Related Experiment Video
Updated: Aug 7, 2026
11:52
Microbubble Fabrication of Concave-porosity PDMS Beads
Published on: December 15, 2015
Selective coalescence of bubbles in simple electrolytes
1Department of Applied Mathematics, Research School of Physical Sciences and Engineering, The Australian National University, Canberra 0200, Australia. stjepan.marcelja@anu.edu.au
The Journal of Physical Chemistry. B
|June 30, 2006
Summary
Simple ions in electrolytes affect bubble coalescence. Ion attraction to water surfaces can either promote or inhibit bubble merging, depending on the specific ion and electrolyte concentration, as shown by electrostatic interaction calculations.
Area of Science:
- Physical Chemistry
- Colloid and Surface Science
- Electrochemistry
Background:
- Simple ions in electrolytes display varying affinities for water surfaces.
- This leads to ion-specific effects, notably in the selective inhibition of bubble coalescence.
Purpose of the Study:
- To calculate the electrostatic interaction between electrolyte surfaces due to ion accumulation or depletion.
- To investigate the role of ion-specific effects on bubble coalescence inhibition.
Main Methods:
- Calculation of electrostatic interaction between electrolyte surfaces using effective potentials.
- Evaluation of ion density profiles from published simulations.
- Application to NaCl and HCl solutions.
Main Results:
- In HCl solutions, van der Waals attraction facilitates bubble coalescence.
- In NaCl solutions, an electric double layer forms, creating a repulsive barrier between surfaces.
- Calculated repulsion in NaCl matches experimental bubble coalescence inhibition at specific concentrations.
Conclusions:
- The study explains ion-specific effects on bubble coalescence inhibition.
- Electrostatic interactions, particularly the electric double layer in NaCl, are key to preventing bubble coalescence.
- Results align with experimental observations on the transition to coalescence inhibition.
Related Concept Videos
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...
01:06Coagulation
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...
02:42Aqueous Solutions and Heats of Hydration
Water and other polar molecules are attracted to ions. The electrostatic attraction between an ion and a molecule with a dipole is called an ion-dipole attraction. These attractions play an important role in the dissolution of ionic compounds in water.
When ionic compounds dissolve in water, the ions in the solid separate and disperse uniformly throughout the solution because water molecules surround and solvate the ions, reducing the strong electrostatic forces between them. This process...
When ionic compounds dissolve in water, the ions in the solid separate and disperse uniformly throughout the solution because water molecules surround and solvate the ions, reducing the strong electrostatic forces between them. This process...
01:23Theory of Strong Electrolytes
The interionic forces of the strong electrolytes depend on the solvent's dielectric constant, which is the ability of a solvent to store electrical energy, based on its polarizability. and the solution's concentration. In high-dielectric solvents and in dilute solutions, weak electrostatic forces keep ions apart. However, in low-dielectric solvents or concentrated solutions, stronger interionic forces may cause ions to pair up as ionic doublets despite being fully ionized. The theory of strong...
01:28Ionic Association
The ionic association is the association of oppositely charged ions in an electrolyte solution to form ion pairs. Bjerrum defined ion pairs as two oppositely charged ions whose electrostatic attraction exceeds the thermal energy of the system, typically expressed as 2kT. Electrostatic attraction depends on ionic charge, separation distance, and the dielectric constant of the medium. Thermal energy, represented by kT, reflects the tendency of ions to move independently due to molecular motion.