1. Chinese National Engineering Research Center of Coal Preparation and Purification,China University of Mining and Technology,Xuzhou　 221116,China; 2. School of Minerals Processing and Bioengineering,Central South University,Changsha　 410083,China; 3. Henan Province Industrial Technology Research Institute of Resources and Materials,Zhengzhou University,Zhengzhou　 450000,China

To explore the origin mechanism of long-ranged and short-ranged hydrophobic force in bub-ble-particle system,atomic force microscopy (AFM) and flotation dynamic wetting film apparatus (DWFA) were used to measure the hydrophobic force between air bubble and the same hydrophobic glass substrate. AFM results showed that the force be- tween hydrophilic glass substrate and bubble was always repulsive since the both van der Waals force and double layer force were repulsive. There was no attractive force triggering film rupture in the system. The film between hydrophobic glass and bubble was unstable. When 19. 3 nN loading force was reached,a significant jump-into contact was observed in the force curves. The hydrophobic force was attenuated by a single exponential model with 3. 50 nm decay length. Film ruptured at 32. 96 nm critical thickness. This kind of hydrophobic force tented to be a short-ranged force,origina- ted from the entropy effect due to the re-arrangement of interface water molecules. DWFA results also showed that the film between hydrophilic glass and bubble was thermostatically stable. 133 nm equilibrium film thickness was reached when the total disjoining pressure was equal to the Laplace pressure inside air bubble. Also,the film between hydro- phobic glass and bubble was unstable. The liquid film thinned rapidly and ruptured at the critical thickness of 185 nm. The decay length of hydrophobic force was 47. 30 nm and was a kind of long-ranged force, originated from the nanobubble cavitation effect on solid-liquid interface. The bubble used in AFM and DWFA experiments was micro-me- ter and millimeter,respectively. The hydrophobic force was influenced by the bubble size and related with the capillary wave on bubble surface. Under the attraction force,more intensive interface wave was formed on the big bubble sur- face. Due to the thermodynamic instability of water molecules at hydrophobic interfaces,this kind of interface wave in- duced the precipitation of cavitation bubble on the hydrophobic interface and increased the range of hydrophobic force.

国家重点研发计划资助项目(2018YFC0604702);中国博士后科学基金面上资助项目(2018M642369);第四届中国科协青年人才托举工程资助项目(2018QNRC001)

XING Yaowen,GUI Xiahui,HAN Haisheng,et al. Bubble-particle attachment science-study on hydrophobic force be- tween bubble and particle based on AFM and DWFA[ J]. Journal of China Coal Society,2019,44(5):1580 -1585.