Foam is ubiquitous in our daily lives. It can significantly limit production capacity and cause significant waste of raw materials. Many companies choose to use defoamers to defoam.
1. Localized surface tension reduction in foam leads to its collapse
This mechanism originates from sprinkling alcohol or vegetable oil onto foam. When it dissolves into the foam liquid, it significantly reduces the surface tension in that area. Because these substances are generally less soluble in water, the surface tension reduction is localized to the bubble, while the surface tension surrounding the bubble remains largely unchanged. The area with reduced surface tension is strongly pulled outward, extending, and ultimately bursting.
2. Defoamers can disrupt film elasticity, causing bubbles to collapse.
When added to a foam system, defoamers diffuse toward the air-liquid interface, making it difficult for the foam-stabilizing surfactant to restore film elasticity.
3. Defoamers can promote film drainage, leading to bubble collapse.
The rate of foam drainage reflects foam stability, and adding a substance that accelerates foam drainage can also have a defoaming effect.
4. Adding hydrophobic solid particles can cause bubbles to burst. Foam is everywhere in our lives. Foam can greatly limit production capacity and cause a lot of waste of raw materials. Many companies choose to use defoaming agents to defoam. (1) The local surface tension of the foam decreases, causing the foam to burst. The origin of this mechanism is that alcohol or vegetable oil is sprinkled on the foam. When it dissolves in the foam liquid, it will significantly reduce the surface tension at that location. Because these substances generally have low solubility in water, the surface tension is reduced in the local area of the foam, while the surface tension around the foam remains almost unchanged. The part with reduced surface tension strongly pulls and extends to the surrounding area, and finally bursts. (2) Defoaming agents can destroy the membrane elasticity and cause bubbles to burst. When defoaming agents are added to the foam system, they will diffuse to the gas-liquid interface, making it difficult for the surfactant with foam stabilization function to restore the membrane elasticity. (3) Defoamers can promote the drainage of liquid films, thus causing bubbles to burst. The rate of foam drainage can reflect the stability of the foam. Adding a substance that accelerates foam drainage can also have a defoaming effect. (4) Adding hydrophobic solid particles can cause bubbles to burst. The hydrophobic solid particles on the bubble surface will attract the hydrophobic end of the surfactant, making the hydrophobic particles hydrophilic and entering the water phase, thereby playing a defoaming role. (5) Solubilizing and foaming surfactants can cause bubbles to burst. Certain low-molecular substances that can be fully mixed with the solution can solubilize the bubble surfactant and reduce its effective concentration. Low-molecular substances with this effect, such as alcohols such as octanol, ethanol, and propanol, can not only reduce the surfactant concentration in the surface layer, but also dissolve into the surfactant adsorption layer, reducing the closeness between surfactant molecules, thereby weakening the stability of the foam. (6) Electrolytes break down the double layer of surfactants and cause bubbles to burst. For foaming liquids that are stable due to the interaction of the double layer of surfactants in foam, adding ordinary electrolytes can break down the double layer of surfactants and have a defoaming effect. Hydrophobic solid particles on the surface of bubbles will attract the hydrophobic end of the surfactant, making the hydrophobic particles hydrophilic and entering the water phase, thereby playing a defoaming role. 5. Solubilizing and foaming surfactants can cause bubbles to burst. Certain low-molecular substances that can be fully mixed with the solution can solubilize the bubble surfactant and reduce its effective concentration. Low-molecular substances such as alcohols such as octanol, ethanol, and propanol can not only reduce the surfactant concentration in the surface layer, but also dissolve into the surfactant adsorption layer, reducing the closeness between surfactant molecules, thereby weakening the stability of the foam. 6. Electrolytes break down the double layer of surfactants and cause bubbles to burst. For foaming liquids that are stable due to the interaction of the double layer of surfactants in foam, adding ordinary electrolytes can break down the double layer of surfactants and have a defoaming effect.