Related Experiment Video
Updated: May 29, 2026
14:22
Activating Molecules, Ions, and Solid Particles with Acoustic Cavitation
Published on: April 11, 2014
Bubble coalescence during acoustic cavitation in aqueous electrolyte solutions
Christine Browne1, Rico F Tabor, Derek Y C Chan
1Particulate Fluids Processing Centre, The University of Melbourne, Parkville, Victoria 3010 Australia.
Langmuir : the ACS Journal of Surfaces and Colloids
|August 27, 2011
Summary
Electrolytes impede bubble coalescence in ultrasound fields by forming ion-pair complexes at the gas-solution interface. This alters fluid flow, slowing bubble merging and impacting processes involving bubble dynamics.
Area of Science:
- Physical Chemistry
- Colloid and Surface Science
- Acoustics
Background:
- Bubble coalescence is crucial in various industrial processes.
- Electrolytes are known to affect bubble coalescence, but the mechanisms are complex.
- Ultrasound fields introduce dynamic forces influencing bubble interactions.
Purpose of the Study:
- To investigate the effect of different electrolytes on bubble coalescence under ultrasound.
- To determine the role of solubilized gases and ion adsorption in acoustic bubble coalescence.
- To elucidate the mechanism behind electrolyte-induced impedance of bubble coalescence.
Main Methods:
- Examining bubble coalescence in aqueous solutions of MgSO(4), NaCl, KCl, HCl, and H(2)SO(4) under a 213 kHz ultrasound field.
- Quantifying the extent of bubble coalescence and correlating it with solubilized gas content (He, Ar, air).
- Comparing results with previous studies in the absence of ultrasound.
Main Results:
- Bubble coalescence extent depended on electrolyte type and concentration, linked to solubilized gas.
- No specific ion effects were observed in acoustic bubble coalescence.
- A critical transition concentration was identified, marking the shift from mobile to immobile interfacial fluid flow.
Conclusions:
- Electrolyte-induced impedance of bubble coalescence results from ion-pair adsorption at the gas-solution interface.
- Adsorption alters interfacial hydrodynamics, reducing film drainage and coalescence rates.
- The critical transition concentration signifies the point of interfacial immobilization, likely by ion-pair complexes.
Related Concept Videos
01:06Coagulation
Colloidal solids are solid particles suspended in solution. They are usually negatively charged, attracting a compact primary layer of positively charged ions, which attract more counterions to form an electrical double layer. Electrostatic repulsion between the charged double layers prevents the particles from colliding, stabilizing the colloids. These solids are often undesirable because they can contain toxins that are difficult to remove. Coagulation is a technique that helps aggregate and...
01:29The Colloidal State
The formation of a colloidal system is exemplified by an aqueous solution containing Cl− ions is introduced to another containing Ag+ ions, resulting in the precipitation of solid AgCl as extremely tiny crystals. Instead of settling out as a filterable precipitate, these crystals remain suspended in the liquid, showcasing a colloidal system.A colloidal system involves colloidal particles within the approximate range of 1 to 1000 nm in at least one dimension, dispersed in a medium called the...
01:09Theories of Dissolution: The Danckwerts' Model and Interfacial Barrier Model
Various dissolution theories provide insight into the factors that influence the dissolution rate. Danckwerts' Model suggests that turbulence, rather than a stagnant layer, characterizes the dissolution medium at the solid-liquid interface. In this model, the agitated solvent contains macroscopic packets that move to the interface via eddy currents, facilitating the absorption and delivery of the drug to the bulk solution. The regular replenishment of solvent packets maintains the concentration...
01:09Colloidal precipitates
The high insolubility of some precipitates can result in an unfavorable relative supersaturation. This can lead to colloidal particles with a large surface-to-mass ratio, where adsorption is promoted. For instance, in the precipitation of silver chloride, silver ions are adsorbed on the surface of the colloidal particles, forming a primary layer. This layer attracts ions of opposite charge (such as nitrate ions), forming a diffuse secondary layer of adsorbed ions. This electric double layer...
01:28Standing Waves in a Cavity
A household microwave and lasers are examples of standing electromagnetic waves in a cavity. When two conducting metal plates are placed parallel at the nodal planes, it creates a cavity where standing waves are formed. The cavity between the two planes is analogous to a stretched string held at the points x = 0 and x = L. Here, the distance 'L' between the two planes must be an integer multiple of half of the wavelength. The wavelengths that satisfy this condition are given by:
01:07Cohesion
Cohesion is the attraction between molecules of the same type, such as water molecules. Water molecules have an overall neutral charge but are polar molecule. An oxygen atom in one water molecule has a partial negative charge that can bind to a hydrogen atom with a partial positive charge in a second water molecule, forming a hydrogen bond. Each water molecule can form up to four hydrogen bonds with other water molecules. Hydrogen bonds are responsible for water's cohesive nature.
On a surface,...
On a surface,...