Effects of surface roughness on the hydrophilic particles-air bubble attachment

Abstract

Bubble-particle attachment is a key factor in various material processing such as wastewater treatment and flotation separation. Nanobubble's formation and its stability on hydrophobic surfaces with and without surfactants have been scientifically proven and extensively studied in various investigations. However, the influence of particle roughness on the hydrophilic particle-air bubble attachment, which could be completely different from hydrophobic particle-bubble attachment in the presence of nanobubbles, has not been addressed. For tackling this gap, the present work investigated the impact of nanobubbles on the roughed surfaces of glass bead particles. The temperature rise technique as a known method was used for micro/nanobubble size generation. The glass beads were modified by the commonly applied abrasion method to create different roughness magnitudes. The particle-bubble assessment results indicated that the particle roughness could potentially affect the bubble attachment of hydrophilic glass beads while the attachment area of smooth particles was almost zero. Outcomes also were revealed that the modified attachment rate constant increased from 0.1180 to 2.2802 s−1 with the increase of particle surface roughness, indicating a shortening of attachment performance by enhancing the particle surface roughness. However, it was observed that the temperature rise method could improve the particle-bubble attachment only to a marginal extent.

Keywords

• Roughness
• Particle-bubble attachment
• Nanobubbles
• Hydrophilicity