کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
607378 | 1454581 | 2014 | 9 صفحه PDF | دانلود رایگان |
• The coalescence of bubble pairs is partially controlled by surface tension phenomena.
• A minimum elasticity of 1 mN m−1 is required to dampen the post-rupture oscillation.
• Damping is optimal in a visco-elastic region.
• A decrease in damping can be associated with high diffusional frequencies.
Most processes involving bubbling in a liquid require small bubbles to maximise mass/energy transfer. A common method to prevent bubbles from coalescing is by the addition of surfactants. In order to get an insight into the coalescence process, capillary bubbles were observed using a high speed cinematography. Experiments were performed in solutions of 1-pentanol, 4-methyl-2-pentanol, tri(propylene glycol) methyl ether, and poly(propylene glycol) for which information such as the coalescence time and the deformation of the resultant bubble upon coalescence was extracted. It is shown in this study that the coalescence time increases with surfactant concentration until the appearance of a plateau. The increase in coalescence time with surfactant concentration could not be attributed only to surface elasticity. The oscillation of the resultant bubble was characterised by the damping of the oscillation. The results suggested that a minimum elasticity is required to achieve an increased damping and considerable diffusion has a detrimental effect on the dynamic response of the bubble, thereby reducing the damping.
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Journal: Journal of Colloid and Interface Science - Volume 414, 15 January 2014, Pages 50–58