Air bubble-induced detachment of polystyrene particles with different sizes from collector surfaces in a parallel plate flow chamber

Particle size was found to be an important factor in air bubble-induced detachment of colloidal particles from collector surfaces in a parallel plate flow chamber and generally polystyrene particles with a diameter of 806 nm detached less than particles with a diameter of 1400 nm. Particle detachment increased linearly with decreasing air bubble velocity and increasing liquid–air interfacial tension, regardless of particle diameter. The influence of air bubble velocity and liquid–air interfacial tension upon particle detachment was stronger on a hydrophilic collector surface than on a hydrophobic collector surface, whereas detachment was also less on positively-charged collector surfaces. In general, polystyrene particles with a diameter of 806 nm were less sensitive to the air bubble velocity than particles with a diameter of 1400 nm. However the larger particles were less sensitive to variations in liquid–air interfacial tension than the smaller ones. Hence, it is proposed that for larger particles, the liquid film in between the air bubble and the particle takes more time to thin down and form the three-phase contact, necessary to induce a detachment force.