Is the higher the iodine value of activated carbon, the better?

We usually think that the higher the iodine value, the greater the adsorption value of activated carbon, the better the activated carbon is. In fact, this is not necessarily the case, but we should pay attention to analyzing the microbial pollution components in the raw water and grasp its changing law with seasons , Choose carbon species with large adsorption capacity, qualified and stable effluent quality, and long regeneration cycle.

Activated carbon varieties include nutshell charcoal and coal-based charcoal. The production raw materials of nutshell charcoal include apricot kernel, coconut shell, walnut shell, etc.; coal-based charcoal raw materials are anthracite, bituminous coal, lignite, etc.

In recent years, coconut shell carbon is considered to be a good activated carbon due to its small pore radius, large specific surface area and high iodine value, and is widely used in the drinking water purification industry. However, by analyzing the pore size distribution of the pores of coconut shell carbon, we can know that the proportion of micropores in the pores of coconut shell carbon is high, so its iodine value may be high, but these adsorption capacities are not fully utilized in practical applications. The raw material source of coconut shell charcoal is limited, and its price is almost the most expensive among all kinds of charcoal.

In terms of cost performance, coconut shell charcoal is not economical enough. Coal-based activated carbon has more transition pores and larger average pore size, which can effectively adsorb and remove organic matter with a large amount of water in water. Coal-based charcoal has higher mechanical strength and lower price. Therefore, in the advanced treatment of building water supply, coal-based charcoal is a more economical and applicable type of charcoal. It should also be noted that the same coal-based charcoal is used in the advanced treatment of building water supply, and the charcoal with anthracite as the raw material should be selected.

The technical indicators of activated carbon should be viewed objectively. For example, the iodine value is not as high as possible. The iodine value reflects the specific surface area of activated carbon. However, because the diameter of water molecules is only 0.532nm, they can all enter the pores of activated carbon, while the diameter of organic molecules in water is much larger than that of water molecules. It cannot completely enter all the pores of activated carbon. Therefore, although the iodine value reflects the adsorption capacity of activated carbon to a certain extent, when selecting activated carbon for advanced treatment of building water supply, one should not pursue an excessively high iodine value, because the price of carbon will increase by a higher iodine value. However, the adsorption effect is not necessarily improved or is improved very little, which also reduces its performance-to-price ratio.