Defoamer can destroy the elasticity of the membrane and cause the bubble to burst

As the surface of the bubble film adsorbs the surfactant, the surface tension is reduced. Therefore, when the bubble film is locally thinned by local pressure, the surface tension will increase due to the thinning of the surfactant. It is precisely because of the difference in surface tension between the new surface and the original surface that when the bubble film is thinned by the external impact, an elastic restoring force is generated, and the bubble film can not be broken and played a role in stabilizing the bubble. If we manage to destroy this elasticity, we can destroy the stability of the foam. Some experts believe that the function of defoamer is to destroy the elasticity of the bubble film. When the defoamer is added to the foam system, it will diffuse to the gas-liquid interface, making it difficult for the foam-stabilizing surfactant to recover the elasticity of the film. The defoamer can promote the drainage of the liquid film, thus causing the bubble to burst

Adding a substance that accelerates the drainage of the bubble film (defoaming agent) can defoam. If the bubble film is thick, the process of draining to 30~40nm is long, and the self-healing effect of the bubble film is strong, and the bubble film has good elasticity, so the bubble life of the thick bubble film is long, and the bubble film drainage rate can reflect the bubble. The stability. The liquid film discharge rate is fast, so that the liquid film becomes thinner, and the bubble bursts when it is thin to a certain extent.

Adding hydrophobic solid particles can cause bubbles to burst

In the foaming water system, the hydrophobic silica (hydrophobic silica) particles are added separately to have defoaming effect. The hydrophobic silica particles will attract the hydrophobic end of the surfactant on the surface of the bubbles, and the hydrophobic particles will become hydrophilic particles and enter the water phase to complete the defoaming effect. The solid particles of hydrophobic silica are generally white carbon black particles treated with methyl silicone oil, silazane or DMC. It is partially immersed on the surface of the bubble to reduce the local surface tension of the bubble, plus the effect of solid particles. Inserting a bubble like a needle tip accelerates the bursting of the bubble. Therefore, defoamers containing hydrophobic silica generally have better defoaming effects.

Solubilizing and foaming surfactants can cause bubbles to burst

Certain low-molecular substances that can be mixed with the solution can solubilize the bubble surfactant 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 to reduce the tightness between the surfactant molecules. Degree, thereby weakening the stability of the foam.