Improving separation efficiency of crystallization by ultrasound-accelerated nucleation: The role of solute diffusion and solvation effect

•Probability distribution method was used to study nucleation under ultrasound.•Ultrasound accelerates nucleation in all solvents, especially at low supersaturation.•The degree of enhancement on nucleation varies with the diffusion ability of solute.•Ultrasound does not change the order of nucleation difficulty in the three solvents.•The stronger the solvation of solvent on solute, the more difficult the nucleation.