Dear Colleagues, when measuring size distribution of solid dispersions by light scattering, it is a usual practice to approximate the equilibrium size distribution by applying ultrasound treatments of various power and duration. I woudl appreciate if someone could suggest a good review on the size effects achieved by such treatments and on the conclusions that can be drawn on the granular system from the differences measured after such treatments. (De-agglomeration and mechanical degradation of strongly anisometric particles are obvious consequences). What may cause an INCREASE in the average particle size after ultrasonication?
So far I have got one possible answer (a simple one) to increasing average particle size form a colleague: in some cases under ultrasonic treatment the fine fraction of the poweder tends to adhere to the wall of the container - leading to a shift of the remainder toward higher values.
This could occur for a system out of the thermodynamical equilibrium (ie in a metastable state stabilized by energy barriers).
Ultrasounds may provide the energy necessary to jump over these barriers (ie the repulsion between particles).
In case the association is energically favored this may be an explanation.
Is this correct ?
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