Selection of defoamer


The selection of defoamer should accord with the following points:


01 insoluble or insoluble in foaming fluid


To dissolve the foam, defoamer should be concentrated and concentrated on the bubble film. For the case of defoamer, it should be concentrated and concentrated instantaneously, and for the case of foam suppression, it should always be kept in this state. So defoamer is supersaturated in foaming liquid, only insoluble or insoluble can it easily reach supersaturated state. Insoluble or insoluble, it is easy to gather at the gas-liquid interface, it is easy to concentrate on the vesicle membrane, in order to play a role at a lower concentration. The molecule of active ingredient must be strong hydrophobic and weak hydrophilic. The HLB value is in the range of 1.5-3, and the effect is the best.


02 Surface tension is lower than foaming liquid


Only when the intermolecular force of the defoamer is small and the surface tension is lower than that of the foaming liquid, the defoamer particles can be immersed and expanded in the membrane. It is noteworthy that the surface tension of foaming solution is not the surface tension of solution, but the surface tension of foaming solution.


03 has a certain degree of affinity with foaming fluid


Since the defoaming process is actually the competition between the rate of bubble collapse and the rate of foam formation, defoamers must be dispersed rapidly in the foaming solution so as to play a role in the wider range of foaming liquid. In order to make the defoamer diffuse quickly, the active ingredients of defoamer must have affinity with the foaming fluid to a certain extent. The active ingredients of defoamers can dissolve when they are related to the foaming fluid; they are too sparse and difficult to disperse. Effectiveness will be better only if it is appropriate to be close and sparse.


04 does not react with foaming fluid


The defoamer reacts with the foaming fluid. On the one hand, the defoamer will lose its function, on the other hand, it may produce harmful substances, which affect the growth of microorganisms.


05 has low volatility and long action time.


First of all, it is necessary to determine the system that needs to use defoamer, which is water-based system or oil-based system. For example, in the fermentation industry, oily defoamers, such as polyether modified silicon or polyether, should be used. Water-borne coatings industry needs water-borne defoamer, organosilicon defoamer. The most suitable and economical defoamer can be obtained by choosing defoamer and comparing the amount of defoamer and the reference price.


Defoamer dosage


There are many kinds of defoamers, and different types of defoamers require different amounts of additives. Here we introduce six kinds of defoamers:


1. Alcohol defoamers: When alcohol defoamers are used, the dosage is generally less than 0.01-0.10%.


2. Oil defoamers: The amount of oil defoamers is between 0.05-2%, and that of fatty acid esters is between 0.002-0.2%.


3. Amide defoamers: The effect of amide defoamers is better, and the dosage is generally within 0.002-0.005%.


4. Phosphoric acid defoamers: Phosphoric acid defoamers are most commonly used in fibers and lubricants, with the addition of 0.025-0.25%.


5. Amine defoamers: Amine defoamers are mainly used in fiber processing, with the addition of 0.02-2%.


6. Ether defoamers: Ether defoamers are widely used in papermaking, printing, dyeing and cleaning, with the addition of 0.025-0.25%.


Environmental protection reagent for self-dressing