Use of defoaming agent
Use of defoaming agent
The physical and chemical properties of an ideal defoaming agent must meet the requirements of the system in which it is used. Generally speaking, the following requirements must be considered when selecting a defoaming agent:
(1) Strong defoaming ability, which can effectively eliminate foam when used in very small amounts;
(2) It has a lower surface tension than the defoaming system;
(3) The addition of the defoaming agent does not affect the basic properties of the defoaming system;
(4) It is insoluble in the defoaming system and is not easily solubilized by the surfactant in the system;
(5) It has a good surface tension balance;
(6) It does not react with the defoaming medium, nor will it be decomposed and degraded by it, and has good chemical stability;
(7) It has good diffusivity and permeability, has a positive diffusion coefficient in the foam medium, and has a fast diffusion coefficient on the foam surface Spreading ability;
(8) Good heat resistance, will not lose effectiveness at high temperature;
(9) Good gas solubility and permeability;
(10) High physiological activity and safety in the defoaming system, the defoamer itself is a non-toxic or low-toxic substance;
(11) Low chemical oxygen demand (COD), biochemical oxygen demand (BOD) and total oxygen demand (TOD);
(12) Good storage stability;
(13) Long-term defoaming effect, some defoamers can defoam quickly, but they will become ineffective after a long time;
(14) Low cost;
(15) Do not increase the surface viscosity of the surfactant aqueous solution.
It is difficult for a defoamer to meet the above requirements at the same time, and it can only meet the requirements of the defoaming system in terms of its main performance. Each defoamer can only be effective for a certain system or several systems. The same foam system can also use a variety of different defoamers. For this reason, users should conduct experiments and select the most effective and economical defoamer.
