Ultrasound monitoring of colloidal systems

The authors have developed a novel wide bandwidth ultrasonic spectrometer for the study of flocculation processes in colloidal systems. The instrument measures the ultrasonic compression wave absorption coefficient and phase velocity as functions of frequency between 1 MHz and 60 MHz, and has a measurement time of less than 100 ms, depending on the signal to noise conditions. The high speed of operation implies that the instrument can be used to study systems undergoing chemical reaction, ordering phenomena such as flocculation, and other physical changes. The authors summarise the measurement technique, ultrasonic wave propagation in colloidal systems, and their preliminary experiments on stable and unstable colloids