The standard for high-quality defoaming agents
The physical and chemical properties of a high-quality defoamer must meet the requirements of the system in which it is used. Generally speaking, the following requirements must be considered when selecting a defoamer:
(1) Strong defoaming ability. Effectively eliminates foam when used in very small amounts;
(2) It has a lower surface tension of the defoamed system, that is to say, the surface tension of the defoaming agent itself should be low;
(3) After the defoaming agent is added, it will not affect the basic performance of the system being defoamed;
(4) It is insoluble in the system being defoamed and is not easily solubilized by the surfactant in the system. If it is solubilized, it will lose its defoaming ability and its foam suppression ability;
(5) The balance of the surface should be good;
(6) It does not react with the medium to be defoamed, nor will it be decomposed or degraded by it, and has good chemical stability;
(7) It has good diffusivity and permeability, that is, it has a positive diffusion coefficient in the foam medium, and has Fast spreading ability on the foam surface;
(8) The defoaming agent should have good heat resistance and will not lose effectiveness at high temperatures;
(9) It has good gas solubility and permeability, making it difficult for gas to accumulate and disappear from the foam, and the foam is easy to eliminate;
(10) It has high physiological activity and high safety in the system to be defoamed. The defoaming agent itself is preferably non-toxic, or at least a low-toxic substance;
(11) Has low COD, BOD and TOD values;
(12) Has good storage stability;
(13) It has a long-term defoaming effect. Some defoaming agents can defoam quickly, but they will lose effectiveness over time;
(14) The cost should be low;
(15) Does not increase the surface viscosity of the surfactant aqueous solution.
It is difficult to obtain a defoaming agent that meets the above requirements at the same time. It can only meet the requirements of the system being defoamed in terms of main performance. Each defoaming agent is only effective for a certain system or several systems. You cannot expect that a defoaming agent can achieve the purpose of defoaming. In addition, a variety of different defoaming agents can also be used in the same foam system. Because of this, there are many varieties of defoaming agents, at least 500 or more. Users must conduct experiments to select the most effective and economical defoamer. Nowadays, the research on defoaming agents has aroused the interest of many researchers. More than 100 documents are published every year, and new varieties and new patents emerge one after another.
