Mechanism
1.
Local surface tension reduction of the bubble results in the bubble bursting
The origin of this mechanism is that high alcohol or vegetable oil sprinkled on the foam will significantly reduce the surface tension when it dissolves into the foam liquid.
Because these substances are generally less soluble to water, the reduction in surface tension is limited to the area of the foam, while the surface tension around the foam is almost unchanged.
The reduced surface tension is strongly pulled around, extended, and finally ruptured.
2.
Defoaming agent can break the membrane elasticity and cause bubbles to burst
When defoamer is added to the foam system, it will diffuse to the gas-liquid interface, making it difficult for the surfactant with foam stabilizing effect to restore the membrane elasticity.
3.
Defoaming agents can cause the liquid film to drain, thus causing bubbles to burst
The rate of foam drainage can reflect the stability of foam, and adding a substance to accelerate foam drainage can also play a role in defoaming.
4.
The addition of hydrophobic solid particles can cause bubbles to burst
The hydrophobic solid particles on the bubble surface will attract the hydrophobic end of the surfactant and make the hydrophobic particles produce hydrophilicity and enter the aqueous phase, thus playing the role of defoaming.
5.
Solubilizing surfactants can cause bubbles to burst
Some low molecular substances that can be fully mixed with the solution can make the bubble surfactant solubilize and reduce its effective concentration.
Low molecular substances with this effect, such as octanol, ethanol, propanol and other alcohols, can not only reduce the surfactant concentration of the surface layer, but also dissolve into the surfactant adsorption layer, reducing the tightness between the surfactant molecules, thereby weakening the stability of the foam.
6.
The electrolyte dissolves the surfactant double layer and bubbles burst
With the help of foam surfactant double electric layer interaction to produce a stable foaming liquid, adding ordinary electrolyte can disintegrate the surfactant double electric layer for defoaming.
