Evaluation method of defoamer performance
The auxiliary agent that plays the role of suppressing foam, breaking foam and defoaming is called defoaming agent. The important indicator of the quality of defoaming agent is the length of defoaming time. So how to test the performance of defoaming agent? Let’s follow the editor to learn about it.
1) Light intensity method: According to the scattering and transmission characteristics of bubbles on foam, when light with a certain intensity passes through a certain area of foam, the intensity of the transmitted light will be greatly reduced. According to the change of the transmitted light intensity, the change of the foam amount can be directly reflected, so as to compare the performance of defoaming agent. The biggest advantage of this method is the timeliness of detection and continuous data processing.
(2) Conductivity method: Because foam is a mixture of gas and liquid, when the solution contains conductive ions, the liquid in the foam system is conductive while the gas is not conductive. Therefore, the foam content can be measured according to the size of the conductivity, so as to compare the performance of the defoaming agent. The advantage of this method is high sensitivity and accurate measurement, but this method is not applicable when the defoaming agent has an effect on conductivity.
(3) Video and photography method: This method first uses light to illuminate the foam area, uses CCD to photograph the sampling area, and then uses certain image processing technology to analyze the image. By comparing the changes in foam in the image before and after the addition of the defoamer, the quality of the defoamer can be compared. The biggest advantage of this method is that it is intuitive, but it requires that the quality of the image should not be affected by the color change after the defoamer is added.
(4) Acoustic detection method: When the foam breaks, it will make a sound because the liquid film moves too fast. According to this principle, the bubble breaking rate can be detected by measuring the size of the sound, so as to compare the speed of the defoamer. The disadvantage of this method is that the requirements for background noise are relatively strict, and it is difficult to grasp the degree of foam breaking.
(5) Flow display method: The generation of foam is inseparable from liquid. The task of flow display is to visualize the movement process of the liquid. In the study of foam, the technologies that can be used include holographic photography and infrared imaging technology, or when the bubble content is low, a high-speed camera can be used to compare the bubble content and study the changes in the number of bubbles in the foam, so as to compare the advantages and disadvantages of different defoamers. However, this method is similar to video and photography and has certain application limitations.
