The selection of defoamer should meet the following points:


1, insoluble or insoluble in the foaming liquid


In order to burst the foam, the defoamer should be concentrated and concentrated on the bubble film. For the case of defoaming agent, it should be concentrated and concentrated in an instant, and for the case of defoaming agent, it should always be maintained in this state. Therefore, the defoamer is supersaturated in the foaming solution, and only insoluble or insoluble is easy to achieve supersaturation. Insoluble or insoluble, it is easy to gather at the gas-liquid interface, it is easy to concentrate on the bubble film, and it can play a role at a lower concentration. For the defoamer used in water systems, the molecules of the active ingredients must be strong hydrophobic and weak hydrophilic, and the HLB value should be in the range of 1.5-3 for the best effect.




2, the surface tension is lower than the foaming liquid


Only when the intermolecular force of the defoamer is small and the surface tension is lower than that of the foaming solution, the defoamer particles can be immersed and expanded on the foam film. It is worth noting that the surface tension of the foaming solution is not the surface tension of the solution, but the surface tension of the foaming solution.





3. It has a certain degree of affinity with foaming liquid


Since the defoaming process is actually a competition between the speed of foam collapse and the speed of foam formation, the defoaming agent must be able to disperse quickly in the foaming solution in order to quickly play a wider range of roles in the foaming solution. In order to make the defoamer diffusion faster, the active ingredient of the defoamer must have a certain degree of affinity with the foaming solution. The active ingredient of defoamer is too close to the foaming solution and will dissolve. Too sparse and difficult to disperse. The effectiveness is good only when the intimacy is right.





4, no chemical reaction with foaming liquid


The defoamer reacts with the foaming solution, on the one hand, the defoamer will lose its effect, on the other hand, harmful substances may be produced, affecting the growth of microorganisms.






5, small volatility, long action time


First of all, it is necessary to determine the system that needs to use defoamer, whether it is a water-based system or an oil-based system. If the fermentation industry, it is necessary to use oil-based defoamer, such as polyether modified silicon or polyether. Water-based coating industry must use water-based defoamer, silicone defoamer. Select the defoamer, compare the added amount, and get the most suitable and economical defoamer product at the reference price.