Views: 0 Author: Site Editor Publish Time: 2024-03-20 Origin: Site
Iodine adsorption value (iodine value) is one of the most commonly used indicators to measure the adsorption performance of activated carbon. It is widely used in the production, research and development, and application of activated carbon. The selling price of activated carbon on the market is also directly related to its iodine value.
The iodine value refers to the mass of iodine adsorbed by activated carbon in a solution of 0. 02 N 12 / (1 000 L) [N is the equivalent concentration, 0. 02 N is 0. 02 equivalents (0. 02 mol) contained in 1 L of solution ) ion], is generally considered to be used to characterize the number of micropores in activated carbon and its degree of activation, especially directly related to the surface area of pores with a diameter greater than 10 Å.
Usually in the selection process of activated carbon, indicators characterizing adsorption performance such as specific surface area and pore volume also need to be considered. The correlation between the iodine value and specific surface area of various activated carbons involved in research and water plant practice. It can be seen that the iodine value is closely related to the specific surface area. The indicator role of iodine value in the application of biological activated carbon in water plants is closely related, and its numerical value depends on the degree of development of the micropores of the activated carbon. Pore volume refers to the total volume of pores per gram of activated carbon particles, including all pores such as macropores, mesopores and micropores. It is the main place where pollutants and activated carbon adhere to biofilms. The ratio of various types of pores is not defined in the existing relevant standards. Activated carbon for water plants usually uses the steam activation method, and the ratio of the three types of pores in the prepared activated carbon is generally 2:2:6. There are certain differences in the role of various types of pores in the purification treatment of water plants.
It is generally believed that micropores and mesopores are directly related to adsorption efficiency, while macropores mainly provide channels for pollutants to enter the mesopores and micropores and provide attachment locations for microorganisms. Appropriately increasing the macropore ratio of activated carbon can increase the number of attached microorganisms and strengthen its biological purification efficiency. The evaluation of the performance of new activated carbon can also be combined with its specific pore structure composition characteristics, and selectively use the iodine value and methylene blue corresponding to the specific pore structure.
Value and other common indicators are used to characterize it.
The adsorption effect runs through the entire use cycle of biological activated carbon, and there is a certain correlation between the change in iodine value during the application process and the purification efficiency. Combined with the action path of activated carbon at a specific stage of a specific water plant, the correlation analysis between iodine value and purification efficiency can be carried out in stages, and a better correlation can be established to judge the change trend of activated carbon. Carbon purification efficiency. Changes in iodine value during activated carbon application can establish a certain correlation with ash content, mechanical strength and biological diversity.