalies and specific characteristics of the charged colloidal surface. A more sophisticated electroacoustic measurement provides the particle size distribution and potential in a polydisperse suspension. Not limited to dilute suspensions, in this experiment, one characterizes the sonic waves generated by the motion of particles in an alternating electric field. O Brien and co-workers have an excellent review of this technique [65]. 

Recent advances have been made in the theory and application of acoustic and electroacoustic spectroscopies for measuring the particle size distribution (PSD) and -potential of colloidal suspensions, respectively.67-69 To date, the use of acoustics has been confined mainly to industrial applications, despite the clear potential for the technique to characterize colloids with environmental or agricultural significance. 

We are optimistic about the future of acoustics in colloid science. It is amazing what this technique can do especially in combination with electroacoustics for characterizing electric surface properties. We hope that this review will allow you to taste the power and opportunities related to these sound-based techniques. 

The combination of acoustic and electroacoustic spectroscopy provides a much more reliable and complete characterization of the disperse system than either one of those techniques separately. Electroacoustic phenomena are more complicated to interpret than acoustic phenomena because an additional field (electric) is involved. This problem becomes even more pronounced for a concentrated system. It makes acoustics favorable for characterizing particle size, whereas electroacoustics yields electric surface properties. 

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